4256670_P5_final_report.

4256670_P5_final_report.
TU DELFT
Faculty of Architecture & the Built Environment
Architectural Engineering + Technology// Msc: Building Technology
Sustainable Design graduation studio, Facade design
Master Thesis, final report, 07/2014
BIODEGRADABLE
MATERIALS
A research and design handbook;
enhancing the use of biodegradable
materials on building's envelopes
in the Netherlands.
by Eleni Ganotopoulou /4256670
MENTORS:
Dr.Ing. Tillmann Klein
Dr.Ir. Fred A. Veer
1
Report:
Master Thesis, final report
Title:
Biodegradable materials. A research and design handbook;
enhancing the use of biodegradable materials on building's
envelopes in the Netherlands
University:
Technical University of Delft
Faculty:
Faculty of Architecture & the Built Environment
Master track:
Building Technology,
Graduation lab:
Sustainable Design Graduation Studio, Facade Design
Main Tutor:
Dr. Ing. Tillmann Klein
2nd Tutor:
Dr. Ir. Fred A. Veer
External Examinor:
Cecile Calis
Date:
04 / 07/ 2014
Student:
Eleni Ganotopoulou
Student Number:
4256670
Contact info:
elenganot@hotmail.com
eganotopoulou@gmail.com
2
Eleni Ganotopoulou
Biodegradable materials.
A research and design handbook; enhancing the use of
biodegradable materials on building's envelopes in the
Netherlands
3
4
Contents:
1. INTRODUCTION
1.1 Preface and motivation
1.2 Problem statement & topic relevance
1.3 Research questions
1.4 Methodology
1.5 Boundary Conditions
1.6 References
5. RESEARCH RESULTS
5.1 Process description
5.2 General properties comparison
5.2.1 Price and density
5.2.2 Thermal properties
5.2.3 Acoustic properties
5.2.4 Fire resistance
5.2.5 Mechanical properties
5.2.6 Environmental parameters
5.3 Research conclusion
8
10
13
14
15
19
RESEARCH
2. RESEARCH A: GENERAL ASPECTS
2.1 Biodegradable materials –selection
2.2 Reasons of obsolesce
2.3 Benefits from using biodeg. materials
2.4 “Achilles Heel” of biodegr. materials
2.5 References
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28
35
42
45
3. RESEARCH B1: MATERIALS OVERVIEW
3.1 Unfired Earth products
3.2 Rammed Earth products
3.3 Straw products
3.4 Sheep wool products
3.5 Wood-fibrous products
3.6 Flax fibrous products
3.7 Hemp fibrous products
3.8 Hemp-lime fibrous products
3.9 Paper products- Cellulose flakes
3.10 Paper products – papercrete
3.11 Paper products – paperboards
3.12 Cork products
49
63
73
85
95
103
113
123
133
141
147
155
4. RESEARCH B2: PRODUCTION
4.1 Products variety - typical sizes
4.2 Prefabrication - products levels
4.3 Production processes & techniques
4.4 Application Schemes
168
170
176
180
189
196
196
198
201
201
204
210
211
DESIGN
6. DESIGN IMPLEMENTATION
6.1 Design case & methodology
6.2 Case study: Materialization
6.3 Case study: Redesign proposal A
6.4 Case study: Redesign proposal B
6.5 Case study: Redesign proposal C
6.6 Comparisons
216
219
224
228
232
297
7. Conclusion
216
7.1 Final conclusion
7.2 Thesis contribution & suggestions 219
LITERATURE
APPENDIX
5
254
265
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Chapter 1 Introduction
This chapter deals with the severe damage that has occurred in the ecosystem the latest years, the
relation between the current industrial and environmental situation, and more specifically the
environmental impact related to building industry and buildings. It examines the degree of damage
that current modern building materials are causing in the environment and the size of the solid
waste that occurs during construction and demolition works resulting in an accumulation in landfills
and the possibilities to be decreased via the use of biodegradable materials as building materials. It
presents facts and data about the mentioned concerns as well as my motivation to work on a topic
focused on biodegradable materials. The relevance of the chosen topic for a master thesis with the
field of Building Technology and sustainability is explained. Lastly, in this chapter are also explained
the research question that this thesis deals with, the methodology and method tools that are going
to be used, as well as the boundary conditions that are set.
7
1.1 Preface
For centuries, the society needs were focused on the immediate
satisfaction of its needs and improvement of life quality through
technical and other achievements, neglecting any possible
considerations about future consequences that would be caused
to the ecosystem. The former human attitude was also usually
accompanied with human activities harmful for the environment
and with ignorance towards the scientific community that the last
decades alerted for the severity and urgency of the environmental
problems that had occurred during the course of time.
The severe impact to the ecosystem that the human activities and
choices of the past have had, is now more than ever present; the
finite resources are coming to an exhaustion, shortage of water,
CO 2 emissions are dramatically increased, the phenomenon of acid
rain and acidification causes severe damages to forests, wetlands
and to the soil, killing directly or indirectly living organisms,
and so on, without forgetting one of the most severe problem; the
climatic change into an unpredictable climate with more frequent
and extreme weather that will have severe consequences to earth
distribution. Spiegel & Meadows (1999, p.2) report that over
50% of the wetlands in United States have been destroyed –filled,
contaminated, or otherwise “reclaimed” and the building industry
consumes almost about 3 billion tons of raw materials annually.
Moreover, the percentage of fresh water that is needed for the
building industry accounts of 16% annually, while fresh water
constitutes only 3% of the water on planet (most located in polar
ice) (Spiegel & Meadows, 1999).
In 1980s, a new term was introduced, the term of “sustainability”, in
an attempt of ecological awareness, where it’s most quoted definition
was used in the context of the term “sustainable development” that
can be defined as “a development that meets the needs of the present
without compromising the ability of future generations to meet their
own needs” . The last decade, there is a positive shift towards the
awareness of the problem and there is a stronger motivation for
more sustainable way of living.
Construction industry contributes largely in the current
environmental problems. More specifically, construction industry
is one of the largest and most active sectors throughout Europe
representing about 28.1% in the industry and about 7.5%
employment in the European economy (Pacheco-Togal F., and Jalali
S., 2011). Buildings have significant impacts to the environment
and to the natural sources. For instance, buildings account for 45%
of worldwide energy use, 80% of potable water use, and 50% of the
timber Harvest in North America, 40% of municipal solid waste
and 30% of the U.S. greenhouse gas emissions (Zhai and Previtali,
2009). This indicates that buildings have a big share of the energy
consumption so consequently they need certain improvements to
achieve the goal of sustainability.
8
Building materials constitute also a big part of the problem, since
the modern materials that are so widely used nowadays magnify the
problem by their inability to be recycled or decomposed after their
disposal, ending up in huge piles to landfills, but also by their high
energy intensity for their production and manufacturing process.
Vernacular architecture of the past, proved to be in the most cases
energy efficient with the use of materials that were local available
and working with building techniques influenced by the local
climate. The materials used in vernacular architecture –most of them
biodegradable- presented a paradigm of ecological construction with
materials that could be reused or decomposed easily without harming
the environment.
Motivation:
The awareness of this problem and my interest in the Built
environment and architecture, make me interested in a topic related
to sustainability via the aspect of the implementation and use on
building envelopes of more ecological materials with minimal
environmental consequences as regards to aspects such as embodied
energy, use of finite sources, CO 2 and other harmful gases emissions.
Eleni Sgouropoulou had studied about biodegradable materials in
her master thesis with topic “Possibilities of applying biodegradable
materials in solid building envelopes in the Netherlands” (TU Delft,
June 2013). In her thesis, a wide range of biodegradable materials
were collected and divided into categories according to their resource
origin. A brief description was given about each material and the way
it is produced and constructs a solid wall as well as the advantages
and disadvantages of each material were shortly presented. Moreover,
Eleni Sgouropoulou had identified via interviews some reasons that
these materials may had fallen into disuse for so many decades in
the developed countries, as well as some precautions that should be
kept when constructing with these materials. In the design stage, she
implemented rammed-earth as the basic building’s envelope material
via four different versions of the material’s application, trying at
the same time to improve and solve current problems noticed in the
case study. Her thesis indicated the possibilities that biodegradable
materials may have also in north climates like the Dutch climate.
In combination with my interests, her thesis gave me the motive to
wish to explore further and deeper the building potentials that some
of these biodegradable materials may present in a more industrialized
aspect; for instance, their correlation with “craftsmanship Vs
industrialization”, their availability in the Netherlands, their
prefabrication possibilities in building industry, their on-site
production potentials as well as their properties and performance,
in order to encourage their use in a greater extent, at least in the
Netherlands.
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1.2 Problem statement, facts & topic relevance
Architects and engineers need to address their design into more
sustainable forms of architecture and building practices, not only
by focusing on the use of renewable energy sources but also by
introducing more sustainable materials into the building industry.
The demand for energy neutral buildings implies to reconsider
the building’s operational cost and energy as well as the whole
embodied energy of the materials and components used on each
building case. The construction and demolition waste has also a
great impact in the environment, since the products that are used
commonly in the building industry are in their majority products
produced by finite resources that cannot degrade very readily;
so the volume resulted as waste disposal in landfills is very high.
Environmentally speaking, this industry accounts for 30% of carbon
dioxide emissions; in addition the global construction industry
consumes more raw materials (about 3000 Mt/year, almost 50% by
weight) than any other economic activity, which shows clearly an
unsustainable industry [F. Pacheco-Torgal and Said Jalali, 2011, p.
2]. Halliday (2008, p.31) also reports that for instance in UK, the
construction industry is responsible for over 25% of all industryrelated pollutions incidents while at the same time the construction
and demolition waste represent 19% of the UK waste. Thus, it is
evident that current construction and building industry constitutes
one part (albeit an important one) of the environmental problem.
Consequently, building practices should be altered in order to be
achievable an eco-efficiency of the construction industry.
In addition, according to Blackburn, by the middle of the 21 st
century, the population is expected to rise to ten billion from
six billion which will lead to an increase of the demand on
food, energy, water, resources and chemicals, and will effect a
corresponding increase in environmental pollution and a deletion of
finite resources (e.g. fossil fuels) [Blackburn R.S., 2005]. Research
and development in synthetic chemical products that has started
since 1930s, resulted in a significant improvement of life-quality
and in a great availability of products for consumption. However,
Blackburn [2005, p. xv] states that the main problem of the above
mentioned products is that these products are neither renewable
neither degradable, causing an increase of oil consumption for
their production that consequently causes various environmental
problems in turn. Fossil fuels are non-renewable resources,
expected to last for another 50-60 years, and their use is related to
huge translocation of carbon from the ground into the atmosphere
accompanied by emissions of sulphur and nitrogen oxides. Moreover,
they are the dominant global source of anthropogenic greenhouse
gases (GHG) causing rising concentrations of which are widely
perceived to lead to global warming and to an unstable and
unpredictable climate [Blackburn, 2005,p.xvi].
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The Royal Dutch Weather Institute (‘KNMI’) states that the human influences on climate are
unmistakable; the most important of these influences is the change in the chemical composition of
the atmosphere due to anthropogenic emissions of long-lived greenhouse gases like CO2 and
CH4. Anthropogenic emission of short-lived trace gases, like NO2 and HCHO, lead to a change
in heating rate of the atmosphere via tropospheric ozone formation. Anthropogenic emission
of aerosols can either cool or heat the atmosphere. Clouds are an important natural feedback
factor, since clouds mostly cool the surface. In 1970s, a map about “the European import
and export of acid rain” was presented in UN Conference on the Human Environment
(UNCHE). The map showed that for instance the Netherlands had 75% import and 25% of
domestic production of acid rain (Halliday, 2008, p.15), demonstrating clearly that none
environmental change can occur without the collaboration of all European countries, since
the environmental consequences are not restricted in a local level but are globally affected.
The contemporary products used in the building industry, provide on the one hand a high
life-expectancy and durability along the building’s life-cycle but on the other hand create a
major waste problem when it comes to their disposal. Moreover, the most of them demand
high amounts of energy for their production. The last decades, there was common practice
to construct buildings with synthetic and other inorganic materials that can stand for more
than 70-80 years without the building’s life to be provident to stand for so long. Consequently,
this trend warded off products that are degrading easily although their high eco- friendliness.
The lifespan of building was requested to be long without taking into consideration the
alterations or changes needed in the buildings during the coming years, even for buildings
that shouldn’t have such permanent character. For instance; pavilions, residential units for
urgent situations, facades of commercial and office buildings that demand frequent renewal,
and so on. Global Green USA [2007, p. 162] shows that scrap and debris from construction
and demolition (C & D) work- including maintenance and rehabilitations projects-makes
up approximately 30% of the waste stream that is dumped in landfills. Thus, conventional
materials that can fulfill the long life–service expectancy usually do not allow the easily
refurbishment of the building in the new contemporary needs without any environmental
impact. Consequently, the implementation and use of more ecological friendly materials and
their appropriate selection according to the requested life-expectancy of a building structure,
are essential steps towards a sustainable design and architecture.
Dean Yvonne [1996] states that the “architects are the major energy users though the
specification of material and components”. They have to make choices that present sensible
design decisions in terms of limiting the total energy demand of the building by its
performance and by considering the energy needed in the processing and transportation
of materials [Dean Y., 1996, p. 6]. Therefore, architects, clients and people involved in the
building industry should decide wiser the desired lifespan of a building’s component by
taking into consideration its use and function as well as by anticipating the future needs.
A life–cycle of 15-20 years by using materials with less or zero environmental impact, may
give a sustainable design solution to the alternating society’s needs for new architectural
expression forms and structures during time and also it would make possible the renewal
of the city content. Biodegradable materials can be a design answer towards this direction,
since on the one hand, they can allow a short life-cycle without the environmental impact
of construction and demolition waste of the non-biodegradable materials that accumulate
the landfills, and on the other hand they can last for long if they are adequate protected
from moisture and other external factors. Moreover, they are made from natural renewable
resources and the majority needs low amount of energy for their production. But although,
biodegradable materials were introduced since antiquity and were commonly used, nowadays
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their use is not preferred. This occurred as a result of various reasons such as the revolution
and development of synthetic and new materials that set aside the “old” materials leading
to a loss of knowledge to work and design with such materials. Some other reasons are the
lack of developed production techniques and their high moisture-sensitivity. Additionally,
the mistaken belief that they can have only a very short life-span contributed to their
disuse. According to Dean Yvonne [1996, p. 24], one other main reason that techniques
with biodegradable materials are not used today “is due to the ease with which all countries
have adopted the Western Industrialized techniques and the assumption that these are the only
correct methods of building even though over 1/3 of the world’s housing stock uses earth as a
building material”.
Fortunately, as the society becomes more concerned and aware about environmental quality,
there are moves towards the production and use of materials that will not accumulate in
the environment and a “return” to the “old” materials. For instance; already in composites
there is a trend to produce them with natural fibers that can break down after their disposal
[Fedorak P., 2005]. What is most evident is that the building-material choices are important
in sustainable design due to the extensive steps needed for their productions (extraction,
processing, manufacturing and transportation) and their correlation that may create building
materials that pollute the air and the water, destroy natural habitats and deplete natural
resources. In an attempt to reduce the above harmful effects, a new term was brought to the
surface in the building industry; the term of “Green Building” which is actually the process
of creating buildings and supportive infrastructure that reduce the use of resources, create
healthier living environment for people and minimize negative impacts on local, regional and
global ecosystems. [Global Green USA, 2007, p. 2].
To conclude, buildings consume large quantities of resources and can cause a number of
negative impacts on their occupants. In order to save energy, minimise waste (construction
and demolition) and decrease C0 2 emissions, it is necessary to enhance largely in the
buildings the application of ecological natural materials that can be easily reused, recycled
or decomposed. Materials that contain low embodied energy content and are not hazardous
either for the environment either for human health. Materials selection in buildings plays
an important role to the indoor air quality as it concerns hazardous emissions (VOCs) and
consequently affects human’s health. Studies have shown that there is an improvement in
productivity and health when accompanied with good air quality, daylight and other factors,
as well as that asthma and allergy incidents are strongly connected with poor indoor air
quality, dust particles and VOCs emissions (Halliday, 2008, p. 77). The implementation
and use of materials that are not toxic and emit none hazardous gases in buildings (such
as biodegradable materials) are necessary steps to achieve healthier indoor spaces and
consequently healthier and more productive people. The building envelope (performance,
emissions), building construction processes (energy, resources, and emissions) and building
products (extraction, process, manufacture, transportation, installation, and emissions)
are all linked strongly with each other for the ecological footprint they cause. Ecological
building design shall be characterized by the use of natural materials with a minimum of
processing and transportation. Ideally such materials should also contribute to passive
forms of environmental control and contribute positively to building energy performance.
Biodegradable materials show potentials to contribute to a sustainable construction and are a
promiscuous field of exploration as “alternative” to modern materials for building envelopes.
They are mostly made of renewable natural resources or recycled natural products, require
small amount, present almost no toxicity and are breathable. They can be decomposed
relatively easily so they can result in reduce of solid waste in landfills.
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1.3 Research Question
The research question of this thesis that emerged from the previous acknowledgements is connected
with the field of sustainability and industrialization, and in request of “new alternative/biodegradable”
materials and their implementation manners. Their application possibilities in the contemporary
buildings envelopes and their production potentials in order to be used in a greater extent in
the Netherlands are fields of interest for this thesis as well as aspects such as “craftsmanship Vs
Industrialization methods” are considered. The main research question that this thesis will deal with
is:
“Which products and systems will enhance the use of biodegradable materials
on the building envelopes in the Netherlands? How can we enhance their use
as façade components?”
In order the above question to be answered; smaller sub-question should be answered too. Those are:
01_which biodegradable materials and products are
already available in the market?
04_ which production processes and techniques
are needed to design and produce biodegradable
products or façade components?
05_ how can manufacture availability and processes
influence the design of a biodegradable product
with improved quality and properties?
An overview of the building biodegradable materials
and products availability in the market will result
in a clear overview of the possible potentials for
building applications and combinations, as well as
awareness of the total cost.
Both “04” and “05” sub-questions can give
answers in the question how biodegradable
materials can be used to produce a greater variety
of products regarding the size, shape and possible
properties, as well as how much are influenced
and affected by the available production processes
and techniques.
02_ which are the parameters that affect positively or
negatively the performance of these materials?
The parameters that can affect positively or
negatively the performance of biodegradable
materials are very important to be studied in order
to understand the nature of these materials and
their flaws. Since the flaws will be identified and
the material’s weak points will be understood,
then further improvements can be suggested and
studied, leading in improvements on a material’s
and product’s level.
06_ Can they be prefabricated? What kind of
production technology, equipment and so on
is needed to produce it while keep still low the
embodied energy and cost?
One of the most important advantages of
biodegradable materials is their low embodied
energy content. Those products require low
amount of energy to be extracted, produced
and transported when they are made by local
materials. Seeking to find their prefabrication
potentials as well as the production techniques
and equipment needed to produce high-quality
building products next to the building site, will
have a significant environmental positive impact,
since less transportation energy and cost will
be demanded. By achieving lower cost and high
quality, biodegradable building components can
become competitive alternative solutions in the
building industry.
03_ which properties and characteristics should
these products have in order a) to fulfil the
multiple functions of a façade and b) compete the
“conventional” and common-used materials of
the building market?
If biodegradable products can obtain similar
characteristics and properties with the “conventional”
building materials that are commonly used, as well
as they can provide a similar variety in types and
products, then it is more likely to increase their use
as building components.
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1.4 Methodology
The methodology of this research is focusing on developing a database of biodegradable products
that can be found already in the building (and other) market, acknowledging the reader with their
properties, advantages and defects, as well as identifying for which applications those products
are suitable to be used by focusing more on a façade’s level. Additionally, a study in the current
production techniques and processes will be made for similar non-biodegradable products in order
the mechanisms of prefabrication production to be understood. This may result in suggestions and
proposals for the improvement of biodegradable products by “following similar processes” in order
to achieve a greater availability of shapes and sizes in the market. Furthermore, the reasons of disuse
of these materials for so long will be searched and presented in this thesis, since this will help to
understand better the nature and problems of these materials-products.
The research method that will be mainly used for this thesis is literature study that includes books,
publications, conference proceedings and scientific articles. One other important research tool will
be internet by site visits on companies involved with these materials (producers, manufacturers or
providers) as well as technical and product data sheets provided by them. CES EduPack (Granta
Design Limited, Cambridge, UK, 2013)– a material’s engineering software- and similar software will
be an additional method tool for comparisons between materials and properties, and lastly interviews
with people that design, built or produce such products may be also a potential tool that can help me
significantly by feedback on my work on the last phases of this thesis. The thesis report will be divided
into two research parts that will result in a design topic that will apply the findings of the research
study.
Research part A:
Research part B1:
Research part B2:
General research on
biodegradable materials
Research focused on current
biodegradable products
Research focused more on
production related aspects
-
Theoretical background of
biodegradable materials
-
Properties (numerical values) and
Performance (thermal , acoustic, etc)
-
Reasons of obsolesce/disuse
-
Environmental impact
-
Products types
-
Benefits emerging from the use
of biodegradable materials
-
Positives & negative aspects ,
defaults that need improvement
-
Products levels (prefabrication)
-
Problems related to use and
nature of biodegradable materials.
Products techniques &
processes – influencing parameters on products
Suitable applications on building
envelopes
Products typical shapes, sizes
and dimensions
Design Step:
This step focuses on the application of various biodegradable building materials and products on a
building envelope that is selected for the design theme. A building in the Netherlands is selected
and a façade section is chosen to be redesigned with three proposals wherein different biodegradable
materials are applied. The current façade section with its materialization is calculated under
parameters that are set, and then it is been re-examined and calculated under the three different
redesign proposals.
Design scope: firstly to observe the problems that arose during the primary design phases as well as
the design decisions taken that are related with design precautions in practice to achieve long-term
durability of such materials and building’s safety standards, and secondly to compare between the
different facades materializations and the current façade, in order to observe if indeed biodegradable
materials can have a positive contribution to lower CO2 emissions and embodied energy related with
building’s materialization .
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1.5 Boundary conditions
Since the field of material and processes is a very vast field of study and research, for the purposes
of this master thesis, some boundary conditions will be set in order to:
a) help reduce the field of research and the study to be possible to finished in the given time span,
b) to be able to have some evaluation criteria for the design step.
The basic boundary conditions that will be set from the start and will affect the selection of materials for both the research and design step are the following:
a. Performance characteristics – life span
The performance characteristics that a material or a product should fulfil are very important. There
is a major variety of the characteristics that a researcher and designer should look closely before
selecting a material and materials selection is strongly connected with its material’s intended use
and application. The chosen materials will often have to combine several properties to fulfil specific
functions. In the current study, since the materials and products are prevised to be applied on a
façade, then the most important characteristics are their structural serviceability (wind and rain
resistant, structural adequacy), their fire safety (resistance) and non-toxicity, habitability (thermalacoustic properties), durability (resistant to water, vermin infestation, to weathering etc) , and their
compatibility to each other. The properties and characteristics of the material should fulfil the façade
requirements and indoor requirements that will be set.
A safe interior space should include provision of a living or working space that is healthy and not just
physically secure; so not exposed to toxic materials, mold, and extremes of heat or cold, as well as
noise. The selected materials should fulfil this condition, and should be also capable to have a specific
life serviceability that is set to be minimum 15-20 years.
Table 1.5.A: Performance Characteristic
WĞƌĨŽƌŵĂŶĐĞŚĂƌĂĐƚĞƌŝƐƟĐ
STRUCTURAL
SERVICEABILITY :
FIRE SAFETY :
Self-load-bearing ability
Secondary structural support
EŽŶͲŇĂŵŵĂďůĞ
Fire resistance
Good
Flame spread
Not easily spread
Non-toxic
dŚĞƌŵĂůƉƌŽƉĞƌƟĞƐ
Good to excellent
ĐŽƵƐƟĐƉƌŽƉĞƌƟĞƐ
Good
Resistance to water
Fair
Resistance to alkalis/acids
Fair
ZĞƐŝƐƚĂŶĐĞƚŽhsƌĂĚŝĂƟŽŶ
DURABILITY :
[for 15 years]
ENVIRONMENT :
AVAILABILITY :
-Dependent on intended use-
Flammability
Toxicity
HABITABILTY :
Minimum
Good
ZĞƐŝƐƚĂŶĐĞƚŽǀĞƌŵŝŶŝŶĨĞƐƚĂƟŽŶ
Excellent
Mildew resistance
Excellent
Resistance to wear
Adequate
Resistance to weathering
Adequate
Dimensional stability
Adequate
Resistant to human damage
Fair-Good
tŝƚŚŵĞƚĂůƐ͕ƉůĂƐƟĐƐ͕ĞƚĐ͘
Good
Embodied Energy / CO2 emissions
Low
Derived from Natural Resources
Local availability
15
Renewable
Adequacy /surplus in NL
Ă͘ Environmental Impact
The environmental impact of materials is a very important criterion for their selection; materials and
products must be not hazardous in any phase of their lifespan, must be derived from natural resources
that are either not in short supply either renewable, and that can be replaced easily without any high
environmental impact. They should contain low embodied energy and offset minimal C02 emissions
in the environment.
ď͘ Local Availability
The availability of the materials in the Netherlands will be also a criterion for their selection; the
selected materials that will be used for the building applications should be in adequacy and surplus
in the Netherlands or in near surrounding locations, whilst the shipping distance should not exceed
if possible a radius of 200 km from Utrecht in order the transportation cost and energy to be kept
low. Raw materials transportation to the manufacturing facilities and later on to the building site
includes train, trucks and boats, fossil fuel, and so on. Thus, the greater the distance, the greater the
cost and energy demand as well as the amount of pollution that is produced. Additionally, the material
and production techniques that will be selected to be used, should be possible to be applied near the
building site. Materials that cannot be produced in the Netherlands will be excluded from the research
study as well as materials that are able to be produced in the Netherlands but they present a low
prefabrication potential level that will be explained in the next chapters. These boundary conditions
helps to minimize the transportation cost and energy as well as to obtain a low energy content level
(if possible) since the goal is the final product to remain sustainable.
Đ͘ Dutch climate
The performance characteristics as well as the façade requirements that are set in this report are
strongly related to the climate conditions. And since the research question deals with a specific
country as a case study; the Netherlands, then consequently it is important to understand the Dutch
climate in order to choose the most suitable materials and detect future problems dependent on
climate conditions (e.g. high moisture levels, strong winds, etc.).
The Netherlands have a temperate maritime climate influenced by the North Sea and Atlantic Ocean,
consequently is characterized by cool summers and moderate winters. Daytime temperature varies
from 2 °C - 6 °C in the winter and 17 °C - 20 °C in the summer [WEATHER ONLINE, 2013]. The small
and flat size of the Netherlands does not allow any strong variations in climate from region to region,
although the marine influence decreases inland and among the coastal areas there are observed more
breezy conditions both during summer and winter. The country suffers from often rainfalls and
wind storms throughout the year, but especially in fall and winter gales are present as a result of
strong Atlantic low-pressure systems. The dryer period is usually present from April to September
[WEATHER ONLINE, CLIMATE OF THE WORLD, NL, 2013]. The Dutch climate characterized by
a stormy weather; during summer, the increased humidity as a result of the increased atmospheric
pressure leads to an unpredictable quick thunderstorm which usually is repeated every one or two
days, and afterwards results in a clear sky. In addition, longer-lasting storms often occur among
coastal areas as a result of the differential in sea and land temperatures. These storms occur during all
year with peak point around September [NL PLANET, DUTCH CLIMATE, 2013].
Moreover, except of frequent and strong rainstorms, the Netherlands is one of the countries that have
been affected from the phenomenon of global warming and climate change. The Royal Dutch Weather
Institute (‘KNMI’) has confirmed that temperatures are rising much faster in North West Europe than
in other parts of the world. The effects can indeed be felt on a day-to-day basis, with milder winters
and more rainfall. [NL PLANET, DUTCH CLIMATE, 2013]. All these data are important parameters
that should be kept under consideration during the selection phase of materials as well as during the
design phase of the final product of this thesis.
16
Ă͘ Facade requirements
The building envelope is one of the most important part of a building; it mainly works as a filter between the exterior and interior having a high impact to its interior, whilst having also a significant
aesthetical function for the building. A building envelope includes basically the walls, a vapor barrier,
insulation, openings (windows, doors) and a supporting structure and should protect structural members from moisture build-up, reduce thermal transfer and air infiltration, allow satisfactory daylight
to enter to the interior and prevent any pest or mold problems [Global Green USA, 2007, p. 37]. A
building envelope or a façade can have multiple functions. According to Knaap U. et al [2007], façades
are an integral element of the entire building with direct relation to design, use, structure and building
services. The more the technology develops, the more constantly the range of possibilities that a façade can fulfill is expanding, aiming to increase the user’s comfort level. However, building envelopes
are mainly divided in two types; cold facades (air cavity+ insulation) and warm facades (insulation)
that can contain single or multiple layers of materials and elements [knaap U. et al, 2007, p. 12-14].
One of the most well-established façade systems nowadays, is the prefabricated unit system façade
constructed by several different materials and components. This type of façade allows an improvement in cost estimation, a variable degree of prefabrication according to the desired reduction in costintensive in situ assembly and man-hours, and its size depends on the transportation options although
the typical dimensions are; one storey high and 1,20 - 2,70 meters wide. [Knaap U. et al., 2007, p. 46].
The building envelope should be able to fulfill specific indoor, outdoor and other requirements that
can be shortly defined as:
Table 1.5.B: BUILDING ENVELOPE - REQUIREMENTS
INDOOR REQUIREMENTS:
Good Thermal comfort;
Users should be satisfied with the indoor temperature during the whole years and the
facade should improve thermal performance of the building reducing the demands for
heat or cooling. The indoor air Temperature (Tair i), the indoor relative humidity (RH),
the surface temperature as well as the airflow across the body height are factors that
influence the thermal comfort of the users.
Good Acoustic comfort:
The façade should provide adequate acoustic comfort level according to the use and
function of indoor space
Sufficient natural lighting & view
to exterior site
Adequate daylight levels can reduce the artificial lighting demand while view to the
outside can create a more productive and pleasant living and working space.
Ventilation;
The air circulation should be adequate in order to provide to the interior space the
necessary clear air, as well as to remove any odors and harmful substances.
OUTDOOR REQUIREMENTS
water – moisture resistance:
The façade outer layer should create a protective layer that leaves out any moisture and
never allow any moisture to be trapped in the interior of the façade.
Good adaptability:
Adaptable to climatic or weather changes.
LOAD-BEARING REQUIREMENTS:
Self-load-bearing ability:
Carry self-weight of façade and any possible weight of snow, water, etc.
Load-bearing to internal forces:
Carry out any live loads (fall protection)
Load-bearing to external forces:
Carry out any lateral loads (mainly wind in the case of Netherlands) or any other natural force (seismic forces). And of course, carry out any stress loads that may occur due
to changes in temperature or humidity.
SUSTAINABILITY REQUIREMENTS:
A sustainable design approach demands a concept for the end of life
phase of the façade which needs to
be developed in the early phases
from architectural design to assembly [Tillmann K., 2013, p. 44].
A sustainable façade and building
envelope can be considered the one
which can;
a) reduce the operational energy of building by its high insulation level or by its adaptability to climate conditions,
b) reduce the embodied energy with materials of low impact or by reducing the material quantity needed for its construction,
and c) be re-used, recycled or easily decomposed as a whole (or the majority of it components) [Tillmann K., 2013, p. 76].
17
Table 1.5.C: FAÇADE REQUIREMENTS
THERMAL
COMFORT:
U-value
LIGHTING
(Luminance)
WĞƌĨŽƌŵĂŶĐĞŚĂƌĂĐƚĞƌŝƐƟĐ
Minimum
Indoor air temperature (Tair indoor)
(most preferable)
18 oC-27 oC
(20 oC – 25 oC)
Surface average temperature
< 2-3 oC from Tair indoor)
ŝīĞƌĞŶƟĂůďĞƚǁĞĞŶ
various surfaces
ɷT <3-4 oC
U-value for Building Envelope
(Ideal U-value)
< 0,38 W/m2 K
(0,20 W/m2 K)
U-value for roofs
< 0,23 W/m2 K
hͲǀĂůƵĞĨŽƌŇŽŽƌ
< 0,41 W/m2 K
U-value for windows
< 1,68 W/m2 K
Workplaces near windows
300 lux
ƵďŝĐƚLJƉŝĐĂůŽĸĐĞƐ
500 lux
KƉĞŶͲƉůĂŶŽĸĐĞƐ
700-1000 lux
;ĚĞƉĞŶĚĞŶƚŽŶƌĞŇĞĐƟŽŶƐƵƌĨĂĐĞƐͿ
ZĞǀĞƌďĞƌĂƟŽŶƟŵĞĨŽƌĚǁĞůůŝŶŐƐͬ
ŽĸĐĞƐ
ACOUSTIC
COMFORT
To=0,5 sec
^ŽƵŶĚƉƌŽŽĮŶŐ'AĨŽƌŽĸĐĞƐ
(/ĨŽƵƚĚŽŽƌƐŽƵŶĚƉƌĞƐƐƵƌĞůĞǀĞůŝƐ
40 dB
ϳϱĚͿ
^ŽƵŶĚƉƌŽŽĮŶŐ'ĨŽƌĚǁĞůůŝŶŐƐ
[/ĨŽƵƚĚŽŽƌƐŽƵŶĚƉƌĞƐƐƵƌĞůĞǀĞůŝƐ
35 dB
70 dB]
in all cases the minimum GA
ŵŝŶ͘ϮϬĚ
ZĞƋƵŝƌĞĚǀĞŶƟůĂƟŽŶ
25-30 m3/h [50 m3/h]
(most preferable]
Allowable air permeability level for
ȴP=10 Pa
&ŽƌŶĞƩŽďƵŝůĚŝŶŐǀŽůƵŵĞфϱϬϬŵϯ
qv;10 < 0,2 dm3/sec
&ŽƌŶĞƩŽďƵŝůĚŝŶŐǀŽůƵŵĞхϱϬϬŵ3
qv;10 < 200 dm3/sec
Allowable CO2 levels
ŵĂdž͘Ϭ͘ϭͲϬϭϱй
Air velocity for draughts avoidance
< 0,15 m /sec
VENTILATION
ŽŵĨŽƌƚĂďůĞ/ŶĚŽŽƌZĞůĂƟǀŝƚLJ ϯϬйͲϳϬй
Humidity (RH)(most preferable)
;ϰϬйͲϲϬйͿ
18
References:
books_
Blackburn, R.S. (2005) Biodegradable and sustainable
fibers. USA: Woodhead Publishing Limited. pp:
xv,xvi
Dean, Y. (1996) Materials Technology. Mitchell’s
building series. Singapore: Longman Publisher.
pp: 6, 24
Global Green USA (2007) Blueprint for greening
affordable Housing. USA: Island Press, pp: 2,37,
162
Halliday, S. (2008) Sustainable Construction.
Butterworth-Heinemann, pp.:15, 31,77
Knaap, U. et al (2007) Facades: Principle of
Constructions. Berlin: Birkhäuser, pp:12-14, 46
Pacheco-Torgal, F. and Jalali, S. [2011] ĂƌƚŚ
ŽŶƐƚƌƵĐƟŽŶ͗ >ĞƐƐŽŶ ĨƌŽŵ ƚŚĞ ƉĂƐƚ ĨŽƌ
ĨƵƚƵƌĞ ĞĐŽͲĞĸĐŝĞŶƚ ĐŽŶƐƚƌƵĐƟŽŶ͘ Journal:
ŽŶƐƚƌƵĐƟŽŶ Θ ƵŝůĚŝŶŐ DĂƚĞƌŝĂůƐ͕ ǀŽů͘
Ϯϵ ;ϮϬϭϮͿ ΀KŶůŝŶĞ΁ ƉƉ͘ϱϭϮͲϱϭϵ͘ ǀĂŝůĂďůĞ
Ăƚ͗
ŚƩƉ͗ͬͬǁǁǁ͘ũŽƵƌŶĂůƐ͘ĞůƐĞǀŝĞƌ͘ĐŽŵͬ
ĐŽŶƐƚƌƵĐƟŽŶͲĂŶĚͲďƵŝůĚŝŶŐͲŵĂƚĞƌŝĂůƐ ΀ůĂƐƚ
accessed: 05 February 2014]
Spiegel, R. and Meadows, Dr. (1999) Green building
materials; a guide to product selection and
specification. Wiley series in sustainable
design. Wiley, p. 2
Zhai, Z. and Previtali, J. (2009) Ancient vernacular
architecture: characteristics categorization and
energy performance evaluation. Department
of Civil, Environmental and Architectural
Engineering, University of Colorado
KNMI: Royal Netherlands Meteorological Institute.
Ministry of Infrastructure and the Environment.
Available at:
http://www.knmi.nl [Last
accessed: 13th June 2014]
19
20
Chapter 2 General aspects
This chapter focuses on giving a general overview of the materials and the aspects that this master
thesis will be focused. More specifically, it deals with biodegradable materials and their possible
uses and applications on building envelopes in the Netherlands. The current availability of building
biodegradable materials and products in the Dutch (and other) market is been investigated. The 40
materials that Eleni Sgouropoulou had presented in her thesis “Possibilities of applying biodegradable
materials in solid building envelopes in the Netherlands” are collected and presented here briefly
while the main focus will be on a small sample of them that will be chosen to be examined further
by set criteria that are described in detail. The definition about which material can be considered a
“biodegradable material” for this thesis is given. Moreover in this chapter, the reasons that led in such
long-term disuse for such natural materials are discussed, as well as general benefits and flaws of these
materials are described to make the reader understand biodegradable materials in a general scope.
21
22
2.1 Biodegradable materials - selection
To start, it is necessary to be given in this phase a definition about what will be considered in this
thesis as a “biodegradable product or material”. Therefore, a material that can be broken down into
simpler substances by naturally occurring decomposers and manners can be defined and considered
as “biodegradable” one. Generally, the majority of materials are somehow biodegradable since they
all can degrade in a long term period of time. Some needs months, and some centuries. But for this
thesis, a very important parameter in order a material to be considered “biodegradable” is to be able
to be broken down by ingesting processes occurring by living organisms in a relative short period of
time -even measured on a human time-scale. Moreover, one other important parameter is that these
materials should not cause any harm to the living organisms during or after the ingesting process.
That simply means that the materials -or products derived from them- should not be toxic during any
of the phase of its life; extracting, manufacturing, processing, using it or when it comes to its disposal.
Any product made from biodegradable material that fulfills these parameters can be also considered
biodegradable.
Eleni Sgouropoulou [2013, p. 43] already had sorted out some of the biodegradable materials in seven
basic categories according to their source of production and use. Five of the categories are filled in by
materials that were (or are) already used as building materials and can be made by natural resources
such as earth, plants, animals hairs and trees, while the two last categories present materials that are
either used in different sector (mattress industry) or are derived by new technologies that are still in a
research level, although both of them present possibilities for a future use of the materials in building
applications. Table 2.1.1 shows the materials in short whereas a more extensive description for its
materials is given in table 2.1.4)
TABLE 2.1.1 : Biodegradable materials - Categories
[1]
[2]
[3]
[4]
[5]
[6]
Traditional
Earthen
Forestry
Farming
Agriculture
-Peat Sod
-Limestone
-Cork
-wool
-Hemp
- Coconut fiber
- Ingeo-corn fibers
-Wattle
-Earthbags
-Papertubes
-Bamboo
- Natural rubber
- Canatex
-Mud coating
-Papercrete
-straw bale
- Horse hair
- Pine sap
-Rammed earth
-Paperstone
- Seaweeds
- Zelfo
-Cordwood
- Cactus
- BatiPlum feathers
-Adobe bricks
- Cotton
- Nettle textile
- Compressed
earth blocks
- Linen
- Mushroom
packaging material
-Cob
- Goose down
- Moniflex
& daub
- (wood)
Mattress
[7]
New Technology
-Clay dyes
*Modified table based on table in “Possibilities of applying biodegradable materials in solid building envelopes in the Netherland”, p.43-44
From these 40 materials, only some of them will be selected to be examined further in this thesis.
This selection is strongly correlated with the boundary conditions that were set in the chapter 1.5 and
related to local availability, current production in the Netherlands and potential level for prefabrication
production of building components. From these materials, some are inadequate to be applied in a great
extent in the Netherlands since a vast use of them will automatically lead to high transportation cost
and energy, consequently high embodied energy and the product will end up being an unsustainable
building option. This is mainly caused due to the fact that since some of these materials cannot be
produced in the Netherlands as a result of the unsuitable climatic conditions for their production so
they must be transferred from other countries very far from the Netherlands. For instance, the growth
of bamboo requires usually warm and temperate climatic conditions, thus it is largely produced in
Asia, India and so on [WIKIPEDIA, 2014] but the Dutch climate is unsuitable for its growth.
23
Moreover, some of the above materials are great to be used for constructing solid walls in-situ but may
present very low level of prefabrication potential, for instance to be converted in solid prefabricated
wall panels in various shapes or sizes (e.g. corkwood gives interesting monolithic walls but cannot
give many different options for prefabrication elements). Therefore, the prefabrication possibilities
for each material are examined and only those that present good possibilities will be researched
further.
Lastly, it is not only important to know if the material can be produced in the Netherlands or in
near neighboring countries, but also the amount of current production and if they are used in other
applications except building ones. Those who are defined as “by-products” or earthen materials are
great to promote their use as building materials instead of only disposing them. The following table
presents an estimated prefabrication potential and availability for each material (*as these terms were
described earlier):
TABLE 2.1.2 : Materials availability and Prefabrication potentials
EARTH
FORESTRY
products
products
TRAD.
product
Name
Prefab.
Potent.
Plants FIBROUS
products
Available
Producer country
Product. size
WATTLE & DAUB
8
++
- N/A -
- N/A -
PEAT SOD
8
++
[NL, used mainly as fuel]
- N/A -
ADOBE / MUD BRICKS
9
++
NL, DE,UK
- N/A -
COMPR. EARTH BLOCKS
9
++
NL, DE, UK
- N/A -
COB
û
++
NL, DE
- N/A -
EARTHBAGS
û
+
-
- N/A -
LIME STONE
ü
++
Mesozoic Limestone [NL]
- N/A -
RAMMED EARTH
9
+
NL,DE, FR, UK
- N/A -
CORK (Cork Oak)
ü
-
Portugal, Spain, France
- N/A -
CORKWOOD
8
--
-
- N/A -
WOOD FIBERS
ü
++
NL,DE, BE, FR, UK
- N/A -
CELLULOSE
9
+++
NL, UK, France, Austria
- N/A -
+++
NL,DE, BE, FR, UK
- N/A -
RECYCLED PAPER
BYproducts
Possible availability in NL or neighboring countries
CACTUS
ü
--
- N/A -
- N/A -
COCONUT (COIR)
9
--
- N/A -
- N/A -
COTTON
9
--
- N/A -
- N/A -
FLAX
9
+++
NL,DE, BE, FR, UK
HEMP
9
++
NL,DE, FR, UK
SEAWEEDS
ü
+
-N/A -
GOOSE DOWN (feathers)
9
+
-N/A -
HORSE HAIR
9
+
-N/A -
STRAW
9
+++
SHEEP WOOL
9
+
NL: 25. 000 t1
2
- N/A -N/A -N/A -N/A -
NL & Western Europe
NL, BE, DE, UK
(--) zero availability, (-) low availability, (+) adequate availability, (++) good availability , (+++) very good/in surplus
(ü) symbol indicates adequate to good possible prefabrication potential, (û) indicates poor prefabrication potentials
24
150.000 t3
NL: 2.500 t4
The selected materials from the above table that will be examined further are the following ones,
and are been divided in three main groups; products with main ingredient the earth (soil), products
made mainly by fibrous plants, and products derived by recycled products (such as paper, cork bottle
stoppers, and of course animal and plants by-products.
TABLE 2.1.3: Selected materials for research
Earthen products
Plants Fibrous products
By-or recycled derived products
ƒ Adobe/mud/ clay products
ƒ Flax based products
ƒ Sheep wool products
ƒ CEB/compressed earth blocks
ƒ Rammed earth
01
02
03
04
ƒ Hemp based products
(like hemp insulation
and hemp-lime)
05
06
01/ Unfired earth products ( adobes, CEB, clay products)
02/ Rammed-earth products
07
ƒ Wood fibrous products
ƒ Straw based products
ƒ Recycled paper products
ƒ Cork products
08
09
10
11
Earthen materials
03/ Straw products (straw bales, compressed straw)
04/ Sheep wool products
05/ Wood-fibers products
Fibrous materials
(by-products)
06/ Flax products
07/ Hemp products
08/ Hemp-lime products
09/ Cellulose products (flocks)
Cellulose recycled materials
(paper, wood bark)
10/ Papercrete products
11/ Paper products: paperboards
12/ Cork products
The above represent a representative sample of biodegradable materials for further
research. Cork although it cannot be produced in the Netherlands -but only in
Mediterranean countries such as Portugal which is the major producer countrywill be also examined thanks to to its good waterproof properties and since it
can be gathered also by recycling programs of cork wine-bottles stoppers in the
Netherlands. However, its proposal use should be in small quantities and only
when necessary.
25
12
TABLE 2.1.4 : BIODEGRADABLE MATERIALS – BRIEF DESCRIPTION
TRADITIONAL
Peat Sod WĞĂƚ;ƚƵƌĨͿŝƐĂŶĂĐĐƵŵƵůĂƟŽŶŽĨƉĂƌƟĂůůLJĚĞĐĂLJĞĚǀĞŐĞƚĂƟŽŶďLJĂĐŝĚŝĐĂŶĚĂŶĂĞƌŽďŝĐĐŽŶĚŝƟŽŶƐ͕ĂŶĚŝƐĨŽƵŶĚŝŶƉĞĂƚƐŽŝůƐŬŶŽǁŶĂƐŚŝƐƚŽƐŽů͘WĞĂƚŝƐŚĂƌǀĞƐƚĞĚĂŶĚƵƐĞĚĂƐĂŶŝŵƉŽƌƚĂŶƚ
source of fuel in some parts of the world but it can also be used as building material to conƐƚƌƵĐƚǁĂůůƐ͘/ŶƚŚŝƐĐĂƐĞ͕ƉĞĂƚƐŽĚŝƐĐƵƚŝŶƚŽƌĞĐƚĂŶŐůĞƐ;ŽŌĞŶϲϬyϯϬyϭϱĐŵͿĂŶĚƉŝůĞĚŝŶƚŽ
ǁĂůůƐŝŶƐĞǀĞƌĂůůĂLJĞƌƐ͘
Wattle & daub tĂƩůĞĂŶĚĚĂƵďŝƐĂĐŽŵƉŽƐŝƚĞďƵŝůĚŝŶŐŵĂƚĞƌŝĂůƵƐĞĚƚŽĐŽŶƐƚƌƵĐƚǁĂůůƐ͘tĂƩůĞŝƐŵĂĚĞďLJ
ǁĂǀŝŶŐǁŽŽĚĞŶƚŚŝŶďƌĂĐŚĞƐǁŚŝĐŚĂƌĞĚĂƵďĞĚǁŝƚŚĂƐƟĐŬLJŵĂƚĞƌŝĂů;ƵƐƵĂůůLJĂŵŝdžƚƵƌĞŽĨǁĞƚ
ƐŽŝů͕ĐůĂLJ͕ƐĂŶĚ͕ĂŶŝŵĂůĚƵŶŐ͕ƐƚƌĂǁŽƌŚĂLJͿ͘/ƚŚĂƐďĞĞŶƵƐĞĚĨŽƌĂƚůĞĂƐƚϲϬϬϬLJĞĂƌƐĂŶĚŝƐƐƟůů
ƵƐĞĚŝŶŵĂŶLJƉĂƌƚƐŽĨƚŚĞǁŽƌůĚ͘
Limestone >ŝŵĞƐƚŽŶĞŝƐĂƐĞĚŝŵĞŶƚĂƌLJƐƚŽŶĞĨŽƵŶĚĂůƐŽŝŶƚŚĞEĞƚŚĞƌůĂŶĚƐ͘/ƚŝƐƵƐĞĚĂƐĂǁŚŝƚĞǁĂƐŚ͕
ĂŐŐƌĞŐĂƚĞ͕ůŝŵĞŵŽƌƚĂƌ͕ďƵŝůĚŝŶŐďůŽĐŬĂŶĚĐůĂĚĚŝŶŐƟůĞƐ͘>ŝŵĞƐƚŽŶĞƉƌŽĚƵĐƚƐĂƌĞĂŶĞŶǀŝƌŽŶŵĞŶƚĂůĨƌŝĞŶĚůLJĂůƚĞƌŶĂƟǀĞƚŽĐŽŶĐƌĞƚĞƉƌŽĚƵĐƚƐ͘
Earthbags ĂƌƚŚďĂŐƐĂƌĞďĂŐƐŽƌƐĂĐŬƐĮůůĞĚŝŶǁŝƚŚĂƐŽŝůŵŝdžƚƵƌĞĂŶĚƉůĂĐĞĚŝŶƐƵĐŚǁĂLJƚŽĨŽƌŵǁĂůůƐ
ĂŶĚĚŽŵĞƐƚƌƵĐƚƵƌĞƐ͘dŚŝƐĐŽŶƐƚƌƵĐƟŽŶŵĞƚŚŽĚŽƌŝŐŝŶĂƚĞƐĨƌŽŵŚŝƐƚŽƌŝĐŵŝůŝƚĂƌLJďƵŶŬĞƌĐŽŶƐƚƌƵĐƟŽŶƚĞĐŚŶŝƋƵĞƐĂŶĚŇŽŽĚĐŽŶƚƌŽůĚŝŬĞďƵŝůĚŝŶŐŵĞƚŚŽĚƐ͘ĂƌƚŚďĂŐƐƐƚƌƵĐƚƵƌĞĐĂŶďĞƌĞŝŶĨŽƌĐĞĚďLJƚŚĞƵƐĞŽĨĐŚŝĐŬĞŶ͕ƚǁŝŶĞŽƌƌĞďĂƌ͘
Mud coating DƵĚĐŽĂƟŶŐŝƐƵƐƵĂůůLJĐŽŵƉŽƐĞĚďLJǁĂƚĞƌ͕ƚŚƌĞĞƉĂƌƚƐŽĨƐĂŶĚ͕ĮďƌŽƵƐŵĂƚĞƌŝĂůƐƵĐŚĂƐƐƚƌĂǁͬ
ĐĂƩĂŝůŇƵīŽƌĂŶŝŵĂůŵĂŶƵƌĞ͕ĂŶĚŽŶĞƉĂƌƚŽĨĐůĂLJ͘/ƚŝƐƵƐĞĚĂƐĂĐŽĂƟŶŐĨŽƌƚŚĞďƵŝůĚŝŶŐ͛ƐǁĂůů͕
ĂŶĚĂŌĞƌŝƚ͛ƐĚƌLJŝƚĐĂŶďĞŚĂƌĚ͘
Rammed earth ZĂŵŵĞĚĞĂƌƚŚŝƐĐŽŵƉŽƐĞĚďLJĂŵŝdžƚƵƌĞŽĨƐŽŝů͕ǁĂƚĞƌ͕ŐƌĂǀĞůĂŶĚƐŽŵĞƟŵĞƐƐŽŵĞĂĚĚŝƟǀĞƐ
EARTHEN
ůŝŬĞĐĞŵĞŶƚŽƌůŝŵĞ͘/ƚŝƐĂĐŽŶƐƚƌƵĐƟŽŶŵĞƚŚŽĚƚŽďƵŝůĚǁĂůůƐǀŝĂĂĨŽƌŵǁŽƌŬǁŚĞƌĞŝŶůĂLJĞƌƐŽĨ
ƐŽŝůŵŝdžƚƵƌĞĂƌĞĐŽŵƉĂĐƚĞĚƚŽĂƌŽƵŶĚϱϬйŽĨŝƚƐŽƌŝŐŝŶĂůŚĞŝŐŚƚǁŝƚŚƚŚĞƉƌŽĐĞƐƐƚŽďĞƌĞƉĞĂƚĞĚ
ƵŶƟůƚŚĞĨƵůůŚĞŝŐŚƚŽĨƚŚĞďƵŝůĚŝŶŐŝƐĂĐŚŝĞǀĞĚ͘
Cordwood ŽƌĚǁŽŽĚŵĂƐŽŶƌLJŽƌŽƚŚĞƌǁŝƐĞĐĂůůĞĚ͞ƐƚĂĐŬǁŽŽĚ͟ĐŽŶƐƚƌƵĐƟŽŶŝƐĂŵĂƐŽŶƌLJŵĂĚĞďLJƚŚĞ
ĐŽŵďŝŶĂƟŽŶŽĨƉŝĞĐĞƐŽĨǁŽŽĚƐƚĂĐŬĞĚƚŽŐĞƚŚĞƌĐƌŽƐƐǁŝƐĞĂŶĚĂƩĂĐŚĞĚǀŝĂĂŵŽƌƚĂƌŵŝdžƚƵƌĞ͘
tŽŽĚ ĐŽŶƐƟƚƵƚĞƐ ϰϬͲϲϬй ŽĨ ƚŚĞ ǁĂůů ƐLJƐƚĞŵ͕ ǁŚĞƌĞ ƚŚĞ ƌĞŵĂŝŶŝŶŐ ƉĞƌĐĞŶƚĂŐĞ ŝƐ ŝŶƐƵůĂƟŶŐ
ŝŶĮůůĂŶĚŵŽƌƚĂƌďĞĂĚ͘
Adobe / mud bricks ĚŽďĞŽƌŵƵĚďƌŝĐŬƐĂƌĞƌĞĐƚĂŶŐƵůĂƌůĂƌŐĞďƌŝĐŬƐŵĂĚĞďLJĂƐŽŝůŵŝdžƚƵƌĞĂŶĚůĞŌƚŽĚƌLJƵŶĚĞƌ
ƚŚĞƐƵŶ͘ŌĞƌƚŚĞLJĂƌĞĚƌŝĞĚ͕ƚŚĞLJĐĂŶďĞƵƐĞĚƚŽĐŽŶƐƚƌƵĐƚǁĂůůƐ͘^ŽŵĞƟŵĞƐĮďƌŽƵƐŵĂƚĞƌŝĂůƐ ůŝŬĞ ƐƚƌĂǁ ĂƌĞ ĂĚĚĞĚ ĂƐ ǁĞůů ƐŽŵĞ ƐƚĂďŝůŝnjĞĚ ĂĚĚŝƟǀĞƐ ůŝŬĞ ĐĞŵĞŶƚ͕ ŵŽƌƚĂƌ Žƌ ĞŵƵůƐŝĮĞĚ
ĂƐƉŚĂůƚ͘
compressed earth Compressed earth blocks are made by similar soil mixture with rammed earth and a similar
blocks (CEB) ƚĞĐŚŶŝƋƵĞďƵƚŝŶĚŝīĞƌĞŶƚƐĐĂůĞ͘dŚĞLJĂƌĞƵŶĮƌĞĚďůŽĐŬƐƚŚĂƚĂƌĞƉƌŽĚƵĐĞĚďLJŵĞĐŚĂŶŝĐĂůƉƌĞƐƐƵƌĞǀŝĂƉƌĞƐƐƵƌĞŵĂĐŚŝŶĞƐ͘dŚĞLJĐĂŶďĞƵƐĞĚĂƐŶŽƌŵĂůďƌŝĐŬƐƚŽĐŽŶƐƚƌƵĐƚŵĂƐŽŶƌLJ͘
Cob ŽďŝƐĐŽŵƉŽƐĞĚďLJŵŝdžŝŶŐƵƉƐƚƌĂǁ͕ƐĂŶĚ͕ĐůĂLJĂŶĚǁĂƚĞƌĂŶĚĐƌĞĂƟŶŐƐŵĂůů͞ďĂůůƐ͟ŽĨƚŚĞ
ŵĂƚĞƌŝĂůƐƚŚĂƚĂƌĞƐƚĂĐŬĞĚƚŽŐĞƚŚĞƌůĂLJĞƌďLJůĂLJĞƌƵŶƟůƚŽĐŽŶƐƚƌƵĐƚƚŚĞǁŚŽůĞǁĂůů͘ĂĐŚůĂLJĞƌ
ŵƵƐƚďĞƚŽƚĂůůLJĚƌLJŝŶŽƌĚĞƌƚŽƉƵƚƚŚĞŶĞdžƚŽŶ͘/ƚŝƐĂĐŽŵŵŽŶŬŶŽǁŶďƵŝůĚŝŶŐŵĞƚŚŽĚŝŶEŽƌƚŚ
ƵƌŽƉĞůŝŬĞŶŐůĂŶĚĂŶĚ'ĞƌŵĂŶLJŝŶŽůĚĞƌĂƐ͘
Clay dyes ůĂLJĚLJĞƐĂƌĞŵĂĚĞďLJĂŵŝdžƚŽĨůŝŵĞ͕'ůƵƚŽůŝŶ͕ǁĂƚĞƌ͕ĐŽůŽƌĂĚĚŝƟǀĞƐĂŶĚĐůĂLJǁŚŝĐŚŝƐƚŚĞďĂƐŝĐ
ŝŶŐƌĞĚŝĞŶƚ͘dŚĞLJĂƌĞƉĂŝŶƚƐĨŽƌǁĂůůƐƚŚĂƚĐĂƵƐĞŶŽƚĂůůĞƌŐŝĞƐŽƌĞŵŝƚŶŽsKƐĂƐĂƌĞƐƵůƚŽĨƚŚĞŝƌ
͞ŶĂƚƵƌĂů͟ĐŽŵƉŽƐŝƟŽŶ;ƚŚĞLJĐŽŶƚĂŝŶŶŽĂĐƌLJůŝĐŽƌŽŝůͿ͘ůƐŽƚŚĞLJĂƌĞŽĚŽƌůĞƐƐ͕ŚŝŐŚůLJďƌĞĂƚŚĂďůĞ
ĂŶĚƐƚĂƟĐƌĞƐŝƐƚĂŶƚ͘
Cork Cork is a material that is extracted from the skin of the Cork Oak tree which can be found in
ǀĞƌLJƐƉĞĐŝĮĐƌĞŐŝŽŶƐŝŶƚŚĞǁŽƌůĚ͘/ƚŝƐĂŵĂƚĞƌŝĂůƚŚĂƚŝƐƵƐĞĚĨŽƌŝƚƐǁĂƚĞƌĂŶĚĂŝƌͲƉĞƌŵĞĂďůĞ
ƉƌŽƉĞƌƟĞƐĂƐǁĞůůĂƐŝƚƐŝŶƐƵůĂƟŶŐĂŶĚƐŽƵŶĚƉƌŽŽĮŶŐŽŶĞƐ͘/ƚŝƐĂůƐŽƵƐĞĚŝŶƚŚĞĨŽƌŵŽĨĐŽŵƉŽƐŝƚĞƉĂŶĞůƐǁŝƚŚŽƚŚĞƌŵĂƚĞƌŝĂůƐ͘
FORESTRY
Papertubes WĂƉĞƌƚƵďĞƐ ĂƌĞ ŚŽůůŽǁ ƚƵďĞƐ ŵĂĚĞ ĨƌŽŵ ĐĂƌĚďŽĂƌĚ ƉĂƉĞƌ͕ ƵƐƵĂůůLJ ƌĞĐLJĐůĞĚ ƉĂƉĞƌ͘ dŚĞLJ ĂƌĞ
ǀĞƌLJůŝŐŚƚĂŶĚŝŶĞdžƉĞŶƐŝǀĞĐŽŵƉĂƌĞĚǁŝƚŚŽƚŚĞƌƉĂƉĞƌďĂƐĞĚŵĂƚĞƌŝĂůƐ͘,ĂǀĞŐƌĞĂƚƐƟīŶĞƐƐ
ĂŶĚŚŝŐŚĐŽŵƉƌĞƐƐŝǀĞƐƚƌĞŶŐƚŚ͘dŚĞLJĂƌĞĂůƐŽŇĞdžŝďůĞ͘dŚĞŝƌǀĞƌLJǁĞĂŬƚŽŵŽŝƐƚƵƌĞůĞǀĞůƐĚƵĞ
ƚŽŝƚƐƉŽƌŽƵƐŶĂƚƵƌĞ͘
Papercrete Papercrete is a composite material made from re-pulped paper (recycled), Portland cement or
ŽƚŚĞƌƐƚĂďŝůŝnjĞƌ͕ĐůĂLJĂŶĚͬŽƌŽƚŚĞƌƐŽŝůŽƌĮďƌŽƵƐŵĂƚĞƌŝĂůƐ͘/ƚǁĂƐĮƌƐƚƉĂƚĞŶƚĞĚŝŶϭϵϮϴďƵƚŝƚ
ǁĂƐƌĞǀŝǀĞĚĚƵƌŝŶŐƚŚĞϭϵϴϬƐ͘/ƚŝƐĨŽƵŶĚŝŶƚŚĞĨŽƌŵŽĨďůŽĐŬƐĂŶĚŝƚŝƐĂůŝŐŚƚǁĞŝŐŚƚŵĂƚĞƌŝĂů
ƚŚĂƚĐĂŶďĞǀĞƌLJĞĂƐŝůLJƉƌŽĚƵĐĞĚ͘
Paperstone WĂƉĞƌƐƚŽŶĞŝƐŵŽƐƚůLJƉƌŽƉŽƐĞĚĨŽƌŝŶƚĞƌŝŽƌƵƐĞƐŽƌůĞǀĞůƐƵƌĨĂĐĞƐ͘/ƚŝƐŵĂĚĞĨƌŽŵĐĞƌƟĮĞĚƉŽƐƚͲ
FARMING
ĐŽŶƐƵŵĞƌ͕ƌĞĐLJĐůĞĚƉĂƉĞƌƚŚĂƚŝƐƚƌĂŶƐĨŽƌŵĞĚŝŶƚŽĂƌŝŐŝĚ͕ĚƵƌĂďůĞĂŶĚƐƚƌŽŶŐƐƵƌĨĂĐĞŵĂƚĞƌŝĂů͘
/ĨŵĂŶƵĨĂĐƚƵƌĞĚǁŝƚŚĂǁĂƚĞƌƉƌŽŽĮŶŐůĂLJĞƌƚŚĞŶŝƚĐĂŶďĞĂůƐŽƵƐĞĚĨŽƌĞdžƚĞƌŝŽƌĐůĂĚĚŝŶŐĂƉƉůŝĐĂƟŽŶƐ͘
Sheep wool ^ŚĞĞƉǁŽŽůŝƐŐĂƚŚĞƌĞĚĨƌŽŵƐŚĞĞƉƐŽŝƚŝƐĐŽŶƐŝĚĞƌĞĚĂůƐŽĂďLJͲƉƌŽĚƵĐƚ͘/ŶƚŚĞďƵŝůĚŝŶŐƐĞĐƚŽƌ
ŝƐŵĂŝŶůLJƵƐĞĚĨŽƌŝŶƐƵůĂƟŽŶƉƵƌƉŽƐĞƐ͘^ŚĞĞƉǁŽŽůŝŶƐƵůĂƟŽŶŝƐŵĂĚĞĨƌŽŵƐŚĞĞƉǁŽŽůĮďĞƌƐ
ĂŶĚĐĂŶďĞĨŽƵŶĚŝŶƚŚĞĨŽƌŵŽĨďĂƩƐĂŶĚƌŽůůƐ͘hƐƵĂůůLJĂƉĞƌĐĞŶƚĂŐĞŽĨƉŽůLJĞƐƚĞƌĮďĞƌƐĂŶĚ
ďŽƌŝĐƐĂůƚƐĂƌĞĐŽŶƚĂŝŶĞĚ͘/ƚŝƐĂǀĞƌLJŚLJŐƌŽƐĐŽƉŝĐŵĂƚĞƌŝĂůǁŝƚŚǀĞƌLJŐŽŽĚƚŚĞƌŵĂůŝŶƐƵůĂƟŶŐ
ƉƌŽƉĞƌƟĞƐ͘
26
AGRICULTURE
Hemp dŚĞ ĂŶŶĂďŝƐ ;,ĞŵƉ ƉůĂŶƚͿ ŝƐ ŚĂƌǀĞƐƚĞĚ ĂŶĚ ŝƚƐ ƐƚĞŵ ŝƐ ƉƌŽĐĞƐƐĞĚ ƚŽ ŐŝǀĞ ƚŚĞ ŚĞŵƉ ĮďĞƌƐ͘
,ĞŵƉĮďĞƌƐĂƌĞƵƐĞĚĂƐĂŵĂƚĞƌŝĂůƚŽƉƌŽĚƵĐĞďƵŝůĚŝŶŐƉƌŽĚƵĐƚƐůŝŬĞŝŶƐƵůĂƟŶŐƉĂŶĞůƐŽƌĐŽŵƉŽƐŝƚĞƐ ƉƌŽĚƵĐƚƐ ůŝŬĞ ŚĞŵƉĐƌĞƚĞ ;ŚĞŵƉͲůŝŵĞͿ ďůŽĐŬƐ ĂŶĚ ŽƚŚĞƌƐ͘ ,ĞŵƉ ĮďĞƌƐ ƉƌĞƐĞŶƚƐ ǀĞƌLJ
ŐŽŽĚŵĞĐŚĂŶŝĐĂůƉƌŽƉĞƌƟĞƐ͘,ĞŵƉŝŶƐƵůĂƟŽŶƉƌĞƐĞŶƚƐĂůƐŽĂǀĞƌLJŐŽŽĚŝŶƐƵůĂƟŶŐĂŶĚƐŽƵŶĚ
ƉƌŽŽĮŶŐĂďŝůŝƚLJ͘/ƚŝƐĂůƐŽĂůŝŐŚƚǁĞŝŐŚƚŵĂƚĞƌŝĂů͘
Bamboo ĂŵŝƐƵƐĞĚĂƐĂĐŽŶƐƚƌƵĐƟŽŶŵĂƚĞƌŝĂůƚŚĂŶŬƐƚŽŝƚƐŚŝŐŚƐƚƌĞŶŐƚŚͲƚŽͲǁĞŝŐŚƚƌĂƟŽǁŚŝĐŚ
ŝƐǀĞƌLJƵƐĞĨƵůĨŽƌůŽĂĚͲďĞĂƌŝŶŐƐƚƌƵĐƚƵƌĞƐ͘/ƚŝƐƵƐĞĚĂƐƌĞŝŶĨŽƌĐĞŵĞŶƚŝŶĐŽŶƐƚƌƵĐƟŽŶ͕ĂƐůŽĂĚͲ
ďĞĂƌŝŶŐĞůĞŵĞŶƚ͕ĂƐĐůĂĚĚŝŶŐ͕ŽƌĂƐƐƵƉƉůĞŵĞŶƚĂůĞůĞŵĞŶƚ͘,ŽǁĞǀĞƌ͕ŝƚŝƐǀĞƌLJǁĞĂŬƚŽƌŽƚŽƌƚŽ
ƉĞƐƚŝŶĨĞƐƚĂƟŽŶƐĂƐǁĞůůĂƐŝƚƐůŝĨĞƐƉĂŶŝƐĚĞƉĞŶĚĞŶƚŽŶŽŌĞŶŵĂŝŶƚĞŶĂŶĐĞǁŽƌŬ͘
straw bale ^ƚƌĂǁŝƐĂŶĂŐƌŝĐƵůƚƵƌĂůďLJͲƉƌŽĚƵĐƚƚŚĂƚŝŶďƵŝůĚŝŶŐĐŽŶƐƚƌƵĐƟŽŶƐŝƐƵƐĞĚĂƐƐƚƌƵĐƚƵƌĂůĞůĞŵĞŶƚ͕
ŝŶƐƵůĂƟŽŶŽƌďŽƚŚ͘/ƚŚĂƐĂŐŽŽĚůŽĂĚͲďĞĂƌŝŶŐĂďŝůŝƚLJĨŽƌϭͲϮƐƚŽƌĞLJƐŚŝŐŚƐƚƌƵĐƚƵƌĞƐďƵƚŝƚŝƐĂůƐŽ
ǀĞƌLJǁĞĂŬƚŽŵŽŝƐƚƵƌĞĂŶĚƉĞƐƚŝŶĨĞƐƚĂƟŽŶ͘^ƚƌĂǁŝƐĂŵĂƚĞƌŝĂůƚŚĂƚƵƐƵĂůůLJŝƐŝŶĂƐƵƌƉůƵƐƐŽŝƚ
ŝƐŵŽƐƚůLJǀĞƌLJĐŚĞĂƉďƵŝůĚŝŶŐŵĂƚĞƌŝĂůǁŝƚŚŐŽŽĚŝŶƐƵůĂƟŶŐƉƌŽƉĞƌƟĞƐ͘
Coconut fiber ŽĐŽŶƵƚĮďĞƌƐĂƌĞƚĂŬĞŶƚŚĞƐŚĞůůŽĨĐŽĐŽŶƵƚƐ͕ĂŶĚŝŶŵĂƩƌĞƐƐŝŶĚƵƐƚƌLJĂƌĞƵƐĞĚĂŌĞƌƚŚĞLJĂƌĞ
ƐƉƌĂLJĞĚǁŝƚŚŶĂƚƵƌĂůƌƵďďĞƌƚŽĂĚĚĮƌŵŶĞƐƐĂŶĚĞůĂƐƟĐŝƚLJ͘dŚĞLJĂƌĞƉůĂĐĞĚǀŝĂůĂLJĞƌƐƚŽĨŽƌŵ
ƐŚĞĞƚƐĂŶĚƚŚĞLJĂƌĞŬŶŽǁŶĨŽƌƚŚĞŝƌŶĂƚƵƌĂůďƌĞĂƚŚĂďŝůŝƚLJ͘
Natural rubber Natural rubber or known also as India rubber is extracted from Caoutchouc tree that grows in
ƚƌŽƉŝĐĂůĐůŝŵĂƚĞƐ͘/ƚŚĂƐƚŚĞĨŽƌŵŽĨĂŵŝůŬLJũƵŝĐĞĂŶĚĂŌĞƌŝƚƐƉƌŽĐĞƐƐŝŽŶŝƚŝƐĂƉƵƌĞĂŶĚĞůĂƐƟĐ
ůŝƋƵŝĚƚŚĂƚŝƐƐƚĂďŝůŝnjĞĚŝŶƚŽƌƵďďĞƌ͘
MATTRESS INDUSTRY
Horse hair ,ŽƌƐĞŚĂŝƌǁĂƐƵƐĞĚŝŶƚŚĞƉĂƐƚĂƐĂŶŝŶƐƵůĂƟŽŶŵĂƚĞƌŝĂůďƵƚĂůƐŽĂƐƌĞŝŶĨŽƌĐĞŵĞŶƚĨŽƌƉůĂƐƚĞƌƐ
ĂŶĚĮŶŝƐŚŝŶŐƐ͘/ƚŝƐƚĂŬĞŶĨƌŽŵƚŚĞŵĂŶĞĂŶĚƚĂŝůŽĨŚŽƌƐĞƐ͕ĂŶĚŝŶŵĂƩƌĞƐƐŝŶĚƵƐƚƌLJŝƚŝƐƵƐĞĚ
ƚŽĨŽƌŵƚŚŝŶůĂLJĞƌƐĂŌĞƌďĞŝŶŐƐƚĞƌŝůŝnjĞĚ͘
Seaweeds ^ĞĂǁĞĞĚƐĂƌĞƵƐĞĚĂŌĞƌƚŚĞŝƌƉƌŽĐĞƐƐŝŽŶŝŶƚŽƚŚŝŶůĂLJĞƌƐŝŶƚŚĞŵĂƩƌĞƐƐŝŶĚƵƐƚƌLJĚƵĞƚŽŝƚƐ
ƉƌŽƉĞƌƟĞƐƚŚĂƚƉƌŽǀŝĚĞĂŶĂƚƵƌĂůƐŚŝĞůĚĂŐĂŝŶƐƚĂůůĞƌŐŝĞƐ͕ĂƐƚŚŵĂĂŶĚƌĞƐƉŝƌĂƚŽƌLJƉƌŽďůĞŵƐ͘/ƚ
ĐŽŶƚĂŝŶƐ/ŽĚŝŶĞĂŶĚŚĂƐĂŶƟďĂĐƚĞƌŝĂůƐƵďƐƚĂŶĐĞƐƚŚĂƚĐĂŶƐůŽǁĚŽǁŶĚĞĐŽŵƉŽƐŝƟŽŶƉƌŽĐĞƐƐŝŶ
ƐƉĞĐŝĮĐŵĂƚĞƌŝĂůƐƐƵĐŚĂƐƐƚƌĂǁ͘
Cactus ĂĐƚƵƐŝƐĐŽůůĞĐƚĞĚĂŶĚŵĂŶƵĨĂĐƚƵƌĞĚŝŶƚŽƚŚŝĐŬůĂLJĞƌƐŽĨĐĂĐƚƵƐͲĮďĞƌƐ͘/ƚŝƐĂŵĂƚĞƌŝĂůŚŝŐŚůLJ
ĚƵƌĂďůĞ͕ƐƚƌŽŶŐĂŶĚĐĂŶĂďƐŽƌďŚƵŵŝĚŝƚLJ͘/ƚŝƐĂůƐŽƵƐĞĚŝŶƚŚĞŵĂƩƌĞƐƐŝŶĚƵƐƚƌLJŝŶƚŚĞĨŽƌŵ
ŽĨůĂLJĞƌƐ͘
Cotton ŽƩŽŶŝƐŽŶĞŽĨƚŚĞŽůĚĞƐƚŵĂƚĞƌŝĂůƐƵƐĞĚŵĂŝŶůLJƚŽƉƌŽĚƵĐĞĐůŽƚŚĞƐĂŶĚĨĂďƌŝĐƐ͘/ƚŝƐĂƐŽŌ͕
ĂďƐŽƌďĞŶƚĂŶĚƐƚƌŽŶŐŵĂƚĞƌŝĂůƚŚĂƚŝƐǀĞƌLJůŝŐŚƚĂŶĚŚĂƐŚLJƉŽĂůůĞƌŐĞŶŝĐƉƌŽƉĞƌƟĞƐ͘/ƚĐĂŶďĞ
ƵƐĞĚĂůƐŽĂƐĂŶŝŶƐƵůĂƟŽŶŵĂƚĞƌŝĂů
Linen >ŝŶĞŶŽƌĂůƐŽŬŶŽǁŶĂƐŇĂdž͕ĐŽŵĞƐĨƌŽŵƚŚĞŇĂdžƉůĂŶƚ͘/ƚŝƐƵƐĞĚĨŽƌĨĂďƌŝĐĂŶĚĮďĞƌƐƉƌŽĚƵĐƟŽŶ
ďƵƚĂůƐŽŝŶƚŚĞďƵŝůĚŝŶŐŝŶĚƵƐƚƌLJĂƐŝŶƐƵůĂƟŽŶƐŚĞĞƚƐŝŶƚŚĞĨŽƌŵŽĨƉĂŶĞůƐ͘>ŝŶĞŶŝƐĂůƐŽŽŶĞŽĨ
ƚŚĞŽůĚĞƐƚŬŶŽǁŶĨĂďƌŝĐŵĂƚĞƌŝĂůƐĂŶĚŝƐǀĞƌLJƌĞƐŝůŝĞŶƚĂŶĚƐƚƌŽŶŐ͘
Goose down 'ŽŽƐĞĚŽǁŶŝƐŵĂĚĞďLJŐŽŽƐĞĨĞĂƚŚĞƌƐƚŚĂƚĂƌĞǁĞůůŬŶŽǁŶĨŽƌƚŚĞŝƌƚŚĞƌŵĂůƉƌŽƉĞƌƟĞƐĂŶĚ
ĐĂŶďĞƵƐĞĚĂƐŝŶƐƵůĂƟŽŶŝŶĮůů͘/ŶŵĂƩƌĞƐƐŝŶĚƵƐƚƌLJŝƚŝƐƵƐĞĚĂƐŝŶĮůůĨŽƌƉŝůůŽǁƐĂŶĚŵĂƩƌĞƐƐĞƐ
ĚƵĞƚŽŝƚƐǀĞƌLJůŝŐŚƚǁĞŝŐŚƚƐĂŶĚƐŽŌŶĞƐƐ͘
Ingeo - corn fibers /ŶŐĞŽͲĐŽƌŶĮďĞƌƐĂƌĞĂĮďƌĞŵĂĚĞŵĂƚĞƌŝĂůĨƌŽŵƉĞƚƌŽůĞƵŵͲĂůƚĞƌŶĂƟǀĞW>;WŽůLJĂĐƚĂƚĞͿƌĞƐŝĚƵĞƐ ;ƐƚƌĂǁ͕ ĐŽƌŶƐƚĂůŬͿ ĐŽŵďŝŶĞƐ ƚŚĞ ƉƌŽƉĞƌƟĞƐ ŽĨ ŶĂƚƵƌĂů ĂŶĚ ƐLJŶƚŚĞƟĐ ĮďĞƌƐ͘ /ƚ ŝƐ ƐƚƌŽŶŐ͕
ƌĞƐŝůŝĞŶƚ͕ŚĂƐĂƐŽŌƚĞdžƚƵƌĞĂŶĚƌĞĂĐƚƐǁĞůůŝŶŚƵŵŝĚŝƚLJ͘
NEW TECHNOLOGIES - COMPOSITES
Canatex /ƚŝƐĂůƐŽĂĮďƌĞŵĂĚĞŵĂƚĞƌŝĂůƉĞƚƌŽůĞƵŵͲĂůƚĞƌŶĂƟǀĞW>;WŽůLJĂĐƚĂƚĞͿƌĞƐŝĚƵĞƐ;ƐƚƌĂǁ͕ĐŽƌŶƐƚĂůŬͿĐŽŵďŝŶĞƐƚŚĞƉƌŽƉĞƌƟĞƐŽĨŶĂƚƵƌĂůĂŶĚƐLJŶƚŚĞƟĐĮďĞƌƐ͘/ƚŚĂƐĂƌŽƵŐŚƚĞdžƚƵƌĞ͕ŝƚŝƐŇĞdžŝďůĞĂŶĚůŝŐŚƚǁĞŝŐŚƚ͘
Pine sap WŝŶĞ ^ĂƉ ŝƐ ĂŶ ĂůƚĞƌŶĂƟǀĞ ĐŚĞŵŝĐĂů ĨŽƌ ŝŽďĂƐĞĚ ƉůĂƐƟĐƐ͘ dŚĞ ŵĂƚĞƌŝĂů ŝƐ ƐƟůů ŽŶ Ă ƌĞƐĞĂƌĐŚ
ƉŚĂƐĞ͕ďƵƚŝƚƐƉƌŽƉĞƌƟĞƐƐŚŽǁƐƚŚĂƚŝƚĐĂŶĚĞŐƌĂĚĞĂŌĞƌŝƚƐĚŝƐƉŽƐĂůĂŶĚĐĂŶďĞĂŐŽŽĚĐĂŶĚŝĚĂƚĞĨŽƌŶĞǁďŝŽĚĞŐƌĂĚĂďůĞƉůĂƐƟĐƐ͘
Zelfo ĞůĨŽŝƐŵĂĚĞďLJĐĞůůƵůŽƐĞĚĞƌŝǀĞĚĨƌŽŵǁŽŽĚͬŚĞŵƉͬďĂŵĂŶĚƐŽŽŶ͘/ƚĐĂŶďĞĐŽůŽƌĞĚǁŝƚŚ
ŶĂƚƵƌĂůƉŝŐŵĞŶƚƐĂŶĚĐĂŶďĞƉƌŽĚƵĐĞĚŝŶŵĂŶLJĚŝīĞƌĞŶƚƚLJƉĞƐ͕ƐŚĂƉĞƐĂŶĚĐŽůŽƌƐ͘
BatiPlum feathers /ƚŝƐĂŵĂƚĞƌŝĂůĐŽŵƉŽƐĞĚďLJϳϬйĨĞĂƚŚĞƌƐ͕ϭϬйǁŽŽůĂŶĚϮϬйƚĞdžƟůĞĮďƌĞ͕ǁŝƚŚŐŽŽĚƚŚĞƌŵĂů
ĂŶĚ ĂĐŽƵƐƟĐ ƉƌŽƉĞƌƟĞƐ͘ /ƚ ĐĂŶ ĂďƐŽƌď ϳϬй ŽĨ ŝƚƐ ŽǁŶ ǁĞŝŐŚƚ ǁŝƚŚŽƵƚ ůŽƐŝŶŐ ƚŚĞ ŝŶƐƵůĂƟŽŶ
ƉƌŽƉĞƌƟĞƐ͘/ƚŝƐƵƐĞĚŝŶďƵŝůĚŝŶŐƐĨŽƌƌŽŽĨ͕ǁĂůůĂŶĚŇŽŽƌĂƉƉůŝĐĂƟŽŶƐĂƐĂŶŝŶƐƵůĂƟŽŶŵĂƚĞƌŝĂů͘
Nettle textile EĞƩůĞƚĞdžƟůĞĐĂŶďĞŵĂĚĞďLJĮďĞƌƐƚĂŬĞŶĨƌŽŵĂŚĂƌĚLJƉůĂŶƚĨĂŵŝůLJƚŚĂƚĐĂŶŐƌŽǁŽŶŶŝƚƌŽŐĞŶŝnjĞĚĂŶĚĨĞƌƟůŝnjĞĚͲƐĂƚƵƌĂƚĞĚƐŽŝůƐ͘/ƚŝƐŵĂŝŶůLJƵƐĞĚŝŶĐůŽƚŚŝŶŐ͘
Mushroom material DƵƐŚƌŽŽŵŵĂƚĞƌŝĂůŝƐƚŚĞĮƌƐƚƉĂĐŬĂŐŝŶŐŵĂƚĞƌŝĂůŵĂĚĞĨƌŽŵĂŐƌŝĐƵůƚƵƌĂůĐƌŽƉǁĂƐƚĞƚŚĂƚŝƐ
ďŽŶĚĞĚƚŽŐĞƚŚĞƌǁŝƚŚŵƵƐŚƌŽŽŵ͞ƌŽŽƚƐ͟;ŵLJĐĞůŝƵŵͿ͘/ƚŝƐĂƌĞŶĞǁĂďůĞŵĂƚĞƌŝĂůƚŚĂƚŚĂƐƐŽŌ
texture, reacts well with humidity and it can be compostable,
Moniflex DŽŶŝŇĞdžŝƐŵĂĚĞďLJĐĞůůƵůŽƐĞĚĞƌŝǀĞĨƌŽŵǀĞŐĞƚĂďůĞƉƌŽĚƵĐƚƐƚŚĂƚĂƌĞƵƐĞĚŝŶŵĂŶƵĨĂĐƚƵƌŝŶŐ
ƉĂƉĞƌĂŶĚƚĞdžƟůĞƐ͘/ƚŝƐĂůƌĞĂĚLJƵƐĞĚĨŽƌŵŽƌĞƚŚĂŶϳϬLJĞĂƌƐŝŶƌĂŝůǁĂLJĐŽĂĐŚĞƐĂƐŝŶƐƵůĂƟŽŶ
ŵĂƚĞƌŝĂů͘/ƚŝƐƉƌŽĚƵĐĞĚďLJŐůƵŝŶŐƚŽŐĞƚŚĞƌ͕ƚƌĂŶƐƉĂƌĞŶƚĐŽƌƌƵŐĂƚĞĚƐŚĞĞƚƐŽĨĐĞůůƵůŽƐĞǁŝƚŚĂŝƌ
ƚƌĂƉƉĞĚŝŶďĞƚǁĞĞŶ͘
* Info based on Eleni’s Sgouropoulou thesis “Possibilities of applying biodegradable materials in solid building envelopes in NL”
27
2.2 Reasons of obsolesce
Before overviewing the materials in details, it is important to understand the reasons why these
materials were for so many years neglected and were finally replaced by other “new invented” materials.
Therefore, this session will research why these materials although known from the antiquity are not
used anymore in the developed countries, and are nowadays even considered as “alternative” materials
instead of traditional ones.
It is well-known that these materials -especially earthen materials- are the oldest building materials
that were used since ancient times to construct from simple small houses until temples and huge
building structures, even entire cities. For instance, Minke (2006, p. 11) mentions as a starting date of
the use of earth as building material back to 9.000 years ago, basing his beliefs on the fact that adobe
blocks were discovered in Turkmenistan that are dated from a period between 8.000 and 6.000 BC.
Others mention that the use of earth as construction material dates from the period of El-Obeid in
Mesopotamia (5000 - 4000 BC), whilst in Tigris River there is earth construction found dated back
to 7500 BC. Thus, earth construction can be considered that was used for more than 10.000 years
(Pacheco-Torgal F. and Jalali S., 2011, p. 513). Earth was used to construct not only small houses but
also temples (e.g. Horyuji Temple in Japan made from rammed earth dated 1300 years ago) and even
entire cities like the city of Chanchán in Peru that is among the most ancient earth based constructions
and another more recent example is the city of Shibam in Yemen with earth buildings up to 11 floors
that were built 100 years ago (Pacheco-Torgal F. and Jalali S., 2011, p. 513).
Other materials like fibers of hemp,
flax, jute and others were also known
since at least 4000 years ago and were
used for textiles, fabrics and paper
production. Hemp use to produce
ropes is documented in China for
over 3.000 years while since Middle
Ages and until the end of sailing
ship period, hemp was very popular
for production of sail canvas and
other items (Carus et al., 2013). The
properties of other biodegradable
materials are also known since
ancient times. The Greek philosopher
Theophrastus, in his botanical
treatises, mentions that he is amazed
from the ability that Cork Oak tree
(Quercus Suber) to renew repeatedly
its bark after it is removed. In 3000
BC, the cork has been in use in
China, Egypt, Babylon and Persia for
the manufacture of fishing tack.
Image 2.2.1: Chan Chan Ruins Peru
Chan Chan in Peru was one of the biggest adobe cities in the World.
Image taken from: http://images.summitpost.org/original/708241.jpg
Cork’s air-impermeability was known since 17th century when cork bottle-stoppers started being
produced massively. In 1909, in Earl Edwin Thomas treatise, the harvesting, manufacture, distribution
and uses of cork and cork insulation products are extensively described. The insulation properties of
cork were known since ancient times; according to Virgil (70-19 BC) Roman soldiers used cork to
cover their heads, as a thermal insulator.
So it is evident that the properties of the most natural and biodegradable materials were known
since antiquity. The resulting question is “how these materials that are dated since then and could
give such magnificent examples of building structures and products had fallen in such disuse and
got forgotten?”. At this part, some general stereotypic beliefs regarding to these materials will be
examined in an attempt to identify the real reasons that led to their marginalization.
28
Aspects:
ϭ͘ The industrial revolution and the new technological inventions are two of the main reasons
that the old materials had been replaced with the new industrialized ones.
Eleni Sgouropoulou [2013, p.104-105] states that the rapidly increase of population had led to a great
demand of shelters which accompanied with the new materials that were produced (like concrete
and brick) and their possibilities had led to a rapid marginalization of the biodegradable traditional
materials that were used until then. Indeed, the new materials with their new promiscuous properties
and structural possibilities as well as the idea of prefabrication made these materials very popular
among the designers and engineers of that era, who were keen on working and testing these materials.
Therefore, many quality -and other- tests were made qualifying these materials as durable and safe for
construction and giving a wide range of new construction possibilities in architecture.
According to Spiegel and Meadows (1999, p.30) prior to Industrial Revolution, society met most of its
needs with materials obtained directly from the earth and then returned those materials to the earth
after their use. But this is not the only reason that the “traditional” materials were replaced by the
new ones. According to Bert van Bommel, cut turfs and peats were used to construct walls and roofs
(“plaggenhut”, image 2.2.2) in country houses even until the beginning of the former century in the
Netherlands. Reed material was also used for the roofs of the country houses and can be found in
specific areas in the Netherlands even nowadays. According to him, the first parts that were made
by stone in the Netherlands were only the foundations of a building for water protection and soil
stabilization reasons, since natural stone was available only in specific areas of Netherlands (‘veldkeien’,
‘ijzeroer’, ‘mergel’) and had to be transferred from far. Therefore it was expensive. Bommel supports
that the development of residential houses and the formation of cities are the main reasons that led to
an establishment of new materials in use instead of the old traditional materials. The problems that
had arisen in the cities as a result of the traditional materials use that were easily flammable and were
causing a great risk of fire and fast fire spread in the cities, had resulted in a gradual replacement of
these materials with more fire resistant and durable ones.
By studying the development of housing in the Netherlands, it is clear that the traditional materials
like wood, peat sod, wattle and daub were gradually replaced by fired bricks and roof tiles due to fire
safety regulations. According to Bommel, housing and building regulations were formed in the cities
in order to prevent any possible fire spreads between houses, so gradually different parts of the house
had to be changed with new incombustible materials and the use of the traditional ones was forbidden
for specific construction parts of the house like roof or external sidewalls. Bommel supports that
at first it was forbidden the use of certain materials for building new houses, but later it was also
forbidden the maintenance of these materials on existing buildings and in a lot of cases of cities, a city
fire was the occasion to pronounce stricter rules (E.g. city fire in Enschede, 1862). Moreover, the new
materials allowed changes in the structure and size of the houses allowing larger or higher spaces to be
constructed; therefore the new industrialized materials became more popular for their possibilities.
The industrial era also brought new changes to the way of transportation, production and consequently
to construction practices. Before the industrial revolution, the materials used in buildings were locally
available and only in specific cases - such as monumental structures-temples and so on- some other
materials were used that had to be transferred from elsewhere due to the high cost. The material
selection was limited to regionally available natural resources and building materials of that eras
included; thatch, adobe, sod, straw, stone, timber, wattle and daub and fabric. Industrial revolution
brought a development also in the transportation means (trains, ships, etc), changing this attitude and
“new” materials from far could be used in buildings with a significant decrease in their cost.
At the same time, Industrial Revolution was followed closely by a scientific revolution that brought
new improved and standardized buildings products like steel, sheet glass, reinforced concrete, and
many others manufactured in a mass production that contributed to make them affordable to an eager
public (Spiegel and Meadows, 1999, p. 108-109). The building industry witnessed mass production
of new products from previously unknown substances which altered the buildings construction and
building business as well. The process of building reflected the process of standardized manufacturing,
designing with standard sizes and products, tested and qualified by industry recognized standards
and contracted on standard industry-recognized forms.
29
The craftsmanship era in developed world
is largely gone and wherein craftsmanship
survives, it is usually extremely expensive
Spiegel and Meadows, 1999, p.110). New
ideas, new materials and new applications,
and as always happens the current engineers
were keen to work on with the new materials
and explore their possibilities neglecting
the old traditional ones. “Society embraced
the promises of the Industrial Revolution
without acknowledging the new problems that
accompanied the new solutions” as mentioned
by Spiegel and Meadows (1999).
Image 2.2.2: Plaggenhut
Image taken from: http://www.surfspin.nl/vincentdrenthe.html
Ϯ͘ The knowledge of how to work with these materials was lost. The “new” industrialized
materials that were produced led to a more and more developed, tested and standardized
construction process, whilst the techniques used with biodegradable-traditional materials
remained the same since antiquities, although only few know how to construct with these
materials anymore.
It is profound that the ability to manufacture pre-cast forms for the new industrialized materials (brick,
concrete, etc) as well as the continuous development in the production techniques of these materials
had resulted in a great availability of different sizes, shapes and properties. With prefabricated elements
in such a variety, the construction time got reduced and the design got influenced by a standardized
design process. The new materials were demanding small or no maintenance for the constructed
buildings in contrast with the old “traditional” that needed often maintenance, increasing the cost of
the building. Moreover, biodegradable materials construction was dependent on weather conditions
increasing the time of construction and cost, giving a big disadvantage in comparison with the new
materials that were not so strongly weather dependent.
In addition, the ability and knowledge to work on with those materials got lost in the course of time
since professions like specialized builders and workers of those materials “vanished” thanks to the
prohibition of using the old materials in the cities. For instance, Keefe, L. (2005, p. 30) had observed
that in the past eras in many parts of Britain, earth buildings were very common and special earth
builders known as “mud masons” were following centuries-old traditions of building with earth that
relied on experience and observation. But since the use of earth as building material largely “died out”
at the end of 19 th century as Keefe L. stated, “much of this knowledge was lost and is now having to be
re-learned ”.
And although still almost 50% of the world’s population lives in earth based dwellings in the less
developed countries [Pacheco-Torgal F. and Jalali S., 2011, p. 513], the most building techniques of
these materials had slightly changed or got further developed. The vast use of biodegradable materials
(such as earth, wood, peat sod and so on) shows that the “extended industrialized materials use” is a
building phenomenon noticed only in the developed world not only due to the availability and variety
of industrialized methods but also due to the wealth level and building regulations of a state. Since the
building techniques and methods haven’t changed much, this is nowadays, a great disadvantage for
the building industry where the majority of architects, engineers, designers and owners require tested
and qualified techniques and building products.
Nowadays, it is commonly accepted that the “correct and safe” way to achieve long lifespan of the
building elements is by constructing them with the industrialized materials like concrete, brick, stone,
plastics, composites, etc, that have been repeatedly tested and qualified, but it should be mentioned
here that these materials are actually in use only for some centuries in contrast with the biodegradable
ones (like earth, straw, and so on) that served building constructions for longer. Of course, this
belief is strongly related to the education and knowledge that the majority of building community
have obtained during their studies in the developed countries. In Europe, education curriculum in
engineering faculties is usually more orientated to the current modern industrialized materials and
methods that are used to each country.
30
As Elizabeth L. and Adams C. (2000, p.71) mention, Bruce King have noticed that “engineers are
schooled to work almost exclusively with the “Big four”- concrete, masonry, steel , and wood” resulting in
many engineers “to be quite cautious or reluctant to work with materials they never read about in their
textbooks”. As an example, in Greece, a country with high seismic risk, civil engineers and architects
studies as it regards to load-bearing structures, are focused mainly on an extensive knowledge for insitu reinforced concrete structures and practices, whilst for instance in the Netherlands (a country with
a minimal seismic risk) such studies focus on a greater range of structures, albeit more significance is
given to steel load-bearing structures and prefabrication.
The majority of engineers lack yet in knowing about how to design and implement biodegradable
materials in their designs. And although nowadays more than 30% of the world’s population is
estimated to live in earth housing, yet there is very little mention and study of earth constructions
both in engineering literature and in building codes (Houben H. and Guillaud H., 1989, p.6). All these
facts, in combination with low demand from clients for buildings made by biodegradable materials,
are retaining the disuse of such materials.
ϯ͘ Biodegradable materials are not able to pass the current European and other regulations so
they cannot be used officially by countries with specific strict regulations. This is why they are
not preferred from the building industry.
Although biodegradable materials are the “original” building materials and present a very low-energy
and sustainable form of construction, nowadays they are considered as “alternative” ones. They had
been replaced from the modern building products; synthetic materials and composites, and the natural
materials were largely unrecognized in building codes until the last decades (Spiegel and Meadows,
1999). Most countries in Europe, as well as the Netherlands, have formed very firm and strict
regulations for Building constructions and especially when it comes to performance characteristics of
the materials used in a building as well as the performance of the building itself. A lot of parameters
must be fulfilled in order a material to be used in a contemporary building.
The stringency of the building regulations makes the application of biodegradable materials the most
times impossible. This occurs not only due to the strict regulations but also because of the lack of
tests and data that are unavailable for these materials. Biodegradable materials were for so long in
disuse that a lot of properties, values and other constructing-related data are unknown or lost. As
Keefe L. (2005, p.31) also points out one of the main problems with earth construction is that Building
authorities reject often such projects –even in parts where there is a long established earth-building
tradition- due to as he mentions “the Building Regulations approval contain insufficient data relating
to the performance, strength and durability of the material to enable building authorities to make a
reasoned and informed judgment”. So, clearly such “forgotten” materials should be able to convince
the authorities with sufficient data about their performance characteristics. Therefore, biodegradable
materials need to be tested with several tests in order to be qualified and be approved to pass the
current regulations in the most European countries, especially in the Netherlands. And since these
materials are mainly used by individual attempts to construct environmental buildings and there are
not many standardized products, the properties and performance of these materials differs a lot from
case to case. So, it is clear that a collective effort should be made from the building and scientific
community so that biodegradable products to be classified and their properties to be acknowledged
with scientific tests and references. The way of how to design also with such materials also must be
taught again. Fortunately, in this level there already some attempts; University of Kassel, the University
of Applied Sciences in Potsdam and the University of Weimar (Bauhaus) provide vocation courses to
this field [Schroeder et al. 2008].
Positively, the last decade there is an increased attention to biodegradable materials (especially about
earth construction) by the scientific community with an increase in published research articles and
papers, compared to the previous decade, which possibly is related to sustainability aspects. Moreover,
some countries have formed new Building regulations in order to include parameters and standards
for building constructions of biodegradable materials. For instance, in Germany since 1998 there
is the “Lehmbau Regeln” with technical recommendations about earth construction formed by the
“German Foundation for the Environment”, with a revised version passed on 2008.
31
In Spain, the “Spanish Ministry of Transport and Public
Works” published a document entitled ‘‘Bases for design
and construction with rammed earth’’ [1992] in an effort
to support rammed earth and adobe based buildings
while New Mexico has a similar state regulation about
rammed earth and adobe based constructions since 1991.
New Zealand is the first country with the most advance
legal regulations on earth construction, known as “New
Zealand Standards (NZS)” and constituted of 3 parts;
-
NZS 4297:1998
“Engineering design and earth
buildings” wherein it establishes performance criteria
for mechanical strength, shrinkage, durability,
thermal insulation and fire resistance
-
NZS 4298:1998 “Materials and workmanship for
earth buildings “ where it defines requirements for
materials and workmanship
-
And NZS 4299:1998 “Earth buildings not requiring
specific design”– this part is applicable for buildings
with less than 600 m2 (or 300 m 2 per floor) and
provides constructive solutions for walls, foundations
and lintels. [Pacheco-Torgal F. and Jalali S., 2011, p.
513].
Moreover,
companies
orientated
in
sustainable
products, are producing new ecological products based
on biodegradable materials; for instance hemp-flax
insulation, sheep insulation, compressed earth blocks,
and so on. Consequently performance tests are been made
that provides the building community with data about the
thermal, structural and other properties of such materials.
Image 2.2.3:
Example of Wetting mechanisms in strawbale walls
Image 2.2.4:
Example of Drying mechanisms in strawbale walls
Images taken from: http://www.buildingscience.com/
documents/digests/bsd-112-building-science-forstrawbale-buildings
ϰ͘ Biodegradable materials are so sensitive in moisture that can be durable only in dry climates,
and they are inadequate for cold-humid climates. Moreover, they are “weather related
construction” materials increasing the cost and time of building construction.
The majority of biodegradable materials and their products are weak in moisture and water penetration.
Long-term exposure to moisture without letting them dry causes in the majority of natural materials
serious decay. They can get easily damaged and highly degradable under specific conditions leading
to an increase maintenance costs. Prolonged use of biodegradable materials under high moisture
levels and water concentrations without any protection can lead in severe building problems such
as fungal growth, efflorescence, rottenness and so on. Thus, when building with such materials it is
always necessitated an adequate protection (e.g. overhangs and roofs, dry foundations, etc) and other
precautions to be taken to prevent any long-term moisture to build-up in the material (Images 2.2.3
and 2.2.4) . As it is expected, biodegradable materials in dry climates with very low relative humidity
and rare rainfalls can last longer without much protection or maintenance but although this factor,
biodegradable materials can also be appropriate to be applied in buildings in more cold and humid
climates. Current examples of unstabilised earth-wall buildings found in France and England that are
more than 100 years old and are preserved with careful maintenance (Heartcote K.A., 1995, p. 185)
prove that buildings made by biodegradable materials can have a great lifespan even in cold humid
climates unless they are adequate protected from damaging factors. The maintenance cost can also be
kept low or minimal with suitable design and construction methods.
Moreover, a development in the construction and production processes of these materials may give
solutions to the moisture vulnerability of these materials in future. Development in production
processes and techniques is always related strongly with a development also in the material’s and
product’s properties.
32
Concrete is one example that shows how developed production processes, improved the material’s
properties. Moreover, by designing carefully the position of these materials in the building envelope
and foreseen their protection from damaging factors, can give solution to the above problem. Lastly,
standardized production, or prefabrication some meters next to the side in a protected environment,
as well as “weather protected in-situ construction ” can minimize any “weather condition dependency”
of the materials at least in the construction level.
ϱ͘ Biodegradable materials can only last for short, their lifespan is very limited and they need
high maintenance cost. Moreover, they can be used only for small building applications.
The belief that biodegradable materials can last only for a very limited and short time as well as
they can construct only small building structures, is mistaken. This is already proved by numerous
examples of buildings made all around the world from such materials in different climates and that
are still present. These examples as mentioned also earlier, are not only small single storey houses, but
temples, entire cities and tall building structures. In Germany, the oldest inhabited house made from
rammed earth dates from 1795 and also one of the tallest earthwall houses is also found in Germany
(Weilburg). It is a house of 6 floors height, still standing and dates back to 1828 [Minke, 2006, p. 13].
It is constructed by solid earth walls that have different thickness depending on the height, Their
thickness gets decreased the higher you get so the 6-floors-structure to be achieved; 75 cm thick wall
in bottom to 40 cm. wall to the top floor. This indicates that biodegradable materials may have some
limitations but they can be overcome with a careful and skillful design.
Biodegradable materials were used for a larger timespan than the ones commonly used today.
According to Minke (2009, p. 11) from 13 th to 17 th centuries (Medieval period) earth was vastly used
throughout central Europe as infill in timber-framed buildings or as a cover for straw roofs to increase
their fire resistance. From the 15th to 17th centuries, in France, rammed earth techniques known as
“terre pisé” were also popular and several buildings near Lyon that are more than 300 years old and are
still inhabited evidence that biodegradable materials can be durable during the course of time and can
have a large life-serviceability. Therefore, the lifespan of a building made by biodegradable materials
that can be achieved can be similar with the one made by more conventional materials as long as
specific protection parameters are kept that prevent the degradation of the materials.
A good design can decrease significantly the maintenance work and costs of the building components
made by biodegradable materials as well as prolong their lifespan. Since the mechanism of degradation
are known and prevented then biodegradable materials can have the required lifespan, while at the
same time providing option to be easily decomposed after the end of their life without causing high
environmental impact. Maintenance is seen in the modern world as something to reduce to minimum
and products that are “maintenance free” are preferred in the most cases, neglecting the disadvantages
of such choices. In order to prevent the natural decay and weathering of materials -since very few
materials are naturally exempt from the ravages of weather and time- chemical products and treatments
are used that cause environmental damage (Halliday, 2008, p.145). But in biodegradable components a
small amount of maintenance is required in often basis and the design should ease their maintenance
than its avoidance. Examples of components that had been treated to protect weathering had in many
cases opposite results, for example timber frames painted by plastic paints in their effort to breathe
led in flaking off the paint that requires higher maintenance and repair cost and effort than treated
the wood regularly with water-based paints.
One other important aspect of biodegradable (low-impact) constructions is the significantly
different cost ratio between materials and labour, compared to conventional modern construction.
Buildings made by biodegradable materials were strongly connected with “craftsmanship”, resulting
automatically in the belief of high cost but in most low-impact construction, labour intensity offsets
much lower material costs (Halliday, 2008, p.145). Modern industrialized materials are assumed to
have lower cost as a result of their prefabrication and standardization production process. Thus, until
recently, there was assumed that buildings made from biodegradable materials were considered to
have a significantly higher cost than the others. As Halliday (2008, p.60) supports: “the construction
industry is constantly making financial decisions that have wide-ranging environmental and social
impacts, driven largely from a viewpoint that we cannot afford to build in a sustainable manner. Until
recently there was very little information on how much more sustainable building costs are. Any amount
of “more” seemingly just too much”. Moreover, the range of companies, builders and engineers that deal
with biodegradable material in Europe –and especially in the Netherlands- is significantly smaller
than that of companies involved with modern materials. This contributes also contributes to a small
range of use of these materials.
33
Conclusion
To conclude, the reasons of the disuse of biodegradable materials are various but all of them are strongly
connected with the Industrial Revolution influence to the building structures and the extended development of
the “new” materials. The industrial revolution influenced not only the construction and building practices but also
transportation and other aspects of life that altogether had contributed to a change in the design, constructing and
consuming attitude.
The new materials with their new structural possibilities were an interesting field for exploration for the contemporary
engineers, architects and builders of that era, while the new transportation means made the application of these
materials affordable to a vast public. In combination with the formation of city and the introduction of the first
building regulations, the old traditional materials got gradually replaced by the new ones. New architectural forms
were banishing the old materials and their building applications leading to a gradually loss of knowledge and
development of these materials. Consequently, professions, specializations, and the knowledge related with the
construction methods, design and properties of these materials were descended in the course of time.
The industrialized “new” materials got developed even more expanding their possibilities and decreasing their
limitations whilst the old biodegradable ones had remained stable since they were mostly abandoned for any
building application. This had as a result, the new industrialized materials to be established as the only building
option for safe and durable building structures. Old materials end up being considered “cheap and trashy” that
cannot ensure building liability and are used only by poor minorities of people in specific areas (homeless,
Romani people, etc.) or for secondary simple structures (stables, etc). Nowadays, the development in building
and construction industry had led to use only tested and qualified materials for safety reasons. However as it is
pointed out, laboratory tests are expensive so materials or systems with no financial backing (e.g. from companies,
commercial enterprises, government, etc.) end up being untested and dismissed by the modern building
community (Elizabeth L. and Adams C, 2000, p. 72)
Moreover, the contemporary prevailing attitude that the cost of a product and related cost to it like maintenance,
should be decreased as much as possible even if in long-term will give a higher cost in total, is one parameter that
affects the preference to inorganic building materials than natural biodegradable ones. Clients do not wish a high
maintenance cost and consequently in the most cases only synthetic inorganic materials can ensure that they can
stand for long with none maintenance needed. But from a long-term view, synthetic inorganic materials “cost”
more in total to the society than natural organic materials. They demand high energy for their manufacture, high
energy and cost for their disposal, high cost indirectly related to the health problem and low productivity levels that
they can cause, and many others. As an example, in the field of insulation, mineral wool is a very resistant material
that is used widely as insulation to the buildings although it is very problematic when it comes to its disposal. It is
defined officially as hazardous material, therefore at the end of its life it can be discarded only on special landfills and
remain there for a long time. Any possible disposal in incinerators will release many compounds that are known
to be toxic for human health and negative for environment. Also, other building applications of synthetic products
imply the use of strong chemical adhesives) that are not only environmentally problematic but yet any dismantling
technology is still lacking (e.g. Polystyrene insulation glued over an area for façade insulation). Consequently, the
criteria set of selecting building materials to be applied in the building envelopes should undergo a wiser and more
careful consideration even from the primary steps of design. Parameters like cost, energy, longevity, and other
factors should be estimated not only from a short-term aspect but also from a long-term one.
The building codes are playing also a very crucial role in the future of natural and alternative building materials
either by inhibiting or by helping these materials and building methods to gain a broader range and achieve a
mainstream acceptance. The “rediscovered” biodegradable materials must meet the contemporary primary criteria
that are set in the current building codes for safety, health and durability and should demonstrate an adequate
performance and life service. How transportation, materials availability and building codes can influence the
building materials and practices, is evident in the example of Germany. In Germany, because of a lack of transported
or processed building materials, after the World War I, thousands of earth-walled buildings were constructed
whereas by the end of World War II, another 40.000 German earth-walled homes were built (Elizabeth L. and
Adams C., 2000, p.98). Although this fact, in 1970, German government prohibited any further construction of
buildings with structural earthen walls (Elizabeth L. and Adams C., 2000, p. 98).
Lastly, it is very important to understand that the economic law of “Supply & demand” is very present in the
architecture and building industry. Simpler parameters such as cost, price, and relation between demand and
supply, and even “promotion” of a “new material” can be also significant factors that can “banish” a range of
materials in disuse or bring them back to vast use.
34
2.3 %HQHÀWVIURPXVLQJELRGHJUDGDEOHPDWHULDOV
Fortunately, the increasing demand on sustainable building
materials and on a decrease of the energy used in any phase
of the building let biodegradable and natural materials to
come again to the fore of attention. Biodegradable materials
except of the limitations that they present, they present
also a vast field of advantages compared to others. These
advantages are mainly related with benefits in sustainable
and environmental aspects, thermal and acoustic building
performance, health issues and many others that will be
particularly described in this sub chapter.
From the viewpoint of sustainability, biodegradable
(organic) materials and their majority of products, present
a good alternative for common (inorganic) materials owing
to their good thermal properties, low embodied energy
content and low CO2 emissions. The benefits that are
described further are divided in 3 categories:
͘ General benefits
connected with their general nature of the materials
9Renewable resources
9Low embodied energy and CO2 emissions
9Easy degradation (when required)
9Thermal & acoustic properties
9Breathability & Hygroscopicity
͘ Benefits related to health problems
that occurred by synthetic-chemical building products
9Indoor air quality improvement & avoidance of VOCs
9Avoidance of installation health problems
͘ Benefits related to specific properties.
9Purification of heavy metals contaminated water and soils
9Cases where it’s more beneficial their use than their disposal
35
A. GENERAL BENEFITS
9Renewable resources:
Biodegradable materials-products are derived from natural resources that either are considered
infinite (for instance, soil-earth) either they are renewable like the cultivation of plants, trees and so
on, requiring a relative small amount of energy to be produced, in contrast with the common inorganic
materials that use not only high amount of energy to be extracted, produced and manufactured but
also a wide range of them are dependent on finite resources. More specifically, insulation products
made from biodegradable materials are made either by fibrous plant (e.g. hemp, flax, straw) either by
animals by-products such as hair or feathers (e.g. sheep wool, horsehair, goose downs) or in some cases
even by recycled products that are converted to building useful products instead of being disposed in
landfills (e.g. cellulose insulation, insulations from recycled bottles, and Matisse insulation made by
recycled clothes). [The last case are products made not by “pure” organic biodegradable resources but
due to the reduction in solid waste ending up to the landfill that can be achieved by their reuse with a
relevant low energy content, can be also considered as an environmental option with some benefits and
shall be examined further to see how much biodegradable or not they can be.]
These insulation products require small amount of energy for their manufacturing process, are safe
for installers and safe to handle (Tuzcu, 2007, p.3). Not all of the biodegradable products are made
by fast renewable resources and therefore their production must be carefully measured; for instance
cork products are made by harvesting the bark of Querqus Suber (Cork Oak) which can be harvested
about 17-18 times in its overall life. In this case, harvesting can occur every 9 years so no harm to be
caused in the tree. But the most of biodegradable products can be easily reused or be recycled with
low amount of energy reducing the amount of raw materials. For instance, building products made
by cork be produced also by recycled cork stoppers of wine bottles, or unstabilised earth walls can be
reused as soil mixture for new constructions after their demolition.
Image 2.3.1
Image 2.3.1: Harvesting of Hemp
Image 2.3.2
Images taken from:
http://www.thegreenhome.co.uk
Image 2.3.2: Harvesting of Hemp
Images taken from:
http://www.thegreenhome.co.uk
Image 2.3.3: Harvesting of straw
Images taken from: http://www.clickgreen.
org.uk/opinion/opinion/122644-feeding-9billion-people-is-possible-with-sustainablefarming.html
Image 2.3.4: Harvesting of Flax
Image 2.3.3
Images taken from: http://pacificwellness.nl/
informatie/voordelen-van-onze-duurzameisolatietechniek
Image 2.3.4
36
9Low embodied energy and CO2 emission content
Building materials demand different amount of energy to be produced; some require a lot of energy
like cement products or fired-clay products, and some other little energy like adobe bricks or
straw. Cement production is classified as “energy intensive” (3.4 - 6.1 GJ/t) due to firing at very
high temperatures (~1400 oC) and use of fossil fuels for is manufacture (Woolley et al, 1997, p. 92).
Building products made by biodegradable materials usually require much lower amount of energy
for their manufacture so they present a lower embodied energy content and very low emissions of
CO2 emissions and other gases, in contrast with other building materials that are widely used in the
building industry.
According to Woolley T. et al (1997, p. 88) the petrochemicals industry (production of synthetic
resins, etc) is a major source of CO2 ,, NOx, and methane, and responsible for over half of all emissions
of toxics to the environment, releasing particulates, heavy metals organic chemicals as well as VOCs
that contribute to ozone formation in the lower atmosphere with consequent reduction in air quality.
The embodied energy refers to the total energy that is required for extracting and processing of raw
materials, manufacturing, transportation and final installation of a product. It is generally measured
by MJ/kg or MJ/m 2.
Table 2.3.1: Insulation Materials: Example of Embodied energy content
Synthetic materials
Extruded Polystyrene (XPS) insulation
Embod. Energy
Biodegradable materials
Embodied Energy
102-104 MJ/Kg
Hemp/ flax insulation
31-41 MJ/Kg
Extruded Polystyrene (EPS)insulation
95-98 MJ/Kg
Sheep wool insulation
15 MJ/Kg
Glass Wool
25-50 MJ/Kg
Cellulose flakes
4-8 MJ/Kg
*data taken from table 1 on p. 4 of “Ecologic construction materials” Grätz, M. and Indriksone [2011]
Some biodegradable products made from fibrous plants can have even a negative CO2 emission
content since the pants can absorb amount of CO2 during its cultivation, for instance hemp or flax.
According to Grätz & Indriksone (2011, p. 2) the embodied energy and CO2 emissions are not the
only factors connected with environmental effect; the longevity of building components is also an
important indicator, since materials that last longer will need to be repaired less often decreasing the
demand of producing spare parts and protect the environment. Kibert (2008, p. 37) also states that
one other “ecological impact measurement” should be dividing the embodied energy by the product’s
time in use that will yield a truer indicator of the environmental impact. Some materials may present
high embodied energy per kg but if used only in small quantities, can have the same ecologic impact
as a material which is used in large quantities and which has a small embodied energy per kg (Grätz
& Indriksone, 2011, p. 4).
Moreover, the volume of the material should also be considered in some cases when to be transferred it
needed; a material with high embodied energy that accumulates significantly smaller space compared
to a biodegradable one can be more ecological option in that sense. Sine it will needs less amount o
transportation means (e.g. trucks) so therefore it will cost less energy. For instance, for load-bearing
structure elements, a steel column may be “environmentally” more ecological than a column made of
straw. As a fact, biodegradable materials contain low embodied energy when they are found locally
and do not requiring big shipping distances.
9Easy degradation (when required)
Biodegradable materials are natural organic materials coming from renewable resources. They are part of
the earth’s innate cycle so they are able to close materials loops via an organic recycling process that involves
recycling by biodegradation, compost or aerobic/anaerobic digestion, either by nature itself, either by
processes mimic the decomposing action of nature[Kibert, 2008]. This is a great advantage and can reduce
the amount of waste that piles out in the landfills. At the same time this is also the main drawback of these
materials since it requires particular design and construction attention to avoid any possible significant
degradation that will lead into materials failure.
37
For instance, “thatching” which is considered to be the most common roofing material used in the
past, although its advantages such as good insulation properties, local renewable resource (reeds that
are used grow back annually) and being biodegradable, is often not durable and many traditional
types of thatch can lead to important building problems like leakage, fire risk –high flammability and
insects attack (Woolley et al., 1997, p. 162). Similar problems may also occur in bamboo use as roof
material, although its excellent bending and tensile characteristics.
9Thermal & acoustic properties
One other advantage of biodegradable building products is that in majority they have generally very
good thermal and sound insulation properties, and can be used for thermal and sound insulation
applications as well as for impact sound insulation. Such biodegradable products are those made
from fibrous materials; wool, cork, flax and hemp products. Others may not present such good
thermal properties like thermal resistance (R c) but may present a high thermal inertia as a result of
their thermal mass (F. Pacheco-Torgal and Said Jalali, 2011, p. 2) , i.e. the ability to accumulate and
transfer heat steadily later during the day, preventing temperature fluctuations and causing less energy
for heating or cooling. Such materials are earthen materials and earth based architecture can be energy
efficient when it comes to heating or cooling. According to Kibert (2008, p. 363) a relatively massive
structure made of adobe clay and straw bricks has large thermal mass which enables the building to
take advantage of the diurnal temperature swings for heating or cooling while during daytime the
thermal mass absorbs solar radiation that will radiate it later and provides thermal resistant to keep
the interior temperature at a moderate level. As also Halliday (2008, p. 127) states: “Earth is ideal to
regulate and balance the thermal fluctuations in a building and to avoid rapid swings in temperature”.
9Breathability & Hygroscopicity
Biodegradable materials are breathable if none impervious coatings or other mean (e.g. stabilization)
are not applied. The majority of them can also present adequate moisture mass for the building resulting
in regulation of indoor relative humidity. Moisture mass relies on hygroscopicity of materials, which
is the capacity of materials to absorb humidity (ambient moisture vapor) when it is in high levels and
re-emit when the air becomes dry (Halliday, 2008, p. 128). Most of biodegradable materials are highly
hygroscopic meaning that they can regulate the moisture indoors which can be beneficial for the
building and its occupants, since it can decrease any potentially harmful fungal and other organisms’
growth that can occur at the extremes of relative humidity and are linked to a number of health
problems. Biodegradable materials such as timber, earth, flax, wool, hemp and clay plasters have
hygroscopic properties in a varying degree and it is necessary in order to retain their hygroscopicity,
none impervious coatings, varnishes, paints, stabilizers and other to be applied to them.
B. BENEFITS RELATED TO HEALTH PROBLEMS occurring from synthetic building products
9Indoor air quality improvement – avoidance of VOCs
Almost all materials have emissions that may contribute to deterioration of the air quality. Material
selection can have a significant impact on indoor air quality. The extensive use of synthetic building
products which contain various chemical additives in combination with poor ventilation and fresh
air supply often leads to poor indoor air quality resulting in the known as “Sick Building Syndrome”.
Global Green USA (2007, p. 2) states that: “Over 30 of buildings have poor indoor quality which cause
for concern when considering that people spend approximately about 90% of their time indoors”. This
is confirmed also from World Health Organization (WHO) reporting that about 30% of buildings
experience some kid of sick building syndrome problems.
Common-used building products such as: particleboards, melamine, plywood, various paint, solvents
and adhesives, can cause health problems such as allergies through the release of toxins either during
their manufacturing process either during their usage stage. These toxic and hazardous substances
emitted by such building materials are known as VOCs (Volatile organic compounds) and can impact
the nervous and respiratory systems.
38
Especially if accompanied with dust-mold-pet can even create asthma in children and elderly people,
while some other are classified as carcinogen (Global Green USA, 2007, p. 2). Spiegel & Meadows
(1999, p. 11) also report that poor indoor air quality (IAQ) is according to “The EPA” one of the 4 th
major factors for cancer risks stating that 3.500-6.000 deaths per year are attributed to indoor air
pollution. There is also a new term of disability named as “Biochemically handicapped” that had arisen
nowadays, which refers to individuals diagnosed with “multiple chemical sensitivity (MCS)” that
are acutely affected to different degrees by chemicals commonly found in many building products
(Spiegel & Meadows, 1999, p. 10-11). As it is reported, biochemically handicapped people suffers
headaches, nausea, rashes, and asthmatic attacks in a degree that can be life-threatening. Spiegel &
Meadows (1999, p. 12) support that the use of materials that are natural, organic and nontoxic can
help reduce such cases mentioned above.
Regarding to the commonly-used building products, two are the major adhesive resins that are used,
especially in the manufacture of composite boards (for instance MDF boards); Urea Formaldehyde
(UF) and Phenol- and Melamine-Formaldeyde (PF and MF). Both of them have been found to emit
measurable amount of Formaldehyde to the indoor space during its product usage stage and are
linked to sick building syndrome. Possible health problems caused by Formaldehyde are; locomotive
disorders, respiratory problems, dermatitis, rashes and other skin diseases (Woolley T. et al, 1997, p.
85). Generally, chemical compounds released to the atmosphere can be linked with cancer-causing (e.g.
dichloromethane), can be related to reproductive disorders (e.g. carbon disulfide) or developmental
problems (e.g. toluene), and can be respiratory or other toxicants (e.g. acid aerosols) (Kibert, 2007,
p. 43). In contrast to that, biodegradable materials and their products are considered non-toxic;
with none or minimal VOCs and are breathable allowing a good indoor air quality in the indoor
space. Some biodegradable materials have even the ability to contribute positively to the decrease
of those VOCs by filtering out the indoor air. For instance, according to Tuzcu (2007, p.90), sheep
wool has the ability to react chemically and inactivate a wide range of hazardous gases and metals
in its environment by binding them in the wool fibers reversibly or irreversibly. (More particularly
explained in sheep wool section)
9Avoidance of installation health problems
Some building materials, cause health problems like allergies, dermatitis or respiratory problems
when people come in long-term or direct contact with them. For instance for installing Polyurethane
insulation or other synthetic-based insulation products, the installers need to wear special equipment
such as protective gloves and masks to protect themselves and prevent any allergy or skin irritation to
occur during the installation. In contrast, insulation made by biodegradable materials such as sheep
wool, hemp and flax do not require any such equipment since they are safe and non-toxic even during
their installation. Exception to this is cellulose fibers which require protective masks for protecting
installers to breathe any particles, and hemp-lime insulation that requires protective equipment as a
result of the caustic nature of wet lime.
Image 2.3.5
Installation of synthetic insulation .Image taken from: http://www.superiorsprayfoaminsulation.com/
39
C. BENEFITS RELATED TO SPECIFIC PROPERTIES & TO THEIR DISPOSAL
9Purification of heavy metals - contaminated waters and soils
According to studies made by the USA Environmental Protection Agency, sheep wool can absorb up to
30% of its weight of mercury from polluted water under a wide range of environmental conditions, while
research in USA indicates that treated wool can remove cadmium, iron, zinc, lead, mercury, cobalt,
nickel, copper, uranium and other metals from contaminated water (Tuzcu, 2007, p. 90).
Similar ability seems to have also hemp plant during its cultivation, since experiments showed that
hemp cultivation in contaminated soils with heavy metal can clean the soil as a result of the absorbing
ability of the plant to extract and accumulate heavy metals from the ground during is growth affecting
the plant or developing any toxicity. Blackburn (2005, p. 55) reported that hemp can absorb substantial
amounts of elements like copper, lead, zinc, and cadmium during its cultivation without any detrimental
effect on its crop either in quality or quantity.
The experiments that were made showed that the total calculated, extracted and fixed copper and lead
can reach 377 gr. and 141 gr. per hectare respectively (Blackburn, 2005, p. 55). As it is mentioned, this
results in gradual remediation of the soil and eliminates the threat of introduction of heavy metals to
nutritive chain of humans and livestock. Therefore, the environmental benefits that hemp cultivation
can provide are explicit.
9Cases where exploit of biodegradable materials it is more beneficial than its disposal
Some biodegradable materials are in such surplus that their disposal can be harmful for the
environment, whilst their use can be more beneficial twofold; a) either by using them as building
materials to replace conventional materials with high embodied energy, or b) either to prevent any
harmful emissions by their disposal or any increase of solid waste and debris ending up in landfills.
For instance, building products made by straw can be used in building applications either as insulation
infill or even structurally supportive to the building structure as load-bearing wall elements. Straw
is a by-product of agriculture that is also used as rural energy, bedding and animal feed but not in
a great extent. Therefore, often it can be in such a surplus that farmers have as a common disposal
method its field burning according to NL agency reports. One such case is North America wherein
ca. 128 million tones of straw are produced and are mainly burned whilst their use in production of
19 mm particleboards would produce 2.1 billion m 2– corresponding to 5 times the current total US
production of particleboard (Woolley et al, 1997, p. 95). During the burning, it offsets carbon, N 2 O,
and fine dust emissions with retention of minerals in the ash, which has a negative environmental
impact (NL Agency, 2013, p.5). In California where field burning takes place every autumn from rice
producers, it is reported that this leads to an estimated 51.000 tones of CO 2 emissions (Woolley et
al, 1997, p. 95). Consequently, implementation of straw in building components production and in
mushroom production can be beneficial to prevent such environmental harmful disposal practices.
One other example is the use of soil (earth) for building purposes. The soil extracted from the building
site can be used as the main building material for the building construction under the condition that
the soil is adequate for earth wall constructions. This strategy can decrease significantly the amount
of debris produced during construction phase that is dumped in landfills. As Keefe L, (2005, p. 51)
points out in Britain, for instance, “every year approximately millions of tones of earth, some of which
could be used for building, is removed from construction areas and are transported (at great expense), to
inert waste tips, where it is simply dumped or used as landfill”.
40
9Larger CO2 storage by cork harvesting
Cork harvested can not only be significant
ecological thanks to its renewable resource
but can be also beneficial for the harvested
tree itself. Experiments that were made
showed that barked Oaks are able to retain
and store 3 to 5 times more CO2 than
a Cork Oak that is not harvested. As it
is stated; “a cork oak from which cork is
periodically extracted produces between
250% to 400% more cork than it would if
the cork was not extracted, thereby also
increasing CO2 retention”(APCOR, 2013
http://www.apcor.pt/artigo/9.htm).
In addition, the cork exploitation allows
the preservation of cork forests which
contributes positively to decrease soil
erosion or decertification, and allowing
biodiversity. The cork as a renewable
product that is being used in long-term
products and in this way can increase
significantly the retention of carbon
dioxide.
Image 2.3.7
A worker harvests bark from a cork tree in the vast
forests that cover southern Portugal.
Image 2.3.6: Annual cork production by country. Image taken from:
http://www.amorim.com/en/why-cork/cork-oak-forest-area/
Image 2.3.8
Image 2.3.7: Harvesting of Cork
Images taken from: http://brasspaperclip.typepad.com/.a/6a00e398202d
Images taken from:http://i.dailymail.co.uk/i/
pix/2008/11/29/article-1090462-029EC960000005DC959_468x448.jpg
3d8833017c3409a4c7970b-pi
41
2.4 “Achilles Heel” of biodegradable materials
Biodegradable materials do not present only a range of various benefits for the built and natural
environment as well as advantages above the conventional synthetic building materials but they
have also some drawbacks and weak points. Their drawbacks are connected with weathering if
unprotected, fire resistance and pest infestations, as well as sometimes dimensional instability. They
can present weak points, “their Achilles heel”, that if no careful consideration and design will take
place, then serious problems of decay can occur in the building. The majority of drawbacks that these
materials present are connected strongly connected with their biodegradation mechanisms. Some of
the drawbacks are related to problems occurring by: biological contamination, buildup of moisture,
pest infestations (insects’ attacks) or because of low tensile ability in some cases. These drawbacks
with their occurring problems and their damaging mechanisms will be explained in more detail later.
Before that, someone should understand the
parameters that can affect the biodegradability
degree of a natural material. These parameters are
different to each material and dependent on its
nature and chemical structure of the material, with
a common “factor” the weather (frost, rain and water
penetration, etc) and in the possible chemical change
in the material that weather changes may result in.
Weather changes, rain penetration, rising damp and
others, can cause gradually from light to severe decay
to the materials. For instance, surface changes like
scaling, efflorescence, crypto-florescence, crust, or
loss of cohesion of the material like crumbling, or
even biological growth like algae, lichens, mosses, are
some of the damages that can occur due to weathering.
Earthen products such as adobes, CEB, rammed
earth walls and so on, can decay significantly in
the presence of prolonged moisture without drying.
They are highly affected by build-up of moisture and
erosion related problems. Typical sources of decay
can be water penetration, splash up, rising damp,
and so on. Also salt can rapidly decay unfired earth
surfaces.
On the other hand, fibrous products made from
hemp, flax are dependent on the arrangement of
their polymeric molecules that can be either random
creating amorphous regions either parallel creating
crystalline regions. The percentage of amorphous
and of crystal regions affects the fiber strength and
biodegradability. Those with greater crystalline
regions have better strength whilst those with
greater amorphous regions are more susceptible to
biodegradation. Lastly, other materials like wool
can degrade more by a breakdown of organic matter
(bacteria, fungi, etc)
42
Image 2.4.1
Efflorescence at rammed-earth wall
Image taken from: http://farm3.staticflickr.
com/2350/1503528633_a9d874d082_o.jpg
Image 2.4.2
Efflorescence at rammed-earth walls
Image taken from: http://photos1.blogger.com/
blogger/1662/2055/1600/efflorescence%20at%20
waterfeature.jpg
The problems that can occur when working with such materials and that need to be taken into
consideration to prevent them during the design process are:
}PROBLEMS IN BUILDINGS DUE TO BIOLOGICAL CONTAMINATION
Biodegradable materials form a greater risk to biological contamination as a result of their nutrition
content for fungi (Tuzcu, 2007, p. 15 ). Growth of biological organisms like fungi and bacteria can
cause not only problems in the indoor environment of a building abut also create health problems to
people such as respiratory symptoms, respiratory infections allergy and asthma (Tuzcu, 2007, p. 14).
Symptoms like headache, eye, nose and throat irritation or fatigue have been associated with volatile
compounds produced by fungi (Samson, 1985). In order to prevent that, relative humidity should be
kept indoors around 50% (Tuzcu, 2007, p. 15) and thermal bridges should be avoided since are the
weakest points for a building envelope to form fungal growth. Weather affects indoor temperature and
humidity; therefore it can also affect the growth of fungi. January is considered the month with the
highest risk for fungal growth in cold climates (Bosch & Smolders, 1994). Factors that affect positively
the speed of fungal growth are water, temperature, nutrients (amino acids inorganic nitrogen, etc),
and alkalinity (pH 2.2-2.6), while UV-radiation and air movements can slow down the growth (Tuzcu,
2007, p. 96). The main influencing factors for fungi to grow on a building’s envelope surface are; the
surface temperature, humidity of air on the surface, pollution of the surface and pH of the surface,
while the relative humidity influence the speed of this decay; since growth becomes more rapid.
}PROBLEMS IN BUILDINGS DUE TO BUILD-UP OF MOISTURE
One common problem of the most biodegradable materials is their high sensitivity to any source of
moisture, which can cause decay in the material. Biodegradable materials are not very resistant to
prolonged high moisture levels. If any moisture will be trapped in the material or the levels of relative
humidity will extent continuously a specific level, then there is great risk for the material to fail. It
has been estimated that 75% of building failures are due to water (Tuzcu, 2007, p. 14). For instance,
prolonged exposure of straw or sheep wool in high moisture levels can lead to favorable conditions for
fungal growth. Especially, straw is very prone to rot in wet and humid conditions. It can remain wet
for such a period of time that can be enough for fungal and other bacteria growth. Wet straw will turn
into black and fungi will start growing quite fast, while in the decaying area an increasing number of
insects will be observed (Woolley and Kimmins, 2000, p. 163). Fungi can develop in organic material
that contains cellulose under moist and warm conditions and they are usually growing in areas where
there is a lack of air-flow (ventilation) (Hugues, T., 2004, p. 77). Prolonged moisture content above
20% in the material can cause fungal growth (Hugues, T, 2004).
Such fungal growth and rottenness can create not only problems in the building performance but also
into the occupants, for instance the “Farmers lung” that can occur by breathing fungal spores (Woolley
and Kimmins, 2000, p. 13). Earthen products like adobes, compressed earth blocks and rammed
earth buildings are also susceptible under wet conditions for long period of time. The compressive
strength for unstabilised earth walls is significantly decreased (in sometimes even resulted in its
half strength) under 24 hours of water exposure. This sensitivity to dampness is one of the major
disadvantages of biodegradable materials in comparison with the most conventional materials derived
from petrochemical and other chemical resources.
43
}PROBLEMS DUE TO PEST INFESTATION
Biodegradable building products are produced by natural resources and if they do not contain any
chemical agents then they are very vulnerable to insect and pests infestation as a result of their
nutritional content. Some of them form a greater risk of insect attacks like moths and larvae; especially
products of keratinaceous materials such as wool, hair and feather products, while others must be
protected from pest attacks like flax insulation or straw. Wool or wood-based materials present a great
risk from vegetable pests’ growth like fungi and insect infestation like beetles and others (Hugues, T
et al, 2004, p. 76).
Beetles are mainly attracted by the “sap area of wood” as a source of food, so wood-based materials
with moisture content lower than 10% won’t present such problem. Except of such insect attacks, others
like small pest attacks from small animals can also happen. For instance, although in most literature
it is claimed that straw walls are not attacked by rodents or termites, since they is no food matter in
the material, straw may present sometimes chances to possess a nutritional content as Woolley and
Kimmins support (2000, p. 163). In this case, it may attract pests like rodents, mice and birds, which
can even break through a lime plaster if it is freshly applied (Woolley and Kimmins, 2000, p. 163). To
prevent such situation, straw that is used in any building application, should be dry and free of grain
seed to prevent any insects or rodents attack and to ensure that the building envelope is not attractive
to them (Kwok, A., 2011, p. 49).
This vulnerability of natural organic products in combination with fire regulations makes necessary
the chemical treatment of such products in order to prevent pest, rodent and insects infestation as
well as to make them more resistant to fire. Nowadays, the most common method is to add polyester
fibers and chemical agents like borate, boric salts, soda and ammonium. However, there are also
natural ways to treat biodegradable products to protect them from such infestations. For instance,
Quassia chips can be used instead of chemical insecticides. Quassia chips are derived from the white
bark of Picrasma excelsa a tree that is indigenous to Jamaica and many other islands of the West
Indies. The tall elegant trees are not troubled by insects or pests as the entire tree in particular the
timber, contains quassin an astringent resin which is a bitter and very effective insecticide. Potato
starch is also a natural organic solution instead of synthetic fibers and binders.
}LOW TENSILE STRENGTH; INADEQUATE FOR SEISMIC AREAS WITHOUT reinforcement
Biodegradable materials occurring from natural fibers have great tensile strength but in contrast
other biodegradable materials such as earthen materials are very low in tensile strength and present
better compressive strength. In general, biodegradable products and materials that exist already in the
building market are inadequate to be applied without any reinforcement in seismic areas that have a
risk for earthquakes.
}INTERIOR SPACE QUALITY
The use of biodegradable materials as building materials can result in indoor spaces with sometimes
very different quality than those created from conventional materials like brick masonries and
concrete walls. Constructing walls of rammed earth or adobe and compressed earth bricks will bring
limitations in the most cases to the interior decoration on walls. Shelves and hanging decorative items
is possible but often it should be very limited. Moreover, in straw bale buildings the wall surface
even when plastered very carefully sometimes the wall may not be so totally “perfect and straight”
as in other finished walls. Load-bearing walls like rammed-earth and straw bale masonries also need
more space on plan than the conventional masonries of brick, concrete and stones. These draws may
make some conventional materials more favorable when the maximum possible area of indoor space
is requested.
44
References.:
books_
& Building Materials, vol. 29 (2012) [Online]
pp.512-519. Available at: http://www.journals.
elsevier.com/construction-and-buildingmaterials [last accessed: 05 February 2014] pp.:
2, 513
Blackburn, R.S. (2005) Biodegradable and sustainable
fibers. USA: Woodhead Publishing, Ltd p.51-60
Carus, M. et al. (2013) The European Hemp Industry:
Cultivation, processing and applications for fibres,
shives and seeds (online). European Industrial
Hemp Association (EIHA). Available at: http://
www.eiha.org/attach/8/13-03%20European%20
Hemp%20Industry.pdf [accessed: 11 March
2014]
Sgouropoulou, E. (2013). Possibilities of applying
biodegradable materials in solid building
envelopes in the Netherlands. Msc thesis. Delft:
TU Delft, Faculty of Architecture, pp.: 42-44,
94-100, and 104-105
Elizabeth, L. and Adams, C. (edited) (2005) Alternative
construction; contemporary natural building
methods. Canada: Jon Willey & sons, pp: 71-72,
78
Spiegel, R. and Meadows, Dr. (1999) Green building
materials; a guide to product selection and
specification. Wiley series in sustainable design.
Wiley, pp. 10-12, 30, 108-110
Grätz, M. and Indriksone, D. (2011) Ecologic
Construction Materials. [Online] Available
at:
http://www.intense-energy.eu/fileadmin/
content/broshures/04_Ecomaterials.pdf
[last
accessed: 15th February 2014]. p.2-4
Tuzcu, T.M. (2007). Hygro-Thermal Properties of Sheep
Wool Insulation. Msc Thesis. Delft: TU Delft,
Civil Engineering Faculty, pp:3,14-15, 90, and
96.
Global Green USA (2007) Blueprint for greening
affordable Housing. USA: Island Press, p.2
Van Bommel, B. (2013). Residential 1 & 2 , lecture notes
distributed in Building History & construction
AR0014 (RMIT) at the Delft University of
Technology [TU Delft], on 28 March 2013 &
02 May 2013
Halliday, S. (2008) Sustainable Construction.
Butterworth-Heinemann, Elsevier, pp.60, 127128, 145
Heartcote, K. A. (1995). Durability of earthwall
buildings. Sydney: University of Technology, pp.
182-189
Schroeder H, Rohlen U., and Jorchel S. [2008]
Education and vocational training in building
with earth in Germany. In: 5th International
conference on building with earth – LEHM
2008. Weimar: Germany. pp. 193–197.
Houben, H. and Guillaud, H. (1994) Earth construction;
a comprehensive guide. France: practical action
publishing, p. 6
Woolley, T. et al. [1997] Green Building Handbook; a
guide to building products and their impact on
the environment. London: E & FN SPON, pp:
84-88, 92, 95, 162-163
Hugues, T. (2004) Timber Construction; Details,
products, case studies. Birkhäuser, pp.: 77, 76
Keefe, L. (2005) Earth building; methods and materials,
repair and conservation. USA and Canada:
Taylor & Francis, pp: 30-31, and 50
Woolley, T. and Kimmins, S. (2000) Green Building
Handbook; volume2. Great Britain: E and FN
Spon, pp:13 ,163
Kibert, Ch. J (2008) Sustainable Construction; Green
Building Design and Delivery. USA: John Wiley
& Sons, Inc., pp.: 37,43,363
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the Biobased Economy. (Edited by Bakker, R.,
Elbersen,W. Poppens, R. and LesschenRice, J.P.)
Study was carried out in the framework of the
Netherlands Programmes Sustainable Biomass
by Wageningen UR, Food & Biobased Research.
Kwok, A. et al. (2011) The Green Studio Handbook;
Environmental strategies for schematic design.
(2nd edition) USA: Architectural Press, Elsevier,
p.48-49
Minke, G. (2005). Building with Earth: design and
technology of a sustainable architecture. Basel:
Birkhäuser, pp. 11-13
Pacheco-Torgal, F. and Jalali, S. [2011] Earth
Construction: Lesson from the past for future
eco-efficient construction. Journal: Construction
45
46
Chapter 3 Materials Overview
This chapter gives a detailed overview of the biodegradable materials that have been selected for further
research in chapter 2. Representative samples of different products of biodegradable materials have
been collected and presented in datasheets, giving an overview of their size, properties, advantages
and disadvantages as well as the processes and technologies that are applied in to produce them. For a
start, companies that manufacture and produce products from biodegradable materials were selected
and are listed in each material’s section. Τhe intention was firstly to find mainly Dutch companies that
produce products from the selected materials in order to investigate the level, variety, sizes and costs of
prefabricated products that already exist in the market since the target of this thesis is to enhance the
use of such products. In most cases that this was not possible, companies from neighboring countries
were selected to be examined (like from Germany, Belgium, United Kingdom and France). For each
company, their products were examined in terms of material content, production technique, properties
and whenever possible energy consumption during its manufacture. These are then grouped and
presented in each company in the datasheet of properties, wherein next to can be compared with the
corresponding data found in the “formal literature”. Lastly, an extended description is given for each
material about general information that someone should know, its production processes, steps and
techniques that are involved in the production and the positive-negatives characteristics. Moreover,
alternative solutions and design advices are been noted down and the references used for each product
are listed separately to each material section.
47
48
3.1 8QÀUHG(DUWKSURGXFWV
Material: earth (adobe, mud, clay) (leem)
Category: building material
Application: wall interior or exterior masonry,
ceiling and floor construction
3.1.1 Unfired Earth products companies list:
NL
DE
DE
DE
UK
UK
NL
Company name
code
Mfr
(Pvr)
Mfr
Mfr
website
http://www.claytec.nl/
www.claytec.de/
http://procrea.de
http://www.thermo-hanf.de
http://www.conluto.de/
http://www.ibstock.com/
contact /email
info@claytec.nl
service@claytec.de
info@procrea.de
info@thermo-hanf.de
info @conluto.de
-
CLAYTEC e.K.
Mfr
ProCrea® GmbH
(Thermo-Hanf)
Conluto
Ibstock (EcoterreTM)
Limestone technology LtD
(Sumatec ®)
Groenebouwmaterialen.nl
Mfr
ŚƚƚƉ͗ͬͬǁǁǁ͘ůŝŵĞƚĞĐŚ͘ŝŶĨŽͬ
info@limetechnology.co.uk
Pvd
http://www.groenebouwmaterialen.nl/
-
*Pvd: Provider / Mfr : manufacturer
Notes: During the research step, it wasn’t possible to find Dutch manufacture companies of unfired earth products. The most
close factories to the Netherlands were companies in Germany and United Kingdom. Given the fact that Netherlands are one
of the major providers of fired earth bricks, it is assumed that it is possible also a production of unfired earth products like
lightweight bricks, heavyweight adobe bricks and compressed earth blocks to take place in the Netherlands in the coming years.
49
3.1.2 a. Unfired earth products (industrial) datasheet: Products & sizes
Company
BLOCKS and BRICKS
Claytec
ProCrea®
Conluto®
Ecoterre TM
Sumatec®
Composite BOARDS
Company
Claytec
ProCrea®
Conluto
d (mm)
52
71
113
113
71
71
113
71
52
71
113
113
100
100
69
69
113
113
52
71
113
113
67
133
100
d (mm)
40
60
16
20
25
40
60
80
20
15
25
35
50
35
16
22
25
w(mm)
L (mm)
115
115
115
175
115
115
115
115
115
115
115
115
250
250
120
120
115
175
115
115
115
175
105
105
215
w(mm)
600
600
625
625
625
400
400
400
600
625
250
250
250
250
125
125
125
ρ (kg/m3)
240
240
240
240
240
240
240
240
240
240
240
240
250
520
247
247
240
240
240
240
240
240
220
220
215
λ ( W/m
K)
0,910
0,910
0,730
0,730
0,470
0,210
0,210
0,910
0,91
0,91
0,97
0,59
0,47
0,47
0,47
0,47
0,21
0,21
0,91
0,91
073
0,73
-
L (mm)
1020
1020
625
1500
1500
1020
1020
1020
1020
1250
1250
1250
1250
1250
625
625
625
λ ( W/m K)
0,046
0,046
0,14
0,14
0,14
0,45
0,45
0,45
0,45
0,33
0,33
0,33
0,33
0,33
0,53
0,53
0,57
ρ(kg/m3)
ca.210
ca.210
ca.700
ca.700
ca.700
ca.140
ca.140
ca.140
50
ca.1900
ca.1900
ca.1600
ca.1600
ca.1200
ca.700
ca.700
ca.1800
ca.1900
ca.1900
ca.1700
ca.1500
ca.1280
ca.1280
ca.1200
ca.800
ca.700
ca.700
ca.1900
ca.1900
ca.1600
ca.1600
ca.1940
ca.1940
ca.1950
Product/code
06.010
DF- II
06.012
NF,-II
06.003
2DF-II
06.004
3DF-III
07.011
NF- Ia
CEB extruded
CEB extruded
perforated
€/m2
23,921
26,432
27,663
33,574
19,645
07.012
NF-Ia
07.013
2DF-Ib
07.002
NF-II
32,166
82GDF
DF
28,217
31,07
34,28
28,33
49,95
49,95
20,348
20,68
30,00
29,52
15,71
16,78
18,93
17,38
-
82GNF
NF
82G2DF
2DF
82G3DF
3DF
81LE2526
100HF
81LE2552
100
07.011
NF-Ia
07.012
NF-Ia
07.013
2DF-Ia
07.015
3DF-II
06.010
DF-II
06.012
NF-II
06.020
2DF-II
06.022
3FD-II
EB3590
-
EC3590
-
unfired CEB
form beaten
Greenfinch
CEB extruded
perforated
form beaten
CEB extruded
CEB extruded
CEB extruded
perforated
CEB extruded
perforated
-
perfor.extruded
Product/code
€/m2
09.240
CLAYTEC Pavaboard
-
09.260
CLAYTEC Pavaboard
-
09.010
CLAY +REEDS+ hessian
-
09.004
CLAY +REEDS+ hessian
39,029
09.002
CLAY +REEDS+ hessian
44,410
09.340
CLAYTEC Pavadentro
21,211
09.360
CLAYTEC Pavadentro
-
09.380
CLAYTEC Pavadentro
50,71
Ca,140
09.320
ca.1300
ca.1400
ca.1100
ca.1400
ca.1100
ca.1300
ca.1300
ca.1440
80LLP016
Light clay plate
CLAYTEC Pavadentro
19,95
-
80LP025
Clay plate (+wood fibers)
19,95
80LP035
Clay plate (+wood fibers)
21,20
80LP050
Clay plate (+wood fibers)
32,33
80LPW035
Clay plate (wall heating)
21,20
09.001
Clay building board
39,512
09.004
Clay building board
09.005
Clay building board
-
3.1.2 b. Sample of unfired Earth products worldwide (literature datasheet):
weight
(kg)
accurate
457
254
15.87
6.80
1783
1743
ca.1800
ca.1700
Yemen
4-8 storey houses
Iraq
254
140
254
229
457
229
508
457
20.41
4.08
22.68
14.06
1701
1700
1718
1765
ca.1700
ca.1700
ca.1700
ca.1800
Greece/Rome
hand-formed, tempered with
straw
reported by Vitruvius, ca.30 BC
New Mexico
below ground building
New Mexico
church
152
127
152
76
89
305
254
305
330
267
457
381
381
610
406
36.28
20.86
29.48
27.21
16.78
1727
1738
1638
1814
1748
ca.1700
ca.1700
ca.1600
ca.1800
ca.1700
UK
“clay lumps”
Australia
“Mudbrick”, traditional size
1870
1936
1981
102
102
76
178
305
127
330
406
254
21.77
3.62
1728
1448
ca.1700
ca.1400
New Mexico
1998
1998
25
64
114
178
152
457
7.71
4.98
1793
957
1998
2005
89
101
254
305
356
406
14.51
21.77
1814
1742
d
(mm)
W
(mm)
L
(mm)
1000 BC
6000 BC
64
102
305
152
antiquity
1250
ca.1600
ca.1646
102
76
102
76
ca.1800
1840-1950
1845
1854
1870
Adobe Bricks
Date
rounded
ρ (kg/m3)
location
Other information
New Mexico
New York
2 storey residence
New Mexico
church
New Mexico
adobe bricks with high straw
content
old town,
California
present until today
New Mexico
used for arches and walls
ca.1800
ca. 950
New Mexico
adobes used for vaults & domes
Texas
ca.1800
ca.1700
New Mexico
low-cost housing, for domesvaults
industrial adobe bricks, 8%clay
Arizona
industrial adobe bricks
Unfired earth bricks
*table information are based on tables given by Elizabeth L. and Adams Cassandra (2005, p.90-92)
The dimensions and weight of adobe bricks were given by the authors in inches and pounds so they were converted to the metric system to mm and kg
respectively. From the dimensions the volume of the brick was calculated. The density of each adobe brick was calculated by the given weight of each brick
divided with its volume in kg/m3.
Date
CEB
ADOBE
d
(mm)
W
(mm)
L
(mm)
weight
(kg)
ρ
(kg/m3)
100
100
75
100
225
50
100
250
225
100
150
225
110
300
500
420
225
300
450
220
600
36-38
-
ca. 1600
-
51
Reference
Lyons, A. (2010, p.44)
Keefe, L. (2005, p.63,80)
(used in repair works in East Anglia, UK)
Houben H. and Guillaud H., 1994, p.180
3.1.3 a. Properties of six different tested unfired earth products:
Tensile strength
(MPa)
Bending Strength
(MPa)
Shear strength
(MPa)
Poison’s ration
Young’s modulus E
Bulk density
Water absorption %
Total absorption
Kg/m3
Frost susceptibility
Efflorescence
susceptibility
Duration upon
exposure to weather
CEB (12-19% lime)
ADOBE (unstabilised)
ADOBE (5-9% emulsion)
EXTRUDED hollow
28 days, compressive
strength, (MPa),
24hours water
CEB (unstabilised)
CEB (8% cement)
28 days compressive
strength (MPa)
Table information based on tables given by Houben, H. and Guillaud, H. (1994, p. 148-155)
~2
<0,5
-
0.5-1
~0.5
-
-
1700-2200
-
-
high
Low
poor
2-5
>2
1-2
-
-
7007000
-
1700-2200
-
low
Low
good
>12
>2
-
-
-
0.150.35
-
>2200
-
1020
<7,5
negl.
v low
excel
~2
<0,5
-
-
-
-
-
1200-1700
-
-
high
-
poor
-
1200-1700
<5%
-
low
-
good
>1200
<5%
>20
-
-
good
2-5
-
-
-
-
-
5-12
>2
-
-
-
-
3.1.3 b.Compressed
Compressed stabilized
Stabilized Earth
(CSEB) specific
1.3b.
earth Blocks
block (CSEB)
specificproperties:
properties:
PROPERTIES
symbol
unit
CLASS A
CLASS B
γ
Kg/m3
1900-2200
1700-2000
σ d28
σ w 28
MPa
MPa
5 -7
2-3
2-5
1-2
τ 28
β 28
S 28
μ
E
MPa
MPa
MPa
MPa
1-2
1-2
1-2
0.15- 0.35
700 -7000
0.5 - 1
0.5 - 1
0.5 - 1
0.35 - 0.50
-
C
λ
m
d
-
mm/m°C
mm/m
mm/m
mm/sec
% weight
J/Kg K
W/m K
%
hours
dB
-
0.010-0.015
0.5 - 1
0.2 - 1
1.10-5
5 - 10
~850
0.46 – 0.81
5 - 10
10 - 12
50
Good
Poor
1-2
1-2
General Properties
Apparent bulk density
Mechanical Properties
dry compressive strength (28 day, +20% after 1 year)
wet compressive strength (28 day, after 24 hours
immersion)
tensile strength (on a core, 28 day dry)
bending strength (28 day dry)
shear strength (28 day dry )
Poisson’s ratio
Young’s Modulus
Other properties (thermal, acoustic, etc)
Coefficient of thermal expansion
Swell after saturation (24 hours immersion)
Shrinkage (due to natural air drying)
Permeability
Total water absorption
Specific heat
Coefficient of conductivity
Damping coefficient
Lag time (for 40 cm thick wall)
Coefficient of acoustic attenuation (for d: 40 cm wall @500Hz)
Fire resistance
Flammability
10 - 20
650-850
0.81 – 0.93
10 - 30
5 - 10
40
Average
Average
Notes: 1 MPa = ~ 10 Kg / cm2
These values are the result conducted in laboratories by recognized authorities. They give an idea of what can be reasonably expected
of a product made in accordance with the rules of the art. The soil quality, the nature of stabilizer, the percentage of stabilizer and the
compression pressure influence a lot these values. These values can be obtained with 5 to 10 % cement stabilization and a
compression pressure of 2 – 4 MPa.
Data are taken from: AUROVILLE EARTH INSTITUT: UNESCO chair earthen architecture. “Earth based technologies; compressed
stabilized earth blocks.pdf” (online). Available at:http://www.earth-auroville.com/maintenance/uploaded_pics/4-cseb-en.pdf
[Last Accessed at: 10th February 2014]
52
3.1.3 c. Unfired earthen products, datasheet: properties
Source/Company
country
products
Claytec
NL, DE
ProCrea®
DE
Conluto®
DE
EcoterreTM
UK
bricks, boards,
CEB blocks
Bricks, boards
CEB blocks,
Bricks, boards
CEB blocks,
CEB blocks
clay mix
clay mix
clay mix, sand
clay mix
sawdust, wood
fibers
wood chips,
chopped straw
-
Fiberglass mesh
plastic (boards)
Literature (bricks)
Worldwide
adobe bricks & CEB
unstabilised
stabilized
Product Composition
Clay mix
Fibrous material
Mesh/Fabric
Other/stabilizers
wood chips,
chopped straw
(jute, hemp),
reed or hessian
fabric
(boards)14
perlite
-
-
-
Clay mix (clay ~8-15%, sand, silt, water)
[specific mix for CEB: gravel 15%, sand 50%,
silt 15%, clay 20% + stabilizer (cement3-5%)
Or CEB gravel 15%, sand 30%, silt 20% and
clay 35% + stabilizer (lime 2-6%)]13
may be contained:
Straw, rice husk, bagasse, dung, manure,
-
-
-none-
-none-
-none-
Portland cement (~8%),
lime, or bitumen, or
other animal, or
vegetable stabilizer15
General Properties
3
Density (kg/m )
Price € /m2
Price €/kg
Mechanical Properties
Young’s modulus
Shear modulus
Bulk modulus
Bending modulus
Poisson’s ration:
Yield strength
Tensile strength
700-1900
1280-2000
700-1900
1940
19.64-50.71
-
28.21-49.95
-
15.71-39.50
-
-
≤ 2 MPa
2.3 MPa
2 MPa
2.9-3.8 MPa
3-4%
3-4%
3-4%
Compress. Strength
Elongation
Fatigue strength
Fracture toughness
Mech. Loss coeffic.
3-4%
Thermal & combustion Properties
<110016, 1200-1700 (adobe bricks)17,
1700-2200 (CEB)18 , ca.160019, 1800200020
Ca.2MPa24
2,9-3,8 MPa 25,
5-7MPa26
-
700-7000 MPa21
0,15-0,3522
1-2MPa (CEB)23
2-5 (adobe, CEB), 512 (extruded), >12
(CEB) MPa 27
-
0,2428,
Thermal cond. (λ)
Specific heat capacity
(J/kg k)
Expansion coefficient
Maximum service T.
Decomposition T.
Ignition point T.
Flammability36
0,21(adobe),0,95
0.14, 0.210.91
0.33-0.91
1000-1100
1260
1000
-
ca.850 33
650-850 34, ca.100035
1000 oC
2000 oC
A1-B2
A2-B1
A1-A2/B2
-
-
-
0.21-0.91
-
(CEB)29, 0,04330,
0,46-1.0432
0,46-0,81(adobe),
0,81-0,93(CEB)31
53
Hygro - thermal properties
Water absorption
Water vapour
permeability
Vapour diffusion(μ)
5-10
25-50
Vapour resistivity
MNs/gm
Air permeability
Acoustic properties
Sound absorption
(Alpha w)@500Hz:
51-53dB
Sound reduction (Rw)
-
-
-
-
<5%37
-
5-10
25-50
MNs/gm
-
5-10
25-50
MNs/gm
-
5-10
-
-
-
-
-
1*10-5 mm/sec38
-
-
-
-
-
-
-
-
Primary material production: energy and Co2
Embodied energy
-
-
-
-
-
-
-
-
-
0,44 MJ/kg41
582 MJ /m3 (wall)42
1,112.36 MJ/m343
57,1 kg/m344,
110.11 Kg//m345
-
-
-
-
-
-
-
-
-
CO2footprint:Kg/kg
-
-
Water Usage (l/kg):
Material Recycling: energy, CO2 and recycle fraction:
Embodied energy,
(cradle to cradle)
Heat of combustion
Combustion CO2
-
45 dB(100mm)39,
40(200mm)-50dB(400mm)40
Durability
Water (fresh)
Water (salt)
Weak acids
Strong acids
Weak alkalis
Strong alkalis
Unacceptable
/Limited use
Unacceptable
/Limited use
Unacceptable
Unacceptable
Unacceptable
Unacceptable
Durability
Processability
Organic solvents
Acceptable
Castability
UV radiation
Excellent
Moldability
Wear resistance
Industrial atmosph.
Rural atmosphere
Marine atmosphere
Limited use
formability
Machinability
Weldability
Solder/ brazability
Limited use
Limited use
Limited use
1 to 5
X
5
4
4
X
x
ϭ
Price per brick is 0,85€ incl. VAT. Vat is 21% so price without VAT is ca. 0.67/brick. Prices taken from: http://www.groenebouwmaterialen.nl/a26097526/leemstenen/leemstenen-df-24-x-11-5-x-5-2cm-pallet-a-318-stuk/ Ϯ
Price per brick is 0,93€ incl. VAT. Vat is 21% so price without VAT is ca. 0.74/brick. Prices taken from: http://www.groenebouwmaterialen.nl/a26097582/leemstenen/leemstenen-nf-24-x-11-5-x-7-1cm-pallet-a-237-stuk/ ϯ
Price per pallet (168 blocks) is 164,35 € (incl.VAT) so price per brick is 0,98€ incl. VAT. Vat is 21% so price without VAT is ca. 0.77 per brick. Prices
taken from:http://www.groenebouwmaterialen.nl/a-26290714/leemstenen/leemstenen-2df-24-x-11-5-x-11-3-cm-pallet-a-168-stuk/ ϰ
Price per brick is 1,19€ incl. VAT. Vat is 21% so price without VAT is ca. 0.94/brick. Prices taken from:http://www.groenebouwmaterialen.nl/a26290720/leemstenen/leemstenen-3df-24-x-17-5-x-11-3cm-pallet-a-112-stuk/
ϱ
Price per brick is 0,69€ incl. VAT. Vat is 21% so price without VAT is ca. 0.55/brick. Prices taken from: http://www.groenebouwmaterialen.nl/a22656856/leemstenen/lichte-leemsteen-nf1200-24x11-5x7-1cm-p-pallet-van-416-stuks/ ϲ
Price per brick is 1,14€ incl. VAT. Vat is 21% so price without VAT is ca. 0.90/brick. Prices taken from: http://www.groenebouwmaterialen.nl/a22656866/leemstenen/lichte-leemstenen-2df700-24x11-5x11-3cm-p-pallet-van-350-stuks/
ϳ
All prices for ProCrea ® products are taken from the official price list of the company for 2014. Available at:http://www.thermo-hanf.de/wpcontent/uploads/2014/01/preisliste_deutsch1.pdf ϴ
All prices for Conluto products are found in website:http://www.naturbauhof.de/lad_lehm_stein_produkte.php . The price is given per €/item so the
prices are converted to €/m2
ϵ
Price is converted to €/m2 by dividing the price found by the clay board area (0,94m2) and multiply it with the current rate 1£=1,21€. Prices found per
board £30.32 (ex VAT). Taken from: http://www.phstore.co.uk/render-systems/clay-boards-and-plasters/claytec-clayboard.html
54
ϭϬ
Price is converted to €/m2 by dividing the price found by the clay board area (0,94m2) and multiply it with the current rate 1£=1,21€. Prices found per
board £34.49 (ex VAT). Taken from: http://www.phstore.co.uk/render-systems/clay-boards-and-plasters/claytec-clayboard.html
ϭϭ
Price found for wood fiber boards Pavadentro. For details check: 5. wood fibers
ϭϮ
Price found for 5 clay boards of 16mm, and converted to €/m2, at:http://lehm-bau-shop.de/lehmbauplatte-26.html#
ϭϯ
͞Earth based technologies; compressed stabilized earth blocks. pdf” Available at:http://www.earth-auroville.com/maintenance/uploaded_pics/4cseb-en.pdf ϭϰ
Reed or hessian fabric is used in clay boards as a reinforcement fabric
ϭϱ
The most common industrial stabilizers used in unfired earth products like adobe bricks and compressed earth blocks are cement (usually 8%), lime,
and bitumen emulsion. In the literature, there were also found natural substances for the stabilization of unfired earth like mineral stabilizers (e.g.
bentonite), animal derived stabilizers (e.g. animal excrements such as cowpats, horse or camel dung, animal blood like fresh bull’s blood, casein, termite
hills, etc) and vegetable derived stabilizers like ashes, coconut, cotton or linseed oil, castor oil, tannins, sap from juice of banana leaves, and others. Also,
some other industrial waste stabilizers can be used like fly ash, silicates, stearates, paraffin, waxes, latexes and soap, as well as molasses (sugar industry)
(Houben H. and Guillaud H., 1994, p.87-101)
ϭϲ
ϭϳ
Lightweight earth blocks have a dry density lower than 1100kg/m3 (Keefe, L., 2005, p.96)
In tests, Houben H. and Guillaud H., (1994, p.148-149) did, the density for adobe bricks both unstabilised and stabilized (with 5-9% bitumen
emulsion) is between 1200-1700kg/m3, whereas for compressed earth blocks both unstabilised and stabilized (with 8% cement) ranges between 17002200 kg/m2, with an exception of stabilized compressed earth blocks with lime 12-19% that can present higher density than 2200 kg/m3.
ϭϴ
Houben H. and Guillaud H., 1994, p.148-149
For unfired earth bricks and blocks made typically from clay, silt, and fine sand, will have that density (Keefe, L., 2005, p.43)
ϮϬ
Density given for unfired earth blocks that contain large proportion of stone, gravel and coarse sand (Keefe, L.,2005,p.43)
Ϯϭ
For CEB with 8% cement stabilizer (Houben H. and Guillaud H., 1994, p.148-149)
ϮϮ
For CEB with 8% cement stabilizer (Houben H. and Guillaud H., 1994, p.148-149)
Ϯϯ
For stabilized CEB with 8% cement and compressed at 2-4MPa (Houben H. and Guillaud H., 1994, p.148-149)
Ϯϰ
Compressive strength after 28 days for unstabilised adobe bricks and compressed earth blocks (Houben H. and Guillaud H., 1994, p.148-149)
Ϯϱ
Lyons, A., 2010, p.17
Ϯϲ
Compressive strength given for very dense CEB blocks (Roaf S.et al., 2013, p.286)
Ϯϳ
The compressive strength of unfired earth products is dependent on the stabilizer and the production technique used. According to Houben H. and
ϭϵ
Guillaud H., (1994, p.148-149), the compressive strength after 28 days, for stabilized CEB with 8% cement that between 2-5MPa and for CEB stabilized
with 12-19% lime reached is greater than 12MPa. Similarly, for stabilized adobe bricks with 5-9% bitumen emulsion, the compressive strength reached
is between 2-5MPa. Extruded hollow unfired earth bricks present the compressive strength of 5-12MPa.
Ϯϴ
λ given for unfired perforated clay blocks (Lyons, A., 2010, p.17)
Given λ for uncompressed adobe bricks is 0,21W/mK and for compressed is 0.95 W/mK (www.greenspec.co.uk)
ϯϬ
Elizabeth L, and Cassandra, A., 2005, p.96
ϯϭ
Houben H. and Guillaud H., 1994, p.152-153
ϯϮ
λ given for stabilized CEB (8% cement) and stabilized CEB (10-12% lime) is 0,81-0,93 W/mK and 0,93-1.04 W/mK respectively. For stabilized adobe
with 5-9% bitumen the λ is same with the unstabilised adobe brick and is 0,46-0,81 W/m K .(Houben H. and Guillaud H., 1994, p.152-153)
ϯϯ
Houben H. and Guillaud H., 1994, p.152-153
ϯϰ
Houben H. and Guillaud H., 1994, p.152-153
ϯϱ
Elizabeth L, and Cassandra, A., 2005, p.96
ϯϲ
Flammability tests: Euroclasses (A,B, C, D, E,F) or Building Material classification (A1,A2,B1,B2,B3) for more look at Fire resistance section.
ϯϳ
For stabilized adobes with 5-9% bitumen emulsion and hollow extruded adobe bricks (Houben H. and Guillaud H., 1994, p.152-153)
ϯϴ
For CEB with 8% cement stabilizer (Houben H. and Guillaud H., 1994, p.152-153)
ϯϵ
Lyons, A., 2010, p.17
ϰϬ
Houben H. and Guillaud H., 1994, p.154-155
ϰϭ
Data taken from www.greenspec.co.uk ϰϮ
͞Earth based technologies; compressed stabilized earth blocks. pdf” Available at:http://www.earth-auroville.com/maintenance/uploaded_pics/4cseb-en.pdf ϰϯ
For CEB with 5 % cement, info from ͞Earth based technologies; compressed stabilized earth blocks. pdf” Available at:http://www.earthauroville.com/maintenance/uploaded_pics/4-cseb-en.pdf ϰϰ
͞Earth based technologies; compressed stabilized earth blocks. pdf” Available at:http://www.earth-auroville.com/maintenance/uploaded_pics/4cseb-en.pdf ϰϱ
For CEB with 5 % cement, info taken from: ͞Earth based technologies; compressed stabilized earth blocks. pdf” Available at:http://www.earthauroville.com/maintenance/uploaded_pics/4-cseb-en.pdf Ϯϵ
55
General info:
Earth, as a building material is known since ancient times and was used in the form of big bricks or
blocks to construct walls. Unfired earthen products is shaped to form adobe bricks and blocks (CEB),
clay boards and others that can be used to construct non load-bearing masonry or for ceiling and
floor constructions. Masonry walls constructed by unfired earth products are usually finished with
an earth- or lime based plastered. Such products are very common used in New Mexico and Arizona
(America), Africa and Asia (Halliday S, 2008, p. 148) but its use is also start being again widespread
in European countries (Germany, UK).
Historically, adobe was already used since antiquity to construct tremendous structures. To protect
adobes structures from weathering the structures were faced with stone or fired bricks. Example of
such adobe structures can be found in Egypt (4000 BC) wherein pyramids were built with grand adobe
bricks and faced with stone, in Babylon, where a 160-foot-high adobe ziggurat was faced with fired
bricks and a more early example, the Tower of Babel (7 Th century) that has been built of adobe, faced
with fired bricks and asphalt mortar (Elizabeth L., and Adams C., 2005, p.90). Unfired bricks (adobes)
are probably one of the oldest known “mass-produced” building products (Keefe, L. 2005, p. 62).
Subsoil is mixed with water and fibrous and/or organic material, creating a relatively thick and
malleable muddy mix that will be used to form the bricks (Halliday S, 2008, p.148). The bricks are
formed and left to air-dry under sun, hence known also as “Mud Brick/mudstones” or as “sun-dried”
bricks. Structures made with adobe bricks are dated even back to 8000 BC. But the term “adobe” can
be traced back to the Egyptian “thobe” (mud brick) ca 2000 BC. Later, the word borrowed by Arabs,
it became “al-tub” (meaning al “the” + tub “brick”), which in Spanish became “adobe” (Wikipedia,
2014). In early 18 th century, English borrowed this word from Spanish to name mud sun-dried bricks.
Other names that are found to describe adobe bricks are: “clay lumps” or “clay -earth” (England), as
“brique crue” (raw earth in French), as “Lehmziegel” (Germany) or simple as “clay” (Elizabeth L. and
Adams C., 2005, p. 86).
Image 3.3.1
Compressed earth blocks (CEB) are masonry units
that are similar to adobe bricks but generally larger
in size. The difference with adobe bricks regards
to their production process and that they do not
contain fibrous or organic matter. CEB are made
by a dry process (meaning water is about 10%)
by compressing the soil mixture in a manually
or mechanically operated press. The mechanical
compression that is used will drive out more
moisture than sun baking (Halliday S, 2008, p. 148).
The production process is similar to rammed earth
technique, only in this case the products are blocks
of earth instead of monolithic walls.
Manually production of adobes . Image taken from:
http://www.chiangmailifeconstruction.com/tag/wall/
According to Keefe L., (2005, p.65) compaction of soil under pressure can result in an increase of its dry
density to 10-12%. As Houben & Guillaud (1994, p.227) discovered, uncompacted earth, for instance
adobes, can have a density between 1000-1400 kg/m 3 whilst under compression, the minimum density
will be at least 1700kg/m3 (compressed earth blocks). On the other hand, earth products containing
high proportion of fibrous material (e.g. straw) usually have lower density than 1100kg/m3. These
adobes will be found named as “light Mudbrick”, and because of its lightweight are used to improve
the thermal insulation as an external skin of a mass earth wall (Keefe, L., 2005, p. 96).
56
Building products:
bricks, blocks, boards, plasters
Building products made from unfired earth include adobe bricks, compressed earth blocks of
various sizes and composition, extruded perforated bricks, as well as composite boards made of
mixed clay with fibrous material, and plasters. Nowadays in Europe, commercial adobe bricks
and CEB can be found in a rectangular and parallelepiped shape, but in the past more shapes
were commonly used like pyramidal and cylindrical bricks. Houben and Guillaud (1994, p. 180)
mention that after the World War I, in Germany, a known as “Dünner” method was followed
which resulted in the construction of about 350 houses. In this method, only cylindrical shaped
bricks were used as infill in timber framed structures that were pressed hard against each other
which allowed constructing masonry without the need of adhesive mortar. Conical and pyramidal shaped bricks seem to be much in use in West Africa (Houben and Guillaud, 1994, p. 180).
Picture; range of compressed stabilized earth blocks that a press machine can produce (in this case “Auram press 3000”)
The soil mixture used includes mainly clay (8-30%), silt (≤ 30%), sand and water (≥10%). The
best adobe bricks are reported to contain clay between 8-15% according to Elizabeth L. and
Adams C., (2005, p. 99).Adobe bricks or clay boards often contain also fibers to increase their
thermal insulating properties as well as to prevent cracking, while in traditional old adobe
bricks even animal’s excrement can be contained. Contemporary unfired earth products can be
found unstabilised (raw material), semi-stabilized (use of stabilizer less than 4% of weight) or
stabilized (≥5-12% of weight) (Elizabeth and Adams, 2005, p. 104). More specifically:
clay: works as the “binder” to stick and bonds the soil particles and all the ingredients together. It becomes sticky when wetted and is hard when dry. Content higher than 30% causes excessive cracking. Suitable clay; clay loam and sandy clay (Elizabeth L. and Adams C., 2005, pp: 99-100).
Sand: works as an inert filler held together by clay (like gravel in concrete). It consists of fine grains of
various rocks, mostly quartz. Suitable sand: any type except of beach sand because of the high salt
content.
Water: gives to the mixture the necessary moisture to make possible the forming of bricks. In compressed
earth blocks the water is about 10-12% (dry method) while in other clay products water is usually
more.
Fibers: (When added) can be chopped straw, rice husk, bagasse, and other waste by-product of plants or
animals (hairs, fur). Fibrous materials do not add strength to the bricks but helps to allow the brick
to shrink without cracking during its curing.
Organic: (when added) can be animal’s excrement (manure, dung, etc) or animal urine, blood, etc.
Stabilizers: Common used stabilizers for industrially produced unfired earth are: Portland cement (8%), lime
(12-19%), bitumen emulsion for waterproofing, and fly ash (by-product). There are also natural
animal or plant based stabilizers that can be used. Due to their high cost and sometimes ineffectiveness are not used by companies. Stabilizers are added to increase either the water resistance of
the products either their compressive strength.
57
Processes applied:
Forming by compaction and moulding, sun and air-drying
Production process:
The steps followed to produce unfired earth products are the following:
Ă͘ Soil excavation and screening; At first, soil should be excavated from the site (if the soil is suitable)
either manually (e.g. with shovels, crowbars, rakes, etc) either mechanically (e.g. clamshell excavator,
bulldozer, etc.) and then it is often necessary the excavated soil to be screened in static screens with a
mesh size corresponding to the desired grain size of soil needed (Houben and Guillaud, 1994, p. 202).
Large stones (diameter greater than 50 mm) can be removed manually by hand before the screening.
ď͘ Pulverizing and mixing: Afterwards, soil is mixed with the other ingredients (water, chopped fibers,
stabilizers) either by hand either –most preferable- mechanically by a mud mixer wherein all ingredients
are blended until the mixture becomes uniform and homogeneous. Pulverizing of soil maybe necessary
only in the case of compressed earth blocks.
Đ͘ Stabilization (optional step); soil stabilization can occur with 3 different ways; either by adding fibers
to the soil mixture to reinforce it, either by increasing the soil density by compaction methods or either
by using additives like cement, lime .bitumen and others (Houben and Guillaud, 1884, p. 73) Literature
recommends that stabilization should be avoided for only water resistance and should be made only in
areas with high seismic risk.
Ě͘ Forming (via shape handed, casting): When the mixture is ready, then the bricks can be formed.
For the formation of bricks, various techniques exist; from hand-shaped bricks until casted bricks in
wooden molds of preferable shape and size. In the case of casting, the mixture is poured into a mould or
multiple molds, and the excess material is removed manually. Then the framework (mould) is removed
and adobe bricks are left side to dry under shade (Image 3.3.1).
Ğ͘ Forming (via sawing); One other common way of brick formation (esp. in commercial produced bricks
that a high amount of bricks should be formed within a day) it is the mechanized production method
that takes place in commercial brick making yards by the use of brick making machine to make adobes
on site. The mixture is poured on ground forming a single very large adobe (e.g. 4m2) which is then
cut into several smaller adobes with a taut wire saw or is separated into bricks by a movable formwork
with multiple molds.
Ĩ͘
Forming (via extrusion/pressure); Perforated extruded adobes are also possible to be produced via
the use of vacuum extrusion machines or pressure machines like vertical extruder, horizontal extruder,
mobile extruder (Houben and Guillaud, 1994, p. 219 and block-making press (Keefe L., 2005,p. 67).
The mixture is poured into the machine and under pressure it forms the block. The moulding pressure
applied can be very low (1-2MPa), low (2-4 MPa), average (4-6 MPa) or even higher (6-40 MPa)
(Houben & Guillaud, 1994, p. 226) producing compressed earth blocks with different compressive
strengths if stabilized. Such machines can produce about 500 blocks per day (Keefe L., 2005, p. 67).
This method gives also a greater range of shapes and perforations.
Ő͘ Drying-curing: In all cases, after the earth products are formed, then are left to dry, preferably protected
from strong sun and wind, so under shade in order to prevent cracking from rapid drying of its surface
(Houben and Guillaud, 1994, p. 87). When a stabilizer is used, the curing period and drying conditions
are dependent on the type of stabilizer used. For instance, earth products stabilized with cement must
let to dry in a moist environment protected from sun and wind with a curing drying period of 14-28
days. On the contrary, lime stabilized earth bricks can be dried under sun or in tunnels constructed by
corrugated iron, since lime can dry/cure at ± 60 oC or in autoclaves at 60-97 oC with RH 100% for 24
hours. The curing period in this case can last for weeks (Houben and Guillaud, 1994, p. 87-91).
58
Here it should be mentioned that the forming method influence slightly the compressive strength
of products if they are unstabilised ; compressed earth blocks have been found to have similar or
sometimes less than that of adobe or clay lump (Minke, 2000). In contrast, for stabilized products, the
compaction method can contribute significantly to an additional increase of the compressive strength
of the final product. Compressive strength of individual blocks consistently increases as dry density
increases (Morel, Pkla and Walker, 2005, p. 307). The geometry of the unfired earth unit (block), and
the ratio of height to thickness (aspect ratio) of the block, seems to have a significant influence on
the value of measured compressive strength as compressive strength tests had shown (Morel, Pkla and
Walker, 2005, p. 306). More specifically, tests shows that under direct (confined) compression block
strength increased from 8.5 MPa (aspect ratio 125/140) to 16.0 MPa (45/140) despite a 3% reduction in
density of the thinner block. The experimental skew in apparent strength due to geometry is at least
88% of the measured performance (Morel, Pkla and Walker, 2005, p. 306).
(+) Positive Characteristics:
9Earth that is used to produce the adobe or compressed blocks that will be used like conventional
bricks to form walls, can be in many cases excavated from the site that the building will be
constructed (Woolley et al, 1997, p. 55). Adobes and CEB are also requiring a low energy input
for drying (Lyons A., 2010, p. 17). All these, contribute to a very low embodied energy and almost
minimized transportation cost and energy compared with the one needed for fired manufactured
bricks.
9Fire proof; unfired earth blocks are highly fire resistant (A1-B2 building material classification)
9If unstabilised it can be fully biodegradable. It has also a high potential of recyclability.
9Unfired earth products have usually a significant thermal mass, inertia or insulating properties
when containing also straw and other fibrous material. It masonry made from heavyweight unfired
earth blocks, the solar energy reached the wall will be stored within the walls and radiated into
the interior space after some hours, resulting in warmer space during winter and cooler during
night. Thanks to its thermal mass, the indoor space can take advantage of the diurnal temperature
swings prevalent (Kibert, 2008, p. 363) to decrease heating and cooling.
9Earthen building products present also a degree of hygroscopicity that can passively regulate the
humidity by storing and re-emitting moisture, creating a healthy living environment (Roaf S. et
al, 2013, p. 286). Since they are vapor permeable and breathable, they can restrain condensation
which is a great advantage (Lyons A., 2012,p. 17)
9It can function as self-supporting masonry wall and performs adequately structurally if the ratio
between height and thickness of wall is appropriate/correct (Roaf S. et al, 2013, p. 286).
9Compressed earth blocks can have a high resistance to air-borne sound even in a wall of 150
mm thickness (Keefe L., 2005, p. 96). This is a great advantage for indoor spaces that a significant
noise reduction is required. In tests made by Houben and Guillaud (1994, p. 154-155), the sound
reduction achieved with a masonry made of unstabilised and stabilized compressed earth blocks,
was 40-50 dB for a wall thickness from 20 to 40 cm. Lyons A. (2010, p. 44) reports a sound
reduction of 45 dB for a 100 mm. thick wall built from compressed earth blocks.
9Unfired earth products have also the ability to absorb odours (Lyons A. ,2010, p.44)
9Depending on the composition and density of the adobe bricks and compressed earth blocks,
they can often be self-supportive resulting in internal walls structural walls. Earth products with
compressive strength more than 2 MPa are considered able to build structural self-supporting
walls.
59
(-) Negative Characteristics:
8 Unfired earth products, if left under prolonged exposure to water they will degrade. Table in 3.1.2
b with information based on the tests made from Houben and Guillaud (1994, p. 145-146) showing
the compressive strength after 28 days in six different unfired earth products demonstrate this
very clearly. In unstabilised CEB the compressive strength of 2 MPa was reduced rapidly to 0,5
MPa after 24 hours of being under water condition. This illustrates clearly that unfired earth is
extremely sensitive to water and should be adequate protected not to be penetrated with water for
long periods.
8 Compressed earth blocks can have a great mass but require additional insulation (Roaf S. et al,
2013, p. 286) in order to fulfill regulations for the U-value of exterior walls that is requested by
regulations.
8 Adobe bricks due to their pre-cast molded nature result in some variations which may contribute
to a not very good uniform result on the finished wall, requiring always being plastered for a
better finish. There might be restrictions on the internal decoration on interior walls made from
earth products (depending on the density of the earth block used).
8 Stabilizers are often added when water resistance or higher compressive strength is required. But
when stabilizers are added, it will affect the biodegradability and recyclability of the products.
Portland cement and lime addition can increased the embodied energy of the product but still it
will be lower than compared to baked bricks.
8 Adobe has high compressive strength but is very weak in tension (Elizabeth and Adams, 2005,
p.98).
Alternative Solutions:
Extensive research made by Houben and Guillaud (1997, p. 98-101) had shown that there are also
alternative solutions regarding the stabilization process. Except of the industrial stabilizers that are
used like Portland cement, lime and bitumen, there are also stabilizers that can be produced from
mineral, animal or vegetable products. As Houben and Guillaud (1997, p. 98) states such alternatives
are not used much because of they are less effective. Although, there are natural derived stabilizers
that can have a very high performance similar to the synthetic ones, they are not used due to its high
cost. Animal products that can reduce water sensitivity are excrement (cow pats, horse and camel
dung, pigeon droppings), animal urine which if combined with lime can give surprisingly results
as well as fresh animals blood and casein (Houben and Guillaud, 1994, p. 98-99).One very effective
natural stabilizer is termite hills but it costs 3 times more than cement.
From vegetables, ashes (5-10%) can improve compressive strength and make it more water resistance,
while coconut, cotton and linseed oils can also improve the water resistance of the earth products.
Especially castor oil is highly effective but it is extremely expensive so it is not used (Houben &
Guillaud, 1994, p. 99). Other alternative is stabilizers that are by-products, derived from industrial
waste like paraffin, waxes, molasses, latexes, and fly ash that can replace cement and is a more
environmentally friendly. Soap (at 0.1-0.2%) has also been found to increase water resistance up to
25% although it affects none the strength. Molasses (a product from sugar industry) was found out to
be able to reduce 5% the capillary and improve the compressive strength when added to unfired earth
products (Houben and Guillaud, 1994, p. 101)
60
Applications :
Unfired earth bricks and blocks can construct masonry walls, floors and ceiling in every part of the
building that can be adequately protected from water penetration and continuous high levels of moisture. Clay boards can be applied for acoustical applications and then plastered.
More specifically:
In floors as:
In walls, as:
-
Impact sound insulation and floor surface
-
Insulating floor surface with sub-structural function.
-
As external skin working as additional insulation to a massive wall.
-
Thermal mass and masonry behind cladding or rain-screen protection
-
Self-supportive infill in timber-frame construction
-
External acoustical and thermal mass walls (protected from rain) self-supported
-
Acoustical interior partition walls (no load-bearing but self-supportive)
Design Advices:
When designing with unfired earth products, basic principles should be kept in mind and good detailing is necessary for a successful adobe construction. These are mainly concerned with control of
moisture, water penetration, and therefore erosion. Unstabilised adobe and clay plasters, for minimal
maintenance should be protected by adequate roof overhang and a waterproof foundation (Elizabeth
and Adams, 2005, p. 95). For a larger lifespan, structure should be protected from rain-water damage
which means earth structure should be protected from rain by roof overhangs (Woolley et al, 1997, p.
55). As a first design step, structure should be sited on higher ground protected from areas of standing water or possible flash flooding (Elizabeth and Adams, 2005, p. 95). The base should be made with
durable and water resistant material, and adobe structure should begin after 200-300 mm to prevent
erosion by splash-up or rising damp. In unfired earth constructions, attention to drainage its critical;
roof drainage spouts (canals) should be placed on the south side of the structure so that melting snows
and ice will dray away instead of freezing and blocking the canals with ice dams.
Adobe bricks or CEB should be laid with clay or moderately hydraulic lime mortar and finished with a
breathable plaster or wall finish such as clay or lime plaster (Lyons A., 2010, p. 17). Impermeable paints,
plasters and finish can influence severely the decay of the earth structure instead of restraining it, by
a potential risk of buildup of moisture. Water-soluble Salts can greatly affect the durability of adobe
because they can absorb water, swell and cause spalling of the surface of the blocks, therefore the soil
mixture during the production should not contain more than 0.2% of salt by weight (Elizabeth and
Adams, 2005, p. 100).
Lastly in cold climates, for an optimum thermal performance of the building, the exterior of adobe
constructed walls should be insulated, for instance with rigid insulation that can be attached with
4-inch roofing nails or 6-inch pole barn nails driven into the adobe which can be then covered with metal
chicken wire and plastered with three-coats of stucco (Elizabeth and Adams, 2005, p. 104).
61
References.:
books_
websites_
Elizabeth, L. and Adams, C. (edited) (2005)
Alternative construction; contemporary
natural building methods. Canada: Jon
Willey & sons, pp: 73-105
ARCHI EXPO: ProCrea® Clay Building Elements. Available at: http://pdf.
archiexpo.com/pdf/hock-gmbh-co-kg/procrea-clay-buildingelements/59332-130851.html
Halliday, S. (2008) Sustainable Construction.
Butterworth-Heinemann, p.146-149
AUROVILLE EARTH INSTITUT: UNESCO chair earthen architecture. “Earth
based technologies; compressed stabilized earth blocks.pdf ” (online).
Available at: http://www.earth-auroville.com/maintenance/uploaded_
pics/4-cseb-en.pdf [Last Accessed at: 10th February 2014]
Houben, H. and Guillaud, H. (1994) Earth
construction; a comprehensive guide.
France: practical action publishing, pp.
73, 82-83, 87, 91, 98-101, 148-155, 212,
240-241
BIOHOME: provider.
Available
at:
http://biohome.be/ecologischebouwmaterialen/leempleister/item/procrea-leemplaten [Last Accessed
at: 10th March 2014]
Keefe, L. (2005) Earth building ; methods and
materials, repair and conservation. USA
and Canada: Taylor & Francis, pp: 13, 43,
52, 57, 58, 62-64, 67, 94, 96.
Kibert, Ch. (2008) Sustainable construction; green
building design and delivery. Canada: John
Willey & Sons, p.363
Lyons, A. (2010) Materials for architects and
builders. (4th edition) Elsevier, pp.15, 17,
44, 400
Morel , J. , Pkla, A., and Walker, P. (2005)
Compressive strength testing of compressed
earth blocks. (online) Available at: www.
elsevier.com/locate/conbuildmat [Last
accessed: 20 March 2014)
Peter, S. (2011) Materials revolution; sustainable
and multi-purpose materials for design and
architecture. Birkhäuser, p.150-151
Roaf, S. et al (2013) Ecohouse; a design guide (4th
edition), Routledge: pp. 286
CLAYTEC: adobe manufacturer. Available at: http://www.claytec.de / and http://
www.claytec.nl/producten.html [Last Accessed at: 10th March 2014]
CONLUTO; adobe manufacturer. Available at: http://www.conluto.de/SchwereLehmsteine.123.0.html [Last Accessed at: 10th March 2014]
CONSTRUCTION
RESOURCES.
Available
at:
http://www.
c o n s t r u c t i o n r e s o u r c e s . c o m / p r o d u c t s / e nv e l o p e / c l ay t e c _ l .
asp?PageCategoryID=2
GROUNEBOUWMATERIALEN.NL: Provider with green-ecological building
materials. Available at: http://www.groenebouwmaterialen.nl/ [Last
Accessed at: 10th February 2014]
GREENSPEC: National Green Specification. Unfired clay blocks [online].
Available at: http://www.greenspec.co.uk/building-design/blocks/#dense
[Last Accessed at: 10th March 2014]
GREENSPEC: National Green Specification. Unfired bricks and structure
[online]. Available at: http://www.greenspec.co.uk/building-design/
unfired-clay-and-structure/ [Last Accessed at: 10th March 2014]
GREENSPEC: National Green Specification. Unfired clay bricks [online].
Available at: http://www.greenspec.co.uk/building-design/bricks/#unfire
[Last Accessed at: 10th March 2014]
Sutton, A., Black, D. and Walker, P. (unknown)
Unfired clay masonry; an introduction to
low-impact building materials (online).
Available at: http://www.bre.co.uk/
filelibrary/pdf/projects/low_impact_
materials/IP16_11.pdf
LEHM- BAU-SHOP. Available at: http://lehm-bau-shop.de/lehmbauplatte-26.
html [Last Accessed at: 10th March 2014]
Quagliarini, E. and Lenci, St. (2010) The
influence of natural stabilizers and natural
fibres on the mechanical
NATURE BAUHOF: online shop. Available at: http://www.naturbauhof.de/lad_
lehm_stein_produkte.php [Last Accessed at: 10th March 2014]
properties of ancient Roman adobe bricks..
Department of Architecture, Building
and Structures, Polytechnic University of
Marche, Italy. Journal of cultural heritage,
vol. 11 (2010) pp;309-314 (online)
Available at: http://www.sciencedirect.com
[Last Accessed at: 10th February 2014]
Woolley et al., [1997] Green Building Handbook;
Great Britain: E& FN Spon, p.55
IBSTOCK; Ecoterre CEB products. Available at: http://www.ibstock.com/
Ecoterre-intr-design.asp [Last Accessed at: 10th March 2014]
THE PASSIVE HOUSE STORE. Available at: http://www.phstore.co.uk/
render-systems/clay-boards-and-plasters/claytec-clayboard.html [Last
Accessed at: 10th March 2014]
THERMO-HANF: ProCrea® .Available at: http://www.thermo-hanf.de/
produkte/procrea-produkte/procrea-lehmplatten/ [Last Accessed: 3th
march 2014]
PROCREA; adobe manufacturer. Available at: http://procrea.de/wordpress/
[Last Accessed at: 10th March 2014]
62
3.2 Rammed-Earth products
Material: earth (rammed earth) (geramd aarde)
Category: building material
Application: interior or exterior
(non or) load-bearing masonry
3.2.1 Rammed-Earth products companies list:
Company name
code
CLAYTEC e.K.
Mfr
DE
Conluto
UK
Earth structures (Europe) Ltd
NL
DE
Mfr
website
http://www.claytec.nl/
www.claytec.de/
http://www.conluto.de/
contact /email
info@claytec.nl
service@claytec.de
info @conluto.de
Mfr
http://www.earthstrcuture.co.uk
info@earthstructure.co.uk
*Pvd: Provider / Mfr : manufacturer/ Blder: rammed-earth builder
Figure 2.1.1:
Locations with experts on earth constructions
(processors of rammed-earth buildings) in the Netherlands
ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
Bloemendaal Projecten
Joost Boender
Jeffrey de Boer
Leembouw Capiau
Chris Drijvers
Ecostuc
Ecowonen
Euroleem
Frijns Leembouw
Stukadoorsbedrijf Groothuysen
Hanssen Bouwbiologisch
Aannemersbedrijf
ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
ƒ
Interstuc Oudewater
Kloppenburg Stro en
Leembouw
Laugs Bouw BV
Thomas Laugs Leembouw
leemstuc.nl
Maas Oplossingen
Oudshoorn Leemwerk
Sebunga
Tuvalu Strobouw
Van der Veer BV
63
RAMMED-EARTH
3.2.2 a. Rammed-earth datasheet: products & sizes
U (W/m2K)
3.3-1.7
3.30
3.00
2.70
2.10
1.70
Rw (dB)
53-57
53
55
57
57
57
ρ (Kg/m3)
2300
2.94
0,34
-
-
λ ( W/m K)
0,79-0.81
~0.66
~0.72
~0.81
R (m2k/W)
0.3-0.537
0.30
0.33
0.37
U (W/m2K)
3.3-12.7
3.30
3.00
2.70
Rw (dB)
53-57
53
55
57
ρ (Kg/m3)
2400
2400
2400
2400
0.8
~1.50
-
-
-
2400
variable
variable
-
-
-
-
1700-2200
variable
variable
variable
-
-
-
40
300
variable
variable
-
-
-
58.3
h (m)
max.6
max.6
max.6
max.6
max.6
max.6
variable
max.6
d (mm)
250-300
200
240
300
w(mm)
variable
variable
variable
variable
h (m)
variable
variable
variable
variable
Claytec®
facade
80-100
1500
Conluto®
150-200
Claytec®
In-situ
d (mm)
200-650
200
240
300
450
650
300+[100
(insulation)]
Company
RAMMED-EARTH (precast)
R (m2k/W)
0.3-0.59
0.30
0.33
0.37
0.48
0.59
w(mm)
variable
variable
variable
variable
variable
variable
Company
Claytec®
Wall
Earth
structures Ltd
SRE panels
λ ( W/m K)
0,79-1,10
~0.66
~0.72
~0.81
~0,95
~1,10
0.096 +[0.04
(insulation)]
2300
20002100
3.2.2
Rammed-earth,
specific properties
(literature):
2.2b.b.Rammed
Earth Literature:
Properties
Table information based on tables given by Houben, H. and Guillaud, H. (1994, p. 148-155) and Birznieks, L. (2013, p.16-47)
Houben, H. & Guillaud, H. (1994)
Rammed-earth
Rammed-earth
(stabilized)
(unstabilised)
(8% cement)
28 days compressive strength (MPa)
28 days, wet compressive strength,
24hours water (MPa)
Tensile strength (MPa)
Bending Strength (MPa)
Shear strength (MPa)
Poison’s ration
Young’s modulus E (MPa)
Bulk density (kg/m3)
Thermal expansion coefficient (mm/moC)
swelling
Shrinkage due to drying (mm/m)
Sorptivity (mm/min)
permeability (mm/sec)
Total water absorption (kg/m3)
Specific heat capacity , C (J/kg K)
Thermal conductivity, λ (W/m Κ)
Frost susceptibility
Efflorescence susceptibility
Duration upon exposure to weather
Fire resistance
Birznieks, L. (2013)
Rammed-earth
Rammed-earth
(stabilized)
(unstabilised)
(3-9% cement)
~2
<0.5
2- 5
> 2.0
0.5-5
-
3-20
-
0.5 - 1.0
~0.5
1700-2200
1- 2 mm/m
~850
0.81-0.93
average
low
average
excellent
1- 2
0.15 - 0.35
700 - 7000
1700-2200
0.010 – 0.015
1–2
1,10-5
>20
650-850
0.81-0.93
low
Low
excellent
excellent
0.05-0.65
0.5-0.65
0.30-2.60
0.3-2.60
600-850
1700-2100
0-20%
0.29-1.21
1830
0.5-1.2
-
600-850
1700-2100
0.25-1.63
1830
0.5-1.2
-
64
3.2.3 Rammed-earth datasheet: properties
Source/Company
country
products
Claytec
Conluto®
NL, DE
DE
Earth
structures Ltd
UK
prefabricated
walls/facades
prefabricated
walls/facades
-
-
-
yes
-
yes
2300-2400
-
1700-2000
-
2000-2100
-
600 MPa
0.3-2 MPa
-
-
-
3,5-12 MPa
-
-
0.43-0.8623, 0.5-0.1224, 0.81-0.9325 , 0. 8-1.526
-
-
183027 , 650-85028
-
4hours /noncombustible
On-site walls,
prefabricated
walls/facades
Literature (bricks)
Worldwide
Rammed earth
unstabilised
Rammed earth
stabilized
Product Composition
Clay mix
Stabilized
General Properties
Density (kg/m3)
Price € /m2
Price €/kg
Mechanical Properties
Young’s modulus
Shear strength
Bulk modulus
Bending strength
Poisson’s ration:
Yield strength
Tensile strength
Compress. Strength
Elongation
Fatigue strength
Fracture toughness
Mech. Loss coeffic.
Thermal & combustion Properties
Thermal cond. (λ)
0,79-1,10
Specific heat capacity
(J/kg k)
Expansion coefficient
Maximum service T.
Decomposition T.
Ignition point T.
Flammability29
noncombustible
-
30% gravel, 45% sand, 13%silt,
12% clay, water (5-7,5%)1
-none5-8% cement/8-12% lime
1700-21002, 1700-22003
80-250 (d:300mm)
80-250 5(d:300mm)
6
≤ 0.02 €/kg
0.05-0.033 €/kg7
4
600-8508, 700-70009
0.5-0.65 MPa
0.3-2.6011 MPa
0.5-1.0012 MPa
0.15 - 0.3513
0.05-0.6514 MPa
1-215, 0.30-2.6016 MPa
3-2020 MPa, 2-521 MPa,
0.5-517 MPa, 05-218
19
MPa, ≤1 MPa
≤1022 MPa
10
-
0.010-0.015 mm/moC
-
Non-combustible, excellent fir resistance
Hygro - thermal properties
Water absorption
Water vapour
permeability (μ)
Vapour diffusion(μ)
5-10
25-50
MNs/gm
-
-
Vapour resistivity
Air permeability
Acoustic properties
Sound absorption
(Alpha w)@500Hz:
Sound reduction (Rw)
53-57
Primary material production: energy and Co2
Embodied energy
-
3
15 MNs/gm
-
-
7,2-11,5% w/w,30
>20 Kg/m3
-
-
-
1.10-5 mm/sec31
-
-
-
40-58.3
-
40- 50 (200-400mm)
-
-
(unstabilised)18-36
65
CO2footprint:Kg/kg
Water Usage (l/kg):
Recycle content
Material Recycling: energy, CO2 and recycle fraction:
Embodied energy,
(cradle to cradle)
Heat of combustion
Combustion CO2
-
-
-
MJ/m332
-
-
-
-
-
-
-
Durability
Water (fresh)
Water (salt)
Weak acids
Strong acids
Weak alkalis
Strong alkalis
Unacceptable
/Limited use
Unacceptable
/Limited use
Unacceptable
Unacceptable
Unacceptable
Unacceptable
1 to 5
X
Durability
Organic solvents
Acceptable
Processability
Castability
UV radiation
Excellent
Moldability
4
Wear resistance
Industrial atmosph.
Rural atmosphere
Marine atmosphere
Limited use
formability
Machinability
Weldability
Solder/ brazability
4
4
X
x
Limited use
Limited use
Limited use
ϭ
Birznieks, L. (2013, p.16)
Birznieks, L. (2013, p.16)
ϯ
Houben and Guillaud (1994, p.148-149)
ϰ
Maniatidis & Walker (2003, p.84)
ϱ
Maniatidis & Walker (2003, p.84)
ϲ
Birznieks, L. (2013, p..43)
ϳ
Birznieks, L. (2013, p.43)
ϴ
Minke (2000)
ϵ
Houben and Guillaud (1994, p.148-149)
ϭϬ
Birznieks, L. (2013, p.16)
ϭϭ
Birznieks, L. (2013, p.16)
ϭϮ
Houben and Guillaud (1994, p.148-149)
ϭϯ
Houben and Guillaud (1994, p.148-149)
ϭϰ
Birznieks, L. (2013, p.16)
ϭϱ
Houben and Guillaud (1994, p.148-149)
ϭϲ
Birznieks, L. (2013, p.16)
ϭϳ
Birznieks, L. (2013, p.16)
ϭϴ
Houben and Guillaud (1994, p.148-149)
ϭϵ
Greenspec.co.uk, 2013
ϮϬ
Birznieks, L. (2013, p.16)
Ϯϭ
Houben and Guillaud (1994, p.148-149)
ϮϮ
Greenspec.co.uk, 2013
Ϯϯ
Maniatidis & Walker (2003, p.19)
Ϯϰ
Birznieks, L. (2013, p.33)
Ϯϱ
Houben and Guillaud (1994, p.148-149)
Ϯϲ
Lyons, A. (2010, p.399)
Ϯϳ
Birznieks, L. (2013, p.33) and Maniatidis & Walker (2003, p.19)
Ϯϴ
Houben and Guillaud (1994, p.148-149)
Ϯϵ
Flammability tests: Euroclasses (A,B, C, D, E,F) or Building Material classification (A1,A2,B1,B2,B3) for more look at Fire resistance section.
ϯϬ
King, B. (p.62, Buildings of earth and straw; structural design for rammed earth and straw bale architecture)
ϯϭ
Houben, H. & Guillaud, H. ,1994, 148-155
ϯϮ
Keefe, L. (2005, p.4)
Ϯ
66
General info:
As it was mentioned earlier in unfired earth (adobe/CEB) constructions, earth construction is one
of the oldest forms of construction that mankind achieved and as Woolley et al. (1994, p. 55) stated
“building with earth is set to become one of the main ingredients of a truly sustainable architecture of the
future, provided that regulations and codes don’t hamper progress”. Rammed-earth buildings are made
of earth with a different technique than the adobe-earth buildings and building examples can be found
in many countries around the world from dry climates ‘till cold-tempered climates, many of which
have survived hundreds of years (Lyons, A., 2010, p. 397). Especially, in southern coast of England
in the UK (in Hampshire) from about 1830 onwards, numerous buildings were constructed by using
rammed-earth method and chalk additive, from which at least 100 of them are still standing (Keefe,
L., 2005, p.16). Historically, rammed-earth can be found in a range of climate zones, from Himalayan
Mountains to deserts of North Africa (Elizabeth L. and Adams C., 2005, p. 160-161).
Rammed earth, known also as “taipa” (Portuguese), “tapial” (Spanish) and “pisé de terre” (French)
can be defined as “an ancient earth building technique that involves dynamically compacting moist
sub-soil between removable shuttering to create an in-situ monolithic compressed earth wall that is both
strong and durable”. The technique used for rammed earth is similarly to the one used for production
of CEB and known since antiquity, but only over the last 25 years (Halliday, S. 2008, p.148) through
research and field experiments has been significantly developed especially in Australia and Germany
(Keefe, L. (2005, p. 88), and is now often carried out in a largely mechanical site process by specialist
construction companies (Halliday, S. 2008, p. 148).
Rammed-earth walls can be built either on site or can be produced as prefabricated heavyweight façade
and wall elements in specific construction companies. In both cases, the compaction and pressure of
the clayey soil by rammers (manual or pneumatic) into a strong formwork (often of metal-reinforced
plates) either on site either in the manufacture companies results in production of monolithic heavy
and load-bearing walls.
Building products:
monolithic walls in-situ / prefabricated façade and wall systems
Rammed-earth monolithic walls or prefabricated wall and façade systems are mainly used when loadbearing massive walls are required as an alternative reduce significantly the structure required for the
building as well as decrease the air-borne sound. It is made from:
Clay& silt: works as the “binder” to stick and bonds the soil particles and all the ingredients together. It
becomes sticky when wetted and is hard when dry. Content higher than 30% causes excessive
cracking (Elizabeth L. and Adams C., 2005, pp: 99-100)
Suitable clay; sandy- clay or clayey-sand, sandy loam, stony clay (Lehmbau Regeln)
Note: topsoil (soil on 400-450 mm depth) is unsuitable to be used because of its high content of
organic matter (Keefe, L., 2005, p. 34) which biodegrades rapidly, absorbs water and is highly
compressible. Thus, such soil should be totally avoided or used at max. 1-2% of total mass.
Sand: works as an inert aggregate by granular soils that held together by clay (like gravel in concrete).
Any types of sand and small gravels are suitable except of beach sand because of the high salt
content.
Water: gives to the mixture the necessary moisture to make possible the forming of bricks.
water content should be less than 10% (dry method)
Stabilizers: Most common used industrial stabilizers are: Portland cement (5-8%. optimum is considered
the 8%), and non-hydraulic Lime (3-10% (Keefe, L., 2005, p. 53) and 8-12%) or bitumen (asphaltic emulsion) as waterproof agent (Houben & Guillaud (1994) and Keefe, L,2005, p. 53)
67
Note: Houben and Guillaud (1994, p. 78) present a table where it is clear that for compressive strength,
an optimum mixture of soil particles exists; for instance, soil containing 10% silt was giving a compressive
strength of 4.5 MPa while soil with 40% silt presented a higher compressive strength of 6 MPa. And
although, by adding more silt someone would expected that may increase more the soil’s compressive
strength, contrary, the soil with 70% had a lower compressive strength (5.5 MPa) than the soil containing
40% silt. This indicates that probably optimum percentage of the ingredients; clay, silt, sand, water and
so on exists which gives the best performance characteristics of earth-made walls.
Processes applied:
Casting and forming via compaction (pressure or vibration), air-drying & curing
Production process:
The first steps that are followed for producing unfired earth bricks and blocks are also followed to
construct rammed-earth walls. These are concerning more to soil excavation, preparation and mixing.
The main difference of rammed earth and adobe/clay products are mainly to the proportion of the
ingredients that are used (for instance water is only used here is max. 10%) as well as to its forming
process. More specifically, the steps to construct a rammed-earth wall are:
Ă͘ Soil excavation and screening; (similar with described in “1. Unfired earth”)
ď͘ Pulverizing and mixing: (similar with described in “1. Unfired earth”. In rammed-earth mixtures,
fibrous materials (like chopped straw, fibers, etc) are usually avoided to create more smooth and
“uniform” wall finish although there are examples with rammed earths containing flax fibers for
reinforcement)
Đ͘ Stabilization (optional step); For the soil stabilization of rammed-earth, mostly industrial
stabilizers are used like Portland cement and lime in order to improve cohesion of the stabilized
earth mix, increase its strength and water resistance. It is preferably to let rammed-earth walls
unstabilised or environmentally reasons since such additives influence the biodegradability of the
material.
Ě͘ Forming (via formwork): Rammed-earth is a production forming method whereby a mixture of
soil earth is compacted in multiple layers via usually a wood or metal formwork. The formwork
can be either small units or integral (Houben and Guillaud, 1994, p. 202). The formwork is
filled with earth layer by layer, typically approximately 100-150 mm deep (Lyons, A, 2010, p.
399) and within the rigid formwork, it is firmly tamped down and compressed to approximately
2 /3 of the filling height. Inevitably, ramming gives a variation in density between the upper
part and lower part of the layer of each lift (Lyons, A., 2010, p. 399). Ramming can be made by
impact (dynamic compression) or vibration (Houben and Guillaud, 1994, p. 200). In both cases,
compaction should ensure a good compressive strength and smooth finish wall appearance. The
formwork that is used can be stripped off and removed as soon as the new layer is constructed,
and the forming step is repeated until the required wall height has been achieved. Rammed earth
construction technique is mostly an on-site construction process, although the last years it is
possible prefabricated rammed-earth walls and façade elements to be pre-casted and transferred
to the site, reducing the construction time and their “weather dependency” when constructed
in-situ. In this case, the prefabricated rammed-earth walls are produced in specific size weather
protected workplace near the site, and transferred and assembled on site via tow trucks or a crane.
Ğ͘ Drying-curing: Rammed earth walls are left to dry before plastered but needs a shorter curing
period than adobe bricks due to its low content in water and to its compaction technique.
Rammed earth is load-bearing and self-supporting instantly after its construction with increasing
compressive strength as function of time (Houben and Guillaud, 1994 and Keefe, L., 2005).
68
(+) Positive Characteristics:
9Earth building techniques, like rammed earth construction, certainly have a lower environmental
impact compared to conventional building techniques, and have a vastly lower embodied energy
than equivalent constructions with brick, concrete, or steel (Wolley et al., 1997, p.55) As it is
mentioned by David Easton “solid walls of earth can reduce the use of construction materials
with high embodied energy, reduce construction waste, conserve energy in the operation of the built
structure, and offer significant longevity” (Elizabeth and Adams, 2005, p.158)
9Because of their high thermal mass, they demand low energy of heating and cooling so rammedearth buildings “can very much promote the health of the global atmosphere by their very low
emissions of greenhouse gases” (Roaf S. et al, 2013, p.127)
9Rammed-earth walls that are unstabilised are breathable and vapour permeable, allowing good
indoor air quality to be achieved and work also similarly as other biodegradable natural materials
as a humidity and moisture regulator for the indoor space.
9The warm finish and colour of uncoated walls gives a warm feeling to space.
9Very good in absorbing sound vibration and resistance to air-borne sound leading to a sound
reduction of 40-50 dB (for wall thickness of 20-40 cm, Houben and Guillaud, 1994, p.154-155).
CSIRO tests indicate a sound transmission rating of over 50 decibels for a rammed earth wall of
250mm (Rammed Earth Constructions.com, 2014)
9No emission of VOCs. Non-toxic and no emissions of CO2 during their manufacture.
9Unstabilised rammed-earth is fully recyclable and biodegradable.
9Incombustible, present high resistance to fire flammability͘ CSIRO tests showed that a 250 mm
rammed earth block wall achieved a 4 hour fire resistance rating, while a 150 mm wall thick
achieved a rating of 3 hours 41 minutes (Rammed Earth Constructions.com, 2014) 1
( - ) Negative Characteristics:
8 Earth structures (made by unstabilised adobe bricks, CEB and rammed -earth) can be very
susceptible to frost damage and water; the presence of excess moisture can have in significantly
reducing the compressive and tensile strength of the material which can cause severe problems
(Keefe, L., 2005, p. 31).
8 Rammed-earth although presents a high inertia and thermal mass as a result of their thickness
and density, they have poor thermal insulating properties; the thermal conductivity of soil
ranges typically between 0.85 to 1.5 W/m K (Lyons, A., 2010, p. 399).
Thus, in the most cases especially in cold climates, to be able to fulfill thermal requirements of
Building Regulations, a wall thickness of more than 700 mm is required which can increase the
cost of the construction but also reduce significantly the area of the living indoor space. Thus
it is more recommended, rammed-earth to be built in a smaller thickness of 200-350 mm and
additional thermal insulation to be applied in the wall.
8 Rammed-earth constructions in-situ are weather dependent
1
Available at: http://www.rammedearthconstructions.com.au/index.php?mp_id=5
69
8 Prefabricated rammed-earth walls and façade systems can increase significantly the embodied
energy of the wall as a result of transportation needed. Especially in cases that prefabrication
takes place not next to the site but in individual manufacturer companies and the products are
delivered to the site, the embodied energy can be high and maybe similar to conventional wall
systems.
8 Stabilization process can increase properties of the rammed-earth like water resistance and
compressive strength, making it more resistant to erosion, but it can dramatically chemically
change the nature of material reducing or minimizing its biodegradability when industrial
stabilizers are used. For instance, a 6% by weight of Portland cement added to an earthen made
wall can increase it in compressive strength and enables it to have a high resistance to moisture
and surface erosion (Keefe, L, 2005, p. 52), but however, during the stabilization process as Keefe
underlines “the material undergoes a fundamental and irreversible chemical change so it is no
longer recyclable, becoming in fact, a sort of brown concrete”. Thus, it should be avoided unless it
is absolutely necessary. In the most cases, reinforcement and protection of rammed-earth is also
possible with other means than stabilization and good design is the key to longevity of rammedearth buildings. Moreover, stabilizing earth by low-permeability cement and especially when
combined with plastic-impermeable finishes and paints, can prevent earth walls from “breathing”
and losing excess moisture through surface evaporation (Keefe, L., 2005, p. 29)
Alternative Solutions:
The same applied as the ones described in section: “alternative solutions” in “1. Unfired earth (adobe/
clay/CEB)”. Moreover, it is considered that if it is necessary a synthetic stabilizer to be added, this to
be non-hydraulic lime in a percent of 3-10 by weight (Keefe L, 2005, p. 53). This will be sufficient to
improve water resistance, wet strength while it will not have such a drastic effect like cement and thus
it may be reversible in a long-term period.
Applications :
Rammed-earth walls are self-supporting walls and can be load-bearing walls so they can be built as
exterior or internal walls when massive thermal mass is required. Prefabricate façade and wall systems
can be applied also for similarly applications providing a good thermal mass to the overall building.
Design Advices:
In order to improve the durability and longevity of rammed –earth exterior walls, weather protection
at head and base must be provided. Overhangs are necessary in the case of unstabilised rammed-earth
walls, and eaves should be detailed in such way that they protect sufficiently the walls (Lyons, A.,
2010, p. 399). Exterior unstabilised walls should be plastered for more protection with clay render,
lime/sand render, limewash, or even as it is found in traditional earth walls of the past with chalk
slurry, coal tar, and sand (Keefe, L., 200, p. 29).
In rammed-earth masonry , windows and door openings should be limited to no more than 1/3 of the
length of the wall to ensure structural stability and lintels should be sufficiently robust to take static
loading and the effects of ramming further lifts of earth (Lyons, A., 2010, p. 399). Lintels can be hidden
with the top lift of the earth wall or can be visible and can be in the form of timber or reinforced
concrete beams with a required width of min. 300 mm to each edge to ensure ability of loading to be
spread within the structure (Lyons, A., 2010, p. 399).
70
References.:
books_
websites_
Bui Q.B. & Morel J.C. [2008] Durability of rammed earth walls exposed for
20 years to natural weathering. Building and Environment, 44, 2009,
p.912-919 [online] Available at: http://www.elsevier.com/locate/
buildenv [last accessed: 28th December 2013]
EARTH
MATERIAL:
Sustainable
resources. Available at: http://earth.
sustainablesources.com/#Rammed
[Last Accessed at: 20th March 2014]
BUI Q.B. & MOREL J.C. [2008] Accessing the anisotropy of rammed earth.
Construction and Building Materials 23. Available at: http://www.
elsevier.com/locate/buildenv [last accessed: 28th December 2013]
Birznieks, L. [2013] Designing & Building with compressed earth [Msc
thesis]. Delft: TU DELFT. Faculty of Architecture.
Elizabeth, L. and Adams, C. (edited) (2005) Alternative construction;
contemporary natural building methods. Canada: Jon Willey & sons,
pp: 151-171
Hall, M. & Djerbib Y. [09 2005] “Stabilized Rammed Earth (SRE) Wall
Construction.” Earth Structures. [online]. Available at: www.
earthstructures.co.uk/feature_sra_amended.pdf [last accessed 29th
January 2014]
Hall, M. & Djerbib Y. [2005] Moisture ingress in rammed earth: Part 1—the
effect of soil particle-size distribution on the rate of capillary suction͘
Construction and Building Materials, 18, 2006 [online] Available
at:
http://www.journals.elsevier.com/construction-and-buildingmaterials [last accessed: 28th December 2013]
Hall, M. & Djerbib Y. 2005] Moisture Ingress in rammed earth: Part 2 –
The effect of soil particle - size distribution on the absorption of static
pressure-driven water. Construction and Building Materials, 20, 2006:
p. 375-383[online] Available at: http://www.journals.elsevier.com/
construction-and-building-materials [last accessed: 28th December
2013]
Hall, M. & Djerbib Y. [2005] Moisture ingress in rammed earth: Part
3 – Sorptivity, surface receptiveness and surface inflow velocity.
Construction and Building Materials, 18, 2006 [online] Available
at:
http://www.journals.elsevier.com/construction-and-buildingmaterials [last accessed: 28th December 2013]
Halliday, S. (2008) Sustainable Construction. Butterworth-Heinemann,
p.148
Houben, H. and Guillaud, H. (1994) Earth construction; a comprehensive
guide. France: practical action publishing, pp. 5-8, 72, 78, 202-207
Keefe, L. (2005) Earth building ; methods and materials, repair and
conservation. USA and Canada: Taylor & Francis, pp: 4,7,8,13,2829,31,43,52-57, 65, 85-90
Lyons, A. (2010) Materials for architects and builders. (4th edition) Elsevier,
pp.397-399
Maniatidis, V. & Walker P. [May 2003] A Review of Rammed Earth
Construction. [Online]. University of Bath. Available at : http://
people.bath.ac.uk/abspw/rammedearth/review.pdf [Last accessed:
10th January 2014)
Roaf, S. et al (2013) Ecohouse; a design guide (4th edition), Routledge: p.127
Woolley et al., [1997] Green Building Handbook; Great Britain: E& FN
Spon, p.55
71
GREENSPEC: Rammed earth (RE) and
stabilized rammed earth (SRE)
Available at: http://www.greenspec.
co.uk/building-design/rammedearth/ [last accessed at: 25 February
2014]
RAMMED EARTH CONSTRUCTIONS:
Available
at:
http://www.
rammedearthconstructions.com.au/
index.php?mp_id=5 [last accessed at:
25 February 2014]
RAMMED
EARTH
CONSULTING:
Available
at:
http://
rammedearthconsulting.com/
rammed-earth-cement-co2.htm
[Last Accessed at: 20th March 2014]
RAMTEC ®; Rammed earth specialists.
Available at: http://ramtec.com.au/
[Last Accessed at: 20th February
2014]
72
3.3 Straw products
Material: straw (stro)
Category: building & insulating material
Application: thermal and sound insulation,
load-bearing masonry, partitioning walls
3.3.1 Straw products companies list:
73
3.3.2 a. Straw datasheet: straw bales sizes
74
3.3.2 b. Prefabricated compressed straw datasheet: products and sizes
75
3.3.3 Straw datasheet: properties
76
77
78
General info:
Straw is a natural raw material, gathered by the harvesting of wheat, rice barley, oats and rye, hemp
and other crop plants. It is a by-product and its main agricultural use is for animal litter, bedding
and for soil enrichment as part of compost with organic compounds that can work as a fertilizer.
Petrochemicals and artificial fertilizers had reduced the need of straw (Woolley and Kimmins, 2000,
p.157) so in the most cases straw is considered a waste material and is field burnt when not used which
offsets carbon, N 2 O and fine dust particles that are air polluting.
Straw was used as a building material since the first settlements of ancient Egypt but its revival as
“alternative” cheap building material revived again at the end of the 1980s by the introduction of the
baling machines in farming production and especially in USA and Canada (Woolley and Kimmins,
2000, p. 156). Straw fibers are used as tensile reinforcement in earth buildings like adobes and cob
constructions (Elizabeth and Adams, 2005, p. 210)
Straw is a renewable resource in plentiful quantities; about 750.000.000 tons of straw are produced
worldwide annually, which about 60% is baled with the rest ploughed into the soil (Woolley and
Kimmins, 2000, p. 157). Once used it can decay naturally back to the earth. Nowadays, straw bales can
be used to construct buildings that are energy-efficient that have a low environmental impact.
Nowadays, straw is used in the buildings in many forms; straw bales are used as load-bearing walls or
as infill bales, straw panels as partition walls and straw fibers mixed with earth for cob or rammedearth and adobes constructions. In straw bale buildings, the usually rectangular shaped bales are
stacked to each other forming a load-bearing wall. The constructed walls are laid in a staggered
manner like conventional masonry, but without mortar (in general) (Halliday, S., 2008, p. 151) and
then are plastered with clay or lime-based plaster.
Building products:
monolithic walls in-situ / prefabricated façade and wall systems, block units
Building products of straw include straw bales bounded with two or three strings and shaped into
rectangular or circular shapes, prefabricated compressed straw products like straw boards, slabs and
blocks and structural insulating panels (SIP).
Compressed straw products are used mainly as partitions, linings or as
thermal insulation to roof decking (Wolley et al., 1997, p. 44) while straw
bales are used as structural and insulating elements to build masonries
that are load-bearing or as infill in timber frame constructions. In
compressed straw boards, sometimes additives like wood glues or resins
are used, although usually they are avoided. Finishing options for the
surface of the straw boards include foil wrapping, melamine, laminate
and water based spray applications. The products properties vary
depending on the straw used and the crop origin which can present great
variations depending on the strength of stem (wheat straw is considered
the stronger) and other influencing factors like weather, soil, levels of
fertilizer, growing time and so on (Woolley and Kimmins, 2000, p. 157)
Processes applied:
Baling, compacting, forming by heat + pressure, surface treatment-finish
79
Production process:
There are many ways of manufacturing straw products suitable for building applications depending
on the provider company, the intended use, on the builders and on the stringency of each country’s
building regulations. The most common methods are three which result in different building products
and are:
a. Straw bales - method used: Straw baling -with no other treatment: Straw bales are the simplest
building product occurring from straw. It is simply produced by balling machines that remove
the grain and chaff, cut and bale the straw mass into –most often- rectangular big modules that
are bound with propylene twine, hemp or flax tie or wire (King, B. 2006, p. 4). These bales will be
used later on as building blocks for the construction in four ways 1:
1. As infill in “Post and beam” structures; mostly found in NL and Europe wherein straw bales
are stacked to each other as insulation infill in timber frame buildings. They result in selfsupportive walls but have no major load-bearing role in the overall building structure.
2. As infill in wooden trusses system; system mostly found in Belgium. In this case, the construction is consisted of wooden trusses that are placed at mutual distance of 3-4 meters and
then the roof is placed so a dry site to be created. Then, between trusses, the straw bales are
placed and are fixed by rows of 2-3 to the rafters by means of wooden battens. They are fixed
under great pressure by a pneumatic vehicle jacks that set the straw bales under pressure.
3. France style- CUT@ technique: This technique is developed by Tom Rijven and includes
combined “English load-bearing” and “Belgian infill” method. The straw bales are smeared
with a leempap then are placed as infill in between the wooden uprights that have a height of
70-75 cm). Afterwards, wooden slats are used and attached to the wooden uprights and the
process continues until all straw bales that are needed for tine desired wall height are stacked
to each other. Then the strings of the bales are cut in order to allow internal stress of straw to
pass freely over the entire wall. Lastly, the resulting wall is plastered with clay.
4. Nebraska style; is the most common method of building with straw, mostly found in Ireland
and England. It is also known as “English style”. In this construction method, the bales are
stacked as supporting elements under pressure by placing two wooden frames that lie below
and above the straw bales. They are stacked like blocks in a staggered way, providing extra
strength and stability. Afterwards, upon the resulting straw bale walls, a roof is placed which
compresses more the straw bales and gives extra stability to the structure.
b. Prefabricated straw bale wall panels – method used: straw baling, forming via compression
within a frame and plastering; often, straw bales are placed in a wooden frame of high level (usually 1 storey high), variable width dependent on the design and length of usually 90-1.80 meters.
The straw bales are pressed “on each side” in the frame, and then are plastered with about 3 cm
thick clay based plaster resulting in ready prefabricated wall panels. Usually the process takes
places in a weather protected “workspace” that is located close to the building site (some meters
next). The resulting panels are then transferred and applied into the building structure by small
cranes and other equipment. This method is very common in Germany and in UK.
c.
Compressed straw boards – method used: forming loose straw into boards via heat and pressure treatment. In this case, straw is being compressed and compacted under heat at 200 oC and
pressure which enables the straw fibers to bond together without any additional external additive
(Woolley et al, 1997, p. 44 and 95). Usually, then the two sides of the straw slab are covered with
thick and heavyweight Kraft paper which may require the use of additives (glue) (Woolley et al,
1997, p. 95) or are can have a plasterboard finish (Woolley et al, 1997, p. 44)
1
Information about the construction techniques used with straw bales are taken from Woolley and Kimmins, 2000, p.158-189 and
from the website “strobouw”: http://www.strobouw.nl/Technieken/Post_and_Beam/
80
(+) Positive Characteristics:
9Straw has a low embodied energy, especially when local straw bales are used for the construction
of walls. However, prefabricated compressed straw slabs require a certain amount of energy that
is used for heating and compaction of straw.
9Straw is a waste by-product of agriculture; it is non-polluting, recyclable, reusable and
renewable, as well as biodegradable. Straw has high cellulose content and high ration carbon to
nitrogen. If protect it has a low degradability. Most of the time, straw is in surplus leading farmers
to field burning in order to dispose it. A practice that environmentally creates high impact via
the emission of CO2 and gases. As Woolley et al (1997, p. 95) mentions about 128 million tonnes
of straw are mainly burned in North America as a result of its surplus production. Thanks to
its surplus quantity, it is mostly a very cheap construction material compared to other wall
materials that bring direct income to farmers (Halliday S., 2008, p. 151).
9Straw bale construction is also a quick and very simple construction method, ideally suited
to self-build, which leads to very low construction cost. Straw bales are strong and very easy to
manage building blocks compared with adobes or compressed earth blocks.
9Straw has a great advantage to other natural biodegradable insulating materials, like sheep wool,
flax, and hemp; except of good insulating thermal properties, has also a load-bearing ability
that enables it to construct load-bearing external and internal masonry. Moreover, even by the use
of it as infill, thanks to its load-bearing ability, it can contribute to a minimization of structure
demand.
9In straw bales, straw is non-flammable and fire resistant. In tests, straw plastered from both
sides could stands fire for 2 hours and 15 minutes (ModCell, 2013 and Woolley and Kimmins,
2000, p. 161). This is due to the fact that compacted straw in bales do not contain enough air to
support any combustion.
( - ) Negative Characteristics:
8 Compressed straw boards may contain glues and external petrochemical additives.
8 Straw bale construction can take a lot of space on plan since usually the average thickness of
straw walls are 450 mm (Halliday, S., 2008, p. 151). This can be in many cases a very important
disadvantage compared to other materials.
8 Straw burning and incineration should be avoided because straw burning emits hazardous gases
that are air-pollutant.
8 King, 206, p. 20). Straw is highly problematic with dampness; it will rot in wet and humid
conditions and its prolonged exposure to high moisture will lead possibly to severe problems.
Its high sensitivity to moisture requires protective measures to be taken in order to avoid future
resulting problems. Straw must be protected from any external or internal source of moisture
like water, splashing water, wind-driven rain, rising damp, mist, condensation, and so on. Any
moisture trapped in the straw must be avoided and only breathable plasters must be used in this
case to avoid any moisture buildup. In literature, the moisture content is recommended to be kept
below 14% by weight (Woolley and Kimmins, 2000, p. 157) or below 20% by weight as others state
(Kwok et al.,2011, p.49 , Lyons, A., 2010, p. 356, and Elizabeth & Adams, 2005, p. 222)
8 Straw is capable of absorbing a great amount of water and holding it for long before drying.
Thanks to this, it can remain wet for long enough period creating very favorable conditions for
fungal growth and mould. Straw must be kept dry to prevent such cases.
81
8 Straw with crops can be also very prone to pest infestations since it possesses nutritional value. To prevent
that, straw that is used in building application must be dry and free of grain seed to prevent attracting insects
or rodents (Kwok, A., 2011, p. 49).
8 Straw bale walls are roughly modular as mentioned by Elizabeth and Adams (2005, p. 230) which creates in
the most cases informal and not totally straight perfect wall surfaces which may be an unwanted surface for
some occupants.
8 In contrast with tight straw that can stand fire, loose straw is extremely flammable.
Applications :
Design advices:
Straw can be used in structural or
insulating applications. Straw bales
are mostly used either as infill in
walls, either as load-bearing modules
to construct structural load-bearing
walls, while straw prefabricated
slabs and boards are mostly used as
structural insulating panels (SIP).
More specifically:
When designing with straw it is very important to keep in mind
every possible resource of moisture either external like mist,
fog, flood, rain, relative humidity, either internal like cooking
steam, bathing steam, condensation and so on. Straw is very
prone to rot so it is important to keep it always dry (Woolley et
al., 1997, p. 44) and prevent any wetting due to water penetration
or moisture buildup. Protective plastering will help to keep
straw dry as long as it is breathable and non-vapour permeable
coatings. Suitable plasters are clay and lime-based ones, with
lime being the most preferable in situation with high moisture
conditions, since a lime plaster can be durable, not too brittle
and self-healing when it comes to small cracks occurring in the
wall surface. Wide overhangs are advisable (in the most cases
totally necessary) along with total protection from rising damp
(Halliday, S. 2008, p. 151). Thus, a distance of 200 mm above
ground level is necessary (Kwok et al., 2011, p. 49).
Ă͘ Straw bales and wall panels
In construction:
-
As infill in walls for thermal and
acoustic insulation
-
As load-bearing modules to
construct load-bearing walls (for
1-2 storeys)
-
(in the form also as prefab ready
walls) as load-bearing and selfsupporting masonry
ď͘ Compressed straw prefabricated
slabs
In roof & floor:
-
Thermal insulating roof decking
-
Impact sound and thermal
insulating floor surface with substructural function
In walls:
-
As partition walls (with thermal
insulating properties and selfsupporting)
-
As acoustical interior walls or
linings to other internal/external
walls
-
As structural insulating panels
(SIP) to be used in exterior
building envelopes
If straw will be used as load-bearing element and not only as
insulating loose material, then it is useful to plan the building
from the primary design steps according to the bale size
modules in order to reduce the need to cut or create any special
sizes for the building construction (Halliday S, 2008, p.51), This
will reduce significantly the construction and building cost and
will increase the building speed during the construction phase
of the building. Although, straw bales are usually baled in a
relatively similar size, they are not yet having a standardized
size and can come in different sizes. Thus, it is important the
exact size of the straw that can be supplied and is available
locally near the building site to be known before any design
plan of the building. Openings should not exceed 50% of the
wall surface area in any wall and maximum unsupported wall
length should be 6 meters and the maximum height of wall in
cases of self-load-bearing straw bale buildings should be less
than 5,5 times of its straw bale thickness (width) in order to
have sufficient compressive strength (Woolley and Kimmins,
2000, p.160)
Lastly, reinforcement of straw bale constructions is possible
through various ways; using steel reinforcing bars or galvanized
threated bars, as well as timber and bamboo can be used for
such purpose (Woolley and Kimmins, 2000, p.159).
82
References.:
books_
websites_
Ashby, M. F. (2009) Materials and the
Environment: Eco-informed Material
Choice.
Butterworth-Heinemann.
Chapter 15 pp.594-595
ASTUDIO: Hajo Schilperoort (2010), Bouwen met stro. Available
at: http://www.a-studio.nl/bouwen-met-stro-interviewmet-rene-dalmeijer/index.php [Last Accessed at: 20th
March 2014]
NL agency, Ministry of Economic Affairs
(June 2013). Straw and Wheat
straw; Potential feedstocks for the
Biobased Economy. (Edited by
Bakker, R., Elbersen,W. Poppens,
R. and LesschenRice, J.P.) Study
was carried out in the framework
of the Netherlands Programmes
Sustainable Biomass by Wageningen
UR, Food & Biobased Research .
BAU BIOLOGIE: Available at: http://www.baubiologie.at/wp/
[Last Accessed at: 20th March 2014]
Bruce King et al. (2006) Design of straw bale
buildings; the state of art. USA: Green
building press
Elizabeth, L. and Adams, C. (edited)
(2005) Alternative construction;
contemporary
natural
building
methods. Canada: Jon Willey & sons,
pp: 209-234
Halliday, S. (2008) Sustainable Construction.
Butterworth-Heinemann, p. 151
Kwok A. et al. (2011) The Green studio
Handbook Environmental strategies
for Schematic Design. (2nd edition).
USA: Elsevier Inc. pp: 43-57
Lyons, A. (2010) Materials for architects and
builders. (4th edition) Elsevier, pp:
151, 344 and 396
Peters, S. (2011) Materials revolution;
sustainable
and
multi-purpose
materials for design and architecture.
Birkhäuser, p: 86-87
BRE: Sutton, A., Black, D. and Walker, P. (Novemb.2011) straw
bale; An introduction to low-impact building materials.
(Online) Available at: http://www.bre.co.uk/filelibrary/
pdf/projects/low_impact_materials/IP15_11.pdf [Last
Accessed at: 20th March 2014]
ENVIROWALL: manufacturer. Available at: http://www.
envirowall.net/ [Last Accessed at: 10th March 2014]
FOURAGES.NL; supplier. Available at: http://www.fourages.nl/
producten/bodembedekking/stro.html [Last Accessed
at: 10th March 2014]
ORYZATECH: Available at: http://www.oryzatech.com/ and
info also available at: http://stavebnictvo.sk/m/blogpos
t?id=6282648%3ABlogPost%3A20017 [Last Accessed
at: 10th March 2014]
PASSIFHUIS-PLATFORM. Passieve wanden isoleren met
stro. Available at: http://www.passiefhuisplatform.
be/artikel/passieve-wanden-isoleren-met-stro0?tid=luchtdichting [Last Accessed at: 20th March 2014]
STRAMIT: compressed straw boards, manufacture company.
Available at: http://www.stramit.co.uk/ [Last Accessed
at: 20th March 2014]
STRAWJET.INC; Building sustainable futures; straw products
manufacturer. Available at: http://www.strawjet.com/
index.html [Last Accessed at: 10th March 2014]
STROBOUW.NL. Available at: http://www.strobouw.nl/ [Last
accessed: 28th March 2014]
Woolley et al., [1997] Green Building
Handbook; Great Britain: E& FN
Spon, pp.42, 44, 95
STROH HAUS: Available at: http://strohhaus.net/strohhaus/
home [Last accessed: 28th March 2014]
Woolley, T. and Kimmins, S. (2000) Green
Building Handbook; volume 2. Great
Britain: E and FN Spon, pp:7,156-169
MODCELL: manufacturer of prefabricated straw bale wall panels.
Available at: http://www.modcell.com/technical/ [Last
Accessed at: 28th March 2014]
83
84
3.4 Sheep-Wool products
Material: sheep wool (schapenwol)
Category: keratinaceous - biotic insulation material
Application: thermal and sound insulation
3.4.1 Sheep-Wool products, companies list:
85
3.4.2 Sheep-wool datasheet: products & sizes
86
3.4.3 Sheep-wool datasheet: properties
87
88
General info:
Biodegradable products made from wool are mainly used as insulation products and are made from
off-cuts of natural sheep wool. Sheep are providers of natural fiber, the sheep wool - a valuable byproduct from animal meat production. The adaptability of sheep as a domesticated animal since
10.000-12.000 years ago has necessitated a variety of types being utilized in human environments;
today exist about 200 different breeds and crosses producing a great variety of grades and types of
wool. Quality and density can vary considerably depending on wool type that is used. Wool types are
classified according to fiber diameter and length; fineness is considered as the most important quality
attribute due to the more crimps that means the waving ability of wool fibers to stick together during
spinning so creating a stronger product [Tuzcu, 2007, p. 7-8]. In building industry, sheep wool fibers
form insulating panels and roll of various dimensions, as well as insulating felting or infill. Wool is
different from hair or fur; wool is keratin(protein) so it crimped or curls which creates pockets that
insulate and give wool a spongy feel. It is elastic and grows in staples (clusters).
Wool had a principal force in the economy of Western civilizations by providing basic essentials
and capital-luxury goods. Nowadays, the consumption of wool is more limited in the end use due
to the introduction of artificial fibers. Many countries produce wool but 6 are the main producing
countries (France, Germany, Italy, Japan, UK and USA) [Tuzcu, 2007, p. 7]. Except of Australia and
New Zealand, sheep is mainly farmed for meat production, making sheep wool a by-product of sheep.
Building products:
rolls, batts, fleece (felts) and infill
Building products made from sheep wool are insulation roll and panels (sheets or batts) that are mainly
produced in Europe by leftovers of processing the wool of other purposes and comes usually from
non-intensive farming (Grätz M. and Indriksone D. , 2011, p. 13]. Usually sheep wool insulation is
consisted of 60-95% wool fibers that are bonded together in a matrix with about 5-30% melt polyester
synthetic support fibers and also contain a small percentage (usually 0.2-3.0%) of additives for fire
retardant or pests repellent (most common found are boric salts).
Processes applied:
Baling, compacting, forming by heat +pressure, surface treatment-finish
Production process:
The process steps that are followed for the manufacture of sheep wool to its final product are:
Ă͘ Shearing: Firstly, the sheep are shorn and wool is collected carefully by the farmer and sorted
out according to color; white wool is easier to be dyed a variety of colors so it is more expensive
and used in cloth industry, in contrast gray-black wool is limited to darker shades and is more
applicable for insulation and other productions. Sheep’s shearing take place twice a year or three
times in two years usually in the spring/summer months; the time and frequency of sharing has a
great effect on the quality of harvested wool that influence significantly the fiber characteristics.
ď͘ Sorting: After the initial basic color sorting process, the wool undergoes throughout a detailed
classification and is packed into pressed bales to go the scouring (washing) plant. The bales
are press-packed with more than 400 kg to reduce the cost and energy transportation and their
packets include information about fiber thickness, length, color and vegetable matter content.
89
Đ͘ Scouring: At this phase, the wool bale packets are opened and are mixed together to produce a
particular blend that meets required specifications for the final product. Detergent is added into
hot water of about 65 oC, and wool is washed in it multiple times, so any dirt, grease, vegetation
matter and other impurities to be removed as well as the wax (i.e. lanolin) contained in wool to
be dissolved and won’t stick back onto wool fibers. In this phase also, any chemical agents and
additives for fire or mold resistance are added.
Ě͘ Carding: after scouring, wool is dried and passes through a series of rollers covered with fine
bristles or fine wire teeth. There the wool is carded to separate the fibers from each other, take
out any tangles, clumps and stables and align fibers parallel. The fibers are now layered numerous
times to give the final product’s required thickness.
Ğ͘ Cutting & packaging: The wool is cut off in specific dimensions (width X length) and packed in
2-3 pieces per bag or in rolls of specific length, and labelled for easy installation.
(+) Positive Characteristics:
9Chemical reactivity of wool: Wool has the ability to breathe and react with many gases and
metals in its environment due to its reactive nature (as a result of its physical and chemical
structure) without being caused any degradation to the wool. Therefore it can filter out and
clean the indoor air as well as contaminated water. It can absorb permanently substances such
as; Formaldehyde (a carcinogen compound emitted by a lot of building materials), NOx, SOx,
Acetaldehyde, propionaldehyde, pentanal (from building and timber materials), Benzaldehyd
(Lacquer and surface treatment), tobacco smoke and others, while in a reversible way; toluol,
xylene, cresol, Phenol, PCP, and general VOC. According to Tuzcu [2007, p. 91-92] 1 gram of
wool can ideally absorb 3.2-3.8% (by weight) of SO 2. More specifically, treated wool under specific
environmental conditions can absorb and remove a big range of metals (mercury, cobalt, copper,
uranium, nickel, and others) from contaminated water [Tuzcu, 2007, p. 91]
9Wool fibres are completely unique in their ability to permanently bond with 99% of formaldehyde
present within twenty hours of direct exposure [Black Mountain company, 20131].
9Wool insulation does not cause any health harm to the installers during installation or during
its usage stage since the chemical additives are already chemically bonded with wool) and the
most of them can be removed by washed them out in water after their disposal.
9Due to its hygroscopic properties, wool can have a positive effect also on permeable and
hygroscopic buildings. Wool exhibits a hygroscopic behavior that allows it to absorb up to 3335% (Kg/Kg) of its dry density.
9Sheep wool is resistant to compaction unlike some alternatives that will compact over time and
compromise thermal conductivity (Black Mountain, 2014).
( - ) Negative Characteristics:
8 There are some factors that influence significantly the strength of wool fiber like; water, temperature and
alkali (all)-acids (strong). More specifically:
1
Black Mountain UK, brochure: passive solutions to indoor air quality
90
a) The greater the moisture content of the fiber, the further it can be stretched. Water works as a
plasticizer on the fiber giving an elongation degree from 30% (dry) - 70% (wet) while temperature
has the same effect [Tuzcu, 2007, p.86]. Swelling of wool occurs when water is absorbed.
b) Alkali and acid cause a decrease in the strength of the wool fibers [Tuzcu, 2007, p. 10], so
consequently to a wool insulation materials. Because wool is heavily cross linked by disulphide
bonds, it is insoluble in almost all solvents, except for alkalis. Alkalis, damage the wool fiber even in
diluted solutions. Generally it’s accepted that alkaline which is higher than pH=11 causes damage.
The increasing temperature of the environment also accelerates the reaction. The wool fiber shows a
strong absorptive behavior for alkalis. In alkaline fluids with pH higher than 11, the wool swells and
finally dissolves in alkalis. Soda work less aggressive and ammonia is almost harmless. (Tuzcu,
2007, p. 10).
c) The effects of acids on the wool fiber are much less serious than that of alkalis. Diluted mineral
acids cause almost no damage, or only a little, on wool. In very high dilution, the acids even work
as protector for the fiber. Also swelling with acids is low in comparison with wool in an alkaline
solution. The effects of diluted acids on the wool fiber are specific distinguished of those of alkalis.
Swelling occurs less frequently than in alkaline solution because the isoelectrical point (pH value) of
wool is pH = 4,8. A solution of pH 4-5 has less influence than pure water, en even works protective.
Soap doesn’t cause any damage on wool. Soap can be split up a little, and therefore the soap particles
are too large to penetrate into the wool fiber. (Tuzcu, 2007, p. 11)
8 Sheep wool may also start degrading by other factors. As Tuzcu mentions bacteria and fungi
can always be found on wool but they can grow and attack the fibers only under conditions such
as favorable temperature, relative humidity, and specific pH. Wool is a keratinaceous material
(like feathers, hair, and horn) that is insoluble and resistant to degradation by common enzymes.
The main degradation mechanism for wool is four micro-organisms named: Proteus vulgaris,
Pseudomonas aeruginosa, Aspergillus and Penicillium, as well as being attacked by larvae of certain
moths (Lepidoptera) and beetles (Coleoptera) (Tuzcu, 2007, p. 11). For its biodegradation, the
most important wood-digesting insect pets are; Tineola bissiella (common cloth moths), Tinea
(case bearing cloth mouth), Hofmannophila pseudosprettella (brown house moth) and Anthrnus
(carpet beetle).
8 Sheep wool products can contain additives, such as borates, and synthetic support fibre to prevent
problems of larvae of certain moths and beetles attack, since unprotected wool is susceptible
to moth infestation. Moth protection is necessary and additional provisions should be made,
like making the insulation wind and airtight in order to keep larvae away from the insulation.
[Grätz M. & Indriksone D., 2011, p. 13]. For this reason, sheep wool insulation contains insect
resisting agents both to prevent larval attacks and to increase its fire resistance. To make sheep
wool products mothproof, insecticides - usually sulcofuron is used which is toxic to marine
organisms. However, the additives are considered unproblematic for humans. Although some of
the pesticides used in the past by farmers that plunge the sheep twice a year with them could cause
health problems to the like Mitin FF and Eulan-based chemical agents [Tuzcu, 2007, p. 12 & 93].
8 Boric salts (borax) additives are problematic when the material shall be disposed– it cannot be
composted. Borates are classified as reprotoxic and slightly hazardous to water as they seep into
the ground water. [Grätz M. & Indriksone D., 2011, p. 11] Boric acid and borate salts are classified
by the U.S. EPA as “not likely to be carcinogenic to humans” under the 2005 carcinogen assessment
guidelines 1.
2
National Pesticide Center , Available at: http://npic.orst.edu/factsheets/borictech.html
91
Alternative Solutions:
9Nowadays, there are also safe effective environmental alternatives to toxic chemical agents for
pest management purpose, like Neem Leaves (Azadiracha indica A. Juss) that are harmless to both
men and beneficial insect predators as Vogt et al. stated (1996). Neem products are approved worldwide to for use in organic farming [Tuzcu, 2007, p.94].
9Woolley et al. (1997, p.49) support that one other alternative for insect repellent use is the Quassia chips that are proved to be cheap and effective to deter moths and other insects. Quassia chips
come from the white bark of Picrasma excelsa a tree that is indigenous to Jamaica and many other
islands of the West Indies. The tall elegant trees are not troubled by insects or pests as the entire tree
in particular the timber, contains quassin an astringent resin which is a bitter and very effective
insecticide.
9Boric acid and borate salts are soluble in water 1, therefore it can be removed from sheep wool
insulation products before their disposal in order to be recycled or decomposed.
Applications :
In general, sheep wool insulation can be used as thermal and sound insulation in roof, floor, ceiling
and wall cavities as well as insulating wool felting can be used as impact sound insulation (floor).
Sheep wool insulation is very suitable for use in moist situations such as in brick cavity walls (Woolley et al. (1997), p. 43) and according to Black Mountain Company; Sheep’s wool insulation is ideally
suited to timber frame structures as it has a natural synergy with wood. The sheep wool fibres draw out
the moisture, conditioning the wood and act as a ‘buffer’ to protect the fabric of the building [Black
Mountain, 2013]. More specifically2, wool insulation products can be used:
In roof and suspended floors as:
In walls, as:
-
Insulation between rafters, double-skin roof, topmost suspended floor
-
Internal insulation below suspended floor, below rafters or load-bearing structure
-
Below floor’s screed as impact sound insulation
-
External insulation behind cladding
-
Timber-frame and timber-panel forms of construction
-
Internal insulation to wall and to separating walls
Design Advices:
Wool is a natural product and thus it is to be expected that there will be a range of physical properties.
According to Ballagh (1996, p. 101) wool materials used in relatively thick layers –more than 50 mmcan achieve good acoustical performance and can increase the transmission loss of stud walls by up to
6 dB or more, while when both vibration isolation and cavity absorption are provided, improvements
can reach up to 10 dB achieved (Ballagh, 1996, p. 119). Wool has very good hygroscopic properties
and is able to regulate humidity. However, prolonged exposure in water or sunlight of sheep wool insulation should be avoided since it can cause its degradation (Roaf, S., 2013).
1
National Pesticide Center , Available at: http://npic.orst.edu/factsheets/borictech.html
2
Pfundstein M. et al, (2012) Insulating Materials; principles, Materials, Applications. Munich: Birkhäuser, pp:10, 49
92
References.:
books_
websites_
Ballagh, K. O. [1996] Acoustical Properties
of Wool. Applied Acoustics, Vol.
48, No. 2. Great Britain: Elsevier
Science Ltd, pp: 101-120,
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[Last
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Birkhäuser, pp. 136-138
Hugues, T. [2004] Timber Construction;
Details, products, case studies.
Birkhäuser, p.61
Roaf, S. (2013) Ecohouse; a design guide
(4th edition), Routledge
Tuzcu,
T.M. [2007] Hygro-Thermal
Properties of Sheep Wool Insulation.
Msc thesis. Delft: Delft University
of Technology [TU Delft]
Woolley et al., [1997] Green Building
Handbook; Great Britain: E& FN
Spon, pp: 43-49
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at: http://www.deskundig-isoleren.be/schapenwol.html [Last
Accessed: 31th January 2014]
SHEEPWOOL Ltd: manufacture. Available at: http://uk.sheepwoolinsulation.
com/ [Last accesed: 25th January 2014]
SOUNDSERVICE: Thermafleece - Environmentally friendly Acoustic
Insulation.
Available
at:
http://www.soundservice.co.uk/
documents/ThermafleeceFromSoundService.pdf [Last Accessed:
21th January 2014]
THERMAFLEECE: Manufacturer. Available at: http://www.thermafleece.
com/ [Last accessed: 2nd February 2014]
VVI: Available at: http://www.verantwoordisoleren.nl/schapenwol.htm
[last accessed: 31th Jan 2014]
WALOTEX: Producer. Available at: http://www.walotex.be [ Last
Accessed:31th January 2014]
93
94
3.5 :RRGÀEHUVSURGXFWV
Material: wood fibers (houtvezel)
Category: insulation material
Application: thermal and sound insulation
3.5.1 Wood-fibers products, companies list:
95
3.5.2 Wood fibers datasheet: products & sizes
Image 3.5.1
Installation of various products of wood-fiber insulation .
Image taken from: http://uditherm.files.wordpress.com/2012/12/cropped-pendant_16802.jpg
96
3.5.3 Wood-fibers datasheet: properties
97
98
General info:
Wood fibers are used mainly to produce insulation panels that can be used in different constructions
as supportive boards, as thermal insulation or sound absorbing components, for prevention of thermal
bridges, and others. Such products are known as wood fiber or wood wool products and are mainly
produced by pre-consumer waste wood derived from forestry thinning or saw mill residue. The main
difference between wood fiber and wood wool boards is that in the last case polyolefin fibres are also
added. Wood wool boards can be also formed with cement or magnesite (Woolley et al., 1997, p.48)
but such products are not going to be studied in this report since they are not biodegradable. Insulating
boards made from wood fiber and wood wool can also be known as fibreboards or softboards. In
general, they present good mechanical properties in comparison with other natural-based insulating
materials but often they may contain larger percentage of chemical additives in contrast with other
natural insulation products.
Building products:
boards (rigid or semi-flexible)
Building products that are produced from wood fibers form either rigid boards either flexible battens
that can be used for thermal insulation, as sound impact insulation or even sometimes as supportive
substructure in roofs. The variety of products results from the differing degrees of compression that
is applied during the manufacturing process (Lyons A., 2008, p.148). Wood fiberboards of light or
medium density are produced by wood fibers (~95-98%) and sometimes they contain a small % of
Paraffin or/and PVAc glue (0.5-1% and 1.0-3.0% respectively) in order the bonding process to be
assisted (Hegger, M. et al., 2006, p.138). In some cases, latex, silicates or other water proof agents
are added to the products to make them damp-resistant. Wood wool boards are produced also by
wood fibers (about 85%) but polyolefin fibers (5-10%) are also added and work as a bonding agent.
Depending on the requested board properties, fire retardant and water-resistance agents may are
added (≤8%). A common used fire retardant is ammonium polyphosphate in ca. 8 %.
Processes applied:
Chipping/refining, forming: wet-process (vacuum pumping, rolling pressure), dry-process (spray, air-drying)
Production process:
Building products from wood fibers are produced from pressed wood off-cuts either by wet or dry
processing, and parts of the products can originate from recycled material.
Ă͘ Chipping and refining: Initially, waste from locally harvested coniferous trees such as spruce, fir,
pine, are chipped and shredded to refined fibers (Hugues, T. ,2004, p. 54).
ď͘ Wet-forming process: In wet-forming process, wood fibers from pine and spruce are usually
used. The wood fibers are soaked in water producing a pulp. The pulp is fed onto a moving wiremesh conveyor (a forming box) as a continuous fibre matt where the excess water (ca. half of it)
is remove by suction (vacuum pumping) and pressure (light rolling) which causes the fibers to
felt together (Lyons A., 2008, p. 148). They are sliced and left to dry under high pressure and heat
treatment in air dryer in order to remove any remaining water and to form the final products. The
natural resins that wood fibers contain work as a natural binding agent via the heat-steam process
and bond the wood particles together without need of additional binders. Afterwards, boards are
conditioned to the correct moisture content, cut to size; edges milled, and are packaged.
99
In thicker panels, manufacturers add chemical binding agents such as Paraffin, PVAc or PMDI glue. In some
cases, the boards are coated with bitumen or latex for waterproofing applications, like for instance if the boards
will be used as water resistant layers of wood frame walls or inside roof constructions (Grätz M. and Indriksone,
D., 2011, p.18).
c.
Dry- forming process: In a dry-forming process, the fibres are sprayed with the adhesives (like Paraffin,
etc) and are dried with warm air. Then fibre boards are placed in a unit where the adhesives are cured and
hardened through exposure to a mixture of air and water vapor. Wood wool is produced by blending the
wood fibers with Polyolefin fibers that works also as a binder to form the insulation boards and panels.
Polyolefin fibers are produced from polymers that are nonrenewable materials. Fire retardants such as
ammonium polyphosphate or aluminum Sulphate are also added.
(+) Positive Characteristics:
9Wood fibers can be derived from pre-consumer wood waste so they are a by-product, or from
forest thinning (renewable resource) and their processing is not considered high energy intensive.
9The combination of high density and specific heat capacity of wood fiberboards makes them have
a significant thermal mass in comparison with their thickness. Thermal mass enables the boards
to store temporarily thermal energy and released it when internal temperature levels are low.
9Most wood fibers are vapour-permeable and have good hygroscopic properties that enable them
to buffer excess moisture in indoor environments and improve the indoor air quality and the
breathability of a building, since they work as a humidity regulator. However, these properties
are declined in case of air-permeable additives contained on the boards, for instance bitumen.
9Wood fiberboards with moisture content lower than 20% are highly resistant to wood pests,
bacteria, fungi and other insects (Hugues T., 2004, p. 54).
9Wood fiber insulation boards present good mechanical properties (compressive and tensile
strength) in contrast with other natural insulation boards (e.g. sheep wool insulation, flax
insulation, etc).
9Uncoated panels without certain additives or impurities (e.g. without polyvinyl acetate) can be
decomposed or be used in an incineration with energy generation (Grätz and Indriksone, 2011,
p. 18).
( - ) Negative Characteristics:
8 Wood fiber products contain often chemical additives and polyester binders that are not from
renewable resources but are derived from petrochemicals. Thus, they require large amounts of
energy for their manufacture. For instance, Paraffin wax water is repellent which a petrochemical
derivative is. Despite this, some of the additives are biodegradable, some can be recycled and
others can only be discarded. More specifically, PVAc (Polyvinyl acetate) that is added in wood
fiber panels is a polymer that is used in a range of glues; wood glue, carpenter’s glue, and so on.
It is a type of thermoplastic meaning that it can become pliable or moldable above a specific
temperature, and returns to a solid state upon cooling. Therefore, with heating processes it can be
removed when the product should be discarded. Also, polyvinyl acetate is considered to be able
to be degraded by a number of microorganisms like filamentous fungi, algae, yeasts, lichens and
bacteria.
8 Untreated wood fiber boards should be protected against extended exposure in UV- radiation and
humidity (Hugues T., 2004, p.54).
100
Alternative Solutions:
For the production of flexible wood fiber panels, it is possible the polyolefin fibers to be replaced by
Bico-fibers that are a more ecological alternative option since those fibers can biodegrade. Moreover,
for wood fiber boards that will be used for internal applications, chemical glues are possible to be
replaced by “natural” glues such as glues made from soya, blood albumen, casein, and animal products
(Woolley et al, 1997, p. 85). Such glues have lower toxicity than the synthetic glues and are also derived
from renewable resources, however they are only suitable for internal use and so their application
should be more limited.
Applications :
Generally, wood fiber boards are utilized for thermal and impact sound insulation in roof structures,
in floor, wall or ceiling constructions. More specifically, wood fiber insulation boards can be used:
In roof and
suspended
floor as:
In walls, as:
-
External insulation below roof covering (protected from weather)
-
Roof insulation on formwork or without formwork when using double-threaded screws
and large slabs
-
Insulation between or on top of rafters (sufficiently compression resistant to carry the load
of the cladding, e. g. roofing tiles). double skin roof, topmost suspended floor
-
Internal insulation below suspended floor, below rafters or load-bearing structure for
additional insulation
-
Below screed floor as impact sound insulation
-
External insulation behind façade cladding (on formwork or solid walls)
-
External cladding in combination with plaster-base finish.
-
Internal insulation or insulation to separating walls.
-
Cavity insulation in wood frame and wood panel construction
Design Advices:
Wood fiber boards are very suitable for sandwich construction
in combination with hard board of gypsum board or SIPs panel
construction. They can be also available in insulating plasterbase elements to be used as cladding materials for exterior
walls (Hugues, T, 2004, p. 54). In roofs, some types of wood
fiber boards can function as additional supportive load-bearing
element for other natural insulation board. Since the range
of wood fiber products is so wide, special attention should
be given to the density, mechanical and damping properties
of each fiberboard to ensure that is suitable for the requested
application. According to Black Mountain Company, wood
fiber insulation panels “are ideal for vertical applications in
timber frame structures and an excellent solution for insulating
pitched roofs making it perfectly suited to loft conversions”.
NBT’s Pavatex Diffutherm system : wood-fibers
Image 3.5.2
Image taken from:http://www.ttjonline.com/features/wood-fibre-insulation-boardsmake-waves/image/wood-fibre-insulation-boards-make-waves-1.html
101
References.:
books_
websites_
Grätz M., Indriksone, D. (2011)
Ecologic
Construction
Materials
[online].
Available
at:
http://
w w w. i nt e n s e - e n e r g y.
eu/fileadmin/content/
broshures/04_
Ecomaterials.pdf
[last
accessed: 29th January
2014] pp: 4, 14
BIOHOME: Ecologisch duurzaam wonen; Bouwmaterialen > Isolatie > Houtvezelisolatie.
Available at: http://biohome.be/ecologische-bouwmaterialen/isolatie/item/steicoprotect [last accessed: 22 February 2014]
European Commission, (June
2010)
Green
Public
Procurement
Thermal
Insulation
Technical
Background.
Brussels:
European Commission,
pp: 4, 14. Available at:
http://ec.europa.eu/
environment/gpp/pdf/
thermal_insulation_
GPP_%20background_
report.pdf [Last accessed:
15th February 2014]
Hegger,
M. et al. (2006)
Construction
materials
manual.
Germany:
Birkhäuser, pp. 136-138
Hugues, T. (2004)
Timber
Construction;
Details,
products, case studies.
Birkhäuser, p.54
Lyons A., (2008) Materials for
architects and builders
(4th edition). China:
Elsevier, pp.146-149.
Pfundstein M. et al (2007)
Insulating
Materials;
Principles,
Materials,
Applications.
Munich:
Birkhäuser, pp: 10-15
Roaf, S. (2013) Ecohouse; a design
guide
(4th
edition),
Routledge, pp: 74-76
Peters,
S. (2011) Materials
Revolution; Sustainable
multi-purpose materials
for design and architecture.
Germany: Birkhäuser, p.
87, 108-109
Woolley et al., [1997] Green
Building Handbook; Great
Britain: E& FN Spon, pp:
43-48, 85
BLACK
MOUNTAIN
LTD:
manufacturer.
Available
at:
http://www.
blackmountaininsulation.com/products/natuflex [last accessed: 22 February 2014]
DIEFFENBACHER (2010) Plants for wood fiber insulation boards (pdf) [online]. Available
at:
http://www.dieffenbacher.de/fileadmin/Inhalte_gb/101_daten_sprache/004_
pdf/001_holzplattentechnik/000_faserdaemm/DSE_Fiber_insulation_board.pdf
[Last Accessed: 8th March 2014]
DUTCH BLUE LABEL NL provider. Available at: www.dutchbluelable.nl [last accessed: 22
February 2014]
GREENSPEC: National Green Specification.
1/Wet-formed wood fibre insulation board & Wood wool insulation [online].
Available
at:
http://www.greenspec.co.uk/building-design/insulation-plantfibre/#woodfibre [Last Accessed: 8th March 2014]
2/Wood fibre insulation: Introduction [online]. Available at: http://www.greenspec.
co.uk/building-design/woodfibre-insulation-intro/ [Last Accessed: 8th March
2014]
3/Wood fibre insulation: Manufacturing processes [online]. Available at: http://www.
greenspec.co.uk/building-design/woodfibre-manufact-process/ [Last Accessed:
8th March 2014]
4/Wood fibre insulation: Timber frame applications [online]. Available at: http://
www.greenspec.co.uk/building-design/woodfibre-timber-frame-wall/
[Last
Accessed: 8th March 2014]
5/Wood fibre insulation: Xlam / solid wood applications [online]. Available at: http://
www.greenspec.co.uk/building-design/woodfibre-xlam-wall/ [Last Accessed: 8th
March 2014]
6/Wood fibre insulation: Masonry wall applications [online]. Available at: http://
www.greenspec.co.uk/building-design/masonry-external-walls/ [Last Accessed:
8th March 2014]
7/ Wood fibre insulation: Pitched roof applications [online]. Available at: http://www.
greenspec.co.uk/building-design/woodfibre-pitched-roof/ [Last Accessed: 8th
March 2014]
8/ Wood fibre insulation: Retrofit to masonry walls [online]. Available at: http://
www.greenspec.co.uk/building-design/woodfibre-retrofit/ [Last Accessed: 8th
March 2014]
HOMATHERM: manufacturer. Available at: http://www.homatherm.com/ [Last Accessed:
8th March 2014]
NATUREPRO: wood fiber – provider. Available at: http://www.natureproinsulation.co.uk/
woodfibre_main.htm [Last Accessed: 8th March 2014]
PAVATEX.NL: wood fiber boards-manufacturer. Available at: http://www.pavatex.nl/nl/
home/ [Last Accessed: 8th March 2014]
P GEENS CONSULT BV BA: Isolate with houtvezel [online]. Available at: www.deskundigisoleren.be/houtvezels.html [Last Accessed: 31th January 2014]
SIEMPELKAMP: wood-fiber insulation board; siempelkamp dry process (pdf) [Online]
At
available:
http://www.siempelkamp.com/fileadmin/media/Englisch/
MaschinenundAnlagen/prospekte/Siempelkamp_wood-fiber_insulation_boardeng.pdf [Last Accessed: 31th January 2014]
STEICO: wood fiber –manufacturer. Available at: http://www.steico.com/int/products/
wood-fibre-insulation.html [last accessed: 31th Jan 2014]
102
3.6 Flax products
Material: flax (vlas)
Category: biotic insulation material
Application: thermal and sound insulation
3.6.1 Flax products, companies list:
103
3.6.2a Flax datasheet: products & sizes
104
Images: Various products of Flax
strips, bands
tow, shives
sheets
rolls
felts
3.6.2b Flax datasheet: products & sizes
105
3.6.3 Flax datasheet: properties
106
107
General info:
Building products made from flax are insulation products. They are made mainly by flax fibers
harvested from a fibrous plant called “Linum usitatissimum”, which is an upright plant with slender
stems that grows up to 1.2 meters. Flax plant can be cultivated annually in deep loam soils with a large
proportion of organic matter and under optimal growth conditions it can reach 70-80 cm within 15
days. Wet temperate climates are suitable for its cultivation. Flax is harvested for fiber production
after approx. 3 months or 1 month after the plant flowers and two weeks after the seed capsules form.
The base of the plant will begin to turn yellow. If the plant is still green the seed will not be useful,
and the fiber will be underdeveloped. The fiber degrades once the plant is brown. Flax is harvested
either involving mechanized equipment (combines) either manually by pulling the mature plan by its
roots; a method that maximize the fiber strength in contrast with the mechanized method that cuts
the plant in a specific height.
Flax is considered the oldest textile fibre (Linen) is in the world and its use is dated back to 8000 BC 1.
Linseed oil produced from flax is known since 4000 years ago but only recently, large-scale use of its
fibres is used for insulation purposes (Pfundstein, M. et al, 2012, p. 50). About 2/3 of the total world
production are produced in China while 1/3 is produced in Europe 2. In North Europe, flax is mainly
produced for insulation purposes in Belgium, Germany, UK and France, as well as in the Netherlands.
Flax cultivation with chemical insecticides and herbicides is not allowed anymore and organically
grown flax is produced without pesticides and fertilizers. In the Netherlands, organically grown flax
has an EKO-Mark 3͘
Building products:
rolls, sheets, fleece (felts), strips, shivs and infill
Building products that are produced from flax are available as insulating rolls, panels (boards &
sheets), felting and fleeces, strips and bands, as well as shivs that can be used as infill in cavities.
Fibers are bonded together either with natural binders (like for instance, about 10% potato starch 4)
or polyester fibers that are also added for reinforcement. If they contain polyester fibers then they
may not be able to be decomposed easily (Grätz M. and Indriksone D., 2011, p. 15). If there is not any
natural binder used for fire resistance, then usually diammonium hydrogen phosphate or about 10%
borax are used 5.
Processes applied:
Harvesting, dressing (breaking, scutching, heckling), chemical treatment
Production process:
a. Harvesting: Firstly, flax is harvested from the plants either in autumn when the straw is still green
either in spring. According to Blackburn (2005, p. 42, the optimal time for harvesting the plant is the
early yellow maturity of straw (green-yellow maturity). The harvesting process is made either manually
by pulling the plant from the roots (a method that can achieve better mechanical properties) either
1
Blackburn, R.S. (2005) Biodegradable and sustainable fibers. USA: Woodhead Publishing Limited, p.37
2
Linen, available at: http://wiki.watmooi.nl/pages/Linnen [Last accessed;15th February 2014]
3
Linen, available at: http://wiki.watmooi.nl/pages/Linnen [Last accessed;15th February 2014]
4
Peters, S. (2011) Materials Revolution; sustainable and multi-purpose materials for design and architecture. Germany: Birkhäuser, p. 108
5
Pfundstein, M. et al (2012), Insulating Materials; Principles, Materials, Applications. p.50
108
via a mechanized method by pulling machines that are mostly self-propelled machines that pull out
straw and swath it in the field for the retting process (Blackburn, 2005, p.42). Optimized harvesting
machines can collect, short out, thresh and eject the flax straw in a single operation.
b. Degumming: After harvesting, flax straw is left for the degumming process which is the process
of loosening the bond between the fibres bundles and surrounding tissue (decomposing the natural
adhesive pectin). Degumming of flax (and hemp) can be made with various methods such as water
or dew retting, chemical degumming and physical methods (Blackburn, 2005, p.43). The first two
processes are the most common that is why usually this process is simply known also as “retting
process”. After the retting process is complete, flax is left to dry. When moisture content in flax straw
is under 19% then it is ready to be processed further, and it undergoes under dressing process.
c. Dressing: This process involves breaking, scutching, and heckling operations several times until
flax fibers are satisfactory extracted and separated from the shives. In short, during the breaking
process , flax straw is broken down into short segments via breaking machines. Afterwards, flax fibers
are hanged vertically and are scratched from one edge to the other in order straw to be removed
from the fiber. Lastly, fibers are pulled through various different sized heckling comb devices. The
fibers can remain stiff and coarse either they become quite soft and fine, depending on the degree of
heckling process that they undergo. Usually in the production of insulation products, both coarse and
fine flax fibers are blended and processed. The finest flax fibers are called “tow” and can be used for
textile fabric or infill insulation in cavities, while the “stiffer” fibers are the shives and can be used
for animal bedding.
f. Manufacturing: Flax is processed into blocks of fleece by passing through textile non-woven line
or other similar machines. Usually synthetic fibers (like polyester) are also added for reinforcement
as well as in this stage inorganic (like soda, etc.) or organic natural binders (like, potato starch) are
added to give flax insulation resistance to burning and to rodent and insect infestations.
g. Packaging: Flax then is either packaged into rolls; either is cut in sheets (batts, panels, boards).
(+) Positive Characteristics:
9Flax insulation exhibits good thermal and acoustic insulation properties. Its natural moisture
and temperature regulating properties make it have an unmatched temperature damping factor
and heat accumulation. As Isovlas Company supports, the use of flax insulation can result the
indoor air temperature to be about 23 o C when the exterior air temperature is 30 oC in summer,
whilst a reversible effect results during winter. In winter, when the temperature of air outside is
-5 o C, inside the indoor temperature remains at about 21 o C 1. Flax fibers can absorb vibrations
much better than other insulation materials since flax fibers are flexible and as a result of its open
structure, air movement (sound vibrations) is converted by friction into heat. Thanks to this, flax
products are used as molded parts in composites in the automotive industry and in recording
studios.
9Flax insulating products are not irritating skin or respiratory track since they are natural originated products that do not contain heavy toxic additives. Therefore, none protective clothing,
gloves, masks and so on, are necessary.
6
Info taken from p.2 of Isovlas brochure: Isovlas.nl-brochure-bowisolatie.pdf. Company: Isovlas Oisterwijk BV (Producer and
manufacturer of flax insulation products), Available at: http://www.isovlas.nl/
109
9Flax insulation in contrast with sheep wool insulation is resistant to alkalis. Also, it is very
resistant against moisture and mould. However, it should be prevented to be permanently wet
otherwise it will decay (Pfundstein et al, 2012, p.50). Moreover, Flax insulation can generally
handle large amount of condensation so it is resistant to rot and to fungal infestation (Peters,
Sh. (2011) p. 108) but also in this case, f lax insulation should be able to dry and not kept wet for
long-term period.
9Lastly, the cultivation of f lax plants (“Linum usitatissimum”) that f lax fibers are harvested creates a positive CO2 balance.
( - ) Negative Characteristics:
8 Flax insulation products may contain ammonium phosphate salts or sodium octaborat (borate
salt) that are inorganic additives and may make difficult the products disposal. Nevertheless,
Ammonium phosphate is considered a non-toxic substance because it is filled with monoammonium phosphates. Ammonium Phosphate is a salt formed from ammonia and phosphoric
acid.
Applications :
Generally, Flax building products can be used for both thermal and sound insulation applications.
Insulating sheets and rolls can be used in roof structures, in floor, wall or ceiling constructions (Peters,
Sh. (2011, p. 108), as well as insulating feltings for impact sound insulation purposes (Hugues, T.
(2004), p. 62). Fibers (infill) and shivs can be used to fill cavities in sound-boarded ceilings or to
insulate ducts and pipes in the form of pipe casing (Hugues, T. (2004), p.62). Flax insulation products
are also very suitable in timber frame structures and to be used as interior insulation of an outer wall
leaf (Grätz M. and Indriksone D., 2011, p. 14). More specifically, flax insulation products can be used 1:
In roof and
suspended
floor as:
In walls, as:
-
External insulation below roof covering (protected from weather)
-
Insulation between rafters, double skin roof, topmost suspended floor
-
Internal insulation below suspended floor, below rafters or load-bearing structure
-
Below screed floor as impact sound insulation
-
External insulation behind cladding,
-
in timber frame and timber-panel forms of construction
-
Internal insulation or insulation to separating walls.
Design Advices:
Flax insulation products are considered a cradle to cradle product type that can be 100% recyclable
and biodegradable. The products range in their composition content and in their properties. Some
insulating panels are more suitable to be applied in dry conditions like timber and solid wood
constructions like for instance Isovlas insulating panels PL, while others can be more suitable for
filling in brick cavities, like Isovlas insulating panels PN. When flax insulation is used in outer leaf,
always a cladding material should be applied afterwards for its protection from continuous water
penetration. Moreover, when flax insulating panels are used in cavities, an air gap of about 30-40mm
is always necessary to be kept from the cavity side of the outer leaf. More preferably flax insulation
should be placed vertically in the brick or other cavity.
1
Pfundstein M. et al (2007) Insulating Materials; Principles, Materials, Applications. Munich: Birkhäuser, p. 50
110
References.:
books_
websites_
Blackburn, R.S. (2005) Biodegradable and
sustainable fibers. USA: Woodhead
Publishing Limited, p.37
DUTCH BLUE LABEL NL provider. Available at: www.dutchbluelable.
nl [last accessed: 22 February 2014]
Grätz
M., Indriksone, D. (2011) Ecologic
Construction
Materials
[online].
Available at: http://www.intense-energy.
eu/fileadmin/content/broshures/04_
Ecomaterials.pdf
[last accessed: 29th
January 2014] pp: 4, 14
European Commission, (June 2010) Green
Public Procurement Thermal Insulation
Technical Background. Brussels: European
Commission, pp: 4, 14. Available at:
http://ec.europa.eu/environment/gpp/
p d f / t h e r m a l _ i ns u l at i on _ G P P _ % 2 0
background_report.pdf [Last accessed:
15th February 2014]
Hegger, M. et al. (2006) Construction materials
manual. Germany: Birkhäuser, pp. 136138
Hugues, T. (2004) Timber Construction; Details,
products, case studies. Birkhäuser, p.62
Pfundstein M. et al (2007) Insulating Materials;
Principles, Materials, Applications. Munich:
Birkhäuser, pp: 10-50
FLACHSHAUS GmbH. Flax insulation. Available at: www.flachshaus.de
[last accessed: 10 February 2014]
GREENSPEC: National Green Specification. Insulation derived from
organic sources [online]. Available at: http://www.greenspec.
co.uk/insulation-plant-fibre.php#sheep [Last Accessed: 31th
January 2014]
ISOVLAS OISTERWIJK BV: flax insulation. Available at: http://www.
isovlas.nl/ [last accessed: 22 February 2014]
ISOLINA BV. Available at: http://www.isolina.com [last accessed: 22
February 2014]
WAT MOOI WIKI: Linen. Available at: http://wiki.watmooi.nl/pages/
Linnen [Last accessed; 15th February 2014]
MATBASE.COM: Materials> Natural & synthetic Polymers. Available
at:
http://www.matbase.com/material-categories/naturaland-synthetic-polymers/polymer-fibers/ [last accessed: 2nd
February 2014]
P GEENS CONSULT BV BA: Isolate with vlaswol [online]. Available
at: http://www.deskundig-isoleren.be/vlaswol.html [Last
Accessed: 31th January 2014]
Roaf, S. (2013) Ecohouse; a design guide (4th
edition), Routledge
STEICO. Flax insulation. Available at: http://www.steico.com [last
accessed: 18 February 2014]
Peters, S. (2011) Materials Revolution; Sustainable
multi-purpose materials for design and
architecture. Germany: Birkhäuser, p. 108109
VVI: Available at: http://www.verantwoordisoleren.nl/ [last accessed:
31th Jan 2014]
111
112
3.7 Hemp products
Material: hemp (hennep)
Category: biotic insulation material
Application: thermal and sound insulation
3.7.1 Hemp products, companies list:
113
3.7.2 Hemp datasheet: products & sizes
114
115
3.7.3 Hemp datasheet: properties
116
117
General info:
Hemp found use in about 25.000 applications including foodstuffs, energy (fuel), biobased materials
and bio-composites (e.g. biodegradable plastics), cigarette paper, textiles, cosmetics, as well as building
materials (Halliday S, 2008, p. 151) because of its unique properties, particularly for its environmental
benefits and its value for uses in biobased industry (Carus M. et al, 2012, p. 1).
Hemp fibers are harvested from the fibrous crop plant Cannabis sativa, a fast growing plant that is
resistant to diseases and pests and can grow without the need of any fertilizers or other agrochemical
support (Carus et al., 2013 & Halliday S., 2008). Its tap roots aerate the soil allowing a rich mulch
production, such that it is a good rotational crop that benefits subsequent crop yields (Halliday
S., 2008, p. 151) while it can absorb heavy metals cleaning the soil (Blackburn, 2005). Therefore,
cultivation of hemp for building products has a lot of ecological benefits.
Cannabis Hemp can be cultivated easily in a range of climates in Europe and industrial hemp was
cultivated since the Middle Ages. The soil most preferably should be alluvial soils, loesses, lime soils
rich in humus and peat. Soil acidity should be about 7.1-7.6 pH and not below 6.0 (Blackburn, 2005, p.
55). Its strong fibers were used to produced sail canvas, sacks, canvas water hoses, ropes and fabrics so
until the end of sailing ship period, it was an important crop fiber in many European countries like UK,
France, Germany, Spain, Italy and the Netherlands (Carus M. et al., 2013). The last ten years (20022012) hemp cultivation area was between 10.000 and 15.000 ha in Europe (Carus M. et al., 2013, p. 1).
The main producers of industrial Hemp are France, UK, Germany and the Netherlands.
Building products:
batts, rolls, fleece (felts), shives and infill material
Image 3.7.4 : Hemp products. Derived from: http://www.technichanvre.com/?lang=en
Like flax, building products made from hemp include insulation boards and batts, rolls, insulating
underlay sheets and so on. Building elements like blocks, bricks and cladding tiles are also made from
hemp fibers almost always in a combination with lime or/and concrete, that are known as “Hempcrete” blocks or Hemp/lime construction. More about this will be discussed later since these elements
present different properties than the simply hemp insulation products.
Processes applied:
similar with flax material described in chapter 3.6 in part “processes applied”
118
Production process:
Insulation products made from hemp are produced with similar processes that are used in fiber based
industries in specific manufacture companies. Hemp is harvested, cleaned and processed in similar
way with flax until to become soft enough to form the hemp insulation panels, rolls and so on.
(+) Positive Characteristics:
9From an environmental aspect, hemp cultivation can contribute to a reduction of atmospheric
CO2 levels since its rapid growth results in absorption of CO2 in a faster rate than those of other
plants or trees. According to the manufacture company Black mountain, hemp can lock away up to
2 tonnes of CO2 per tonnes of fibre harvested, reducing the effects of global warming 1.
9Hemp fibers present some of the best mechanical properties of all natural fibers. Because of these
properties are nowadays mainly used as insulation material and in bio-composites in automotive
applications. Before 1990s, hemp fibers were mostly (>95%) used to produced high cost pulp and
that was mainly used to produce only technical filters, bank notes, high quality print paper (bible
paper) and cigarette paper (Carus et al., 2013, p. 4).
9According to Blackburn (2005, p. 55) Hemp cultivation is beneficial for soils that are polluted
with heavy metals. As he mentions during experiments hemp was shown to be able to extract
and accumulate substantial amounts of heavy metals like copper, lead, zinc and cadmium with no
detrimental effect on the quality and quantity of the plants crop (Blackburn, 2005, p. 55). Therefore,
hemp cultivation can gradually clean contaminated soils and decrease the risk of introduction
of heavy metals to nutritive chain.
9Hemp is considered highly tear-resistant and sturdy fiber-made insulation. It can resist
compaction from human disturbance. Also, it is considered to be resistant without any additive to
insects and vermin. Thus, hemp insulation requires none chemical treatments against mould, pest
and insects infestation as other natural insulation products require; e.g. wool, flax.
9Non-toxic so no need of any protective equipment during installation stage.
9Hemp insulation is breathable and it can reduce free condensation water preventing mould
problems as well as improving the indoor air quality of the building. As a result of its moisture
absorbing and regulating ability, it can control indoor air temperatures reducing high indoor
temperature fluctuations.
( - ) Negative Characteristics:
8 Hemp insulation contains often synthetic fibers like polyester fibers for reinforcement reasons
in order to ensure that the insulation product will maintain its shape throughout its service life.
Polyester fibers usually constitute 13-15% of the product but in some cases this content is reached
even up to 30%. In that case, although hemp fibers are biodegradable, polyester fibers are not,
reducing the biodegradability of the final insulation product.
8 Hemp insulation is not compatible with any oxidizing agent.
8 Hemp insulation exposure for long periods to UV radiation or wetting must be avoided.
1
Info taken from company “Black Mountain Natural Insulation”. Available at: http://www.blackmountaininsulation.com/products/
natuhemp [Last accessed: 25th February 2014]
119
Alternative solutions :
A natural alternative to polyester fibers are fibers known as PLA (BIcofasern plant-based fibers) or
corn-starch. These can replace synthetic support fibers that are used for reinforcement and can also
work as a binder for the product’s content. Some manufactures of hemp insulation are already using
85-95% hemp fibers and a percentage of 5-15% of PLA.
Applications :
Generally, Flax building products can be used for both thermal and sound insulation applications.
Insulating panels and rolls can be used in roof structures, in floor, wall or ceiling constructions
(Peters, Sh. (2011, p.108), as well as insulating feltings for impact sound insulation purposes (Hugues,
T. (2004), p.62) Fibers (infill) and shives can be used to fill cavities in sound-boarded ceilings or to
insulate ducts and pipes in the form of pipe casing (Hugues, T. (2004), p.62). Flax insulation products
are also very suitable in timber frame structures and to be used as interior insulation of an outer wall
leaf (Grätz M. and Indriksone D., 2011, p. 14).
More specifically, flax insulation products can be used 1:
In roof and
suspended floor
as:
In walls, as:
-
External insulation below roof covering (protected from weather)
-
Insulation between rafters, double skin roof, topmost suspended floor
-
Internal insulation below suspended floor, below rafters or load-bearing structure
-
Below screed floor as impact sound insulation
-
External insulation behind cladding,
-
in timber frame and timber-panel forms of construction
-
Internal insulation or insulation to separating walls.
Design advices :
Hemp is tear-resistant and resistant to mould, insects and pest attacks. Manufacturers propose that its
use in conjunction with a vapor permeable underlay will retain the benefits of water vapour absorption
and release. Hemp insulation products should be protected from prolonged exposure to sunlight and
should be avoided any extended wetting without drying. Also, the ability of Hemp to absorb about 20
% of its own weight without any deterioration, makes hemp highly suitable in applications in timber
frame structures since it can draw out moisture while keep the frame conditioned 2.
Images 3.7.5 showing the application of Hemp insulation in timber studs
image taken from Technichanvre company: http://www.technichanvre.com/1411-2/1499-2/hemp-insulationrolls-and-panels/?lang=en
1
Pfundstein M. et al (2007) Insulating Materials; Principles, Materials, Applications. Munich: Birkhäuser, p. 50
2
Info taken from company “Black Mountain Natural Insulation”. Available at: http://www.blackmountaininsulation.com/products/
natuhemp [Last accessed: 25th February 2014]
120
References.:
books_
websites_
Blackburn, R.S. (2005) Biodegradable and sustainable
fibers. USA: Woodhead Publishing Limited,
p.51-57, 59-60
BLACK MOUNTAIN INSULATION LTD. Hemp insulation.
Available at: www.blackmountaininsulation.com
[last accessed: 24 February 2014]
Bokalders V. and Block M. (2010) The whole building
handbook; How to Design Healthy, Efficient, &
sustainable buildings. UK: Earthscan, p.40
DUTCH BLUE LABEL, NL provider. Available at: www.
dutchbluelable.nl [last accessed: 22 February 2014]
Carus, M. et al. (2013) The European Hemp Industry:
Cultivation, processing and applications for fibres,
shives and seeds (online). European Industrial
Hemp Association (EIHA). Available at: http://
www.eiha.org/attach/8/13-03%20European%20
Hemp%20Industry.pdf [last accessed: 24
February 2014]
European Commission, (June 2010) Green Public
Procurement Thermal Insulation Technical
Background. Brussels: European Commission,
pp: 4, 14. Available at: http://ec.europa.eu/
environment/gpp/pdf/thermal_insulation_
GPP_%20background_report.pdf
[Last
accessed: 15th February 2014]
GREENSPEC: National Green Specification. Insulation
derived from organic sources [online]. Available
at: http://www.greenspec.co.uk/insulation-plantfibre.php#sheep [Last Accessed: 31th January
2014]
HEMPFLAX. Hemp products. Available at: http://
hempflax.com/ [last accessed: 24 February 2014]
NATURE PRO INSULATION. Hemp insulation. Available at
http://www.natureproinsulation.co.uk/hemp.htm
[last accessed: 24 February 2014]
TECHNICHANVRE.
Available
at:
http://www.
technichanvre.com/ [last accessed: 24 February
2014]
Grätz M., Indriksone, D. (2011) Ecologic Construction
Materials [online]. Available at: http://
www.intense-energy.eu/fileadmin/content/
broshures/04_Ecomaterials.pdf [last accessed:
29th January 2014] pp: 4, 14
THERMAFLEECE. Hemp insulation. Available at: www.
thermafleece.com/ [last accessed: 24 February
2014]
Halliday, S. (2008) Sustainable
Butterworth-Heinemann, p.151
Construction.
THERMO HANF. Available at: http://www.thermo-hanf.de
[last accessed: 24 February 2014]
Hegger, M. et al. (2006) Construction materials manual.
Germany: Birkhäuser, pp. 136-138
MATBASE.COM: Materials> Natural & synthetic Polymers.
Available at: http://www.matbase.com/materialcategories/natural-and-synthetic-polymers/
polymer-fibers/ [last accessed: 2nd February 2014]
Hugues, T. (2004) Timber Construction; Details, products,
case studies. Birkhäuser, p.62
Pfundstein M. et al (2007) Insulating Materials; Principles,
Materials, Applications. Munich: Birkhäuser, pp:
8-14
P GEENS CONSULT BV BA: Isolate with vlaswol [online].
Available at: http://www.deskundig-isoleren.be/
vlaswol.html [Last Accessed: 31th January 2014]
Roaf, S. et al. (2013) Ecohouse; a design guide (4th
edition), Routledge
Peters, S. (2011) Materials Revolution; Sustainable multipurpose materials for design and architecture.
Germany: Birkhäuser, p. 108-109
121
122
3.8 Hemp-lime products
Material: hemp-lime or hempcrete
Category: building - insulation material
Application: thermal and sound insulation,
load-bearing, cladding, coating
3.8.1 Hemp-lime products, companies list:
FACTS: Hemp-lime products can have various applications depending on their density, form and shape. When hemp-lime
formulates blocks or walls, it is mostly used as thermal and sound insulation combined sometimes even with a sub-structural
function for the building. Hemp-lime blocks can be used as thermal insulating blocks or also as structural blocks for supportive
secondary load-bearing applications but then their thermal conductivity is increased. In liquid form, hemp-lime is applied
via a formwork to infill and insulate wall cavities or construct insulated walls. Moreover, they can be applied in thin layers as
insulating protective plaster and coatings on the building envelope. Thermal and structural hemp-lime blocks are produced by
the companies and delivered to the client dry and ready for immediate installation. In contrast, in situ applications like hemplime constructed walls , the hemp is mixed with lime and water in specific proportions given by the manufacturer, is applied
and then let to air dry for at least 6-8 weeks.
In the Netherlands, although industrial hemp is produced and limestone is extracted in specific regions that can produce
lime binders, there is not yet found for this research any Dutch company producing and manufacturing industrial hemp-lime
blocks, bricks or other products like there is in UK (Lime technology Ltd) and in France (Technichanvre). This is justifiable
to happen since hemp-lime construction methods were rediscovered and restored in use the last years in France. Since, the
ingredients of hemp-lime production can be found locally available in the Netherlands, this building material will be also
considered that can be produced locally and in a great extent.
Lime Technology Ltd Company provides a product named Tradical ® Hemcrete ® which is bio-composite building material made
from hemp shiv and lime based binder called Tradical® HB. It is suitable for on- site building applications. On the same time it
provides option for prefabricated systems made from hemp-lime, such as structural walling system for buildings up to 3 storeys
(Hembuild® systems) or cladding system with a primary structural frame that can be used as façade construction element that
covers and insulate the building (HemClad ®). Technichanvre company produces prefabricated air-dried Hempcrete blocks
ready for installation as well as provides hemp-lime for in-situ constructions.
123
3.8.2 Hemp-lime datasheet: products & sizes
3.8.3 Hemp-lime datasheet: properties
124
125
126
General info:
Hemp-lime is a bio-composite material produced by hemp shiv and lime-based binders. It is also
known as “hempcrete” because of its composition and structure. It is used as a building material with
good thermal properties to construct monolithic walls or to formulate insulating blocks and bricks.
Hemp-lime construction was established in France and has similarities with light earth construction
in practice although hemp-lime is denser and also less hygroscopic than a light earth mix because
of the use of lime (Halliday S., 2008, p.151). It has been under development since the early 1990s,
mainly through work in France and Belgium (Bevan R. and Woolley T., 2009, p. 2). The last few years,
hundreds of private houses have been built in France, UK and Ireland.
The hemp shiv that is used in hemp-lime constructions is a by-product from the decortication process
for the production of hemp fiber and hemp insulation, whereby the internal woody core of the plant
is separated from the external fibrous materials and chopped into small particles (5-30 mm in length)
and packaged to be mixed with lime-based binders. According to Carus et al. (2013 p.6) about 15%
of hemp shives are used in hemp-lime production. Hemp shives provide good thermal properties to
the composite while lime binder gives good mechanical properties making it on the same time fire,
rot and pest resistant. Although hempcrete cannot be used as load-bearing structure and is used more
as infill, research has indicated that hemp-lime products produced with a certain mix can present a
good compressive strength that is enough to be dispense with, or reduce the timber or other structural
frame required (Halliday S, 2008, p. 151).
Building products:
bulk composite material, block units, facade-wall systems
Hemp-lime products can be used and installed in multiple ways for insulation and other applications
(e.g. wall infill, cladding and coating applications). It can be found in the form of precast, in situ cast
and sprayed mixture of hydraulic or hydrated lime based binder, cement, water and hemp (Greenspec,
2013). Sometimes it can contain sand or even aluminum in its binder and other mineral particles. The
proportions of the hemp lime mixture can vary according to the density and characteristics required.
In-situ hemp-lime is usually either molded into a formwork or either applied by spraying techniques
in order to construct walls around or in between the structural frame of the building. For small
building projects (area smaller than 70m 2), the construction technology that is usually walls is insitu casting of the bulk material in shuttering, whilst for larger projects the most common method
is spraying techniques. Both techniques produce a monolithic structure that has high thermal mass
and good enough insulating properties as well as an adequate compressive strength to carry its own
weight.
Hemp-lime can also be found in the form of precast blocks and bricks that can be used as insulating
and constructing components on a building envelope to create wall or floor surfaces. In the case of
precast forms, the products are manufactured in the producer company and are delivered on site,
already air-dried and ready for installation, decreasing the time of construction compared with insitu hemp-lime casting or spraying. The blocks are usually either structural blocks (that present a
better compressive strength) or thermal blocks (which present a better thermal behavior and poorer
mechanical properties). Precast façade or wall systems are prefabricated panels usually made from
double stud timber cassettes that are filled in with hemp-lime and are delivered on site ready for
installation. Such cladding panels can be hanged out on steel, timber or concrete structural frames
creating an insulating and air-tight enclosure for the building.
127
The dimensions of the products range; for blocks the usual thickness is from 100 to 300 mm and sizes
of 215 X 440 and 300 X 600, while for walls, the thickness can vary from 300 mm to 500 mm and the
length and height vary. For precast hemp-lime wall systems, manufacturer suggests that it is a suitable
design option for low-rise buildings of 1-3 storeys (Lime technology Ltd, 2014).
Processes applied:
Mixing, casting or spraying building method, curing (air-drying)
Production process:
Hempcrete or hemp-lime is produced by mixing hemp hurds (shives) and lime, cement, pozzolans
and/or other mineral additives, and sometimes even sand may is used.
a) Mixing: Hemp and lime are mingled together as well as water is added, all added in a predetermined
ratio that is given by the manufacturer according to the intended use of the product. The ratio
ranges depending on the requested thermal and mechanical properties of the final product. All
are blended altogether in specific mixers suitable for this process in order to form a homogenous
bulk material.
b) Casting in-situ: In case of casted walls on-site, the produced admixture is tipped into the shuttering
and lightly tamped into place. The shuttering is left for 12 to 24 hours and then is removed to
allow the hempcrete wall to dry, protected from weather. The final product is a monolithic wall
that can work in some cases both as insulating and self-supportive load-bearing element.
c)
Spraying method: For large buildings, spraying method is used more often for in-situ hempcrete
construction. In this case, hemp shives are blended dry in the specific proportion with the lime
binder, and then water is added close to the nozzle of the spraying system. Then, the material is
sprayed against single sided shuttering and flattened to the required surface. Shuttering that is
used can be either temporary or permanent. In the case of temporary shuttering it is also removed
after 24 hours. Spraying method requires less water, gives usually better mechanical properties
and is a faster construction method than casting process.
d) Forming: In the case of production of blocks or other prefabricated building components, the
admixture is casted in molds of specific shape and size in the manufacture units of the producer
company in order to form blocks and wall panels of specific dimensions and properties. Then are
air-dried and ready to be delivered on site.
e) Curing: In all cases, the resulting products need to dry out to a certain extent before they are
rendered, or if they are finished with cladding and a well vented cavity. Drying and curing time
ranges from 6 to 8 week. Normally it takes about four weeks (Bevan R. and Woolley T., 2009,
p.3). The time needed for hempcrete to dry is strongly dependent on the mix, weather and site
conditions (for instance; sun radiation, outdoor air temperature, wind speed, relative humidity,
rain, and so on)͘ High humidity levels and low temperatures can delay curing times significantly.
Thus, usually the installation –construction period takes place in March-July (Lime technology
Ltd, 2014).
128
(+) Positive Characteristics:
9Hemp-lime products are breathable and vapour permeable although less hygroscopic compared
to other material. It can function as a moisture regulator for the indoor air by allowing “the
transpiration and diffusion of water vapor between the inside and outside of the building equalizing
humidity within the building thus avoiding humid and cold areas and minimizing condensation
on the inside wall surfaces”. Their high thermal mass and effective inertia allow decreasing
temperature fluctuations in indoor environments, reducing the demands for heating or cooling
of the building. Lime technology Ltd Company supports that “Hemcrete® was shown to completely
dampen a sinusoidal change in external temperature of 20°C to 0 °C, over a 24hours cycle Hempcrete
subjected to sudden heating of 20°C, it took 850 hours for the Hemcrete to achieve a steady state and
the effect of latent heat transfer within the Hemcrete® was shown to reduce the need for cooling by
nearly 10%”
9Hemp-lime can be casted and form any shape of wall or block unit (curved, inclined, etc) and
they can provide both thermal and acoustical insulation but also be structural components on a
building’s envelope.
9Hemp-lime works synergistically with other natural breathable building products and materials
and has also good fire, pest and rot resistance.
9It is a carbon negative material through sequestration of CO2 during the cultivation of the Hemp
plant. Manufacturers (Lime technology Ltd and Technichanvre, 2014) supports that about 165 kg
of CO2 can be captured per m 3 of hemp-lime constructions. Moreover, for 1 m3 of hempcrete wall
mix, it is needed 110 kg of hemp shive that absorb ca. 202 kg of CO2 during the plant growth, and
220 kg lime binder which emits 94 kg of CO2 during its manufacture, giving a net sequestration
of absorbed 108 kg CO2/m 3 (HA HEMP ARCHITECTURE, 2014)
9It is non-toxic and emits no VOCs during its installation or use stage.
9Lime-hemp is a lightweight material with an adequate compressive strength meaning that can
form insulated walls that need fewer supports and lighter foundations.
9No solid waste during construction in case of in-situ casted or sprayed hempcrete.
9The material can be reusable if it is dismantled carefully. For instance, according to Lime Technology
Ltd, the material can be crushed up during demolition works and remixed with lime binder to
reform new walls and structure. Thanks to its high pH (about 11-12, alkaline), the material can
be also crushed into fine powder at the end of its life and can be spread on flower beds to increase
the pH of the soil and introduce mulch. Thus is a recyclable and reusable building material.
( - ) Negative Characteristics:
8 It is a weather dependent material in case of casted or sprayed structures that needs a protracted
drying period. Sometimes a drying period can 100-120 days is required so hempcrete to cure
completely. During construction the weather temperature should not fall below 5°C and the
material must be protected adequately rom frost and heavy rain. Thanks to this, the construction
can be more time consuming compared with other materials and also there is a risk of frost
damage during the curing process if there is no adequate protection.
8 In the case of hemp-lime, protective clothes, gloves and other equipment is necessary since the
material is skin and eyes irritant and can cause burns in the presence of moisture.
129
8 Hemp-lime constructions use large amount of lime-based binder which needs for its production
high kiln temperatures. Generally, Lime is produced from calcium carbonate, a compound that
can be found in raw materials like limestone, chalk, shells, and others. Calcium carbonate heated
in kilns to approx. 900 oC changes chemically and produces lime, whereas any unreacted calcium is
slaked to calcium hydroxide; an inorganic compound. Calcium hydroxide when mixed with water
produces hydrated lime or also known as quick lime. Calcium carbonate (limestone) that contains
clay minerals and/or other impurities will produce during the heating process “hydraulic lime”.
More specifically, Calcium will react under the high temperature with the clay minerals to produce
silicates that enable the lime to set without exposure to air. Hydraulic lime is able to set under
water and is known since the Roman Empire. Although the fact that lime requires high energy
to be produced, it is considered an environmental friendly alternative to cement and concrete
since it demands lower firing temperature, therefore it is less energy intensive than Portland
cement and also it can re-absorbs the carbon dioxide (CO2) emitted by its calcination (firing),
thus partially offsetting the large amount emitted during its manufacture. More specifically, the
hydraulic lime as a building material is breathable. It is has also a lower density that cement thus
creates less cold bridging.
8 Use of cement or aluminum in some binders increases the embodied energy of the products.
8 Hemp-lime is also weak to prolonged exposure to moisture and needs to be protected from
weather both during its production-construction phase but also afterwards. Maintenance is
needed often in the means of adequate plaster coating and wall finishes..
Applications :
Hempcrete can be used in load-bearing applications, integrated with a timber, steel or concrete frame.
It can work synergistically with other natural products and also stiffen structural frames after its
curing period. More specifically, hemp-lime products can be used:
Image 3.8.4
In roof and
suspended
floors as:
In walls, as:
-
Insulation and infill between or
below rafters, in inclined roof etc.
-
Impact sound insulation below
screed as insulating floor surface
with sub-structural function.
-
External insulation and wall behind
cladding or rain-screen protection
-
Insulation and infill in timberframe and timber-panel forms of
construction
-
Insulation and infill in steel or
concrete structural frames
-
Internal insulation to wall and to
separating walls
-
Acoustical interior partition walls
(no load-bearing)
Image 3.8.5
Image 3.8.4: Hemp-lime wall.
Image taken from: http://www.weedist.
com/2013/07/high-scientist-hempcrete/
Image 3.8.5: Hemp products.
Image taken from: http://inhabitat.com/hemcrete-carbon-negativehemp-walls-7x-stronger-than-concrete/hemcretewallsection/
130
Design advices :
When designing with hemp-lime blocks, the same “construction method practices” and design approach
should be followed as those applied for the construction of a brick or stone masonry, meaning that
a regular bond pattern should be maintained, based on a minimum overlap of a quarter of a block
as well as lintels should bear on to full blocks, wherever possible (Lime technology Ltd, 2014). The
fixing that are recommended to be used in hemp-lime block masonries are light and medium weight
fixings (up to100 kg), normal wood screws (without rawl plugs). “Screws should penetrate the block
to a min. depth of 5 cm and heavier items should be fixed using resin fixings. As a general rule, fixings
should not be closer to the free edge of the block than the depth of the fixing penetration, nor should
they be over-tightened as this can affect the pull out strength” (lime technology Ltd, 2014). Hemp-lime
products are suitable for renovation and improvement works since they can increase insulation to
existing buildings. Hempcrete can be used to construct walls in order to reduce the size and number
for load-bearing components.
Careful design attention should be paid for the joints of the buildings. Manufacturers state that vertical
day joints must be avoided so to “achieve that work should be planned to complete up to the side of
openings”. Horizontal day joints should be prepared gently, removing slightly the loose surface of the
older material before the application of more hempcrete mixture. Lime technology Ltd recommends
builders to form a simple physical shape into the day joint surface, such as a rectangular batten, to
provide an interlock between elements constructed at different times.
Hempcrete structures should be protected from weather like all the other biodegradable materials
(earth constructions, papercrete, etc). This can be succeed with roof overhangs, by plastered it or
covered it with a rain-screen cladding (masonry or timber). The plaster, paint or coating used should
be checked to be suitable and breathable for a material like hempcrete. For instance, lime wash,
lime paint for external application or clay paint, lime paint, casein paint and others for internal
application. Impermeable paints, coatings and plaster in external wall surfaces must be avoided since
they can cause severe degradation to the wall due to a potential buildup of moisture within its structure
(Technichanvre, 2014). Maintenance works can take place by refresh of the paint/plaster after 15-20
years and subsequent optional painting every 5-7 years after that. The lifespan of hemp-lime structure
given by manufacturers is approx. 100 years.
Image 3.8.6
Image taken from: http://www.archiga.it/wp-content/uploads/2013/02/biomattone1-1024x768-500x375.jpg
131
References.:
books_
websites_
Carus, M. et al. (2013) The European Hemp
Industry: Cultivation, processing and
applications for fibres, shives and seeds
(online). European Industrial Hemp
Association (EIHA). Available at: http://
www.eiha.org/attach/8/13-03%20
European%20Hemp%20Industry.pdf
[accessed: 11 March 2014]
CHANVRIBLOC: Le bloc chaux chanvre pour isolation et construction.
Available at: http://www.chanvribloc.com/index.html [Last
Accessed: 5th March 2014]
Fovargue, J. (2004) Crops in construction;
handbook. London: CIRIA, p.52
GREENSPEC: National Green Specification. Concrete and its alternatives
[online]. Available at: http://www.greenspec.co.uk/buildingdesign/blocks/#hemp [Last Accessed: 11th March 2014]
Halliday, S. (2008) Sustainable Construction.
Butterworth-Heinemann, p.151
Nielsen
B., (2013) Hennepbeton nieuw
alternatief bijisolatie (online). Available
at:
http://dunagro.nl/wp-content/
uploads/2013/09/DvhN-28-08-2013.
pdf
Sutton, A., Black D. and Walker P., (2011) Hemp
lime; an introduction to low-impact
building materials. (online) Available
at:
http://www.bre.co.uk/filelibrary/
pdf/projects/low_impact_materials/
IP14_11.pdf [Last Accessed: 5th March
2014] Bre press.
Bevan R. and Woolley T. (2009) Constructing a
low energy house from hempcrete and
other natural materials. UK; University
of Bath, pp:2-3
GREENSPEC: National Green Specification. Insulation derived from
organic sources [online]. Available at: http://www.greenspec.
co.uk/building-design/insulation-plant-fibre/#hempcrete [Last
Accessed: 5th March 2014]
HEMPCRETE.COM.AU: hempcrete Australia Pty ltd, energy saving
eco building. Available at: http://www.hempcrete.com.au/ [last
accessed: 24 February 2014]
IZREAL.EU: Hemp Building Blocks. Available at: http://izreal.
eu/2013/04/05/hemp-building-blocks/ [last accessed: 24 February
2014]
LIME TECHNOLOGY LTD: manufacturer. Available at: http://www.
limetechnology.co.uk/ [Last Accessed: 11th March 2014]
LIME TECH INFO (2008) Unique thermal performance of Tradical
Hemcrete®. Available at: http://www.limetech.info/upload/
documents/Hemcrete/Ian%20Mawditt%20Presentation.pdf [last
accessed: 2nd March 2014]
HA HEMP ARCHITECTURE, Innovation-research-design. Available
at:
http://www.hemparchitecture.com/hemp-lime/
[Last
Accessed: 11th March 2014]
HEMP MATERIALS. Hempcrete. Available at: http://hempmaterials.
com/hempcrete/ [Last Accessed: 11th March 2014]
HEMP TECHNOLOGIES. Facts about Lime. Available at: http://www.
hemp-technologies.com/page16/page34/page34.html
[Last
Accessed: 11th March 2014]
HEMP TECHNOLOGIES. Hemp Building Projects around the world.
Available at: http://www.hemp-technologies.com/page14/page14.
html [Last Accessed: 11th March 2014]
TECHNICHANVRE: manufacturer Available at: http://www.
technichanvre.com/ [last accessed: 2nd March 2014]
NUG MAGAZINE: (Jan 2010) Hemp Houses. Available at: http://nugmag.
com/hemp-houses/ [Last Accessed: 11th March 2014]
132
3.9 Cellulose products
Material: cellulose (paper flakes)
Category: insulation material
Application: thermal and sound insulation
3.9.1 Cellulose products, companies list:
3.9.2 Cellulose products sizes
133
3.9.3 a. C datasheet: properties
134
3.9.3 b. Cellulose datasheet: properties
135
3.9.4. Cellulose datasheet: durability & processability
136
General info:
Cellulose is an insulating material produced from recycled paper, in turn, derived from wood. Cellulose
is also known as paper flakes, and is used for thermal and sound insulation. The recycled paper that
is used as basis for the production of cellulose flakes is usually newsprint paper, newspapers, as well
as daily paper. Thus, cellulose is a by-product that is derived from waste recycled paper. There is also
a type of cellulose produced from pure paper free from ink.
Building products:
loose fill - paper flakes
Cellulose insulation is constituted from chopped paper (75-85%) which is treated with fire retardants
(usually 10-15%) such as boric salts or other salts to protect it against rot, mold, fungal and pest
infestation. Cellulose is used to insulate hollow spaces (e.g. ceiling, wall and floor cavities) and can
be found as dry cellulose (loose fill), spray-applied cellulose (wet-spray cellulose), low-dust cellulose
and insulation pellets. It can be installed as loose-fill either by blowing-off machines in different
parts of the building, either by injection processes or by a wet-spraying installation process. In case of
insulation pellets, cellulose is densely packed under floor surfaces and then is covered and protected
by the finish overlay of the floor surface. The density of cellulose insulation ranges and is dependent
on the installation method that is used as well as on the intended use; thermal or/and sound insulation.
Thermal insulation usually requires a density of 35-65 kg/m 3 of paper flakes whereas for acoustical
applications a density of 500 kg/m 3 is suggested.
Processes applied:
Sorting, fine-grinding and chemical treatment (admixtures), packaging
Production process:
Cellulose manufacture process is very simple and is produced with the following steps:
a. Collecting/sorting: Waste paper, like newsprint and daily paper, is firstly collected via recycling
programs and sorted. The paper is first put through the shredder and small parts, e.g. paper clips
or other metal elements are removed by an electromagnet.
b. Fine-grinding: Then, the delivered paper is roughly chopped in a fine-grinding mill in a specific
grain size that will enable paper flakes to retain air influences its later subsidence behaviour and
caloric conductivity. The produced paper flakes are similar to cotton wadding,
c.
Chemical treatment (admixtures): At the same time, in the grinding mill, the paper flakes are
mixed with boron salts and ground with a centrifuge. Thanks to this, paper flakes become fire
resistant and less vulnerable to mould and pest attacks.
d. Water admixture: in case of manufacturing cellulose pellets, the paper is first moisture in water
and then chopped in pellets of approx. 35-5 mm (Thermofloc, 2014)
e. Packaging: Afterwards, the paper flakes are packed in bags weighting usually 12.5-14 kg each.
For the production of cellulose, most European manufacturers are following the strictest standards
(German-Austrian standards) and the European technical approval. The production is continuously
monitored by internal and external control to qualify the product’s quality and safety. Cellulose
production is a relatively low intensive production in terms of energy in comparison with other
insulation materials, such as polystyrene or glass fibre. The primary energy needed for cellulose is
only 1/6 of the energy used to produce polystyrene insulation and about 1/3 compared with glass fibre
(ISOCELL, 2014).
137
(+) Positive Characteristics:
9Cellulose insulation is a by-product produced by recycled waste daily paper, and it has very low
embodied energy. Isofloc (Cellulose manufacture company) also states that “cellulose fibers can
bind about 1,4 Kg of CO2 per kg of installed insulation”.
9It has a high storage capacity that can result in a considerable delayed transfer of warmth from
the sun via radiation so it can help in a reduction of heating and cooling demands.
9Manufacturers state that cellulose is not toxic since once installed, all cellulose materials are safe
and do not emit any gases. They do not contain harmful substances or additives for human and are
not skin irritants. Cellulose is considered a friendly insulation material, although it is suggested
to be worn protective masks for mouth and nose when cellulose is installed for protection of the
respiratory system of the installers (Grätz M. and Indriksone, D., 2011, p. 11).
9Cellulose insulation is also like other natural products (wool, hemp, flax, etc) able to regulate
humidity by accumulating moisture within its flakes (fibers) without losing its insulation value.
It can emit moisture back to the air evenly when the indoor air humidity levels are decreased.
9One great advantage of cellulose compared with other biodegradable insulating materials is its
form (flakes) allows to be installed compactly and joint-free, resulting in a maximum sound and
thermal proofing capacity. ISOCELL Company supports that tests showed that in mid-walls the
achieved sound reduction reached up to 7 dB more compared with conventional fibre insulating
mats.
9Thanks to the installation methods (blowing-off, injection) and its bulk capacity there is also
no construction waste occurring during installation as a result of cutting waste generated in
other forms of insulation like boards, batts and rolls. Only the exact amount of insulation that
is necessary for a particular construction is blown into the building component. Moreover, no
additional supportive or fixing components like bolts, joints etc are needed.
9Cellulose insulation has also achieved one of the best possible ratings for flammability in insulating
materials according to the manufacturers (Thermofloc, ISOCELL, etc.). As they mention, cellulose
insulation does not burn but only the outer layer is charred, and according to Roaf S. (2013, p.
74) it can withstand direct heat from blow lamp.
( - ) Negative Characteristics:
8 A negative characteristic of cellulose insulation that can be mentioned here is its content to inorganic and mineral salts that often are contained even in 10%. These salts –as it is often mentioned earlier- are added in order to strengthen the material against mould and pests infestations
as well as to increase its fire resistance in case of fire. The borates and other mineral salts can
be a problem when it comes to the disposal of the product. Borax is sodium-tetraborate and is
considered moderately toxic, although it is usually considered and environmentally acceptable
pesticide (Woolley T. et al, 1997, p.44). However, the above mentioned additives do not impair the
possibilities of recycling and re-using cellulose flakes (Grätz M. and Indriksone, D., 2011, p. 12)
so cellulose insulation is considered a 100% recycled and recyclable product (Roaf S., 2013, p. 76)
8 Cellulose insulation has very poor mechanical performance. It cannot be subjected to pressure
loads, since this will lead to problems to the materials performance (Hugues, T., 2004, p. 64).
138
8 If cellulose is installed wrongly by non-professionals, it can cause small particles that are
contained in cellulose to be blown into the indoor environment of a building. For instance,
through inadequate seals around the fixtures or minute holes. Thus, cellulose installation should
be made only by professional experienced installers to avoid such problems.
Applications :
Cellulose insulation is ideal to be installed in order to infill hollow spaces and cavities. It is very
suitable when the space that needs to be insulated contains a lot of difficult corner parts since cellulose
can be injected to fill the space until it creates a specific density that can ensure that the requested
thermal and acoustic properties are achieved. More specifically, cellulose flakes can be used onto
horizontal, curved or inclined surfaces, like:
In roof and floor as:
In walls, as:
-
Insulation injected onto ceilings and floor cavities.
-
Insulation under the screed floor as impact sound insulation
-
Insulation between the rafters
-
Insulation injected into external or internal wall linear cavities
Image 3.9.5
Image 3.9.6:
Cellulose installation via blowing machines on roof/attic
Cellulose installation on floor cavity
Image taken from Thermofloc company’s brochure,
downloaded from: http://www.thermofloc.com/
Image taken from: http://www.warmteplan.nl/
producten/isofloc/isofloc-cellulose-isolatie.html
Design advices :
Cellulose insulation can be only applied in closed cavities in roof, walls or ceilings by blow-off or
injection. In floor it can be applied with similar way or by spreading up the material and compact
it on top with the floor finish surface. Cellulose insulation must not be subjected to pressure loads
and should be protected against damp (Hugues T., 2004, p. 64). Subjection to pressure may result in
loss of thermal performance. A vapor barrier should be avoided to be applied in the case of cellulose
insulation. Cellulose accumulates and distributes the moisture within its fibers throughout the cavity
preventing a buildup of moisture in one area and regulating humidity. It is not recommended from
manufacturers to be installed a vapour barrier with cellulose because this gradually will lead into
buildup moisture and consequently to mould problems, since moisture will be trapped in the interior
of the cavity.
139
References.:
books_
websites_
Grätz M., Indriksone, D. (2011) Ecologic Construction
Materials
[online]. Available at: http://
www.intense-energy.eu/fileadmin/content/
broshures/04_Ecomaterials.pdf [last accessed:
29th January 2014] pp: 4, 9-112
BIOFIB ISOLATION. Available at: http://www.biofib-isolation.
com/ [last accessed: 25 February 2014]
European Commission, (June 2010) Green Public
Procurement Thermal Insulation Technical
Background. Brussels: European Commission,
pp: 4, 14. Available at: http://ec.europa.eu/
environment/gpp/pdf/thermal_insulation_
GPP_%20background_report.pdf
[Last
accessed: 15th February 2014]
Hugues, T. (2004) Timber Construction; Details,
products, case studies. Birkhäuser, p.564
Kwok A. et al. (2011) The Green studio Handbook
Environmental strategies for Schematic Design.
(2nd edition). USA: Elsevier Inc: p. 42
Lyons A., (2008) Materials for architects and builders
(4th edition). China: Elsevier, pp.344,348
Pfundstein M. et al (2007) Insulating Materials;
Principles, Materials, Applications. Munich:
Birkhäuser, pp: 10-15
Roaf, S.et al (2013) Ecohouse; a design guide (4th
edition), Routledge: pp.74-76
Peters, S. (2011) Materials Revolution; Sustainable
multi-purpose materials for design and
architecture. Germany: Birkhäuser, p. 38
CLIMACELL GMBH. Available at: http://www.climacell.de/
and http://www.climacellisolatie.be [last accessed: 22
February 2014]
DAKISOLATIE. BE. Available at: http://www.dakisolatieexpert.be/cellulose-isolatie-dak-zolder [last accessed: 10
February 2014]
GREENSPEC: National Green Specification. Cellulose
insulation [online]. Available at: http://www.greenspec.
co.uk/building-design/insulation-plant-fibre/#paper
[Last Accessed: 8th March
HOMATHERM GMBH Available at: http://www.homatherm.
com/ [last accessed: 26 February 2014]
ISOCELL GMBH. Available at: http://www.isocell.at/
accessed: 25 February 2014]
[last
ISOFLOC WARMTEPLAN B.V. Available at: http://isofloc.
com/ and http://isofloc.nl/ [last accessed: 22 February
2014]
ISOPROC CVBA. Available at: https://www.isoproc.be/
accessed: 25 February 2014]
[last
THERMOFLOC BV. Available at: http://www.thermoflocisolatie.nl/ [last accessed: 22 February 2014]
WARMCEL ISOPROFS B.V. Available at: http://www.warmcel.
co.uk/ and http://warmcel-insulation.nl/
[last
accessed: 22 February 2014]
Woolley et al., [1997] Green Building Handbook; Great
Britain: E& FN Spon, pp: 42-44
140
3.10 Papercrete products
Material: papercrete
Category: insulation material
Application: thermal and sound insulation
3.10.1 Papercrete, companies list:
3.10.2 Papercrete datasheet: products & sizes
141
3.10.3 Papercrete datasheet: properties
142
General info:
Papercrete is a “new” experimental material that is not yet produced from many commercial
manufacturing companies (only two found; Econovate and GreenStar BLox). Actually, papercrete was
first patented in 1928 (Wikipedia, 2013) and recently rediscovered by individuals that are curious to
examine the possibilities and potentials of such material that started re-experimenting with it again.
Papercrete presents high environmental potential due to the fact that it replaces an amount of cement
by the use of paper and the total weight, cost and CO2 emissions during production are reduced
(Kokkinos, M. 2011, p.7). It has potentials to become a future building material for lightweight
applications thanks to its low cost and high recycle paper content. However, its use remains limited
since official data about its properties and mechanical and structural behavior are missing.
Papercrete is mainly made from recycled paper that is combined usually with sand and Portland
cement (Lyons, A., 2010, p.401) creating a composite material that is malleable and can be casted
and molded in various forms and shapes. Pulverized waste glass derived from recycled bottles is also
sometimes used instead of sand. Thus, papercrete use in building and other applications is expected
to be able to remove up to 20% of the waste material (Lyons, A., 2010, p. 402) reducing consequently
significantly the size of waste that accumulates in landfills.
Papercrete can be casted and pressed into bricks, blocks and panels and can be used in the building
industry for a variety of applications (Peters, S. 2011, p.91). Papercrete can be used also as a casting
material in-situ that can be applied directly to walls as “gunned/shotcrete” (Peters, S. 2011, p.91) to
construct monolithic structures. Moreover, papercrete mortar and stucco can be produced from the
same ingredients but in a stronger mix of 1:1 proportions (paper: cement) (Lyons, A. 2010, p. 402)
Building products:
monolithic structures (in-situ), pre-casted forms
Building products made from papercrete have usually a white to grayish colour and can be from
blocks until pre-casted panels. The pliable nature of the material allows it to be casted in various
possible forms and shapes allowing a great variety of future products, but also to be casted to construct
monolithic walls and structures. The basic ingredient for papercrete production is the paper (ca. 80%)
which is mostly pre-consumer recycled paper so papercrete can be reconsidered as a by-product
produced from waste paper. Water, sand, , and binders like cement, clay, fibres or even fly ash are
added to make papercrete flame and fungus retardant. Due to its experimental phase, papercrete
products are mainly produced by individuals and researchers in different mixtures and shapes, and
there are not yet any typical commercial sizes or shapes.
Processes applied:
saturation - mixing, forming via casting and moulding, air-drying
Production process:
Papercrete can be produced with different mixtures depending on the percentage of waste paper that
it contains (it can vary from 50-80%) as well as the type of paper and additives. Waste paper can
derived from newspaper, junk mail, magazines, and books. It is noticed that some types of paper work
better than others; newspaper is most commonly used because it produces consistent results (Kokkinos,
M. 2011, p.11). Papercrete production is made in two very simple phases:
143
a. Collecting/soaking/mixing: Waste paper as well as recycled paper is collected and chopped in
small pieces and saturated in water until to create a small paper pulp. Afterwards, the shredded
paper is blended usually with sand and Portland cement in an approximate ratio of 3:1:1 (Lyons,
A, 2010, p.401). Extra water is then may added to make the mixture pliable, and to transform
it into a paper mâche-slurry. Other ingredients that may are added are sand, glass shivers, and
glossy paper from magazines, fly ash, clay and even sometimes dirt (animals’ excrement).
Table 3.10.4: Papercrete mix content- depending the use (Kokkinos, M. 2011, p.11)
Paper (%)
Portland Cement (%)
Sand (%)
Use
80
20
0
Good general use
80
10
10
Good for shaping or sculpting
60
20
20
Outdoors:retaining walls etc.
80
10
10
Can replace sand mix
70
10
20
Indoor floors
b. Forming - casting: After the mixture is ready, it is casted into wooden or metal mould of the
shape that the final product is requested to be formed. The mould is removed after 3-7 days and
then the papercrete product is left to cure via air-drying. Curing period can last a long period
of time depending on the thickness-size of product. For instance, for papercrete blocks of 15 X
15 X 15 cm, the curing period was 50 days (Kokkinos, M., 2011, p. 21). The casting tools used
more often is rectangular forms and linear wooden shuttering. Metal formwork is most preferable
because it is more durable. The inner side of mold is painted or shellacked to provide a silk and
smooth surface and ease the mould removal.
(+) Positive Characteristics:
9Papercrete is a material produced mainly from
waste materials (waste paper, waste glass, etc)
so this decreases significantly its cost.
9It is a lightweight material with good insulating
properties (Lyons, A. 2010, p.402) and when
contains cement it is also fire resistant.
9Papercrete constructions via the use of waste
paper, especially in communities that do not
have intensive recycling services, can be a
material with great positive environmental
potential, since as Lyons A. (2010, p.402)
notices it can “remove up to 20% of the waste
material that are currently deposited in landfill
sites”.
9The use also of magazines and printed paper
in this material can be beneficial from
keeping “printing chemicals out of the water
table” while at the same time preserves tree
Image 3.10.5
resources that may have been used for other
Papercreete bricks. Image taken from: http://www.offthegridnews.
com/2014/04/17/how-to-build-an-off-grid-home-out-of-newspaper/
building products.
144
( - ) Negative Characteristics:
8 Papercrete has poor moisture resistance. It is a material that is
very water-absorbent so it is susceptible to any moisture source
Material susceptible also to termite and mould.
8 Use of additives like Portland cement, change the biodegradability
of the papercrete products. However, when added in papercrete,
it presents usually a fairly small percentage of the material by
volume. Low longevity.
8 Expands and contracts frequently resulting in cracks in the
material’s surface. Material will break in papercrete items with
delicate details or small thickness (≤ 3mm) (Kokkinos, 2011, p.
21).
8 Poor tensile strength, low fracture toughness
8 Experimental phase (yet), not much tested /low longevity
Applications
+ Design advices :
Papercrete
is
a
ver y
lightweight material that
can be used as cladding
or to construct non loadbearing walls. Peters, S.
(2011, p.91) mentions that
the relatively low weight of
papercrete material and its
high elasticity can make it
suitable for applications in
buildings sited in areas of
high risk of earthquakes.
Papercrete
must
be
protected adequately from
any mechanism of moisture.
Image 3.10.6
Papercreete structure. Image taken from:
http://psychic-delia.com/psychic-readings-online/psychic-environments-housing-sou
145
References.:
books_
Kokkinos, M. (2011) Papercrete; another façade cladding material.
(Msc thesis) Delft: Technical University of Delft, pp: 7,11,
21-2, 48
Lyons A., (2008) Materials for architects and builders (4th edition).
China: Elsevier, pp.401-402
Peters, S. (2011) Materials Revolution; Sustainable multi-purpose
materials for design and architecture. Germany: Birkhäuser,
p. 38
Roberts, J. (2008) Green your home: the complete guide to making
your new or existing home environmentally friendly. USA;
Atlantic Publishing Group.Inc (online book) Available at:
http://books.google.nl/books?id=FZkjvgKAXIIC&pg=PA2
35&dq=papercrete&hl=en&sa=X&ei=wyQBU7ziGoGg0Q
Xd44CwDA&ved=0CD8Q6AEwAw#v=onepage&q=paperc
rete&f=false [Last Accessed: 18th March 2014]
Yun, H. et al (unknown) Mechanical properties of papercrete containing
waste paper (18th international conference on composite
materials) Department of Architectural Engineering, Seoul,
Korea: Hanyang University (online) Available at: http://
www.iccm-central.org/Proceedings/ICCM18proceedings/
data/2.%20Oral%20Presentation/Aug23(Tuesday)/T15%20
Green%20Composites/T15-3-IK0961.pdf [Last Accessed:
8th March 2014]
websites_
ECONOVATE Available at: http://www.econovate.com/
Accessed: 8th March 2014]
[Last
MAKE PAPERCRETE. Available at: http://makepapercrete.com/ [last
accessed: 22 February 2014]
LIVING IN PAPER. Available at: http://www.livinginpaper.com/
mixes.htm [last accessed: 22 February 2014]
PRECAST PAPERKRETE PANELS . Available at: http://papercrete.
wordpress.com/page/2/ [last accessed: 10 February 2014]
WIKIPEDIA. Papercrete. Available at: http://en.wikipedia.org/wiki/
Papercrete [last accessed: 25 March 2014]
SEMPER PARATUS. Papercrete. Available at: http://semper.xenxnex.
com/papercrete/ [last accessed: 26 February 2014]
GREEMSTAR BLOX. Available at: http://masongreenstar.com/ [last
accessed: 25 February 2014]
146
3.11 Paperboards
Material: Paperboards
Category: structural, insulation material
Application: thermal and sound insulation, partitioning, wall finish
3.11.1 Paperboards companies list:
147
3.11.2 Paperboards datasheet: sizes and prices
148
3.11.3 Paperboards datasheet: properties
149
150
151
General info:
Paperboards are a paper-based material that can be made with different processes. They can be from
rigid boards until semi-flexible sheets with different surface finish and thickness depending on the
intended use; laminate, printed graphic design, thick Kraft paper, and so on. They can be used in
various applications depending on their composition and manufacture process in interior partitioning
systems or for thermal but mostly sound insulation uses. Paperboards can be found in the form of
sandwich honeycomb panels with or without any surface finish, as rigid paperboards, or semi-flexible
cellulose boards. The exterior layers of paperboards can be of a different material and quality, from
impregnated or colored thick paper to laminated surface.
Building products:
boards, sheets, panels
Paperboards used for building applications can be
found in different thickness and are mainly consist
of three main categories of boards according to their
flexibility, their manufacture process and intended use;
1.
Flat or corrugated thick paper sheets that are
usually used as surface wall or furniture finish (e.g.
image 3.11.4, Wellboards).
2.
Rigid honeycomb cardboard (image 3.11.5) or
sandwich paper honeycomb structure like for
instance EnviroBoards®, Stramit®, are mainly used
for interior applications. Honeycomb paper is a
hexagonal shaped structure which can be used
also as a structural material for doors, interior
partitioning and other uses. It resembles the bees
honeycomb shape and is covered with a variety of
surface finishes according to the desired product’s
performance characteristics.
3.
Semi-flexible paperboards made of cellulose
particles (85%) bonded together with sometimes
polyolefin fibers and boric salts in a percentage
of 7-10% and less than 5% respectively. They
are mainly used as insulating material and one
example of such paper based board is FlexCL from
Homatherm Company (image 3.11.6).
Image 3.11.4
WellBoards, corrugated paperboard
Image 3.11.5
Ecopan honeycomb paperboards
Image 3.11.6
Flock CL Homatherm paperboard
Most paperboards are produced by recycled waste
paper (newsprints, cardboards, etc) and contain about
3% of zero formaldehyde resin type. Cellulose content
of the product is usually more than 85-95%. Sometimes
wood pulp can be used in combination with paper pulp
(e.g. Wellboards) as well as a percentage of gypsum.
Impregnated boards with resins that increase the fire
or moisture resistance of the product can also be found.
152
Processes applied:
saturation-mixing, wet-forming, drying, impregnation
Production process:
Paperboards production is a standard process. In manufacture companies wherein the resources that
are used not virgin but derived from recycle; such as recycled waste paper, recycled water and waste
gypsum, and so on, the embodied energy of the material is lower and its recycled content is much
greater than other building boards. The manufacture process that is followed for the production of
paperboards is the following:
a. Collecting/soaking/mixing: Waste paper like newsprint and cardboard are collected and are
broken down and converted to a paper pulp. The paper pulp (or wood pulp can be also used) is then
forming one or multiple-layered boards. Water and often about 3% of resin (that is formaldehyde
free) added; increase the bondage of the cellulose content of paper and its own.
b. Wet-forming, heat treatment and impregnation; the paper or wood pulp flows onto a conveyor
belt where the excess water is removed drained and compressed causing the paper fibers to bond
together (Lyons, A.2010, p.397). By the hot pressing process, board can be formed without the
need of admixture of adhesives. The natural resin (lignin) that is contained in paper works as a
natural bonding agent. For thicker boards, external additives are necessary and formaldehydefree resin is added. Sometimes, impregnation and addition of hydrating agents are also necessary
depending on the materials intended characteristics.
c.
Finishing: The boards after produced are left to dry until moisture content less than 1-3% is
achieved. Afterwards they are covered by gluing paper or other desired surface layer. It can be
thick white or brown paper like Kraft type paper, printed decorative paper, laminated surface or
other desired surface resembling wood, stone, etc.
(+) Positive Characteristics:
(-) Negative Characteristics:
8 Paperboards can be used mainly for interior
applications and should be protected
from water except if they are covered by
a laminated surface. Prolonged exposure
to moisture will cause significant damage
to the material due to its hygroscopicity.
Thus, paperboards should be avoided
to be used in interior spaces with high
level of steam and moisture (e.g. kitchen,
bathrooms, etc).
9Paperboards are produced mainly from
waste paper, containing a great recycled
content. They are biodegradable and can
be recycled and reused again, decreasing
the waste ending up in landfills.
9It is a lightweight material with good
sound reduction properties.
9Paperboards are greatly impact resistant
9It has exceptional strength to weight ratio.
8 Structural strength of paperboards is
seriously affected by water when the
surface finish is not waterproof.
9A material that can be used easily to create
doors, furniture and sandwich structural
panels that and be used in partitioning
wall systems.
153
Applications :
Paperboards can be used in different applications depending on their type. Boards with a honeycomb
structures are mainly used in partition wall systems, as movable partitions, as exhibition or display
walls and other interior applications. Paperboards like FlexCL are used for insulation or soundreduction and can be used in wall or roof cavities, in floors or suspended ceilings, and between rafters.
Design Advices:
The design approach, limitations and considerations related to the material are strongly dependent
on the type of paperboard, the final surface finish of the product as well as the interred use. In
the most cases, because of the hygroscopicity of the material, it is necessary to protect the boards
from warm moist air when applied in indoor spaces by the use of vapour barriers and impermeable
membranes. For exterior applications, a protective-but yet breathable- surface to prevent water and
rain penetration is also necessary (Lyons A, 2010, p. 397).
References.:
books_
websites_
Jones, E. (2014) A Practical Guide to Greener
Theatre: Introduce Sustainability Into
Your Productions., p.107-108 (online).
Available at: http://books.google.nl/
books?id=kdDeAQAAQBAJ&pg=
PA107&dq=honeycomb+paperboa
rds&hl=en&sa=X&ei=brJXU62zH
Me_ygOR4IEQ&ved=0CEkQ6AEw
AA#v=onepage&q=honeycomb%20
paperboards&f=false [Last accessed:
28th March 2014]
AXXOR: manufacturer. Available at: http://axxor.eu/paginas/
whotocontact?sId=523 [Last Accessed at: 20th March 2014]
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our_products.html [Last Accessed at: 25th March 2014]
DYFAYLITE GROUP: manufacturer. Available at: http://www.dufaylite.
com/honeycomb-technology [Last Accessed at: 20th March 2014]
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products/applications/paperboard [Last Accessed at: 25th March
2014]
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builders (4th edition). China: Elsevier,
p.397
TONELLI. Available at: http://en.tonellism.com/
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Peters,
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com/produkte/flexcl/ [Last Accessed: 28th March 2014]
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Sustainable multi-purpose materials
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Birkhäuser, p. 88-91, 96-97
[last accessed: 25th
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at: http://www.honingraatkarton.nl/produktinfo.html [Last
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partitioning/concor-partitioning-panels.html [Last Accessed at:
20th March 2014]
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en.html [last accessed: 25th March 2014]
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Paperboard [last accessed: 25th March 2014]
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wiki/Paper_honeycomb [last accessed: 25th March 2014]
154
3.12 Cork products
Material: cork (kurk)
Category: cladding-insulation material
Application: thermal and sound insulation, cladding
3.12.1 Cork products, companies list:
155
3.12.2 Cork products datasheet: sizes and prices
156
157
3.12.2 Cork products datasheet: properties
158
159
160
General info:
Cork presents a wide range of products available for interior or exterior cladding and insulation
applications in buildings. Cork is a renewable material that is harvested from the stripping of the thick
spongy bark of the Cork Oak (Quercus Suber) every 9-11 years since the tree has grown undisturbed
for 25 years. Barking is done manually and always during the hot summer months, when the cork
bark by dehydration release of the cambium. Quercus Suber grows mainly in southwest Europe and
northwest Africa, and a tree with an average lifespan of 170-200 years can output about 17-18 times
harvesting bark.
Cork is known since the ancient times in fishing and footwear applications. Cork’s ability to recreate its
own bark repeatedly was known since 4 th century BC when Greek philosopher Theophrastus mentions
and praise cork for this specific ability. Until the 17th century cork material became the standard for
sealing wine bottles and at the end of 19th century in New York it was discovered that cork granules
by heating, they expand and stick together via efflux of their resin Suberin. Thanks to this, nowadays
a wide range of cork products can be produced. Since the late of 1970s, cork flooring and walls became
already very popular. The first floor of “Oval office” of the White House in U.S. was a cork glued in
1934 that lasted until mid-1960s. 1
Cork is a renewable resource material but since its tree can grow up only in specific areas and their
number is limited, careful forestry operation is needed to keep it sustainable. For the production of
building products, the cork that is used is either produced from sustainable forestry operations or
most preferably it is a by-product derived from recycled cork bottle-stoppers of the wine industry.
Chemical composition of cork: boards, rolls, tiles, strips, bands and loose infill
‚ Suberin (45%) - main component of the cell walls - responsible for the elasticity of the cork
‚ Lignin (27%) - insulating compound
‚ Polysaccharides (12%) - components of the cell walls - help define the texture of the cork
‚ Tannins (6%) - polyphenolic compounds - responsible for the colour;
‚ Seroids (5%) - hydrophobic compounds – responsible for impermeability of the cork.
Building products:
boards, rolls, tiles, strips, bands and loose infill
Cork’s high content in suberin (a hydrophobic substance) makes cork products water resistant, elastic
and fire resistant. Thanks to this, cork material is so favorable in producing a wide variety of products
available in a range of shapes and applications. Cork building products can be mainly categorized in
4 groups according to their production process:
1. Natural granulated cork: are cork particles available in various grain sizes that can be used as
infill in cavities for thermal and acoustic insulation applications.
2. Expanded granulated cork or “dark agglomerate” including products such as insulation rigid
panels, floor underlayment sheets for impact sound insulation, insulation boards for acoustic and
thermal insulation, facades cladding panels, floor and tiles. They can also be used as masonry
support/acoustic discontinuity in structural connections.
1
Info taken from: http://www.vanavermaet.be/nl/kurk/kurk_geschiedenis/
161
1. Impregnated granulated cork; products in this group are mainly floor or wall covering tiles that
contain almost always some chemical additives for gluing reasons.
2. Composite cork products: like Corkrubber composites or sandwich panels with cork and a
wide range of other materials (plywood, aluminum, etc) that are glued together 1. Corkrubber
composites are produced by adding carefully selected cork granules to a rubber-formulation in
order to combine the resilience of rubber with cork properties such as; high mechanical strength
and dimensional stability. The result is a flexible, elastic and highly resilient product that can be
used in the automotive, shipbuilding and electromechanical industries, as well as the manufacture
of non-slip flooring.
Processes applied:
Harvesting (barking, drying), crashing, gluing, heat processing, forming, cutting
Production process:
Ă͘ Barking and drying: Cork products can be either produced by virgin cork harvested from Cork
Oak and processed further or by using cork bottle-stoppers that are collected from specific recycle
operation programs. The second case is most common. Cork that is barked from a tree is left for at
least 6 months to dry (evaporate moisture) before it can be processed. After the cork is collected
then cork is processed into building products in a variety of ways depending on the intended use.
ď͘ Crashing-gluing (for natural granulated cork): Natural granulated cork is produced either by
crashing raw cork that will be used without additives as insulating infill in cavities, either by
punching recycled cork bottle stoppers and glue the granules together with a binder. Afterwards,
the sheets that are made are sliced to form floor and wall tiles.
Đ͘ Forming via heat treatment (for expanded granulated cork or “dark agglomerate”): Although the
same cork granules are used, the manufacture process of expanded granulated cork production
differs from the one described before. The cork granules are exposed to superheated steam (of
350-370 oC) under pressure in a hermetically sealed container. The heat forces cork granules to
expand by 20-30% of their original volume (Hegger, M. et al., 2006, p.138). As a result, cork resin
(Suberin) that is released to the outside of the granules is working as a natural binder which enables
granulated particles to be self-bonded without extraneous additives to the cork granules. After the
cork expansion, cork is formed into blocks or large insulation boards. After forming, the blocks
of insulation corkboard go through a natural stabilization process, dimensional rectification and
then are cut into boards of varying thicknesses and size.
Ě͘ Forming via heat and chemical treatment (for Impregnated granulated cork): Impregnated cork
products are manufactured in the same process as expanded granulated cork with the difference
that in this case, additional chemical bonding agents are added during the forming process such
as synthetic resin or bitumen, and so on (Hegger, M. et al., 2006, p. 138). Such products are not
considered so biodegradable due to the chemical agents they contain. Usually with this process,
floor and wall cork coverings are produced.
1
For more info check here: http://www.amorimcorkcomposites.com/industry.php/brand/19
162
(+) Positive Characteristics:
9Cork is a very light material that can float (it weighs only 0.16 gr/cm3 1).
9It is antistatic meaning that it does not absorb dust so it can help protects against various allergies.
9One of the major advantages of cork in comparison with other natural materials, its is natural
substances contained known as Suberin and Seroids. Suberin is a mixture of organic acids that coat
the walls of the cork cells, preventing the passage of water and of gases. Suberin is practically infusible
and is insoluble in water, alcohol, ether, chloroform, concentrated sulphuric acid, hydrochloric acid,
etc 2 and it enables cork products to have high water-resistance and air-impermeable properties
enable them to be airtight. In contrast with sheep wool, straw, flax and hemp products, cork
products are practically impermeable to liquids or gases. Prolonged use to sunlight or to wetting
conditions will not cause any rottenness or biodegradation to cork since its resistance to moisture
enables it to age without deteriorating.
9Cork is also elastic and compressible. If it will be compressed to around half of its thickness, it
will not lose its flexibility and will recover its shape and volume as soon as it is will be released.
As a result of its elasticity it is able to adapt to temperature and pressure variations without
suffering alterations 3.
Cork bark left to dry
Image 3.12.3
Image taken from:
http://www.kurk.be/nl/kurk/
het_belang_van_kurk/
9More than 50% of the volume of a cork product is captive air within its cells, therefore cork
product- unless they are treated with any synthetic resins- are considered as “self-extinguishing”
and are fire retardant (do not also emit any toxic gases during fire). A plank of cork contains
nearly 60% gaseous elements, which explains its extraordinary lightness. These gases contained
in cork cannot escape which is the reason for the elasticity of the tissue. The captive air enables
cork to have low conductivity to heat, noise and vibration 4.
9Generally, weak acids and alkalis do not cause any decay problem to cork product. Although,
Roaf S. (2013) states that cork is unaffected by water, alkalis and organic solvents, strong acids and
alkalis should be avoided because they can damage cork.
9By its very nature is not affected by mice or termites. Cork has a very favorable aging coefficient.
That is, the insulation value of cork hardly decreases in time 5.
9Lastly, cork is resistant to abrasion and has a high friction coefficient as a result of its honeycomb
structure 6
1
Info taken from “cork main properties”. Available at: http://www.materia.amorim.com/?q=en/materia/cork/main-properties
2
Info taken from “cork properties”. Available at: http://www.apcor.pt/artigo/14.html
3
Info taken from “cork main properties”. Available at: http://www.materia.amorim.com/?q=en/materia/cork/main-properties
4
Info taken from “cork properties”. Available at: http://www.apcor.pt/artigo/14.html
5
Info taken from “Isoleren met kurk” Available at: http://www.deskundig-isoleren.be/kurk.html
6
Info taken from “cork main properties”. Available at: http://www.materia.amorim.com/?q=en/materia/cork/main-properties
163
(- ) Negative Characteristics:
8 Cork products may have an intensive odour in the first period of application as a result of its
composition. Although, cork’s characteristic odour is non-intrusive and reminiscent of dry wood, it
can be unpleasant to some users.
8 Cork chars only slowly when subjected to a flame so it cannot support its own combustion. Thus,
when is discarded, if it cannot be reused or recycled, it cannot be used in fuel energy processing.
Impregnated cork may release toxic gases if the additives that were used are hazardous.
8 Cork is expensive in comparison with other natural insulating materials, for instance straw, and also can
be harvested in a limited amount each time in contrast with straw that usually is in surplus. Moreover,
in the Netherlands it is unavailable unless there is adequate amount of recycled cork from the bottlestopper industry, and it must be shipped from producer countries which increase significantly the
transportation energy and cost questioning the final sustainability of the product. Given these facts and
its price cork cannot become an alternative to mass market (Grätz M. and Indriksone, D., 2011, p.21)
and in building applications in the Netherlands it should be used in a very limited grade and only when
their specific properties are required and none other alternative natural option is available.
8 Some cork products like floor finishing coverings can contain glues with small amounts of Formaldehyde,
or other chemical additives which impairs their environmental performance.
Applications:
Cork products can mainly be used as thermal and sound insulation as well as in anti-vibration applications
either in external, internal, cavity walls. They can be also used as wall or floor covering and for impact
sound insulation applications. More specifically, cork products can be used:
In roof, ceilings and suspended floors as:
- Insulation in slabs, level and non-level coverings, in heated flooring and in suspended ceilings
- As decoupling layer in doors, windows and wall partitions
- Below screed, or under final flooring as impact sound insulation
In walls, it can be used as:
- External insulation or wall covering-cladding.
- Insulation in external or/ and internal cavity walls
- Internal insulation to wall and to separating walls
- Masonry support/acoustic discontinuity in structural connections.
Applications:
Cork boards can be applied directly by gluing to brick walls; the boards are reinforced with a net and coated
with 2 layers of construction glue. Some cork insulation boards should be subsequently covered when
are applied in internal wall surfaces for their protection from mechanical damages. However, other cork
products (for instance cork board “MDFACHADA” from Amorim Company) can be applied uncovered
and unprotected to external or internal wall surfaces as cladding elements that present a natural cork
finish. Such façade cladding boards can be installed with hidden mechanical fixing (screws) or glue-down
fixing (adhesive) directly onto the masonry or metal plates of the wall surface. Cork products that are used
in suspended ceilings for acoustic applications should leave a cavity of approximately 350 mm from the
ceiling surface. Lastly, one parameter that someone should have in mind when working with cork cladding
elements, is that tight joints would be hard to be achieved with cork products.
164
References.:
books_
websites_
Gill, L. (unknown) Cork as a building
material; a technical guide
[online]
Available
at:
http://www.realcork.org/
userfiles/File/Caderno%20
Tecnico%20F%20EN.pdf
[last accessed: 3rd March
2014]
AMORIM ISOLAMENTOS S.A.: cork manufacturer. Available at: http://www.amorim.
com/en/ and for Netherlands at: http://www.amorimbenelux.nl/ [Last
accessed: 3rd March 2014]
Grätz M., Indriksone, D. [2011]
Ecologic
Construction
Materials [online] Available
at:
http://www.intensee n e r g y. e u / f i l e a d m i n /
c onte nt / bro s hu re s / 0 4 _
Ecomaterials.pdf
[last
accessed: 22th February
2014]
BCORK; Cork for construction sustainable solutions. Available at: http://www.bcork.
amorim.com/en/constructive-solutions#ap=0&ec=0&ma=6&fa=0
[Last
accessed: 3rd March 2014]
Hegger, M. et al. (2006) Construction
materials
manual.
Germany: Birkhäuser, pp.
136-138
Hugues, T.
[2004]
Construction;
products,
case
Birkhäuser, p. 56
Peters,
Timber
Details,
studies.
S.
(2011)
Materials
Revolution;
Sustainable
multi-purpose
materials
for design and architecture.
Germany: Birkhäuser, p. 5051, 108-109
Pfundstein M. et al (2007) Insulating
Materials;
Principles,
Materials,
Applications.
Munich: Birkhäuser, pp:
8-14
Roaf, S. (2013) Ecohouse; a design
guide
(4th
edition),
Routledge
Woolley et al., [1997] Green Building
Handbook; Great Britain:
E& FN Spon, pp: 44-45
Lawrence, M. et al. (2013)
Hygrothermal performance
of bio-based insulation
materials.
Proceedings
of the Institution of Civil
Engineers: Construction.
University of Bath.
AMORIM CORK COMPOSITES S.A. cork manufacturer. Available at: http://www.
corkcomposites.amorim.com/library.php/?cat=1&type=3&sort=1
[Last
accessed: 3rd March 2014]
BUILDING GREEN.COM: Wilson A. (July 2012) Expanded Cork - The Greenest
Insulation Material? Available at: http://www2.buildinggreen.com/blogs/
expanded-cork-greenest-insulation-material [Last accessed: 3rd March 2014]
CORK FOR US. Available at: http://www.cork4us.com/aboutc.html [Last accessed: 3rd
March 2014]
CORK-2000: Manufacturer. Available at: http://www.cork-2000.com/ [Last accessed:
3rd March 2014]
GREEN BUILDING ADVISOR.COM: Wilson A. (March 213) Installing Cork Insulation
; Climbing the learning curve in working with a new insulation . Available
at:
http://www.greenbuildingadvisor.com/blogs/dept/energy-solutions/
installing-cork-insulation [Last accessed: 3rd March 2014]
ENVIRONOMIX. Available at: http://www.cork-insulation.com/wp-content/
uploads/2009/12/EnviroCork%20Information%20Sheet%20Web%20PDF.
pdf [Last accessed: 3rd February 2014]
IDEAL ACOUSTICS: provider. Available at: http://www.idealacoustics.be/EIS/
EcoIsoSystem.html [Last accessed: 22th February 2014]
JOVAVI: acoustic panels. Available at: http://www.jocaviacousticpanels.com/uk/
products/eco_iso/index.htm [Last accessed: 3rd March 2014]
MATERIA. Cork main properties. Available at: http://www.materia.amorim.
com/?q=en/materia/cork/main-properties [Last accessed: 2nd March 2014]
KURKFABRIEK VAN AVERMAET: cork provider. Available at:
vanavermaet.be/ [Last Accessed: 31th January 2014]
http://www.
VINCKIER: Geluidsisolatie of akoestische isolatie. Available at: http://www.vinckiernv.be/pleister/toebehoren/geluidsisolatie-nl.htm#kurk /
[Last Accessed:
22th February 2014]
GREENSPEC: National Green Specification. Insulation derived from organic sources
[online]. Available at: http://dev.greenspec.co.uk/building-design/insulationplant-fibre/#cork [Last Accessed: 21th February 2014]
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165
166
Chapter 4 Production Processes
This chapter focuses on the current production processes and techniques that are applied in the
production of building products made by biodegradable materials and is trying to answer the subquestions set on chapter 1 that are related to the manufacture processes, conditions and the resulting
products. The correlation between the production processes an the resulting types of products is
discussed in this chapter like for instance the relation between the production equipment and size
of final products. The products level for the 12 materials are presented in an attempt to understand
which biodegradable materials are already developed to satisfy current building needs and which
are left less developed, and why. The prefabrication level and complexity of the products are also
examined here. Lastly, an overview of a representative sample of the products that were examined in
chapter 3 as well as some application schemes that are suggested by specific manufacturing companies
are given in an attempt to provide to the reader a small “design manual” that will help him to design,
work and apply such biodegradable building products in building envelopes in the Netherlands.
167
4.1 Products variety - typical sizes
Research on the 12 biodegradable materials that was made on Chapter 3, showed that those materials
can produce a variety of product types and forms; blocks, bricks, panels, sheets, rolls, covering, bands,
and so on. The most common product types found are:
Units: blocks and bricks
Bulk materials like earthen materials, hemp-lime/hempcrete and papercrete in terms of prefabrication
can generate structural or non-structural units of cubical or rectangular form in various sizes. Straw
can be gathered by balling machines also to form rectangular-shaped large blocks or straw bales. The
most typical sizes found that are produced from such materials are presented in the following table
(Figure 4.1.1). As it is noticed, the minimum thickness of a block unit is 52 mm (earthen material)
and maximum of 300 mm (hempcrete) while the typical length is ~200-600 mm.
Figure 4.1.1 Typical sizes on block units
Boards, sheets, panels and battens.
Fibrous materials like straw, flax, hemp, as well as fibers derived from sheep wool and wood, are used
more often to produce insulation building products in the form of rigid boards or flexible sheets
(battens)and sometimes in the form of structural insulating panels (SIPs). The sizes in such cases vary
significantly depending on the production technique used, the required thickness and the requested
rigidity or flexibility.
The thickness can vary from minimum 13-15 mm to a maximum of 240-300 mm. Most typical widths
are around 400,600 and 800 while the length seems to be a derivative of the typical 600-625 mm since
the most products are found in lengths of around 600,1200, 2400,and 3000 mm. The deviations on the
width and length are related with the rigidity level of the final product. For instance rigid boards that
are found in a size of 580 X 1000 (e.g. wood-fiber boards) are being slightly increased in size when are
produced as flexible boards (batts); the size is now of 575,590, even 600 X 1220 mm.
168
That can be explained by the fact that flexible products for instance in the case of a timber framing,
can be tucked into/ be compressed in order to fit in requiring larger size than the filled-in space,
whilst rigid products should have the exact dimension of the gap they will fill-in. Figure 4.1.2 presents
these variations on such materials giving a general overview of the available sizes.
Figure 4.1.2 Typical sizes on elongated units
Rolls & Felts
The majority of the fibrous materials, when are produced in very thin thickness can produce felts
and rolls that can be used for thermal and acoustic insulation applications. When the thicknesses is
between less than 14 mm, then felts of maximum 50 meters length can be produced. In contrast, when
the thickness increases, the length of the product decreases. A thickness of 20-150 mm can be found
in rolls of 3-10 meters length.
Figure 4.1.2 Typical sizes on rolls and felts.
169
4.2 Prefabrication - products levels
The following tables give an overview on the current prefabrication level that is noticed on products
made by the 12 biodegradable materials that were researched earlier. Table 4.2.2 shows the availability
in shapes and forms that can be found in the current production. The letter “P” indicates that it was
not found yet such a type of form or shape, but it is assumed that it is possible to be produced with the
current production techniques if the market will required it. Table 4.2.3 summarizes the applications
that the 12 materials and their products can be applied, while figures 4.2.4-4.2.11 shows in details the
products levels for each type of materials. Products that are produced with a common basic material
are collected and presented in the same figure. For instance, rammed-earth , adobes , clay products
since they are made from the same basic ingredient (earth mix) are presented in the same figure where
the products level is examined. The same applies for hemp and hemp-lime products and for products
made from paper.
As it is noticed, not all the materials present the same prefabrication level. Some seem to be more
processed and industrialized , while others to remain more related with a craftsmanship degree.
Fibrous materials can be more used for intermediate leafs on a building envelope, whilst bulk materials
can be used more in exterior or interior leafs for impact protection of their cavity-intermediate leaf
thanks to their rigidity.
Figure 4.1.1: Hemp-fiber milling,
Picture taken from: http://www.globalhemp.com/2011/02/world-war-ii.html
170
Figure 4.2.2: Biodegradable materials - shapes availability
Figure 4.2.3: Applications and uses
171
Figure 4.2.4: Products level for earthen products
Figure 4.2.5: Products level for straw products
172
Figure 4.2.6: Products level for sheep-wool products
Figure 4.2.7: Products level for wood-fiber products
173
Figure 4.2.8: Products level for flax products
Figure 4.2.9: Products level for hemp & hemp-lime products
174
Figure 4.2.10: Products level for paper products
Figure 4.2.11: Products level for cork products
175
4.3 Production processes & techniques
The production processes and techniques that are
applied on the 12 selected materials to produce the
various types of biodegradable building products,
were also described particularly in chapter 3 for each
material respectively. In this subchapter, more concise
observations and remarks related to production of the
overall materials are noted down in order to present
in a comprehensive way the relation between the
production process and the final resulting product.
Image 4.3.1
As it can be observed from Graph 4.3.4, materials
that present similarities either in their origin of
resource either on their type of composition, under
similar production processes can generate similar
and specific types of products. More specifically
as it was noticed, bulk materials which are usually
composite materials that consists of small particles
and are always mixed with a percentage of water and
other additives, produce same type of products.
Bulk materials like earthen mix, hemp-lime/
hempcrete, papercrete and so on, via casting into
moulds or into particular pressure moulding
machines where under pressure they generate units
like blocks or bricks. One other method is casting
in-situ in wooden formworks to create monolithic
constructions like walls of various forms. The same
can apply for straw; when the primary production
method that is used is compression via a mould or
pressure machine then it results in similar type of
products that are produced with same process of bulk
materials.
For instance, the “Strawbale Lego Block”or “Stak
block” from Oryzatech company is an experimental
Lego-like building block that is produced from dried
rice straw that is mixed with a small portion of
external additive ( formaldehyde-free glue) that works
as binder and then it is tightly compressed in metal
molds at temperatures around 300 degrees. Under
compression and heat, the final product is a solid
block that resembles both in product type as well as
in form and shape some compressed earth blocks that
are produced in similar way (Images 4.3.1, 4.3.2 and
4.3.3). In this case, the stabilized instead of Portland
cement or lime (like in the case of CEB) is glue.
176
Image 4.3.2
Image 4.3.1 - 4.3.2:
Stack block, produced by Oryzatech
Images taken from:
http://media.treehugger.com/assets/images/2011/10/
Oryzatech-straw-building-blocks.jpg
http://ww4.hdnux.com/photos/10/77/30/2356743/7/
628x471.jpg
Image 4.3.3
Image 4.3.3:
Compressed earth block & pressing machine
Images taken from:
http://casarama.files.wordpress.com/2009/07/typ-ofcinva-ram.jpg?w=500&h=376
Graph 4.3.4: Production processes
Input ------------> Production Processes ----------------------------------> Output
raw materials:
Bulk materials
(water addition)
Secondary processes:
Primary processes:
Manual shaping/forming
casting/ moulding
Machining: cut
Bricks
Blocks
Walls
Machining: cut
Boards
Sheets
Rolls
Felts
Bands
via compression or extrusion
shaping-deformation
Fibrous materials
animal fiber
plant fiber
Granules / flakes:
(cellulose based)
via scouring-carding, etc
via breaking, scrunching, heckling, etc
Heat treatment:
steam, pressure
Machining: cut
Surface treatment:
plate, paint
Shaping:
via wet or dry forming
product
Boards
Sheets
Regarding fibrous materials, it can be noticed that they are processed in similar ways by similar
mechanical means and produce similar types of products like boards, sheets, rolls and felts. The
flexibility of the final product seems to be dependent from the required thickness of the final product
(e.g. the larger the thickness the more rigid it can become in the most cases) as well as from any
external addition to the fiber during their process (e.g. polyester or polyolefin fibers, glues, etc). In
the case of fibers that are made from a plant’s stem like hemp or flax, a primary processing of the stem
via various steps 1 is needed in order to result in workable fibers, whereas in the case of wood-fibers
and straw that step is skipped.
Fibers derived from animal resource like sheepwool, horse hairs, etc need first to be scoured
and carded since it is necessary to remove any
unnecessary substance
and purify them so
the resulting material to be ready for further
processing. All fibers are then passing via
machines that are cut into the required size.
Lastly, when materials are in the form of granules
or flakes like for instance in the case of cork or
paper, then via wet or dry methods are formed
into sheets and boards that are mostly rigid
enough. External additives are needed only in
cases that large thickness is required, otherwise
their natural resins work as binding agents under
heat (steam) and pressure.
Image 4.3.5
Sheep-wool insulation; production
Images taken from:
http://uk.sheepwoolinsulation.com/images/about_finroll.jpg
1 for more information on those steps, read chapter 3.6 and 3.7 on paragraphs under “production process”
177
Additives
As it was noticed during the research of
the 12 materials and its products, in a lot of
cases, external additives are added during the
manufacture of these materials. Such additives
work either as binders (to bond together
particles when a big thickness is required,
e.g. in wood-fiber or cork boards), either as
reinforcement to improve the stability and
rigidity of the final product (e.g. polyester
fibers in fibrous materials or stabilizers in
earthen products), either to prevent any pest
infestations (e.g. sheep-wool) or finally to
increase the fire resistance of the products.
In the most cases, these additives can be
removed after the disposal of these products
relatively easily so the materials can be
recycled, reused or biodegrades. However, in
some other cases, the process is irreversible
and the product stops being biodegradable
one, like for instance in the case of stabilised
rammed-earth with Portland cement.
Although, during the research , a lot of
natural alternatives exist with similar or better
results with inorganic additives, the most
manufacturer companies do not yet apply
them because either such organic additives
costs significantly higher (sometimes even
3 times more), either due to the difficulty to
be found, and either in some cases because
their sufficiency is not tested and qualified
by test controls. However, the following table,
presents some of these natural alternatives.
Table 4.3.6 : Suggestions for natural alternatives
ÂIn earth unfired products (adobe, CEB, rammed earth, clay
boards), natural stabilizers that are derived from animal or
vegetable-plant products are available (see chapter unfired
earth, alternatives for more info). Some of them are very
high efficient but because of their extremely high costs (in
some cases for instance 3 times more expensive than the
conventional stabilizers), industrial synthetic stabilizers are
preferred like cement or lime. Also sometimes such natural
stabilizers seem insufficient and in some other cases are more
scares to be found in major quantities (e.g. fresh bull’s blood,
animals urine and so on).
ÂIn sheep wool, boric salts and other substances that are
added to increase their fire resistance and their insect/pest
resistance can be replaced by natural insecticides, like wor
Neem Leaves (Azadiracha indica A. Juss). In both cases these
leaves, and wood chips can very effective to defend and prevent pest infestations (like beetle, larvae, etc.) In sheep wool
Insulation, lavender oil (impregnated to the fibers during its
manufacture and let it dry) can be also effective to prevent
larvae and moths’ attacks sine Lavender is famous for such
ability.
 A lot of times polyester fibers are used to reinforce the insulation batten made from biodegradable natural material,
which cause problems to its recyclability. Polyester fibers
can be replaced with a natural alternative to polyester fibers
are fibers known as PLA (BIcofasern plant-based fibers) or
corn-starch. These can replace synthetic support fibers that
are used for reinforcement and can also work as a binder for
the product’s content. Some manufactures of hemp insulation are already using 85-95% hemp fibers and a percentage
of 5-15% of PLA.
ÂResins or glues that are chemical and synthetic can be replaced with ”natural glues” like soya, blood albumen, casein,
and animal products (Woolley et al, 1997, p.85). Such glues
have lower toxicity than the synthetic glues and are also derived from renewable resources, however they are only suitable for internal use and so their application should be more
limited.
ÂComposite and combination of materials can be also very
effective. For instance cork is often found with coconut fibers
since acoustic properties like sound absorption and sound
deflection are combined. Also hemp and flax fibers are also
often found combined as well as cellulose fibers with hemp.
Corn and flax fibers are also a good combination and found
in natural bio composites.
178
Quassia fibers
Quassia powder
Quassia chips
Image 4.3.7
Figure 4.3.7: Quassia powder, fibers, chips
Quassia powder. Image taken from: http://i.ebayimg.com/03/!B6+Y4UgBmk~$(KGrHqV,!hEEyr2qBRCLBMy8uG)dQQ~~_35.JPG
Quassia fibers. Image taken from: http://www.papajimsbotanica.com/images/quassiachips.jpg
Quassia chips. Image taken from: http://originalbotanica.com/images/Quassai%20Chips.jpeg
Image 4.3.8
Image 4.3.8: Dried Neem leaves
Images taken from: https://www.heavenly-products.com/cart/images/Neem_leaves.jpg
Image 4.3.9: Neem leaves powder
Images taken from: http://pimg.tradeindia.com/00338078/b/0/Neem-Leaves-Powder.jpg
179
Image 4.3.9
4.4 Application schemes
The most manufacturer that produce building
products from biodegradable materials are giving
some design quides or applications schemes to
present the right way that these products can be
applied and which things should be avoided in
the design phase. Here some products from the
12 materials are presented together with their
application schemes. Pictures are showing that a
lot of biodegradable building products are designed
in such way nowadays that can be used to existing
buildings envelopes to improve their acoustic
or thermal performance. From the following
application schemes and images that are presented
here, some remarks can be made:
a) Biodegradable materials do not always need
vapour barriers but contrary,
sometimes the use of vapour barrier should be
avoided because it can result in higher condensation
risk and build-up of moisture. b) keep their base dry
and with no contact with the ground level.
necessarily
Image 4.4.1
Sheep Wool Insulation Comfort Roll being installed
between suspended timber floor joists at ground floor
level. Note the breathable membrane used to support the
insulation (image 4.4.1 and scheme 4.4.7)
Image taken from: http://uk.sheepwoolinsulation.com
Building products made from biodegradable materials need to be applied in such way that they can
remain breathable in order to regulate humidity by absorbing and re-emitting the excess of the
indoor humidity. As it can be seen from the application schemes based on the ones suggested from
the manufacturer companies, the most suitable way is to apply a vapour barrier in the internal side
of the wall and breathable membrane in the external side of the wall leaf (e.g. sheep wool schemes).
Thermafleece sheep
wool Insulation at
attic and wall timber
frame.
Image taken from:
http://www.
homebuilding.
co.uk/sites/
default/files/styles/
homebuilding_
scale-1680/
public/images/
advice/featured/
InsulationGuide.
jpg?itok=kuFO3AfO
Image 4.4.2
180
scheme 4.4.3
4
4.3
scheme 4.4.4
scheme 4.4.5
scheme 4.4.6
scheme 4.4.7
181
scheme 4.4.8
scheme 4.4.9
scheme 4.4.10
182
Biodegradable materials sometimes
works synergically when combined
with other biodegradable materials. For
instance, wood-fiber products thanks to
their rigidity level and their breathability
are very suitable to be combined with
flexible insulation products like sheepwool, flax and hemp insulation.
scheme 4.4.12
As the application schemes indicate
wood-fiber with large thickness can also
be used individually as insulation on
building envelopes.
Connection details for Diffutherm pavatex plates.
Images taken from: Pavatex company brochure
Image 4.4.11
scheme 4.4.13
scheme 4.4.14
183
There are also some building products
that are compatible with render system
and can be coated with a render skim (clay,
lime, etc), which are very suitable to be
used in exterior wall finish applications.
scheme 4.4.15
Such example of compatible biodegradable
products are: Wood-fiber
insulation
boards from Pavatex (Diffutherm) as well
as Cork insulating boards (MDFachada)
from Amorim company.
Image 4.4.16
Wood-fiber insulation boards that are compatible
with render skim. ( scheme 4.4.15, image 4.4.16
and images 4.4.17) Images are taken from: Pavatex
company and application schemes are based on
brochure given by Pavatex company on website.
Image 4.4.17
184
Image 4.4.18
Pictures showing woodfiber insulation on various spots on a building envelope
before the installation of render skim. Insulating
fixing plugs are installed to keep the boards in place.
Check scheme 4.4.15 for a better understanding of its
application.
Images taken from:
the product’s brochure of Pavatex Company
Image 4.4.17 and image 4.4.19:
Cork insulating boards that can be used
as external insulation and can be coated
with a clay, lime or other render.
Cork insulation can be found in various
thickness and cork natural colour
texture. Cork insulation boards can also
be found combined with coconut fibers.
Images are taken from: Amorim.com
Image 4.4.18 is taken from http://img.
archiexpo.com/images_ae/photo-g/
insulation-panels-expanded-cork-coconutfiber-89328-3814533.jpg
Image 4.4.19 is taken from http://www.
lime.org.uk/uploads/ImageRoot/images/
Ug5pfNF9.jpg
185
186
Chapter 5 Research Results
The 12 selected biodegradable materials that were examined in chapter 3 and 4 are now compared
with each other with charts, graphs and tables in order the reader to understand the similarities and
difference within these materials as well as to help to make remarks about them. The process that
was followed for the comparison of these materials is explained in details, and graphs and tables are
presented in order to help possible observations to be made. Different parameters like cost, density,
thermal and mechanical properties are compared for the total of the materials as well as environmental
properties like embodied energy and CO 2 emissions content are examined. The properties are not
only compared each by each but also in comparison with other properties that there is a correlation.
Lastly, the research findings are discussed in detail and an attempt is been made to explain and
understand the correlation between the properties and the hidden influencing mechanisms or factors.
Conclusions are made after these comparisons that can help the reader decide which material is more
appropriate depending on the intended use.
187
188
5.1 Process description
The research of the selected biodegradable materials presented in chapter 3
has shown that each material may present in many cases variable properties
of the final products. The properties of the biodegradable products are
in a lot of cases very different not only from company to company but
also when compared to the given ones in literature. The variation in
properties values found in the companies’ technical datasheets and in the
formal literature can be explained by the fact that products and materials
development is not always recorded by literature at the same times it takes
place. Literature is often outdated and when a book is written, there is
already a further development of materials occurring whereby the author
of a book has not witnessed at the time the book was written. Therefore,
it is very logical that the current properties of products present in the
majority better values than the ones stated in literature 4-5 years ago.
Biodegradable products based on same material present also different
numerical values on specific properties not only from different
manufacture company but even in the same company. By observing
the data, it can be assumed that the resulting properties of the final
biodegradable products are correlated to various parameters such as;
the product’s specific composition, the production processes that were
applied for their manufacture as well as other parameters. The products
requirements in density, final thickness, overall size and shape, seem also
to influence in a way not only the specific properties of the product like its
compressive strength, its thermal conductivity and its acoustic properties,
but also even the material’s content itself. For instance, in cork products,
when small thickness of the final cork board is required (20-100 mm),
no external additives are added since cork’s natural content in Suberin
is capable to bond the particles of the material itself leading to a pure
100% natural product. In contrast, when larger product’s thickness is
required (e.g. more than 100 mm) then in some cases it may be necessary
an external binder to be added. The thickness of the product it is not the
only one that affects the product’s composition but also in some cases the
manufacture process that will be used; for instance in wood-fibers if it
will be used the “wet” or “dry process”.
Moreover, other secondary parameters like the drying and curing
conditions seem to have an impact on specific final properties of the
product, for instance on its compressive strength, especially in bulk
materials. All these observations and research findings are summed up
under categories on the property they mainly influence, and are described
in details under that current section.
A similar summary table was made also for the durability and
environmental aspects of these materials like their resistance to various
substances related to urbane and other environments (like salt-fresh
water, weak-strong acids and alkalis), to UV radiation, to fire, as well as
their embodied energy content, CO2 footprint content, and others.
189
Step 1: Materials collection in summary tables
In order possible comparisons to be made between the materials, their properties should be summed-up into a specific
range of properties values that would be later inputted into a suitable material’s research software (like CES EduPack
software from Granta Design Ltd, Cambridge, UK, 2013). Therefore, as a first step, the variable values of each material
were collected into one “representative sample of properties” for each material so an easier comparison to be possible.
Then, those “representative samples” of the materials were collected in a summary table so the reader can have at a
glance an overall overview of the performance characteristics of all the 12 biodegradable materials in one table.
Summary table 5.1.1:
Materials properties
Unfired earth
products
Rammed-earth products
Unstabilised Stabilised
Unstabilised Stabilised
Straw
products
Sheep-wool
products
Properties
General
[1a]
[1b]
[2a]
[2b]
[3]
[4]
Density
700 - 2200
1100-2200
1700 - 2200
1700-2200
80 - 750
19-25
0,16-4.52
0,16-4,52
0.02-0.033
0.02-0.033
0.05 - 1.83
3.42 - 9.99
15.7 - 50.71
15,7-50,71
80-250
80-250
2.74 - 24.40
3.03 - 30.76
700 -7000
700-7000
600-850
650-7000
0.54-6.84
-
Price €/kg
2
Price €/m
Mechanical Properties
E modulus]
Tensile strength
0.5-1.0
1.0 - 2.0
0.05-0.65
1.0-2.6
0.01-0.02
-
Compress. Strength
2.0-5.0
2.0 - 12.0
0.5-5.0
3.0-20.0
0.48 - 0.58
-
Thermal conduct (ʄ)
0.14-0.93
0.46-1.04
0.49-1.50
0.49-1.50
0.037-0.10
(0.05-0.10)
0,035 - 0,042
Specific heat capacity (Cp)
650 - 1250
850 - 1000
850-1350
650-850
1660 - 2000
1700 - 1800
Thermal expansion coeff.
Thermal properties
10 - 15
10 - 15
10 - 15
10 - 15
2 - 11
15 - 30
Maximum service T.
1000
1000
1000
1000
90 - 110
110 - 120
Decomposition T.
2000
2000
2000
2000
> 175
> 240
Flammability
-
-
-
-
-
>560
A/B
A/B
A/B
A/B
C
E
A1/2 - B1/2
A1/2 - B1/2
A1/2 - B1/2
A1/2 - B1/2
B2
B2
Water absorption
5 - 20 %
5-20 %
7.2 - 11.5 %
7.2-11.5 %
10 - 20 %
30 - 40 %
Vapour diffusion
10-20
5-10
5-10
3-10
6
1-4
Vapour resistivity
-
25-50
25-50
15-50
32.5
5 - 20
Air resistivity
-
-
-
-
-
-
Sound absorption (ɲw)
-
-
-
-
-
0.91- 1.00
(100mm)
Sound reduction (Rw)
45 - 53
45 - 53
40 - 59
40 - 59
35 - 53
40 - 54
Ignition point
Euroclass
Build. Material Classificat.
Hygro-thermal properties
Acoustic properties
Primary material production: energy and CO2 emissions
Embodied energy
> 0.44
> 0.46
0.011 - 0.016
0.011-0.051
0.13-70
6.0 - 36.80
CO2 footprint
> 0,052
> 0.10
>0.052
> 0,10
-0.5 to 0.64
-0.53 to 3.5
-
-
-
-
23.5
160 - 180000
Water usage
Primary material production: energy and CO2 emissions
Embodied energy
-
-
-
-
-
20,90
Heat of combustion
-
-
-
-
19.8-21.3
20.00 - 21.00
Combustion CO2
-
-
-
-
1.19-1.28
1.39-1.45
190
At a first glance, observing the two tables some observations can be already made between these biodegradable
materials. For instance, in bulk materials like earth materials, hemp-lime products and papercrete, the materials
present very low price per unit of mass (€/kg) but very high price when they are compared to price per square meter in
contrast with the other materials like flax, hemp, sheep wool, etc. The best hygroscopic products seems to be product
made of sheep wool since it has the highest water absorption (~40% of its weight) before it gets saturated whilst cork
is the only hydrophobic material with a water adsorption of only 3.4-4.4% w/w.
Woodfibers
products
Flax
products
Hemp
products
Hemp-lime
products
Cellulose
flakes
Papercrete
products
Paperboards
products
Cork
products
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
40-270
23-50
25-42
250-1200
30-60
400-950
10-1150
67-400
Kg/m3
1.46 - 3.74
2.64 - 5.40
3.69 - 5.88
1.0-1.33
0.29 - 8.05
0.02-0.04
6.7-11.20
3.90 - 5.2
€/kg
4.94-24.40
3.88-33.66
66-130
9.76-30
39.8-79.65
9,70-38,41
6.25 - 66.10
€/m2
0.70-1.75
-
-
-
-
8000
0.026-0.04
5 MPa
MPa
0.0025-0.03
-
0.00417
-
-
-
0.004-0.006
0,846-1,03
MPa
0.02-0.25
-
-
0.46 - 3,00
-
0.84-2.36
0.21-0.23
0.18-10.35
MPa
0.038-0.048
0.035-0.040
0.039-0.048
0.050-0.360
0.035-0.045
0,074-0.250
0.028-0.040
0.038-0.070
W/m K
2100
1550 - 2100
1370 - 2300
1500 - 1870
1600 - 2150
1000
1250 - 1380
1670
J/kg k
ʅstrain/oC
5.13-52.40
UNITS
10 - 15
15 - 30
15 - 30
-
-
10
18.9 - 31.3
25 - 50
110
110 - 130
100 - 120
-
60 - 120
-
142 - 138
110 - 130
o
C
C
> 180
> 180
-
-
> 234
-
-
> 180 - 200
o
-
-
-
-
> 450
-
-
> 850
o
E
C/E
E/F
-
C/E
-
E/F
E
-
B2
B2
B2
B1
B1 / B2
-
B2
B2
-
20 - 40 %
12 - 20 %
17 - 20%
-
7.5 - 20%
-
17 %
3,6 - 4,4 %
% w/w
C
1-5
1-2
1-2
1
1-2
-
2-3
5 - 30
-
5 - 25
5 - 10
5 - 10
5
5 - 10
-
10 - 15
25 - 150
MNs/gm
≥ 5,00-100
≥ 5,00
≥ 5,0
3,0 – 8,0
3,6 - 50
-
43 - 76
-
kPa s/m2
-
0.95
(100mm)
0.65
(100mm)
0.69-0.80
(100mm)
0.95
(50mm)
-
-
0.80
(60mm)
at 500Hz
-
37 - 39
41
50 - 59
45 - 51
20 - 36
52 - 68
39 - 56
dB
10.5 - 11.7
1.6 - 41
10 - 41
1 - 35
0.32 - 7.6
2.00
4.9 - 117
4.2 - 6.3
MJ/kg
0.62-0.68
0.37-0.41
1.15-1.27
-
0.70-3.23
0.18 - 0.22
Kg/kg
665-765
2980-3290
400-600
-
-
-
1390-1530
665-735
l/kg
10,8-17
-
-
2-5
10-16.64
-
-
1.38 - 26
MJ/kg
19,0-20.9
17.0-17.90
17,8-18,7
-
-
-
20.5-22.7
19,8-21,3
MJ/kg
1.73-1.82
1.39-1.46
1,54-1,62
-
-
-
1.6-1.77
1,69-1,78
Kg/kg
-0.14 to-0.43 -0.91 to 0.39
191
A similar summary table was made also for the durability and environmental aspects of these
materials. How the materials react when they are exposed to water either rainwater either salt water,
or how durable they can be in prolonged exposure to sunlight (UV-radiation) are parameters that
should be known when designing with such materials in order to foreseen their life-span as building
products and elements. Therefore, this table present the materials resistance to various substances
related to urban and other environments like salt-fresh water, weak-strong acids and alkalis, their
UV - radiation, to fire, as well as their degree of Processability and the products types that they can
be found.
Summary table 5.1.2 a: Durability aspects
Unfired earth products
Unstabilised Stabilised
Capability / type
[1a]
Rammed earth products
Unstabilised Stabilised
[1b]
[2a]
Straw
products
Sheep - wool
products
[3]
[4]
[2b]
Load-bearing
self-supportive
Insulating
Bulk material
Fibrous material
Particles - granules
Products types
Rigid bricks /blocks
Rigid panels / boards
Semi-flexible sheets
Flexible sheets and batts
Rolls and felts
Particles /flakes (infill)
Durability
Water (fresh)
Unacceptable
Limited use
Unacceptable
Limited use
Limited use
Limited use
Water (salt)
Unacceptable
Limited use
Unacceptable
Limited use
Unacceptable
Limited use
Weak acids
Unacceptable
Unacceptable
Unacceptable
Unacceptable
Unacceptable
Acceptable
Strong acids
Unacceptable
Unacceptable
Unacceptable
Unacceptable
Unacceptable
Unacceptable
Weak alkalis
Unacceptable
Unacceptable
Unacceptable
Unacceptable
Limited use
Limited use
Strong alkalis
Unacceptable
Unacceptable
Unacceptable
Unacceptable
Unacceptable
Unacceptable
Organic solvents
Acceptable
Acceptable
Acceptable
Acceptable
Unacceptable
Acceptable
UV radiation
Excellent
Excellent
Excellent
Excellent
Fair
Fair
Wear resistance
Limited use
Limited use
Limited use
Limited use
Limited use
Unacceptable
Industrial atmosphere
Limited use
Limited use
Limited use
Limited use
Unacceptable
Acceptable
Rural atmosphere
Limited use
Limited use
Limited use
Limited use
Limited use
Acceptable
Marine atmosphere
Limited use
Limited use
Limited use
Limited use
Unacceptable
Acceptable
Processability (levels 1 to 5)
Castability
X
X
X
X
X
X
Moldability
5
5
4
4
X
X
Formability
4
4
4
4
4
4
Machinability
4
4
4
4
3
4
Weldability
X
X
X
X
X
X
Solder/brazability
X
X
X
X
X
X
192
As it is clear from the Table 5.1.2,
biodegradable
materials
present
a
weakness to any source of water either
fresh or salty, and they should be protected
from prolonged exposure to any water
mechanisms (e.g. splash up water, rising
damp, water penetration, etc). The majority
(8 out of 12) of the biodegradable materials
present a good to excellent durability to
sunlight exposure, while only 4 have a fair
durability.
Table 5.1.2 b : UV-radiation Rating & Processability Rating
Rough order of magnitude
durability, temperate climate
Processability Rating
5 process is routine and can be
Excellent : Tens of years +
performed without difficulty
Good : Years
2-4 increasing levels of ease processing )
Fair : Years/months
1 process is impractical
Poor : Days/weeks
*Rating is based on CES EduPack 2013, Granta Design Limited, Cambridge, UK, 2013
wood-fibers
products
Flax
products
Hemp
products
Hemp-lime
products
Cellulose
flakes
Papercrete
products
Paperboards
products
Cork products
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
Limited use
Acceptable
Acceptable
Acceptable
Unacceptable
Unacceptable
Limited use
Acceptable .
Limited use
Acceptable
Acceptable
Acceptable
Unacceptable
Unacceptable
Limited use
Acceptable.
Limited use
Limited use
Limited use
Limited use
Limited use
Unacceptable
Limited use
Acceptable.
Unacceptable
Unacceptable
Unacceptable
Unacceptable
Unacceptable
Unacceptable
Limited use
Unacceptable
Acceptable
Acceptable
Limited use
Good
acceptable
Unacceptable
Unacceptable
Acceptable.
Unacceptable
Limited use
Unacceptable
Limited use
Unacceptable
Unacceptable
Unacceptable
Unacceptable
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Unacceptable
Limited use
Acceptable.
Good
Good
Good
Excellent
Good
Fair
Good
Very Good.
Unacceptable
Unacceptable
Limited use
Good
Unacceptable
Limited use
Unacceptable
Fair. .
Limited use
Limited use
Limited use
Limited use
Limited use
Limited use
Limited use
Acceptable.
Limited use
Limited use
Acceptable
Good
Limited use
Limited use
Limited use
Acceptable.
Limited use
Limited use
Acceptable
Acceptable
Limited use
Limited use
Limited use
Acceptable.
X
X
X
X
X
X
X
X
3-4
X
X
5
X
3
5
5
X
4
4
5
5
3
5
5
5
5
5
X
5
3
5
5
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
193
STEP 2: Materials editing in CES EduPack 2012
As a second step, the “representative properties” for the 12 biodegradable materials were
inputted in CES EduPack 2013 which is a software program specialized in materials
engineering and materials databases developed by Granta Design Ltd. As a working
database level, it was selected the “Architecture” level (Figure 5.1.3) and via the tool
“add record” each material’s properties could be inputted into the program. In the
window “add record” (Figure 5.1.4), a list of properties is listed from general properties
until more specified ones like thermal, mechanical, electrical, and so on, wherein the
numerical values for each materials products can be filled in the correct field (Figure
5.1.5).
Figure 5.1.3: Selection of working Level*
Figure 5.1.4 : Adding material, properties window*
* Images are taken from CES EduPack 2013, Granta Design Limited, Cambridge, UK, 2013.
194
The same process was followed for each material until all 12 materials to
be inputted in the system. For the products of the category “unfired earth
products” and “rammed-earth products” two separate sub-categories were
created to divide “stabilized” and “unstabilised” products in each case,
since the stabilization of earth can give different mechanical properties and
material’s durability.
Figure 5.1.5 : Adding limits to the properties of each material *
After all the materials were edited in the programme, graphs were possible
to be made with the tool that the software provides which is “2. Selection
Stages > Graph”. There, you can chose which property you want to appear in
the x-axis and which property in the y-axis of the graph that will be made.
Comparisons between various properties are possible, for instance price
against density, strength against young modulus, and so on (Figure 5.1.6).
Figure 5.1.6 : Graph making
* Images are taken from CES EduPack 2013, Granta Design Limited, Cambridge, UK, 2013.
195
5.2 General properties - comparisons
5.2.1 Price & density
A comparison on the prices of the 12 materials
was made by the following graphs. Materials were
compared not only for their price per m 2 (Graph
5.2.1.2) but also per unit of mass (Graph 5.2.1.3).
The difference in price between the materials is clear.
Although, rammed-earth presents a high price when
measured per square meter, it has a very low cost as
material when calculated per unit of mass (kg). In
contrast other materials have a very low cost per m 2
but very high per kg. The graphs also indicate that
hemp, flax, sheep wool and straw have similar price
range per m 2, although straw presents a much lower
price when its price is measured per kg.
Graph 5.2.1.1 : Price per unit of mass against materials density*
* image taken from CES EduPack 2013, Granta Design Limited, Cambridge, UK, 2013.
In the above graph (Graph 5.2.1.1) the price per unit
of mass was printed against its density in order to see
the relation between its cost and its density. As the
graph shows, hempcrete, papercrete, straw and earth
products like adobe bricks, compressed earth blocks
and rammed earth, present low price while they have
a very high density value in contrast with fibrous
materials like flax, hemp and sheep wool.
196
Graph 5.2.1.2 : Materials prices per square meter (Euro/m2) *
Graph 5.2.1.3 : Materials prices per unit of mass (Euro/kg) *
* Own illustrations - graphs, info based on the ones edited in CES EduPack 2013, Granta Design Limited, Cambridge, UK, 2013.
197
5.2.2 Thermal properties
The thermal properties of the materials, such as thermal conductivity ( ʄ ) and specific heat capacity
(Cp) were also examined and compared in the following graphs. For the thermal conductivity, an
overall graph (Graph 5.2.2.3) shows the numerical values of ʄ for all the materials while two separate
graphs (Graphs 5.2.2.1 & 5.2.2.2) present the thermal conductivity for load-bearing materials (a) and
materials used as insulating materials (b) respectively. This division is made in order to understand
any relation between the thermal properties of the materials and other aspects. Thermal conductivity
is the property of a material to conduct heat. The lower it is, the better it insulates.
Graph 5.2.2.1: Thermal conductivity (ʄ) for biodegradable load-bearing materials*
Remarks: Straw, hempcrete and papercrete present the lowest value of thermal conductivity (ʄ) while earth-based
materials are bad insulators as the graph shows. The thermal conductivity of earth materials that ranges from 0.5
W/m*K to even 1.5 W/m*K occurs not only from the different density of earth products (700-2200 kg/m3) but also
due to the different product’s composition (different % of clay-earth, % silt, stabilizer additives, fibers or others).
Graph 5.2.2.2 : Thermal conductivity (λ) for biodegradable insulating materials*
* Own illustrations - graphs info based on the data edited in CES EduPack 2013, Granta Design Limited, Cambridge, UK, 2013.
198
Remarks: The graph indicates that the average range of the thermal conductivity of the majority of the above
biodegradable materials is 0,038-0,048 W/m*K. Paperboard, flax, sheep wool, cellulose flakes and hemp insulating
products present similar thermal conductivity (ʄ). Best insulators in the above graph seem to be paperboard, flax
and sheep wool products, as well as cellulose flakes. Cork and straw products present a wider range of ʄ. than
the other materials. This can be explained thanks to the wide range that those products present also in their
density. Cork products are found to have a density from 80 kg/m3 to 750 Kg/m3 depending on their intended use,
and similarly straw-based products have a density of 67 kg/m3 to 400kg/m3 depending on their type and their
compression level.
Graph 5.2.2.3 : Thermal conductivity (λ) for biodegradable insulating materials*
The following table presents both thermal conductivity and density of the biodegradable products. As
it is noticed from the graphs and the tables, thermal properties of the products shall be related with
their density. Thermal conductivity (ʄ) seems to increase when density(ʌ) increases, meaning that a
material with higher density is usually worse insulator than a material with lower density.
Table 5.2.2.4: Thermal conductivity (ʄ) – density (ʌ) of the 12 biodegradable materials
thermal conductivity
ʄ (W/m K)
density,
ʌ(Kg/m3)
thermal conductivity
ʄ (W/m K)
density,
ʌ (Kg/m3)
sheep wool
0,035 - 0,042
19-25
cork
0,038 - 0,070
67-400
wood-fibers
0,038 - 0,048
40-270
Straw
0,05- 0,10
80-750
flax
0,035 - 0,040
23-50
hempcrete
0,05-0,36
250-1200
hemp
0,039 - 0,048
25-42
papercrete
0,074-0,25
400-450
cellulose
0,035 - 0,045
30-60
unfired Earth
0,14-0,93
700-2200
paperboards
0,028 - 0,040
10-1364
rammed-Earth
0,49-1,50
1700-2200
Generally, thermal performance of biodegradable materials is not only dependent on the porosity
and density of the materials but also on the moisture contained within the material. In fibrous-based
products, such as straw, hemp and flax, the orientation of the fibers play a major role to the thermal
properties of the product. For instance, in straw, the type of straw used, the straw’s moisture content,
density and orientation f fibers as well as the type and thickness of plaster applied or cladding material (Bruce King, 20606, p.187). Also, some biodegradable materials perform worse during the course
of time, and give a different Rc value depending on the mean temperature and on the material’s age.
199
Graph 5.2.2.5: Specific heat capacity (Cp) of the overall materials
Heat capacity, or thermal capacity, indicates how much heat energy is required in order to change the
temperature of an object by a given amount. Specific heat capacity (J/Kg K) is defined as the heat
capacity per unit mass of a material.
* Own illustrations - graph info based on the data edited in CES EduPack 2013, Granta Design Limited, Cambridge, UK, 2013.
Wood-fibrous based products and hemp-fibrous products -as it is noticeable in the Graph 5.2.2.5- have
the highest and better specific heat capacity. The lowest specific heat capacity seems to be obtained
by earth-based products and papercrete. However these materials present a high mass, so the thermal
mass that can provide such materials is not negligible but very important. Thanks to their thermal
mass, accumulation of heat, heat storage and heat re-emission later on can contribute to warmer or
cooler indoor conditions.
Table 5.2.2.6 :
U-value and relative material thickness
Thermal
conductivity
Thickness
(mm)
ʄ (W/m K)
min
max
Unfired Earth
0,140 - 0,930
-
-
Rammed-Earth
0,490 - 1,500
-
-
Straw
0,050 - 0,100
250
500
Sheep wool
0,035 - 0,042
160
210
Wood-fibers
0,038 - 0,048
190
240
Flax
0,035 - 0,040
175
225
Hemp
0,039 - 0,048
195
240
hempcrete
0,05 - 0,360
250
-
cellulose
0,035 - 0,045
175
225
papercrete
0,074 - 0,250
270
-
paperboards
0,028 - 0,040
140
170
cork
0,038 - 0,070
190
350
The thermal conductivity (λ) of a material/ product
divided by the the product’s thickness (d) can inform
us about its thermal resistance (R) since it can be
calculated by the formula: R= d/λ and is measured
in m 2K/W. The U-value can also be known by the
equation U-value: 1/R or λ/d and is measured in
W/m2K. The U-Value is the overall heat transfer
coefficient which shows actually how well a building
element or product can conduct heat or the rate
that heat is transferred through 1 square meter of
structure divided by the difference in temperature
across the structure.
By assuming that a building element is made by one of those
12 selected biodegradable materials that were examined
earlier and that will be used in a wall construction, how
much thickness the building element should have in order to
obtain a U-value of 0.20 W/m2K which is considered a very
good U-value for sustainable building structures? - The
required thickness can be found from the equation U-value:
λ/d and in the maximum and minimum required thicknesses
were found by using the minimum and maximum values
found for its material’s thermal conductivity.
200
5.2.3 Acoustic Properties
Sound absorption coefficient (Alpha w) (known as “weighted sound absorption coefficient”) indicates
how much sound one material can absorb thanks to its texture and porosity. Sound absorptive materials
can reduce the reflection of sound that strikes them leading to indoor spaces that are lees “echoey”
(less reverberant) so consequently seem quieter. Efficient absorptive materials are considered those
which have an alpha w ;ɲ w) of 0.70-0.90 along the frequencies of 500-2000 Hz (Linden and Zeegers,
2006, Bouwfysika- chapter 10).
According to Summary table 5.1.1 “Materials properties”, the 12 biodegradable materials that were
examined seem to be efficient sound absorbent. Thanks to their porosity and density, they can
contribute to a sound reduction and sound absorption. In a thickness of 100 mm and measured at
500Hz, sheep wool and flax have similar sound absorption ( ɲ w) of approx. 0.95, while hemp present
a lower one of 0,65. Cellulose flakes and corks products seem to present similar sound absorption
values of 0.95 and 0.80 respectively but with almost half of the thickness needed for the previous
mentioned materials. Materials that are generally lightweight and porous behave as sound absorbers
and provide high levels of sound absorption, while materials that are more massive or impervious
behave as sound reductive ones by reflecting sound thanks to their diffusivity, for instance; rammedearth, unfired earth products, wood-fibers boards and so on.
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Products and materials that are used in buildings, should inform the users for the degree of their fire
resistance, their fire toxicity and the smoke intensity they create during fire-burning and should be
tested with fire tests in order to be classified. The current classifications for building materials and
products are a) Euroclasses and b) Building Material classification.
In order the materials to be checked for their safety as building component, fire tests that resemble
conditions developed during a fire in a building are made. The different tests (flammability, smoke,
droplets) characterize the products and materials with a class (known as Euroclass as a function of
their fire performance according to specific criteria that are set. These criteria are related with 1)
flammability scenario, 2) smoke release, and 3) production of burning particles.
In the 1st criterion, concept of flammability, ignition time, fire propagation and energy contribution
of the product are measured by a representative measurement of heat released from the product
and its potential contribution to fire propagation. The flammability scenarios that the materials are
subjected are three varying in the degree of flame.
Scenario I:(small fire test) : the product is subjected to a small flame such as match or lighter
Scenario II (SBI test) :
the product is subjected to an isolated burning object (e.g. burning paper bin or chair) and in this
scenario the flammability and development of fire on the testing product are taken into account.
Scenario III (Calorimetric the product is subjected to a general flash over in order its performance to be evaluated in the case
bomb test) : of the highest heat application (fire raging in the room)
In the 2 nd criterion: smoke release (s) the smoke that the product is producing is measured and it
is classified (s). It indicates products for which the rate of increase in the production of smoke is:
s1: very limited / s2: limited / s3: large scale of smoke production.
In the last 3 rd criterion: production of burning drops (droplets) (d), the burning product or material
is tested to see if it generate any burning particles as it burns. Burning particles (droplets) can cause
a serious risk for serious burns for firemen entering in a burning as well as secondary fires. When
there is no production of droplets the product is identified with d0, with d1 when it generates droplets
that remains burning for more than 10 seconds, and d2 when the droplets can cause a paper to start
burning during the test with a small flame.
201
The following tables present more details about the fire classifications and give a general overview.
Table 5.2.4.1: Building Materials Classification
A1
Incombustible materials
Rammed-earth , unfired earth
A2
Incombustible materials with combustible components
(adobes/CEB/ clay boards)
B1
Not readily flammable material / Low contribution to fire
Hemp-lime, cellulose
B2
Flammable material / Acceptable behavior in fire
B3
Highly flammable material (not permitted in buildings)
Straw , Sheep-wool, flax ,hemp
Wood-fibers, Paperboards, cork
Table 5.2..4.2: Overview of the European reaction to fire classes for building products excluding floorings.
Euroclass
Smoke
class
Burning
Droplets
class
A1
-
A2
B
Requirements according
to EN fire tests
FIGRA
W/s
Typical products
non
comb
SBI
Small
flame
-
X
-
-
s1, s2, s3
d0, d1, d2
X
X
-
≤ 120
Gypsum boards (thin paper), mineral wool.
s1, s2, s3
d0, d1, d2
-
X
X
≤ 120
Gypsum boards (thick paper) fire retardant wood
C
s1, s2, s3
d0, d1, d2
-
X
X
≤ 250
Coverings on gypsum boards
D
s1, s2, s3
d0, d1, d2
-
X
X
≤ 750
Wood, wood-based panels
E
-
d2
-
-
X
-
Some synthetic polymers
F
-
-
-
-
-
-
No performance determined
-
Stone, concrete
*FIGRA = Fire Growth Rate
Table 5.2.4.3: Indicative performance descriptions and fire scenarios for Euro classes
A
--->
B
--->
C
--->
D
--->
Inert materials
Performance Description
A1
No contribution to fire (very small
contribution to development of a fire
when exposed to a general flash over)
Fire scenario and heat attack
Fully developed
fire in a room
At least
60KW/m2
Very limited contribution to fire
(no general flash over during the first
10 minutes of the test)
E
Acceptable contribution to fire
(attacked by a small flame. This heat
application level is very low. A class E
product will not ignite when a small
flame is applied to it.)
F
No performance requirements
D
F
Example of products
Inert materials and products of
natural stone, concrete, bricks,
ceramics, etc)
Products similar to those of Class A1,
including small amounts of organic
compounds
Gypsum boards with different (thin)
surface linings, fire retardant wood
products
(no general flash over during the 20
minutes of the test)
Limited contribution to fire
C
- -->
highly combustible to fire
A2
B
E
Single burning
item in a room
40 KW/m2 on
a limited area
Phenolic foams, gypsum boards with
different surface linings (thicker than
in Class B)
Wood products with thickness ≥
about 10 mm and density ≥ about 400
kg/m3 (depending on end use)
Small flake attack
Flame height
of20mm
Low density fiberboards, plastic based
insulation products
-
-
Products not tested (no requirements)
202
.
The 12 selected biodegradable materials that
were researched in chapter 3 were also tested
for their fire safety and in their degree of
flammability.
Table 5.2.4.4 :
Biodegradable materials – Euroclass classification
Euroclass Material/product
A1, A2
As the table 5.2.4.4 shows products made
from earthen materials like rammed-earth
products, adobe bricks, compressed earth
blocks (CEB) are highly fire resistant and
can be considered “non-combustible”. They
belong to the same Euroclass (A1,A2) like
products from natural stone, concrete and
fired bricks.
Rammed Earth
Compressed Earth Blocks
B
Adobe
mud bricks
Hempcrete
C
Straw bale
Flax insulation
Cellulose flocks
Hempcrete and straw bale present also a very
good fire resistance, since they have a very
limited to limited contribution to fire and can
stand fire for long time (usually about 1 hour)
D
-
E
Sheep wool insulation
Wood- fibers insulation
Flax insulation
Hemp insulation
Biodegradable materials that are used mainly
for insulation applications like sheep-wool,
flax, hemp, etc seems to have a lower fire
resistance but still adequate for the current
building regulations. The majority belongs to
Euroclass E.
Cellulose
Cork expanded insulation / corkboards
F
Hemp insulation
Paperboards (honeycomb type)
Image 5.2.14
Image 5.2.14
Cork fire test.
Image taken from:
http://www.modernenviro.com/wpcontent/uploads/2012/08/expanded_
cork_insulation_fire_resistance.jpg
203
5.2.5 Mechanical Properties
The materials are also compared for their mechanical properties in the following graphs
excluding those materials that are lacking in numerical values on their mechanical properties
such as sheep-wool, flax and so on.
Graph 5.2.5.1: Young’s modulus against density (E/ρ)
*Graph 5.2.5.1 is taken from CES EduPack 2013, Granta Design Limited, Cambridge, UK, 2013
Young’s modulus, that is
also known as modulus
of elasticity or elastic
modulus (E), is a measure
of the stiffness of an
elastic isotropic material
and is a quantity used to
characterize materials. It
is measured in MPa or GPa
and it is actually the ratio of
the stress to the strain that
the material is subjected.
A material with a very high
value of its young’s modulus
is considered a rigid one.
Table 5.2.5.2: Young’s modulus of typical building materials
Conventional materials
steel structural ASTIM-A36
200 GPa
stainless steel AISI 302
180 GPa
aluminium
69 GPa
concrete
17 GPa
glass
50-90 GPa
lead
210 GPa
MDF medium density fiber board
4 GPa
papercrete
8 GPa
stabilised earth (adobes, CEB, rammed earth)
cork
≤ 7 GPa
≤0.026 GPa
straw
0.006
*info taken from: http://www.engineeringtoolbox.com/young-modulus-d_417.html
Compressive strength is the strength of a material loaded in compression. For load-bearing
structures (1-2 storeys) a compressive strength of 0.1-0.2MPa is sufficient, but for safety
reasons and after the safety factors are applied, the compressive strength should be ca. 2-2.5
MPa (Houben and Guillaud, 1994).
204
As graph 5.2.5.3 shows unfired earthen
products, rammed – earth and cork present
the highest values of compressive strength,
while hempcrete and papercrete present a
slightly lower value of compressive strength
but still a sufficient compressive strength of
more than 2 MPa.
Graph 5.2.5.3: Compressive strength against density (ʍ/ʌ)
*Graph 5.2.5.3 is taken from CES EduPack 2013, Granta Design Limited, Cambridge, UK, 2013
As it is clear in the graph, three categories
of products present the same compressive
strength with different density. More
specifically, cork products present the same
compressive strength with a significantly lower
density (100 kg/m3) than the compressive
strength of rammed-earth and unfired earthen
products with a density of approximately 1200
kg/m 3 and 1800 kg/m 3 respectively. The same
is noticed also with cork products of about
100 kg/m 3 that present the same compressive
strength with papercrete and hempcrete with
density of about 280 kg/m 3 and 490 kg/m 3
respectively, as well as with the earth based
products. Practically, that indicates that the
same compressive strength is achieved by
lighter weighted products
205
Influencing factors of compressive strength :
Material’s content - composition
Moisture content - dry density
As research has shown, the resulting compressive strength of
building elements made from bulk materials such as earth,
hemp-lime, papercrete, is correlated with the material’s
content. As it observed, there is always an optimum level
of material content that helps to either increase either
reduces specific properties, whereby after the optimum
point, the influencing effect is negligible or even opposite of
the desired one (makes it worse). For instance: In rammedearth, the percentage of silt (%) contained in the soil that
is used can affect the compressive strength as Houben
and Guillaud (1994, p. 78) had found. According to them,
rammed-earth containing 10% silt obtained a compressive
strength of 4.5 MPa while when silt was contained at 40%,
the compressive strength improved to 6MPa. In contrast,
when silt was contained at about 70% in rammed earth, the
compressive strength didn’t increased as someone would
expect but instead got lower (5.5 MPa) silt content. Thus, it
is clear, that in this case the optimum level of silt percentage
in the soil was the 40% which gave the best compressive
strength.
The compressive strength of a
material seems also to be a function
of its moisture content and its dry
density. The higher the moisture
content gets within the material,
the lower the compressive strength
results. Increasing dry density
was found to increase compressive
strength. For example, in straw
bale bearing capacity increases
when dry density increases (Bruce
King, 2006, p.71. However, at the
same time, increasing density
results into an increase of the
thermal conductivity (ʄ) of the
material, simply meaning that it
will decrease its thermal insulating
properties. Moreover, in earthen
constructions,
the
moisture
content influences significantly
the expansion and shrinkage of the
material.
Moreover, research has shown that increasing clay content of
soil contributes positively to an increase of its compressive
strength. The optimum clay content seems to be 12-16% by
weight (Quaglianini & Lenci, 2010, p.314). Quaglianini and
Lenci (2010, p.314) observed that the addition of natural
fibers in earthen products controls in a way the “plastic”
behaviour and influences the way that the adobe bricks
samples that were tested, were broken down under pressure.
One other example is hemp-lime and papercrete products
wherein the percentage of each material-substance that is
added to the admixture that will be used to produce the
products is important. Different ratio of the products
content gives different mechanical and thermal properties
on the final product. For instance, Lime Technology Ltd
(2013) for the manufacturing of hemp-lime blocks suggests
three different mix proportions depending on the intended
use of the product; a ratio of 2:3 (hemp: lime) will give a
compressive strength of 0.9 MPa and a thermal conductivity
of 0.06 W/m*K whilst a ratio of 1:2 will result in a structural
block with a compressive strength of 1.1 MPa and thermal
conductivity of 0.07 W/m*K. Lastly if the intended use of
the product is to be used as thermal insulating unit, then the
ratio should be changed in equal proportion of hemp and
lime binder (1:1) that will result in negligible compressive
strength but a better thermal conductivity of 0.05 W/m*K.
206
Specimen geometry
Drying and curing conditions
The geometry of the products
made from the biodegradable
materials seems also to play an
important role to the final resulting
compressive strength. In unfired
earthen products, Morel, Pkla and
Walter’s experiment (2005, p. 306)
showed that the specimen geometry
of unfired earth units (like adobe,
CEB, etc) affects their compressive
strength.
The production process followed for the production of the
various biodegradable products affects both the mechanical
and thermal properties of the final products. In fibrous
materials like flax and hemp, the harvesting process can
have an influence in the final compressive strength of the
material. Harvesting manually by ripping off the hemp or
flax plant from the roots by hand, gives better compressive
strength than harvesting the plants by machines.
The aspect ratio between its
thickness and height of the element
seems to be important. CEB are not
homogenous as a result of friction
during their manufacture and
unconfined compressive strength
value was found to be the greatest
when the ratio is closer to the value
of 5 (Morel, Pkla and Walter, 2005,
p. 306). For instance: an earth
block with dimensions of 140 mm
(thickness) and 125 mm (height)
gives a ratio of 1.12 (thickness/
height) under compression, which
results in a maximum compressive
strength of 8.5 MPa. An earthen
block with dimensions of thickness
140 mm and height of 45 mm (ratio:
3.1) gives a compressive strength of
16.0 MPa.
In structures made by biodegradable
materials
like
rammed-earth,
straw, hemp-lime and papercrete,
the thickness of the resulted wall
(depth) and its relative height also
are important to be kept under
a specific proportion in order
sufficient compressive strength to be
achieved. In straw structures, a rule
of thumb for sufficient compressive
strength is to keep the total height
of straw bale walls to be less than
5.5 times the wall thickness (Bruce
King, 2006).
In bulk materials that are casted, the drying and curing
conditions -especially when stabilizers are used-have a
significant impact on the resulting compressive strength
of the product. A graph (graph 5.2.5.4) of Houben and
Guillaud (1994, p. 241) demonstrates that relation between
curing conditions and compressive strength; one part
of the samples was stabilized with 5% cement (Sample 1)
and others stabilized with 10% (sample 2). The stabilized
samples that gave the highest compressive strength was
those that were let to air-dry in a moist environment of
100% relative humidity whilst the same sample when left
to dry exposed to sun and wind, obtained a significantly
reduced compressive strength.
Graph 5.2.5.4:
Relation between compressive strength & curing conditions
ϯ
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ϭϬйĐĞŵĞŶƚ
Ϯ
ϭ͕ϱ
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exposed to sun protected from covered by wet 100% relative
and wind sun and wind
bags
humidity
Graph based on graph of Houben & Guilaud *1994, p. 241)
207
Other factors; stabilizers and plastering
Compressive strength can also be improved significantly
by the use of stabilizers such as Portland cement, lime,
bitumen and others, on earthen products (e.g. compressed
earth blocks, adobes, and rammed-earth). The compressive
strength with the addition of a stabilizer increases from 5
MPa to 20 MPa (read chapter 3.2 - table 3.2.2b)
Plastering straw bale walls has also been found to be a
practice that contributes to higher compressive strength of
the structure than unplastered straw bale walls. According
to Bruce King, Thompson et al. (1995) found out that bale
density seems to have a greater effect on bale strength than
the bale type used (Bruce King, 2006, p. 71). Additionally
prolonged exposure to high moisture content it was
noticed that decreases the modulus of elasticity (Bruce
King, 2006, p. 72). Thompson et al. (1995) also observed
that the Poisson’s ratio in longitudinal direction is much
greater than the lateral in unconfined tests (Bruce King,
2006, p. 71).
In general, compressive strength of straw bales is a)
proportional to density; increasing density increases
compressive strength, b) proportional to plaster thickness;
increasing thickness will increase compressive strength to a
ration less than a 1:1 increase, and c) proportional to plaster
strength; an increase on the plaster strength will result in
increased compressive strength but also in a less than 1:1
increase. Also, plastered bales on edge will perform a lower
compressive strength than plastered bales flat.
Graph 5.2.5.5 :
Relation tensile strength to plaster thickness
ĐŽƉƌĞƐƐŝǀĞ
ƐƚƌĞŶŐƚŚ;ŬEͬŵͿ
ϴϬ
ϳϬ
ϲϬ
ϱϬ
ϰϬ
ϯϬ
ϮϬ
ϭϬ
Ϭ
ƉůĂƐƚĞƌ
ƚŚŝĐŬŶĞƐƐ
ϭϮ͕ϳŵŵ
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ͲϭϵϯͲ
ϯϴ͕ϭŵŵ
208
Plaster thickness has a great effect in
strength of bales; flat bales plastered with
a thickness of 38.1 mm had an average
ultimate strength of 72kN/m while those
plastered with a plaster thickness of 25,4
mm have and average ultimate strength
of approx. 58kN/m, and those plastered
with 12,50 mm had an average ultimate
strength of approx.32 kN/m (Vardy et al,
2004, found in Bruce King, 2006, p. 76) .
Thus increasing the plaster thickness we
have an increase in strength of less than
1:1 increase. The reason may be that
thicker layers of plaster are not directly
bonded to the straw.
The following diagram summarize all the above mentioned and
shows the correlation between various parameters that influence
each other and affect the resulting properties of the final products.
Diagram 5.2.5.6: Influencing factors - relation between different parameters
product shape/content
material’s
composition
specimen
geometry
dry
density
decreases
thermal insulation
Increases
increases
compressive strength
thermal
conductivity
Increases
moisture
content
production processes
compressive
strength
rigidity &
flexibility level
external
additives
durability
in weathering
curing
conditions
thickness
209
optimum level
ratio (d/h) ~5
5.2.6 Environmental parameters
Table 5.2.6.1:
Embodied energy of various building materials
Biodegradable
materials
are
considered sustainable materials and
environmentally friendly since they
are derived from natural renewable
resources, they can be re-used,
recycled, and decomposed easily via
natural mechanisms and means.
As summary table 5.1.1 indicates
building
products
made
from
earthen materials, straw, cork or
papercrete, appear to have the lowest
embodied energy per unit of mass.
In contrast, sheep wool, flax, hemp
and paperboard present much higher
embodied energy content compared
to the others as a result of their more
intensive processing and production
techniques that are applied during
their
manufacture
to
building
biodegradable products.
However, sheep-wool, flax, hemp and
wood-fibers as insulation products
contain still more than three times
less embodied energy than synthetical
inorganic insulating materials like for
instance, polystyrene insulation as
someone can observe also from the
table 5.2.6.1 where various current
materials are presented.
*Table taken from: http://www.canadianarchitect.com
210
5.3 Research conclusion
The research showed that the majority of the 12 selected biodegradable
materials present similar thermal and fire-resistance behavior although
they vary in their mechanical properties. The 12 selected biodegradable
materials that were examined can mainly be divided in three sub-categories
according to the main characteristics that were noticed previously in the
comparison charts and tables.
Possible materials categorization after research results:
a) Insulating materials: Such materials can be used only as thermal and
acoustic insulation. They are producing mainly flexible or semi-flexible
types of building products, such as sheets-battens, bands, rolls and
felts. They are not self-supportive so they are always requiring a substructure wherein they should be applied. Their flexibility allows them
to be applied easily and be cut in any required shape and dimension.
They also present the best insulating properties compared with the
others.
b) Self-supportive insulating material: Those materials present good
insulating properties like the insulating materials of category (a) with
the main difference that they are self-supportive, meaning that they
can carry they own weight and require less sub-structure. They are
producing mainly semi-rigid or rigid boards, panels, rolls and sheets,
depending on their thickness and manufacturing process.
c)
structural materials with good thermal mass: Materials that belong to
this category present a good thermal mass combined by their use to build
massive walls, but almost always require additional insulation to fulfil
the current building regulations. Although materials of this category are
lacking in their thermal insulating properties, they outmatch in their
structural behavior presenting very good mechanical properties. Those
materials can not only carry their own-weight but in efficient thickness
and dimensions, they can be used to build structural masonries. Their
efficient compressive strength allows them to contribute to a decrease
of the main structure or sub-structure required in the building and
sometimes they present such efficient load-bearing capacity that can be
used as load-bearing structures.
Thanks to their composition and nature of material (porosity), materials
that present the best thermal conductivity (meaning the lowest value of ʄ)
(category a) are also those that present very weak mechanical behavior due
to their flexibility and are less fire resistant (both materials from category
(a) and (b)). Such materials as it can be noticed are either fibrous materials
derived from animal or plants like sheep-wool, flax and hemp, either
materials derived from particles-chops of wood-paper like cellulose flocks,
cork granules and wood-fibers. The majority of these materials belongs to
Euroclass E and has a Building Material Classification of B1/B2 class.
211
Diagram 5.3.1: New categories of materials
Material:
sheep-wool
Caterogies:
a. thermal-acoustic
Insulating materials
high thermal insulation
Ƥ8N,
flexible / semi-flexible
flax
hemp
cellulose flackes
wood-fibers
b. self-supportive
insulating materials
medium thermal insulation
Ƥ8N,
cork
paperboards
semi-flexible / rigid
b. structural -thermal
mass materials
strawboards
low thermal insulation
Ƥ8N,
hemp-lime
papercrete
straw bales/panels
rigid
adobes/CEB
rammed-earth
Bulk materials that are molded into prefabricated forms or are casted in-situ to build monolithic
walls and structures, is noticed to belong mainly to materials category c and they present sufficient
mechanical properties for buildings of 1-2 storeys or more. Straw and hemp-lime materials present
the best insulating properties as well as a very sufficient compressive strength for low-rise buildings
(1-2 storeys). Contrary, earthen materials used to produce adobe bricks, CEB and rammed-earth
products behave as very bad insulators although they present the best mechanical behavior (highest
compressive strength-especially when stabilized). However, their high thermal mass that they provide
can be extremely beneficial for indoor climate control with natural ways. Materials of category c are
also seen to be more incombustible or to have a very limited contribution in the case of a fire. They
belong usually in the Euroclass A/B or C and in Building Materials classification to A1/2 and B1/B2
depending on the thickness of their products and their composition (if they contain fibers or not).
The acoustical properties and durability of each material present a similar degree, and are mostly
dependent on the products content and the precautions taken for the materials protection against
weathering and other damaging mechanisms. All the 12 biodegradable materials require a careful
design approach to avoid high moisture content within the materials to be reached for a prolonged
period of time. Cork seems to be the most resistant and durable in the case of water thanks to its
hydrophobic nature, and stabilised earthen structures also can stand it for a longer period. The most
weak in the terms of rottenness is straw products and needs highly protection from water. However
straw is one of the materials that can present at the same time sufficient thermal and mechanical
behaviour and combined with its low cost and surplus quantity that usually can be found is one of the
most favorable materials for sustainable constructions.
212
Suggested use:
Table 5.3.2: Materials categorization & suggested use
1. Materials from category a (e.g.
sheep-wool, flax, cellulose, etc)
thanks to their excellent insulating
properties and their flexibility
degree are suggested to be used
within building envelopes as
insulation cores since they can be
very easily adjusted to any type of
structure.
2. Materials from category b (e.g.
cork, wood-fibers, and clay panels)
that provide a moderate degree of
insulation and are self-supportive
are better to be used as additional
insulation,
internal
partitions
wall systems, as wall finishes or as
cladding.
3. Materials from category c thanks
to their very good mechanical
properties should be used in cases
wherein
monolithic
masonries
are needed; the building structure
needs to be decreased, as internal
wall partitions and as external or
internal wall finish panels.
Categories
a. Insulating materials
Materials : sheep-wool, flax, hemp, cellulose, cork
Products types: battens, rolls, felts, bands, strips,
flakes ,shives, granules
Suggested use : insulation (thermal & acoustic)
(walls, between rafters, floors, floors, etc)
b. Self-supportive insulating materials
Materials: wood-fibers, cork, straw, paperboards
Products types: boards, panels, blocks, tiles
Suggested use : additional insulation + wall finish panel
Internal wall partition systems/cladding
c. Structural -thermal mass materials
Materials : straw, hemp-lime, papercrete,
unfired earth, rammed-earth,
Products types: casted or sprayed in-situ structures
bricks, blocks, boards,
façade and wall panel systems
Suggested use: Structural
Masonry / Internal wall partitions
External or internal wall finish
structural cladding
To conclude, all the 12 selected biodegradable materials that were
examined can be used as building materials for sustainable buildings.
Each material presents properties which it outmatches and others that
lacks. The intended use of materials within a building envelope is the
one which will provide more requirements about its thermal properties,
its mechanical and fire behaviour as well as its thickness and degree of
f lexibility. Table 5.3.2 summarizes all those mentioned before. As it is
noticed, some materials belong to more than one category depending on
the type of product generated from each material.
213
214
Chapter 6 Design theme
In the current chapter, a façade section from a contemporary public building is selected as a case study
and its current materialization is examined in terms of cost, embodied energy and CO2 emissions,
acoustics, thermal and fire behavior, and so on. The chapter focuses on the redesign of the selected
façade section with three proposals wherein different biodegradable materials are applied. The three
façade redesigns are materialized with different biodegradable materials from the 12 researched in
former chapters in order to display a wide range of design paradigms of how such materials can be
used and combined in practice. Same measurements and calculations that were made for the façade’s
current materialization are also calculated for the new design proposals.
The main objective of this chapter is an ECO- comparison through the current and suggested facades, as
well as relevant assumptions about their performance characteristics, cost and others parameters. Aim
of this design topic is to demonstrate the possibilities of biodegradable materials on the contemporary
architecture and their environmental avail compared to the conventional building materials, as well
as to point out considerations and design precautions related to their drawbacks and to the nature of
the chosen materials in an attempt to enhance their use. in the Netherlands. The number of proposals
and selected materials that are applied is adequate to show clearly the differentiations within different
biodegradable materials and the particularities existing on the construction and assembly processes
among them.
215
6.1 Case study & Methodology
The case study selected to be examined is an one-storey building that nowadays functions as a primary school.
It is called “Bernadette Maria School” with a total area of 1.305 m2 and located in Aan’t Verlaat 30 in Delft. The
building was constructed in various chronological phases (1985, 2009, and 2012) with its last building’s renovation
taken place on 2009. In 2012, an extra classroom with total area of 68 m2 was added on the South-East side
of the building and the main school entrance was slightly extended. The new classroom was materialized with
contemporary materials and its structure is a self-sufficient and autonomous from the old pre-existing building
structure. The façade section that is selected to be studied lies on the new extended part of the school and more
specifically it is the South-East façade of the new classroom. The façade has an a size of about 7.24 m length and
maximum height of 4.22 m., while its wall thickness is 229 mm.
The façade was selected thanks to its latest construction date (2012), its contemporary materialization, and the
interest it presents for its redesign with biodegradable materials. Its size is also sufficient to demonstrate the
possibilities of biodegradable materials and how they can be applied on building envelopes here in the Netherlands
combined with the current constraints of the case study (structure-building use). The selected façade will be
examined under various parameters and will be compared with three proposals that will be suggested for the
façade’s redesign. Each redesign proposal will suggest different biodegradable materials application, so useful
comparisons will be possible to be made.
Case study: location
Image 6.1.1
Image taken from:
https://maps.google.com/
Methodology:
The methodology that will be followed focuses on the evaluation of the current façade section under specific
parameters and the re-evaluation of the new façade suggested in the three redesign proposals (A, B, and C). The
selected façade is redesigned in three variations in order to understand the constraints and precautions needed to
be taken within the design phase when working with particular biodegradable materials. The research results of
the materials analysis as well as the observations that one can make in chapter 3, 4 and 5, lead to the conclusion
that more or less all 12 biodegradable materials that were examined are suitable to be used on building envelopes in
the Netherlands depending on the specific design precautions and constraints of each building case, the intended
use (internal-external application, etc), the requested structural rigidity and prefabrication level, as well as the
available construction cost and time.
Each and every material though presents a variation on features related to moisture mechanisms, as well
as particularities on assembly and construction method. The biodegradable materials that are chosen for
the redesign proposals present both high potential of future and current availability in the Netherlands and
particular characteristics that differentiated from each other either in texture, application use or performance
characteristics in order a wide range of biodegradable materials to be present in the design. Both the current
façade’s materialization and the suggested proposals will be examined and compared under various parameters.
The results will be presented in summary tables where comparisons would be made.
216
Evaluation parameters :
01/ Cost of façade’s materialization
04/ Environmental aspects;
embodied energy – related CO2 emissions
Cost is a major parameter on contemporary
constructions, and often the materials selection
of a building’s materialization is based mainly on
their primary cost since cheaper materials with
similar characteristics are often preferred than more
expensive ones. The studied façade and its redesign
proposals are important to be compared in terms of
cost to inform the reader for the feasibility of building
constructions with biodegradable materials.
The current environmental situation urges for
sustainable buildings structures. Therefore, the
total amount of the embodied energy of the applied
materials in the building envelope and the relevant
production of CO2 emissions is important to be
measured and compared to identify the most
sustainable proposal among them.
02/ Construction related parameters;
craftsmanship Vs industrialization
05/Thermal, acoustic and fire performance
The performance characteristics of the building
materials suggested in each design case are important
to be compared. It is not only necessary to compare
the primary embodied energy and CO2 emissions
footprint to understand which façade’s case is better
in environmental terms, but it is equally important to
assume the way each façade will perform thermally
and its contribution to an increase or decrease of
heating and cooling demands of the indoor space.
The manufacturing and prefabrication level of
biodegradable product’s, the labour intensity of
the materials suggested that are related to current
construction and assembly methods on-site, will be
examined in each design case. Materials and products
that require less degree of craftsmanship are often
more preferable nowadays, since craftsmanship is
often correlated with higher construction cost and
time.
Consequently the thermal behavior of the facade
will be discussed and taken into account. A better
achieved Rc-value of the façade means practically
less potential demand in heating or cooling energy
consumption, so consequently to lower operating
building’s energy.
03/ Durability – maintenance
The life-serviceability of the suggested facade as a
function of cost and maintenance is important to be
compared within the four cases. For instance, a façade
that its primary materialization costs less than a more
expensive ones but requires frequently maintenance
due to weathering, can give finally a higher total cost
during the course of time than the other one that was
initially more expensive but required less or minimal
maintenance.
The indoor space where the selected façade lies is
a classroom for children of primary school. Thus,
the acoustic behavior of each façade case is also an
important parameter to be taken into account and
show which case present better acoustic behavior.
A classroom needs to be a pleasant and quite space
with low indoor sound level pressure. The building is
located about 500 meters away from an A3 and E19
motorway and lies next to two adjacent city streets
surrounded by tress. Therefore it will be assumed
that the exterior sound load is 70 dB (Zeegers, 2006,
“Bouwfysika”, chapter 11”) and the required sound
reduction should be Rw minimum of 35 dB in order
the indoor space (classroom) to be sufficiently quite.
The same can occur if the materials applied in the first
case present a smaller lifespan and service life than
the materials in the case B. Thus, the serviceability,
durability and maintenance requirements of each
façade case should be examined and compared. The
total cost of a façade should not be considered only
the one related to the primary materialization’s cost
but also to the future maintenance cost, if required.
The fire resistance of the current and new suggested
materials is also an important parameter that should
be examined to see which façade’s case is safer in the
case of a fire. A façade that is longer fire resistant
presents a strong advantage when in public buildings,
like a primary school, extra usable time for evacuating
the indoor space can be crucial for the occupants’
safety.
Maintenance cost and its relevant frequency is
related to the product’s durability and lifespan.
Cheaper materials are often refused by materials that
are on the one hand more expensive but require less
maintenance while at the same time provide a longer
span of life-serviceability.
217
Image 6.1.2
Image 6.1.3
Image 6.1.4
Image 6.1.5
Image 6.1.2: view on site, South-East side
Image 6.1.3: view on the building, South-East side
Image 6.1.4: view on site and on the adjacent urban street, East side
Image 6.1.5: view on site and adjacent street, West side.
All image are taken from: https://www.google.com/maps/ (last accessed: 10th May 2014)
218
6.2 Case study: current facade’s materialization
The selected façade is orientated on South-East and has a total area of 27.63 m 2 of which 14.8 m 2 are
occupied by the façade openings (windows). The overall wall thickness is 229 mm and is consisted of:
6 mm HPL cladding façade, 4 mm glue, 44 mm substructure (horizontal and vertical battens), vapor
barrier membranes, 150 mm Rockwool insulation and 25 mm plasterboards.
Image 6.2.1
Image 6.2.2
Image 6.2.1: HPL facade panel, Formica,
Image taken from: http://www.formica.eu/pdf/
brochures/me/pocket_brochure_me.pdf
Image 6.2.2: Rockwool insulation rolls,
Image taken from: http://image.ec21.com/
image/sinroad/oimg_GC06183664/Rock_
Wool_Blanket.jpg
Current façade’s materialization - analytical description:
Structure: The façade’s load-bearing structure is a combination of steel and timber frame structure. More
specifically, steel hollow columns (80X80X5) and timber studs (50X150) of various heights
carry timber beams (50X150) and steel HEA 120 beams alongside their length. Smaller timber
beams work as lintels and sills that carry the windows load.
Sub-structure: A secondary timber structure consisted of vertical and horizontal timber battens (22X75)
carries the weight of the cladding façade elements which are high laminated pressure cladding
panels (HPL) on various sizes and lengths with a thickness of 6mm. The cladding elements
are glued on the timber sub-structure.
Exterior façade HPL façade panels are considered durable, highly resistant to impact damage and suitable
leaf (cladding): as cladding material for ventilated facades. They are made from impregnated multiply paper
layers that are bonded with resins under high pressure and temperature to create a hard
wearing and durable surface. Often they contain a flame retardant additive (VFP grade). The
finish surface of the HPL panels that are used on the case study have a gloss surface finish and
are colored in three shades of blue (Marine blue/Topical blue/Maui) similar with the colors
given by Formica® façade company. HPL panels are neither biodegradable neither recyclable
so consequently the only disposal solution is landfill. A prolonged use to UV-radiation
(sunlight) can cause possible color fading and gradual whitening of surface. The maximum
lifespan given by manufacture companies for HPL panels is 15 years.
For the calculations that will be made, its properties are assumed to be similar with the
material selected and found on CES EduPack software (Granta Design Limited, Cambridge,
UK, 2013) named as “MF (melamine formaldehyde (alpha cellulose filler)” which implies a
material that is filled with paper (cellulose) about 60-80*% and the polymer type used is
melamine formaldehyde resin (20-40%).
Insulation The insulation used on the current façade is Rockwool insulation in maximum thickness of
layer: 150 mm for the wall and 200 mm for roof application, which is applied between the timber
framing and is protected with vapor barrier membranes from both sides. The Rc value of
Rockwool insulation stated for the wall and for the roof is 3.5 and 4.0 m2 K/W respectively
excluding the other wall and roof materials Rc-values.
Interior façade Two plasterboards of 12.5 mm thickness each are applied on the internal layer of the façadeleaf: wall, which provides a fire resistance of 30 minutes.
windows Timber window framing, enameled with aluminium and painted in white color
Roof structure: The roof is a flat roof with a small overhang. It is consisted of two self-supportive and
structural plywood boards’ layers of 15 mm each, wherein the insulation (Rockwool, 200 mm)
is positioned. Vapor barriers and bitumen roof finish layer prevents any water penetration and
accumulation of moisture on the roof structure.
219
Image 6.2.3
Image 6.2.4
Image 6.2.5
Image 6.2.3: Exterior view of South-East side of the
case study (Bernadette Maria school)
Own image / archive.
Image 6.2.4: Studied section: South-East facade
Own illustration based on drawings derived from Delft
Gemeente’s archive.
Image 6.2.5: Construction phages of the Building:
part 1 (243 m2) is the oldest part, part 2 (986 m2),
was constructed in 1985 and part 3 (68 m2) is the
newest part added in 2012.
Own illustration based on similar scheme derived from
Delft Gemeente’s archive.
Image 6.2.6
Image 6.2.6: Exterior view of studied section
Own image/ archive.
Image 6.2.7: 3D scheme - exploded view of current
facade’s materialization.
Own illustration
Table 6.2.8: Data input for calculations.
main structure, facade sub-structure and other
elements were calculated its area, volume in order
to be input later on calculations.
220
Image 6.2. 7
Table 6.2.8: Calculation of the data that will be used for the comparisons
Code
Length (m)
Section/Area (m2)
Volume
(m3)
Hollow steel columns
H1
2.55
-
0,00382
80 X80 mm (thick:5 mm)
H2
2,88
-
0,00432
H3
3,40
-
0,00510
Product Type
Total Volume
(m3)
Main structure
1.
AISI 130 normalized
2.
HEA 120 steel beam oblique
HEA
7,30
0.0021
0,01533
3.
Timber beams (50X150)
B1
7,00
0,0075
0.05250
B2
7,30
0,0075
0,05470
BW
1.22
0.0075 X4
0.00915 x 4
C1
2.55
0,0075
0.01912
C2
2,72
0,0075
0.02040
C3
2,87
0,0075
0.02152
C4
2.88
0,0075
0.02160
C5
2,96
0,0075
0.02220
C6
3,40
0,0075
0.02550
0.02827
(TOTAL Volume of BW: 0.0366)
4.
Timber pillars (50X150)
0.27394
Façade Sub-structure
5.
Timber beams (22X75) Horiz
T1x7
3.45
0.0016X7
0.03864
6.
Timber beams (22X75) Vertic
T2x5
3,05
0.0016 X5
0.02440
T3
2.55
0.0016
0.00408
T4
1.38
0.0016
0.00220
T5
1.30
0.0016
0.00208
all
-
12,83
-
0.07698
2.06
2.06
0.23
0.23
0.0714
Façade cladding
7.
HPL Façade panels (d: 6mm)
High pressure laminated
(cladding )
Others
8.
Insulation (150mm) facade
RW
9.
Vapour barriers X2
VB
10
Plasterboards (25mm)
PB
13,76
-Not calculated- considered negligible9,47
221
Scheme 6.2.9: Horizontal section (curent Facade)
Own illustration based on drawings derived from Delft Gemeente archive.
Scheme 6.2.10: Structure Scheme of the building part where the current facade lies.
Own illustration based on drawings derived from Delft Gemeente archive.
222
Scheme 6.2.11: Cross- section (Current Facade)
Own illustration based on details 001 & 002 derived from Delft Gemeente’s archive.
223
6.3 Case study: redesign proposal A
Redesign Proposal A is a façade that is consisted mainly of
earthen products. The load-bearing structure is kept the same as
in the real façade case excluding the facade’s sub-structure that
was needed for the HPL cladding panels in the former case. The
new resulting thickness of wall is 355 mm. It is mainly consisted
of: 125 mm prefabricated rammed-earth panels, a 50 mm air
cavity, breathable and vapor barrier membranes, 150 mm sheepwool insulation and 25 mm clayboards that are coated with 5
mm clay plaster.
Façade case A; materialization - analytical description:
Structure: The façade’s load-bearing structure is kept the same with the former situation of the façade.
Thus, the steel and timber frame are kept as the main load-bearing structure that will carry
the loads.
Sub-structure: The secondary structure needed in the former HPL façade is unnecessary and removed since
the exterior new cladding is self-supportive and structural.
Exterior façade The exterior façade leaf is consisted of prefabricated rammed-earth panels both stabilised
leaf : and unstabilised, depending on the intended position. The stabilised rammed-earth panels
contain ca. 8% Portland cement and are placed as window’s lintels and sills, under the roof
overhang and near the ground level. All the panels are prefabricated and delivered on site in dry
condition. They will be in different color variations provided by the manufacture company in
order to display an interesting and playful façade pattern. The unstabilised rammed-earth will
be coated with limewash for water resistance. The rammed-earth panels are self – supportive
and connected to each other via adhesive mortar, whilst small reinforcement bars on specific
points ensure the outer wall leaf ’s stability. An air-cavity of 50 mm is constructed to help the
air-drying of any wet rammed-earth.
Insulation The Rockwool insulation is replaced in this proposal with sheep-wool insulation at the same
layer: thickness (150 mm) which has excellent hygroscopic behavior and can regulate both indoor
humidity and temperature levels. On both sides, a breathable membrane that is waterproof
but vapor permeable is installed.
Interior wall The plasterboards are replaced in this proposal by clayboards of 25 mm thickness that are
leaf: connected to the main structure via screws and to each other with reinforcement bands. A
sealing tape is applied in each edge of the boards to protect them before they are covered with
clay plaster of 5 mm.
Other changes: Due to the sensitivity of the material that is used as exterior finish on the façade, a concrete
footing where rammed-earth will be placed was needed with a height of 580 mm (min. height
advisable in literature is ca. 250 mm). This will prevent any risk of dampening due to splashing
water, rising damp or flooding to damage the rammed-earth façade. Moreover, a natural
stone working as window’s sill prevent any water to enter to the rammed-earth structure.
Breathable membrane is installed on the exterior side of the intermediate leaf to allow it
to breath and remove any excess of moisture, whilst from the interior side, a vapor barrier
membrane is installed to protect the wall structure from additional moisture from the interior
space.
windows -same with previous caseRoof structure: The roof remains the same. Only insulation is replaced by two layers of sheep-wool insulation,
100 mm thick each. Additionally, the roof overhang is extended to provide adequate protection
from rainwater.
224
Scheme 6.3.1:
3D scheme section - products information
Products name
d(mm)
ʄ;W/mk) ʌ(kg/m3)
1 Clay plaster
5,0
0,17
600
2 Sealing tape
-
-
3 Clayboards,
Claytec®
(625 X 1500)
25
0,15
700
4 Sheep-wool
insulation roll,
Doscha DP-14
(60mm X 6m)
150
0,035
25
5 Rammed-earth
panels, Claytec®
125
0,41
2400
-
** For a view of the drawings of Redesign case A
in scale, check the relevant section on Appendix
Scheme 6.3.2:
3D exploded_ schematic illustration of facade’s construction
5
3
1
6
7
4
2
1. Facade openings:
Timber windows frames painted in white colour
surface treatment: enamelled with aluminium
5. Facade’s main structure:
current facade’s structure,
timber and steel structure.
2. Facade’s external leaf:
Claytec rammed - earth prefabricated panels
Used in 3 different colour variations and in two types:
stabilized and unstabilised. For more info check
chapter 3.2, table 3.2.2.a
6. Vapour barrier membrane
3. Breathable membrane
4.Thermal- acoustic insulation:
Doscha sheep-wool insulation roll.
For more info check chapter 3.4, table 3.4.2, product’s
code: DP-14
7. Facade’s internal leaf: Claytec
rigid clayboards made from clay
+ hessian and reeds (25 mm).
For more info check chapter
3.1, table 3.1.1a, product’s code:
09.002
8. Surface finish:
clay plaster coating (4 mm)
225
The assembly of this
facade should start from
the interior leaf to the
exterior leaf, installing
first the vapour barrier
to the main structure,
the clay boards, then the
insulation and all the
other elements.
8
Scheme 6.3.3: Facade elevation
Scheme 6.3.4: horizontal section
226
Scheme 6.3.5: Cross-section
** For a view of more drawings of Redesign case A
in scale, check the relevant section on Appendix
227
6.4 Case study: redesign proposal B
Redesign Proposal B is consisted mainly by a choice
of by-products that are derived from fibrous materials
like wood-fibers, flax and compressed straw. The loadbearing structure remains the same with proposal A.
The wall thickness resulted in this case is about 260
mm and more specifically it is consisted of: 80 mm
render-compatible wood-fibers insulation coated with
about 8,5 mm plaster, breathable membrane, 150 mm
flax insulation, a vapor barrier and 18 mm strawboards
covered with hard Kraft wallpaper.
Façade case B; materialization - analytical description:
Structure: -same as case ASub- structure: -noneExterior façade The exterior façade leaf is consisted of wood-fiber boards that are connected to the main
leaf : structure via insulating plastic fixings. The minimum distance for the fixing that should be
kept form edges is 50 mm and the maximum 250 mm. The wood-fiber boards used on the
façade are compatible with an integrated render system so they can be plastered with any kind
of plaster. Therefore by plastering the wall surface, it provides a waterproof resistant and still
breathable exterior wall finish that can be painted in any requested color.
Insulation The thermal and acoustic insulation chosen for proposal B is flax insulation thanks to the
layer: great compatibility that it has with wood-fibers. Flax insulation is also very good in sound
reduction via sound absorption. The insulation is placed in between the timber studs and
is 150 mm. It is protected by a breathable membrane and a vapor barrier on its external and
internal side respectively.
Interior wall Compressed straw in the form of prefabricated strawboards of 18 mm is applied on the
leaf: interior side of the timber frame and is fixed with screws. Then their surface is covered with
2 mm thick Kraft wallpaper. Strawboards except of a fair insulation they also provide a selfsupportive and high resistance to impact damage surface.
Other changes: A concrete base is created so wood-fiber exterior insulation boards to be placed. This prevents
any splashing water, rising damp and flooding to damage severely the construction by
providing a dry base/foot.
Windows -same with previous caseRoof structure: The roof overhang is extended slightly in order to keep a min. 30 mm distance from the
resulting façade. Vapour barrier membranes are installed in between the various layers of
the construction, ensuring the waterproofing of the roof. The insulation is replaced be flax
insulation of 200 mm thickness.
228
Scheme 6.4.1:
3D scheme section - products information
Products name
d (mm)
ʄ;W/m k) ʌ(kg/m3)
1 Kraft paper
2
0,17
700
2 Strawboard
ECOBoards,
1,2 X 2,4 m
18
0,065
7500
-
-
4 Flax insulation,
Isovlas, 0,6 X
1,20 m.
150
0.037
150
5 Wood-fibers
Pavatex
Diffutherm
0,79 X 1,20 m
80
0.045
150
5 Clay plaster
8.5
0,17
600
3 Breathable
membrane
-
** For a view of the drawings of Redesign case B
in scale, check the relevant section on Appendix
Scheme 6.4.2:
3D exploded_ schematic illustration of facade’s construction
6
1
2
3
4
6. Facade’s main structure:
current facade’s structure,
timber and steel structure.
2. Facade’s external leaf: surface finish
clay render skim - purple colour /breathable paint
7. Vapour barrier membrane
3. Facade’s external leaf:
Diffutherm Pavatex wood-fiber insulation (80 mm)
self-supportive and compatible wood-fiber boards
with render system. For more information check
chapter 3.5, table 3.5.2
8. Facade’s internal leaf:
strawboards Ecoboards (18 mm)
Self-supportive boards made
from compressed straw. For more
info check chapter 3.3, table
3.3.2a, product’s code: standard
5.Thermal- acoustic insulation:
Flax insulation batts (Isovlas) (150 mm). For more info
check chapter 3.6, table 3.6.2, product’s code: PL-140
8
5
1. Facade openings:
Timber windows frames painted in white colour
surface treatment: enamelled with aluminium
4. Breathable membrane
7
9. Internal leaf - Surface finish:
wallpaper from thick kraft paper
applied on strawboards (2 mm)
229
The assembly of this
facade should start from
the interior leaf to the
exterior leaf, installing
first the vapour barrier to
the main structure, then
the strawboards and then
all the other elements.
9
Scheme 6.4.3: Facade elevation
Scheme 6.4.4: horizontal section
230
Scheme 6.4.5: Cross-section
** For a view of more drawings of Redesign case B
in scale, check the relevant section on Appendix
231
6.5 Case study: redesign proposal C
Redesign Proposal C is materialized with a combination
of biodegradable materials that differentiated greatly in
their texture and nature of material such as cork, straw
and compressed earth blocks. Cork is a material that can
be found in the Netherlands only via recycling programs
of cork that is gathered from wine bottles. Cork is mainly
harvested and produced in Portugal and Spain. Although
it is not available in the Netherlands in high quantities,
it was selected to be applied on this façade thanks to
its hydrophobic properties. The wall thickness of the
emerging façade is 295 mm.
Façade case C; materialization - analytical description:
Structure: -same case ASub-structure: In this case, a secondary structure for the façade cladding is required to carry the load of the
facade panels. The structure is consisted of vertical and horizontal timber battens (22 X 75)
that create also a small air-cavity between the cladding and the main structure in order to let
the facade panels dry in case of high moisture levels.
Exterior façade Expanded granulated cork panels of size 500 X 100 were selected as a cladding material
leaf : in this redesign proposal and are installed with hidden fixings. Cork as a material present
high resistance to water and it can be considered waterproof, while at the same time it is
highly fire resistant. The particular cork elements that were selected are suggested by the
manufacture as façade cladding elements and the manufacturer suggest to be installed either
by gluing them either by hidden mechanical fixing (screws).
Being aware that cork can start rotting after prolonged exposure to wet conditions, it was
wiser to create a sub-structure where the panels can be fixed in order a possible replacement
to be easier to take place in the future. Moreover, cork will start fading after years of exposure
on UV-radiation in sunlight, which in some cases it may be an interesting effect and may
result in natural pattern on the facade. On the other hand, it can be also disastrous, so it
depends on the case.
Insulation The cork façade panels work twofold; as a cladding material but also as an external insulation
layer: thanks to its thickness (100 mm) and thermal properties. (λ, specific heat capacity).
Interior wall For the interior wall leaf, compressed earth blocks were selected in order to give a warmer
leaf: indoor environment via their thermal mass. CEB are unstabilised and since they are applied
indoors and the space is used as a classroom, there is no need for any additional water
protection. Compressed earth blocks are placed onto the timber beams and are binder
with its other with adhesive mortar (10 mm) while they are also connected with metal ties
like brick masonry on self-supportive and structural strawboards of 25 mm. strawboard
is protected from any exterior moisture via a breathable membrane. The air cavity created
by the façade’s sub-structure not only allows wet cork to dry faster but also strawboards to
remain dry in the desired moisture content.
Other changes: The roof overhang is extended in order to keep a min. 30 mm distance from the resulting
façade. Breathable membranes are installed.
windows -same with previous caseRoof structure: The roof remains the same. Insulation is replaced by cork insulation, 200 mm
232
Scheme 6.3.1:
3D scheme section - products information
Products name
1 Cork façade MD-
d(mm)
ʄ;W/mk) ʌ(kg/m3)
100
0,037
140
22
0,18
350
-
-
4 Strawboards
Ecoboards
(25mm)
(1,2 X 2,4)
25
0,065
750
5 Compressed earth
blocks, Claytec®
(113 X 240)
115
0,21
1900
FACHADA 500
X 1000
2 Timber
battens,
22 X 75
3 breathable membrane
-
** For a view of the drawings of Redesign case C
in scale, check the relevant section on Appendix
Scheme 6.3.2:
3D exploded_ schematic illustration of facade’s construction
5
1
2
3
5. Facade’s main structure:
current facade’s structure,
timber and steel structure.
2. Facade’s external leaf:
MDFACHADA AMORIM cork insulation boards
For more info check chapter 3.12, table 3.12.2.
6. Compressed strawboards
Ecoboards self-supportive
(25mm). For more information
check chapter 3.3
4. Breathable membrane
4.Thermal- acoustic insulation:
Doscha sheep-wool insulation roll.
For more info check chapter 3.4, table 3.4.2, product’s
code: PL-140
7
4
1. Facade openings:
Timber windows frames painted in white colour
surface treatment: enamelled with aluminium
3. Facade sub-structure:
Timber studs horizontal and vertical, 22 X 75
6
7. Compressed Earth Blocks (CEB)
made from clay + hessian and
reeds (25 mm). For more info
check chapter 3.1, table 3.1.2a,
product’s code: 06.003
8. Surface finish:
clay plaster coating (4 mm)
233
The assembly of this facade
should start from the
intermediate leaf to the
external and internal leaf
by first installing and fixing
the strawboards on the
structure of the facade.
Scheme 6.5.3: Facade elevation
Scheme 6.5.4: horizontal section
234
Scheme 6.5.5: Cross-section
** For a view of more drawings of Redesign case C
in scale, check the relevant section on Appendix
235
236
6.6 Comparisons - evaluatiom
In this section, the redesign
proposals (A, B and C) as well as the
current façade’s materializations
are examined and compared under
various parameters (measurable
and non-measurable ones) that
were described in details in 6.1
under the section “Evaluation
parameters”.
The
comparison
among the facade cases aims to
indicate which of the suggested
proposal may be the most favorable
in terms of cost, sustainability
and performance behavior. This
comparison will be held by using
tables, graphs and charts.
Scheme 6.6.1: Overview of current facade & redesign cases A,B,C
current facade
In order to be able to compare
the various facades among them,
specific parameters should be
known and be converted in
same measurement units. Such
parameters are mainly the cost per
cubic meter and per unit of mass
for each material used, the density,
the mass, thermal conductivity,
embodied energy both per unit of
mass (MJ/kg) and per cubic meter
(MJ/m 3) per each material, and so
on.
facade case A
A table was made where all such
relevant data of each material and
product used were input in each
facade case. Later on from this
table, calculations for the total
mass, total cost , total embodied
energy
and
environmental
footprint for each facade case
were possible to be made.
facade case B
The data that were inputted in the
referring table were taken from
the materials tables presented in
Schemes 6.2.8, 6.3.1, 6.4.1 and
6.5.1 as well as can be found from
the specific materials properties
tables in chapter 3.
facade case C
237
The following table presents the most important data that were inputted for the calculation of specific
figures and parameters. It should be noticed here that since the range of properties in some cases can
vary significantly, for all the materials were taken the most favorable values of properties, meaning
the lowest values on embodied energy, CO2 emissions and so on. Moreover, for the cost of the facade,
only the primary material’s and product’s cost was considered. Thus, the results occurring from the
comparisons based on these calculations should be considered as “indications” and not as “exact
accurate results”.
Table 6.6.2: Input data
238
239
A. Comparisons
in measurable parameters :
Graph 6.6.3 : Facade’s total mass (kg)
Cost of façade’s materialization
For the calculation of the facade’s cost only the primary
materials cost was taken into account excluding costs
related to transportation, labour, etc. As table 6.6.2
indicates the current facade seems to have the lowest
primary material’s cost with a total facade’s cost of
1.624 €, whereas case A and B present a relatively
similar cost (ca. 1.853 and 1.936 € respectively) with
case C to present the highest cost (2.398 €).
Mass / total weight :
According to the graph 6.6.3, all the redesign
proposals present significantly higher mass than
the current facade. Case A which is materialized
mainly with earthen materials (rammed-earth,
clayboards) present the highest mass while case B
that is materialized with fibrous materials presents
the lowest mass of the three redesign proposals.
Graph 6.6.4 : Embodied energy per each facade
Total (GJ) and per unit of mass (MJ/kg)
187 GJ
127 GJ
Embodied energy :
111 GJ
143,4
The embodied energy of the materials is a very
important environmental parameter. Thus, it was
calculated both to inform how much embodied
energy it is contained per unit of mass (1 kg) and for
the total mass of each facade case.
MJ/Kg
71 GJ
63,41
42,36
MJ/Kg
43.27
MJ/Kg
MJ/Kg
As it is clear from the relevant graph 6.6.4, the
facades cases A, B and C that are materialized with
biodegradeable products, contain significantly lower
embodied energy per unit of mass. They contain
almost less than 1/2 to 1/3 of the embodied energy of
the current facade (143,5 MJ/kg) with the minimum
embodied energy value resulted from the case A and
C where earthen materials are applied.
Graph 6.6.5 : CO2 emissions per each facade
Total and per unit of mass (1 kg Co2 per 1kg)
1025 kg
973 kg
However, when the facades are embodied energy is
compared for the total mass, the results change. As
it can be noticed now, due to the significantly higher
mass of cases A, B and C, only case B presents a
total embodied energy that is lower than the current
facade’s materialisation (almost half of the embodied
energy of the current facade).
662 kg
7,77
kg/Kg
5,18
kg/Kg
276 kg
3,48
3,21
kg/Kg
kg/Kg
Thus, it is clear that when designing it is not only
important to know the embodied energy contained
per 1 kg of each material that will be used but also to
calculate the total embodied energy for the total mass
of the designed facade. This can indicate better the
environmental impact that a facade’s materialisation
can result in, and which parameters affect which
figures.
240
CO2 footprint:
Total Rc value :
Except of knowing the resulting embodied energy of each facade’s
materialization, it is also equally important to identify how much
CO2 would be emitted from the use of the particular materials in
the facade’s cases.
The thermal resistance of the building
envelope got improved (graph 6.6.6).
Case A and B present a higher Rc value
of the facade section than the current
ones, whereas Case C presents a similar
thermal resistance.
Regarding the CO2 footprint that the current facade and the
redesign proposals would have had, graph 6.6.5 shows that all
redesign proposals present a lower CO2 emission’s content than
the current facade when they are compared to each other per one
unit of mass (1kg). In contrast, when CO2 emissions are calculated
for the total mass of the facade, the results are similar with the
ones noticed on the case of embodied energy content. In this case,
again the redesign proposals due to their significantly higher mass,
present higher CO2 emissions than the current facade in total.
Exception to this, is again redesign proposal case B (276 kg of
CO2) which presents almost 3 times lower CO2 emissions than
the current facade (973 kg of CO2). This indicates that about 697
kg of CO2 could be prevented to be emitted in the atmosphere.
Higher thermal resistance means
a better insulated building, so
consequently a positive contribution to
lower demands in heating or cooling of
the interior space during the year.
The wall thickness of case B as it can be
noticed from the chart is similar with
the current thickness. The wall got only
3 cm wider in the case B whereas its
thermal resistance doubled; from 3,94
m2K/W became 6,54 m2 W/K.
Graph 6.6.6 : Total Rc value (m2K/W) and U-value (W/m2K) of facade and resulted wall thickness
U-value (W/m2K)
0,25
0,15
0,22
0,25
wall thickness
295 mm
260 mm
355 mm
229 mm
From all these remarks, it is noticeable that proposal B is the most sustainable design proposal among
the 2 redesign cases and the current facade’s materialisation, since it presents two times less embodied
energy than the current facade, only 1/3 of the CO 2 emissions of the current facade, two times higher
thermal resistance than the current ones whilst at the same time it presents a relatively similar cost with
the current facade .
241
B. Comparisons in non measurable parameters :
Construction - assembly: Craftsmanship Vs industrialization
Redesign Proposal - Case A
Redesign Proposal - Case B
Redesign Proposal - Case C
The assembly sequence that
should be followed for case
A requires to construct the
facade from the internal leaf
to the external one gradually.
Firstly, the vapor barrier
should be fixed on the
timber structure where the
clayboards will be applied
and fixed on the timber frame
with mechanical fixings (like
screws D25). Afterwards, the
clayboards need to be sealed
with protective tape on their
connection points and to be
plastered.
In the case of proposal B,
the assembly order is similar
with case A. It is more
advisable the construction of
the facade to start by fixing
the vapor barrier membrane
to the timber structure and
placing
the
strawboard
panels that consist the
internal leaf of the facade.
In redesign proposal C, the
construction of the facade
differs from the previous
two cases. While in the
previous one the assembling
of the facade started from
the interior to the exterior,
in this case, the construction
should start from the
intermediate layer of the
facade.
After the internal wall leaf
is finished and its surface
wall finish is left to air-dry,
the insulation (sheep-wool)
can be placed in between
the timber studs of the
structure On its external
side, a breathable membrane
will be installed and overlap
the timber structure and the
insulation in order to protect
them.
Afterwards,
the
flax
insulation sheets can be
installed via compaction in
between the timber studs
and enclosure the whole
structure with a breathable
membranes that will run
alongside the whole external
side of the construction.
Lastly, wood-fibers boards
should be placed and fixed
with insulating plastic fixings
both to the timber frame and
to the flax insulation sheets
for a greater stability, and
then they should be coated
with suitable (breathable)
plaster layers.
Lastly, an air-cavity of about
5 cm is left and then rammedearth panels can be erected.
The panels of rammed-earth
that are prefabricated can be
carried on-site and can be
installed with the help of a
small crane. Their assembly
order should start from
constructing the bottom
to the top, and connecting
the panels with adhesive
mortar and galvanized small
reinforcement bars.
Craftsmanship - labour required:
medium level
Craftsmanship - labour required:
standard level
242
Thus, first of all the rigid and
self-supportive strawboards
should be fixed and placed
in between the timber studs
of the structure. Then the
sub-structure of the facade
consisted
of
horizontal
and vertical timber battens
should be placed and the
facade cladding panels (cork
boards) should be installed
with hidden mechanical
fixings on the sub-structure.
Lastly, the construction of
the internal masonry of the
facade can start by placing
one by one the compressed
earth blocks in between the
timber studs on the left space,
applying the same rules like
building a “brick masonry”.
The earthen blocks will
be adjusted to each other
with adhesive mortar. The
resulting masonry will be
self-supportive
whereas
the timber frame and the
installed strawboards would
provide extra support and
stability to the internal
masonry.
Craftsmanship - labour required:
high level
Maintenance work and frequency
Redesign Proposal - Case A
Redesign Proposal - Case B
Redesign Proposal - Case C
Rammed-earth is a material
that is sensitive to moisture
and
water
penetration.
Stabilised
rammed-earth
present good resistance to
weathering but unstabilised
rammed-earth is really weak
and should be protected. In
case A, both unstabilised
and stabilised rammed-earth
panels are used. Unstabilised
panels will be weaker to
moisture ingress and buildup, and prolonged exposure
to water can even lead to
sever erosion problems.
The facade system that is
applied in this proposal can
be considered a durable
one that requires low or
minimum
maintenance
work.
In case C, the facade is
covered with cork sheets.
Cork is consisted a high water
resistant material thanks to
its material’s composition.
Manufacturers, give about
15 years lifespan without any
maintenance required.
Regular treatment of surface
of the unstabilsed rammedearth panels by applying
linseed oil or lime-wash
coating
will
maintain
the good appearance and
condition of the facade.
The wood-fibers applied
in this facade as external
insulating and construction
elements, are compatible
with any render skim. This
allows them to be plastered
and consequently plaster
will function as a protective
layer for the whole facade
structure from any damage
due to water penetration.
The
maintenance
work
that may be needed is replastering
the
facade’s
surface or refresh the color
paint.
Plastering the surface with a
suitable render skim is also
a way to protect unstabilised
rammed-earth but it was not
chosen in this case, so the
natural texture of rammedearth to be more visible,
although lime-wash will
slightly also affect its final
facade color.
Frequency:
the frequency of maintenance
work can vary a lot depending
on the weathering conditions.
It can be assumed that can be
needed every 6 or 12 months.
However, literature studies
and architectural examples
had shown that cork can also
be susceptible to star rotting
if it is wet for prolonged
period of time and is not let
to air-dry.
To prevent this, a roof
overhang as well as a substructure were formed The
roof overhang will prevent
the top layers of the facade to
get wet with large amounts
of water, while the substructure constructed will
not only support the cork
panels but will allow them to
dry faster thanks to the aircavity that is created by the
combination of horizontal
and vertical battens.
UV-radiation
will
may
be a problematic issue
for this facade case, since
cork will start fading due
to the sunlight exposure.
Therefore, the cork panels
were chosen to be fixed with
hidden mechanical fixings
than glued, so a replacement
of any damaged cork element
to be easier. to take place.
Frequency:
Re-plastering can take place
every 5- 10+ years.
243
Frequency:
depending, ~10-15+ years
Graph 6.6.7 :
Summary table with most important parameters.
case A
case B
case C
CaseStudy
1.852,05
1.935,53 e
2.397,54 e
+++
high
1.624,62 e
+
standard
maintenance:
frequency
+++
6-12
mounths
+/5-10+
years
10-15+
years
10-15
years
maintenance:
work
limewash
coating
total cost (Euro):
craftsmanship
level:
possible
damaging:
thermal
resistance Rc:
++
medium
erosion,
mechanical.
damage
4.56 m2K/W
+
standard
replacement
replacement
damaged
damaged
facade cladding facade cladding
mechanical
peeling off,
erosion,
damage,
mechanical.
mech.damage,
damage
colour fading colour fading
(UVradiation) (UVradiation)
refreshment
plaster/paint
6.54m2K/W
3.93 m2K/W
sound reduction:
** no indication/ assumed similar
fire resistance:
** no indication/ assumed similar
total mass :
3.94 m2K/W
4353 kg
1126 kg
2932 kg
771 kg
total embodied energy
187 GJ
71 GJ
127 GJ
111 GJ
total CO2 footprint
1025 kg
276 kg
662 kg
972,40 kg
Acoustic performance
Fire performance
From observing the data of
chapter 3 and 5, the biodegradable
materials that were used in the
three redesign proposals present
similar acoustical properties.
Some are better absorbent
materials (like flax, sheep-wool,
wood-fibers) thanks to their
porosity, while others present
a better sound reduction via
their sound reflective surface
(strawboards,
rammed-earth,
etc). It is assumed that the sound
reduction that will be achieved
among the facade’s cases will be
similar.
The same as with the acoustic behavior applies also for the
fire performance of the three redesign facade proposals.
Most of the materials used belong to the same Euroclass or
Buildings Materials Classification (check chapter 5). For
instance, sheep-wool, wood-fibers, cork, flax, all belong
to Euroclass E, whereas strawboards in Euroclass C and
rammed-earth and compressed earth blocks in Euroclass
A-B. Thus the combination of rammed-earth, sheep-wool
and clayboards of Case A, I assume that will result in similar
fire performance during a fire with case C that is consisted of
cork, straw and compressed earth blocks. Proposal B that is
made from wood-fibers, flax insulation and strawboards may
present a slightly lower fire resistance. However, due to the
lack of a way to measure their fire resistance on the facade,
it will be perceived as a fact that they will equally durable in
a fire case.
244
From the comparisons that were made previously between the design proposals
A, B, C and the current facade that was studied, it seems that the most efficient
facade is the redesign proposal B.
The combination of the materials in case B appear to give a significantly lower
total embodied energy compared with the current facade’s materialisation as
well as almost only 1/3 of the CO2 emissions respectively, preventing about 700
kg (almost 1 tonne) of CO2 to be emitted in the atmosphere which shows an
environmental prevail over the current facade. The acoustic and fire performance
of facade case B is perceived to be similar with the other cases (A and C) and
much better than the current’s facade, whereas the thermal resistance of 6,54
m2K/W that is achieved with this construction is the highest among all the others
and doubled compared to the current facade’s Rc-value. This results to a U-value
of 0,15 W/m2K. Such U-value will result in lower consumption of building
operational energy related to heating-cooling.
Moreover, the construction of the facade does not require intensive or high degree
of craftsmanship and the high prefabrication level of the products in this case,
makes the installation faster and easier. Thanks to the plastered surface of this
facade case, maintenance work is kept also to minimum. Lastly, the estimated
total price that such facade will cost in terms of material cost does not differ
significantly from the estimated cost of the current facade since case B is about
300 euro more expensive. Wood-fibers, flax, straw used in this facade, are all
renewable materials that are highly available in the Netherlands. They can be
reused, recycled and biodegrade easily, consequently leading to less solid waste to
accumulate in landfills.
Of course, the above results are based on the assumptions that were made in
the first place about the data that were input in the calculation table. Thus, they
should be taken only as indications of the possibilities of such materials and not
as accurate results. The facade variations that can be tried are numerous, but
scope of this design topic was to realize the parameters that can affect the facade’s
features that can be related to the nature of the materials , the construction
and assembly methods, the current size and availability as well as the design
limitations that each case study presented.
245
246
Chapter 7 Conclusion
This section summarizes all the remarks and observations that were made during the research and
design phase, leading to some final conclusions for this mater thesis. The main research question
and sub-questions set in chapter 1, were also answered in this section. Finally, the contribution of
this thesis in the general academic extent and building community is described as well as further
recommended subjects for improvement of this thesis are presented.
247
248
7.1 Final conclusion
This master thesis dealt with 12 biodegradable materials that were selected to be researched extensively under
various parameters, aiming to a better understanding of those materials and their potentials as future building
materials in the Netherlands. The main research question of “which products and systems will enhance the use of
biodegradable materials on the building envelopes in the Netherlands? And How can we enhance their use as façade
components?” was answered via multiple research steps and the final design topic contributes to this direction by
presenting the possibilities of such materials.
The relevance between the master thesis topic and the building technology master track -and more specifically with
façade design- relies on the focus of this thesis on the performance characteristics of those materials and on the
products levels of the 12 biodegradable materials. Those materials were researched on their properties (thermal,
acoustical, mechanical, etc), on their performance (thermal resistance, fire resistance, durability, lifespan) as well
as on the related production processes and resulting products types available already in the building industry
focusing on a buildings envelope level. Moreover, assuming that biodegradable materials may present great
potentials to decrease significantly the construction waste that accumulates in landfills, and contribute to a lower
environmental impact via buildings constructions, these 12 materials were researched in terms of indicating their
embodied energy content, their CO2 footprint as well as they were compared with a contemporary façade study
case via the three design proposals to “test” such terms by numerical figures and facts.
The final remarks that were made are described in this section under the sub-question they answer in order to
make more clear the observations that were made during the process of this thesis.
01: “which biodegradable materials and products are already available in the market?”
During the research step, it was made clear that still biodegradable materials and products are not very well
documented in order someone to find out and be informed easily for their performance characteristics, their product
types and their possibilities. The most useful informations that can be more practical and helpful for designing and
constructing in practice, were derived through extensive research on the technical and materials data sheet derived
from the manufacturing companies (websites) that produce such building products of biodegradable materials. The
current formal literature gives numerical values that usually are not updated and present a wider and more general
range.
Aiming to help to this direction and answer the sub-question set, an attempt to collect and documented a representative
example of products was made. Extensive tables that were made for each of the 12 materials informs the reader
about the current availability of building products made by biodegradable materials that are already available in
the market. In these tables, not only the products types, sizes and country origin are presented but also their specific
properties, advantages and drawbacks, and so on (chapter 3). As the research showed, biodegradable materials are
already available in various types of products in the building market in the Netherlands and neighboring countries
(mainly UK, Germany and Belgium). The majority of materials are available mainly in the form of rolls, sheets and
boards for insulation applications, or as building elements (blocks or other units) for constructing masonries that
are all prefabricated. Bulk materials were also available in a product type that can be produced and installed onsite via casting, spraying or moulding (e.g. rammed-earth, hemp-lime, papercrete), whereas also in some cases more
complicated prefabricated system with combination of materials are available.
The 12 materials researched, can be dividing in three main categories with similar final product types; a)those materials
that are used mainly as thermal and acoustical insulation producing flexible or semi flexible products, b) those used
as exterior or interior cladding elements that can also provide a secondary insulation and have a certain degree of
rigidity and impact resistance, and lastly c) those materials that produce construction elements and parts and are
pure in insulating properties, like earthen materials, or can be produced prefabricated with insulating properties that
are referred often as “structural insulating panels” like straw panels, and so on.
01_“Which are the parameters that affect positively or negatively the performance of these materials”
All the 12 biodegradable materials studied in this thesis, were found out to be affected by similar mechanisms and
factors. They present a lot of similarities in the way they react on weather conditions and weathering. The parameters
that impact greatly on the performance of these materials can be dividing in positive and negative ones. Moisture
ingress, water penetration, moisture build-up and rising damp are some of the factors that can affect all of these
materials negatively and lead to a severe damage of the materials.
249
Prolonged exposure to wet conditions without air-drying was found out to be one of the main damaging
mechanism that can affect severely the safety and performance of biodegradable products, especially in the
case of earthen based products. Thus, precautions to prevent any water related mechanism should be taken via
overhangs, dry base /foot, good surface treatment and so on. Concentration of salt, organic solvents, or alkalis
and acids are also some of the factors that impact slightly or severely those materials.
In some cases, specific factors can affect negatively particular properties of a biodegradable product, whereas at
the same time can improve significantly other properties of the product; for instance when the density of a product
gets increased, in the most situations the products insulating properties decrease but the mechanical properties
(compressive strength), its rigidity or impact resistance are improved significantly. Thus, it is important to know
the intended application that the product will be used in order to classify the priority of the required resulting
product’s properties. Other factors that can affect the performance of a product is its shape and proportions,
its material content, any external additives contained and others that are explained extensively in section “
influencing parameters” in chapter 5.2.5.
Lastly, the research had revealed that often the materials are containing external chemical additives which in
some cases are in a percentage more than 30% which works either as binders and reinforcement (for instance
in the case of synthetic polyester fibers on sheep-wool and flax insulation) either as fire retardants to fulfill
the current building regulations. Sometimes such additives are also added to prevent insect infestations. These
additives obviously improve the performance of these materials but alternate their biodegradability in some case.
However, the research has also shown that such additives can be replaced by natural alternatives (check table
4.3.6), which are not preferred due to their high cost compared with the inorganic ones.
03_“Which properties and characteristics should these products have in order to fulfil the multiple functions of a
facade, and be) compete the conventional and common-used materials of the building markets?”
The properties tables of the materials in chapter 3 showed that biodegradable materials can fulfil the multiple
functions that a facade should have as they were described in chapter 1 in the boundary conditions and that can
compete the inorganic common-used building materials that are used nowadays. Biodegradable materials seem
perform greatly when it comes to thermal and acoustical performance, and lacking in compressive and tensile
strengths in some cases when compared with inorganic materials. Also, they are all susceptible to moisture in
a greater degree than inorganic materials due to their nature but they have a great prevail over the inorganic
materials which is their low embodied energy and CO2 emission’s content. However, with the development of
their processing in future, those weakness may be overcome to create more competitive products. The comparisons
made in chapter 5 helped to an understanding of which materials perform better either mechanically, thermally,
and so on. It helped to understand better the similarities and particularities that these materials present and
understand the correlation between their structure-nature with their properties, for instance the mechanical and
thermal properties with density of a material.
04_“Which production processes and techniques are needed to design and produce biodegradable products or
facade components? ”
05_ “How can manufacture availability and precesses influence the design of biodegradable product with
improved quality and properties?”
Chapter 4 that is focuses on the production process and techniques, answers in details those two sub-questions.
To summarize, the most common-used production processes that are applied in the 12 selected biodegradable
materials were: shaping via casting and moulding, forming via wet or dry process, heat and pressure treatment,
as well as via carding and fiber processing. The manufacture availability and current process techniques seem
to be strongly correlated with the availability of the resulting products’ types, sizes and shapes. A development
to different production techniques or “borrowing” techniques that are applied in different materials, may
allow the production of different product types that are not yet available or a significant improvement of their
properties. Such example is the case of “lego straw block” from Oryzatech -described in chapter 4.3 - wherein
by “borrowing” a production process that is usually used for earthen or bulk materials, it creates a different
product type. Moreover, in the case of “strawjet cable” (table 4.2.5), a new typology of straw product was created
by inventing new production equipment. Those two examples, indicate how strong the relationship between the
production means and the resulting availability in shapes and types of products is.
250
06_“Can they be prefabricated? what kind of production technology, equipment and so on is needed to produce it while
keep still low the embodied energy and cost?”
Yes, biodegradable materials can be prefabricated and produce a variety of prefabricated product not only building
elements but as well as building parts and components. Prefabrication in some cases is possible on-site or some meters
near the site like in the case of straw panels (e.g. ModCell) or in the case of rammed-earth panels, but not always.
Usually prefabrication will ensure the quality and performance of the products, decreasing the labour intensive and
craftsmanship level needed for the construction but on the other hand will demand transportation which will increase
the cost and the environmental impact of these materials. A further research should be made on how biodegradable
materials can produce prefabricated elements on-site and what kind of production technology and means are required,
since in this thesis this research question was not much examined and remains unanswered.
The extensive research that was made had given answers to the give questions while the design topic aimed to
give more design advice and consideration in the application of such materials in a primary design phase, as well
as a better understanding of how these materials may perform when combined. The design topic was strongly
correlated with the research outcome. Focusing on a façade design, the case studied that was selected was examined
with variable materials applied by redesigning the façade, whilst the known properties derived from the research
chapters 3 and 5, made possible calculation and comparisons between the design proposals and a
final evaluation of the design. As it was noticed, fibrous materials presented better environmental and
insulating properties, are cost effective and light enough to be used as insulation alternatives on the
current common-used insulation products.
The design theme and the comparisons made on Chapter 6, shows that contemporary architecture can
be sustainable via the use of biodegradable materials. The façade materialization with biodegradable
materials showed that with a similar given wall thickness and structure but with different infill, exterior
and interior façade leaves, a façade that performs better can be achieved. The façade of the proposal
C performs better than the current realized façade that is consisted of synthetic inorganic products
(Rockwool insulation, HPL facades, plasterboards, etc) without any significant increase on its wall
thickness or on its cost. Moreover, it is a more sustainable solution with very low environmental
impact (1/3 of the CO2 footprint and 1/2 of the embodied energy) compared with the façade as it is
currently realized.
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7.2 Thesis contribution & suggestions for further research
Scope of this thesis was to enhance the use of biodegradable materials as building components on building
envelopes in the Netherlands. Through the research steps and the design step that were followed it this thesis,
it was mainly intended to make clear to the reader the high potentials that biodegradable materials can have
on the current contemporary building envelope, if they are gradually well-documented and tested, as well as
implemented wisely.
This thesis was carried out more in the form to provide a preliminary research and design method for those
interested in more sustainable materials and construction’s materialization. I believe that this thesis can give a
paradigm of the way that other biodegradable materials can be researched as well as how to be processed and
compared under given constraints. The materials data sheets and tables presented on Chapter 3 as well as the
general description given for each material can work as a guideline for students to design with one of the 12 selected
materials. The reader can chose the biodegradable material that is interested, then see the materials specifications
and also get informed about the current size, dimension, price and type of products available in the market leading
to a more feasible design. I personally hope that this thesis can slowly contribute to a wider acknowledgement of
those “forgotten” materials to the majority of the architecture and building community since I believe that they can
be the “sustainable design solution” not only for new constructions but also for the refurbishment and redesign
of the existing housing stock in the Netherlands. The design details that are produced on this thesis can provide a
basic overview of the assembling and constructing with such materials. The scale is kept to 1:10 and 1:5.
Future research topics
that are relevant with the methodological method followed in this thesis can be :
01_ An extensive research focused on production technology and processes, and more specifically how the current
processes and manufacture equipment can affect the product types of biodegradable materials and what kind
of products may result by using different production processes or machines “borrowed” by other sectors. For
instance, load-bearing structures of straw were mainly constructed until recently via the use of large straw bales
that were resulting in very thick walls. Strawjet’s team has designed and used new innovative equipment that is
capable to produce new products from straw like a straw cable that can be used to construct circular load-bearing
walls, columns and other elements. Oryzatech product is also one other new straw-based product derived by
using the pressure molding machines used for compressed earth blocks to produce compressed straw blocks.
Straw can be the future building product. Since it is very cheap, easy to handle, is in surplus and is not used much
for other applications. Using it as building materials has more advantages than disposing it by field burning. It is
local available almost everywhere in Europe, and in the Netherlands. Can have both good insulating properties
and structural properties. I think straw will replace wood fibers. Blocks, panels, lumber-particle boards, orientedstand board (OSB) will be available with straw instead of wood fibers. . Compressed strawboards can be used for
linings, load-bearing components to prefabricated buildings like in suspended cells, roofs, etc as well as even as
doors, office screens and fixed internal space division. The variety of finishes they can take, as well as that they
can be applied either by joining, clips in any timber or metal frame makes them very easy to handle and use them
having at the same time a cost-effective product
02_ Research and implementation focused on one material, its products types and its prefabrication processes.
Researching the possibilities of specific biodegradable materials applied on contemporary structures, and mainly
focusing on the particular product’s types that can be derived from prefabrication processes. Classification of the
material according to its application and use on a building envelope and suggestions of how each material is better
to be used.
03_ Similar research on a group of other biodegradable materials by using similar methodology, in order to enlarge
the data that are known for such materials.
04_ Manufacture companies give often application schemes of how their products can be applied. A collective
“design manual”, can work as guidelines for future designs based on biodegradable materials. A research on the
feasibility of such application schemes, as well as on the assembly and disassembly order that should be followed
to allow those materials to be reused or recycled in future.
Further research on natural alternative solutions and on design precautions that can be followed in each case
material can contribute to a significant improvement of durability of biodegradable materials.
252
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263
264
Appendix
265
266
A
Drawings - Redesign case A
A - cross section 1:10
A1 - roof detail 1:5
A2 - wall detail 1:5
A3 - horizonta detail 1:5
267
268
269
A
Cross-section _ scale 1:10
A1 Roof detail A1 _ scale 1:5
270
A1 Wall detail A2 _ scale 1:5
271
A2
A3 horizontal section _ scale 1:5
272
B
Drawings - Redesign case B
B- cross section 1:10
B1 - roof detail 1:5
B2 - wall detail 1:5
273
274
275
B
Cross-section _ scale 1:10
B1
horizontal section _ scale 1:5
276
Wall detail A2 _ scale 1:5
277
A2
278
C
Drawings - Redesign case C
C - cross section 1:10
C1 - roof detail 1:5
C2 - wall detail 1:5
C3 - horizonta detail 1:5
279
280
281
C
Cross-section _ scale 1:10
A1 Roof detail A1 _ scale 1:5
282
A1 Wall detail A2 _ scale 1:5
283
A2
C3
horizontal section _ scale 1:5
284
285
286
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