Non-Domestic Passive House Guidelines (size 7 MB)

Non-Domestic Passive House Guidelines (size 7 MB)
CONTENTS
DESIGN GUIDELINES
Non-Domestic
Passive House Projects
CONTENTS
Sustainable Energy Authority of Ireland
The Sustainable Energy Authority of Ireland was established as Ireland’s national energy authority under the Sustainable Energy Act 2002. SEAI’s mission is to play a leading role in
transforming Ireland into a society based on sustainable energy structures, technologies and practices. To fulfil this mission SEAI aims to provide well-timed and informed advice
to Government and deliver a range of programmes efficiently and effectively, while engaging and motivating a wide range of stakeholders and showing continuing flexibility and
innovation in all activities. SEAI’s actions will help advance Ireland to the vanguard of the global green technology movement, so that Ireland is recognised as a pioneer in the move to
decarbonised energy systems.
SEAI’s key strategic objectives are:
• Energy efficiency first – implementing strong energy efficiency actions that radically reduce energy intensity and usage
• Low carbon energy sources – accelerating the development and adoption of technologies to exploit renewable energy sources
• Innovation and integration – supporting evidence-based responses that engage all actors, supporting innovation and enterprise for our low-carbon future
The Sustainable Energy Authority of Ireland is financed by Ireland’s EU Structural Funds Programme, co-funded by the Irish Government and the European Union.
Guidelines prepared by SEAI Renewable Energy Information Office and MosArt Architecture
© The Sustainable Energy Authority of Ireland
Reproduction of the contents is permissible provided the source is acknowledged.
DESIGN GUIDELINES For Non-Domestic Passive House Projects
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CONTENTS
Foreword
Prof J Owen Lewis
Chief Executive
Sustainable Energy Authority of Ireland
DESIGN GUIDELINES For Non-Domestic Passive House Projects
The Sustainable Energy Authority of Ireland, SEAI, operates programmes and
activities to advance the Government’s ambition for Ireland to become a world
leader in sustainable energy, part of our transition to a low-carbon economy. Thus,
we seek to accelerate the development and deployment of cost-effective lowcarbon technologies. Following the implementation of the EU Energy Performance
of Buildings Directive, agreement on the recasting of the Directive, substantial
improvements in Building Regulations energy standards and requirement for the use
of renewable energy systems, we have seen significant strengthening in the energy
performance required of new buildings.
The PassivHaus standard is recognized in Europe
as a progressive and advanced benchmark
for building energy performance. In 2008
SEAI published ‘Guidelines for the Design and
Construction of Passive House Dwellings in
Ireland’ which have been very well received, with
some 8,000 copies in circulation. Companion
guidelines on ‘Retrofitted Passive Homes –
Guidelines for Upgrading Existing Dwellings in
Ireland to the PassivHaus Standard’ which extend
the available support and information for the
upgrading of existing dwellings to achieve the
ambitious PassivHaus Standard were published
by SEAI in 2009.
The wide range of building types presented
here as case studies demonstrate that the
PassivHaus standard is just as applicable to
schools and factories, supermarkets and clinics,
and churches and sports halls. Originally
a German Standard, this is now finding
application in different countries as a brand
for thermally efficient and well-constructed
buildings which deliver good comfort
conditions during both winter and summer.
We hope these guidelines will be helpful in
increasing awareness and understanding of
key principles and technologies for designing,
constructing and operating modern low- energy
buildings.
3
CONTENTS
Contents
1 Introduction
5
2 Key Principles
16
3 Key Guidance for Different Building Types 34
4 Completed Case Study Projects
DESIGN GUIDELINES For Non-Domestic Passive House Projects
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1
Introduction
DESIGN GUIDELINES For Non-Domestic Passive House Projects
CONTENTS
1.1
Definition of Passive House
6
1.2
hallenges and Opportunities Presented by Non-domestic
C
Passive House Commercial and Public Buildings 8
1.3
Emergence of Passive House Non-domestic Buildings 11
1.4
Use of PHPP Software – the Essential Passive House Design Tool
12
1.5
Passivhaus Standard and Building Energy Rating
14
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1. Introduction
1.1
Definition of Passive House
The Sustainable Energy Authority of Ireland has previously prepared guidelines on the
Passive House for both new-build and retrofitted single family dwellings. This document
presents guidance for what is loosely referred to hereafter as ‘non-domestic’ Passive House
projects, including buildings such as schools and offices as well as multi-residential apartment
projects. The term Passive House is perhaps, at face value, somewhat misleading insofar as it
implies that this standard of construction pertains only to ‘houses’ (or single family dwellings).
Nothing could be further from the truth, however, as will be well illustrated in these
guidelines. In Section 4, for example, a very broad range of case study Passive House projects
will be presented, including not just offices and schools, but also a large Irish supermarket, a
church, sports hall, factory and veterinary clinic. It would appear that the principles of Passive
House can be applied to just about any building type.
DESIGN GUIDELINES For Non-Domestic Passive House Projects
A Passive House is an energy-efficient building with all year-round comfort and good
indoor environmental conditions without the use of what might be regarded as
‘conventional’ space heating or cooling systems. The space heat requirement is reduced
to the point at which there is no longer any need for a conventional heating system;
the air supply system essentially suffices to distribute the remaining heat requirement.
A Passive House provides very high levels of thermal comfort and provision of wholebuilding even temperature if so desired. The concept is based on minimising heat losses
and optimally using heat gains, thus enabling the use of simple building services. The
appearance of a Passive House does not need to differ from conventional buildings and
living or working in them does not require any lifestyle changes or specialist training.
Passive House buildings are typically light and bright due to large glazed areas designed
to optimise solar gains, as well as healthy buildings in which to work due to fresh air
supply through the ventilation system.
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SECTION 1 Introduction
The Passivhaus Standard is a construction standard developed by the Passivhaus
Institut in Germany (www.passiv.de). The Standard can be met using a variety of design
strategies, construction methods and technologies and is applicable to any building type
as will be illustrated in these guidelines.
The Passivhaus Standard is a specific construction standard for buildings with good
comfort conditions during winter and summer. Typically this includes optimised
insulation levels with minimal thermal bridges, very low air-leakage through the building,
utilisation of passive solar and internal gains and good indoor air quality maintained by
a mechanical ventilation system with highly efficient heat recovery. Renewable energy
sources are used as much as possible to meet the resulting energy demand, including
that required for the provision of domestic hot water (DHW). It should be noted that
the primary focus in building to the Passivhaus Standard is directed towards creating
a thermally efficient envelope which minimises both space heating and space cooling
requirement. There is also a limitation on the amount of primary energy that can be used
by a Passive House building for such uses as cooling DHW, lighting, electrical appliances
(such as computers or fridges).
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CONTENTS
Structural air-tightness (reduction of air infiltration) and minimal thermal bridging
are essential. A mechanical heat recovery ventilation system (MHRV) is used to supply
controlled amounts of fresh air to the building. The incoming fresh air is pre-heated via
a heat exchanger, by the outgoing warm stale air. If additional heat is required, a small
efficient back-up system (using a renewable energy source, for example) can be used to
boost the temperature of the fresh air or indeed to radiators as was found to be the case
in a number of the case studies visited.
The energy requirement of any building built to the Passivhaus Standard is as follows:
•
•
•
Maximum15 kWh/m2 treated floor area (TFA) per year for space heating and cooling
demand.
The upper limit for total primary energy demand for space and water heating,
cooling, ventilation, electricity for fans and pumps, all electrical appliances, and
lighting not exceeding 120 kWh/(m2a), regardless of energy source.
Additionally, the air-leakage test results must not exceed 0.6 air changes per hour
using 50 Pascal over-pressurisation and under-pressurisation testing.
In order to maintain high comfort levels in any building, heat losses must be replaced by
heat gains. Heat losses occur through the building fabric due to transmission through
poorly insulated walls, floor, ceiling and glazing as well as from uncontrolled cold air
infiltration through leaky construction and poorly fitted windows and doors. In a typical
building, such heat losses have to be balanced by heat gains mostly contributed by a
space heating system. In the case of some non-domestics Passive House projects, the
internal heat gains from occupants and other sources such as computers (in the case of
offices) can be quite significant and can contribute a relatively high proportion of the
total overall space heating need. In fact, with certain project types, the internal heat gains
might be so great as to necessitate an active cooling system combined with high thermal
mass. In every Passive House project, however, the heat losses are reduced dramatically
and the internal heat gains are minimised in order that there are major savings to be
made both in terms of space heating as well as space cooling.
Plate 1.1.10 generally reducing cooling demands leaves roof space for renewable technology
(in this case PV cells are being retrofitted to the roof of a commercial project)
DESIGN GUIDELINES For Non-Domestic Passive House Projects
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1.2Challenges and Opportunities Presented by Non-domestic
Passive House Commercial and Public Buildings
•
The design of non-domestic Passive House projects typically follows many of the general
principles used for single family dwellings as presented in SEAI’s previous Passive House
guidelines. The principles listed below are equally as relevant to single family dwellings as
they are to larger commercial or public building projects:
•
•
•
•
•
•
•
•
CONTENTS
Significantly increased internal heat gains, whether from computers (in the
case of office projects) or from humans (in the case of schools) often requiring
incorporation of thermal mass to reduce daily fluctuations;
Typical requirement for external sensor controlled shading in order to reduce
unwanted solar gain and glare and yet maximise natural daylighting;
Highly insulated building envelope, including thermally efficient windows;
Air-tight construction;
Southern orientation to maximise passive solar gain coupled with shading to prevent
overheating outside of the heating season;
Compact form to reduce surface to volume ratio;
Minimised (or fully eliminated) thermal bridging;
Reduced heat load enabling the delivery of back-up heating through the ventilation
system; and
Minimised primary energy consumption through the use of energy efficient lighting,
appliances and mechanical plant.
Outside of the above general principles, it might be expected that there are some very
considerable differences in the detailed design of non-domestic Passive House projects
compared to single family dwellings, as highlighted below:
•
Larger treated floor area, which could be 100 times greater than for a typical single
family dwelling, impacting on the sizing of mechanical plant;
Plate 1.2.1. The size of ventilation equipment for non-domestic projects can be considerable
DESIGN GUIDELINES For Non-Domestic Passive House Projects
Plate 1.2.2. Shading devices are generally required to reduce overheating
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SECTION 1 Introduction
•
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Periodic occupation, limited to office hours, school hours and semesters or even
opening hours in the case of retail projects;
Plate1.2.3. Classrooms are often empty for extended periods during which mechanical plant
is often shut down
•
•
•
Constraints imposed by Building Regulations, tending to place greater demands
on the design team in terms of, for example, fire protection;
Additional thermal-bridge-free detailing, required as a result of using parapets,
balconies and basements which are not typical to single family dwellings in Ireland;
Use of common space and circulation zones (for example in apartment buildings)
which might not require heating and which thus might need to be thermally
separated from the occupied spaces;
DESIGN GUIDELINES For Non-Domestic Passive House Projects
Plate 1.2.4 Stairwells can be designed as integral or separate to the thermal envelope
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SECTION 1 Introduction
•
•
•
Common need for lobby space, especially for projects where there is a large
amount of people entering and leaving the building such as in a shopping centre
(continuous activity) or school (periodic);
Lift shafts are typically required which can have implications in terms of ventilation
and smoke extraction;
Challenging ventilation requirements, including high volume flows in commercial
kitchens and science laboratories, reduced flows in expansive gymnasia and periodic
sensor-controlled operation in offices and schools;
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•
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Possible preference for different temperature zones as might be required in
supermarkets (separating the bulk storage area from the offices, for example) or in
gymnasia (cooler temperatures in the sports hall, with warmer temperatures in the
changing and shower rooms);
Plate1.2.6 Bulk storage in supermarkets are usually kept at cooler temperatures than the
retail area
•
Plate 1.2.5 Commercial kitchens present a challenge in terms of ventilation
DESIGN GUIDELINES For Non-Domestic Passive House Projects
•
Extended period of ‘settling-in’, taking typically about one year for the building
occupants to become fully familiar with the various nuances involved in operating the
Passive House (for example when to leave windows open or closed, when to operate
the ventilation equipment and how to optimise the use of the external blinds);
Possible requirement for more than PHPP in the design of the building, for
example where dynamic simulation might be required (see below for more details);
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SECTION 1 Introduction
1.3
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Emergence of Passive House Non-Domestic Buildings
The first ever Passive House project (built entirely to the Passivhaus Standard) was the
four terraced-house project in Kranichstein, near Darmstadt, Germany, in 1992. Since
then the Passivhaus Standard has been applied to several large scale projects including
schools, offices, commercial properties as well as apartment buildings in Continental
Europe as well as a World 1st in Ireland with the completion of the first ever completed
Passive House supermarket by Tesco in Tramore, Co. Waterford.
Policies promoting Passive House
There are a growing number of regional and trans-European policies and resolutions
supporting the Passivhaus Standard which are providing the basis for this standard
to be ‘the norm’ in some areas and creating the impetus for the development of more
and more projects. This in turn is creating employment opportunities in the research,
development and manufacture of new Passive House products, as well as in design
services and construction. The Passivhaus Standard is thus contributing to both
economic and environmental sustainability. Some of these policies are listed below:
An EU wide database on completed Passive House projects is underway and due to be
launched this year (see www.pass-net.net/database/index.htm ). Ahead of this database
being completed, it is difficult to ascertain how many non-domestic Passive House projects
have been completed. The database developed by the IG Passivhaus Deutschland (see
www.passivhausprojekte.de) currently has the most comprehensive listing of such projects
(but certainly includes all completed projects), including the following:
•
Office / Commercial / Administration building:
Apartment developments:
Mixed office and residential:
Kindergarten / day care:
School / campus / university:
Sports centre / recreation centre:
Public building / church:
Nursing home:
Factory / Industrial Building:
Fire station:
•
32
25
19
12
11
6
3
3
2
1
From this table it can be seen that the most popular Passive House development types
recorded on the register referred to above are offices and apartment projects. Following
this, there has been quite a number of schools and kindergartens also completed, with
fewer examples of other building types such as sports centres, public buildings, churches,
nursing homes, factories, fire stations or supermarkets. It is for this reason that these
guidelines provide a special focus on offices, schools and apartment buildings, both in
the section providing generic guidance (Section 3) as well as the featured case studies
(Section 4). Aside from these, Section 4 showcases other case studies (in order to illustrate
the broad variety of building types that can be built to the Passivhaus Standard. It would
appear that almost any building can be built to the Passivhaus Standard.
DESIGN GUIDELINES For Non-Domestic Passive House Projects
CONTENTS
•
In February 2003 the City Parliament of Frankfurt decreed that all new schools and
kindergartens have to be built to the Passivhaus Standard.
In 2006, the City Parliament of Frankfurt extended the requirement for Passivhaus
Standard from schools and kindergartens to all new ‘city’ buildings. In March 2007 it
was decided that all municipal administration, urban institutions and corporations
and all buildings in the framework of PPP for the city of Frankfurt will be built and
designed accordingly the Passivhaus Standard.
In 2007 / 2008 in Belgium it was decided that all new schools should be built to the
Passivhaus Standard.
Article 9 of the recast on the Energy Performance of Buildings (EPBD) and nearly zeroenergy buildings states that Member States shall ensure that:
• By December 31 2020, all new buildings are nearly zero-energy buildings; and after
December 31 2018, new buildings occupied by public authorities are nearly zeroenergy buildings.
Member States shall draw up national plans for increasing the number of nearly zeroenergy buildings. These national plans may include targets differentiated according
to the category of building. The national plans shall also include inter alia a number of
elements including:• The Member State’s detailed application in practice of the definition of nearly zeroenergy buildings, reflecting their national, regional or local conditions, and including
a numerical indicator or primary energy use expressed in kWh/m2 per year. Primary
energy factors used for the determination of the primary energy use may be based
on national or regional yearly average values and may take into account relevant
European standards.
• Since 2006 / 2007 the Passivhaus Standard is required in the German Cities of Leipzig,
Wiesbaden, Aschaffenburg. Also in Austria, the Vorarlberg Government will only
provide benefit for residential buildings that meet the Passivhaus Standard.
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SECTION 1 Introduction
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In addition to policies and resolutions, there are also a growing number of subsidy
and grant schemes across the EU which specifically support the Passivhaus Standard,
including those listed below (reference www.pass-net.net ):
•
•
•
•
•
In Belgium at a Federal level an index linked annual tax break of €790 for ten years is
allowed on certified Passive Houses. On a regional level in Brussels €100 per m2 of net
useable space up to 150 m2, and €50 for each additional m2 is given for certified Passive
Houses. Other examples include in the Walloon region a grant of €6,500 for a newly built
certified Passive House, €3,000 in the City of Turnhout and €5,000 in the city of Bilzen.
In the Czech Republic a subsidy programme commenced on April 7th 2009 supporting
newly built single and multi-family Passive Houses and use of renewable energy sources.
In Germany the KFW Bank Passive Houses are funded for either “Energy Efficient
Construction” and/or “Energy Efficient Retrofits” with low, fixed interest loans with no
repayment on principal required during the first several years Up to EUR 50,000 per
housing unit for energy efficient construction and up to EUR 75,000 housing unit for
energy efficient retrofits
In Slovenia financial supports are provided for what is referred to as residential
buildings with “low energy or passive technology (LEH/PH)”. The performance of
the building has to be verified in PHPP and there are certain minimum standards
which have to be met, including, for example, heat recovery ventilation efficiency of
80%. Grants of between €75 / m2 (for synthetic materials) and €125 / m2 for natural
materials are provided for a maximum of 200m2 for a single family dwelling and
150m2 for a two-family dwelling, with a maximum grant of €25,000.
In the Swedish Western Götaland region a Programme for Energy Efficient
Buildings was established in the spring of 2007 with a fund of approximately €2.5
million. The form of support includes information spreading about energy efficient
and passive house buildings in order to gain more interested actors (the focus is
directed towards politicians, entrepreneurs, architects and consultants).
Plate 1.4.1 The
PHPP software
CONTENTS
1.4Use of the Passive House Planning Package (PHPP) Software the Essential Passive House Design Tool
The Passive House Planning Package is a software package based on a series of extensive
and interlinked Excel data sheets which collectively allow building designs (including
retrofit strategies) to be verified against the Passivhaus Standard. Verification requires input
of very specific and detailed data about the building design, materials and components
into the PHPP spreadsheets and is then related to the climate data for the region in which
the project is proposed (for Ireland, climate data is available for both Birr and Dublin). The
validity of the result from this process is, of course, highly dependent upon the validity of
the data entered. The PHPP software is available for purchase from the Sustainable Energy
Authority of Ireland Renewable Energy Information Office - www.seai.ie/bookshop
Despite the significant differences between single family dwellings and non-domestic
Passive House projects as highlighted in Section 1.2 above, PHPP can still be used as
the primary design tool for these latter larger-type projects. There are however several
specific conditions provided for in the 2007 Version of PHPP for commercial projects,
discussed in outline under the following headings:
•
•
•
Initial PHPP Set Up;
Special Considerations Using Standard Worksheets ;
Specific ‘Non-Domestic’ Worksheets;
The PHPP is constantly being updated by the Passivhaus Institut to incorporate new
research findings, especially in relation to climate data and non-residential Passive Houses.
1.4.1 Initial PHPP Set Up
At the very outset of the input process, there are some special cells in the Excel sheet that
have to be selected depending upon the project type. Examples of these are provided
below for the purpose of illustration.
is an essential
design tool for
Selection of ‘Building Type’
Passive House
In the second Excel sheet in the 2007 Version of PHPP titled ‘Verification’, there is a
pull-down tab under the button ‘Building type’ used in the calculation of electricity
and internal heat gains with the two options of selecting either ‘Residential’ or ‘NonResidential’.
projects
DESIGN GUIDELINES For Non-Domestic Passive House Projects
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SECTION 1 Introduction
Selection of ‘Utilisation Pattern’
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•
In the same Verification sheet, there are a number of options to be chosen concerning
‘Utilisation Pattern’. If the ‘Residential’ option under ‘Building Type’ above is selected,
the user can choose between the utilisation patterns of ‘Dwelling’, ‘Assisted Living’ or
‘Other’. If on the other hand the ‘Non-Residential’ building type is chosen, then a choice
is provided between ‘Office’, ‘School’ or ‘Other’ under utilisation pattern. Both this and the
‘Building Type’ options above determine the internal heat sources which are thereafter
automatically calculated.
CONTENTS
Electricity Non-Domestic, where it is possible to enter the electricity demand from
lighting, electronic devices (computers, servers, fax machines and copiers) as well as
kitchens and other uses.
Selection of ‘Types of Values Used’
If designing a building with deviating heating loads (for example a non-typical office use
in a fire station which is ONLY used in an emergency case) or for buildings in the ‘Other’
category above, then the user should select the ‘PHPP Calculation’ option under the
‘Types of Values Used’ pull down tab. In this case, internal heat sources can be entered
directly into the IHG (‘Internal Heat Gains’) or IHG Non-Dom (Internal Heat Gains for nondomestic projects) worksheets.
Selection of ‘Number of Occupants’
The standard occupancy rate used in PHPP is 35m2 per person. This standard can be
overridden, however, by manually entering the foreseen number under the pull down tab
‘Planned Number of Occupants’, also in the Verification Sheet.
1.4.2 Special Considerations Using Standard Worksheets
In non-domestic buildings, there are often special circumstances presented which require
the designer to input non-standard values into some of the worksheets. An example of
this includes the ‘Ventilation’ Worksheet wherein the designer can specify whether the
ventilation system is working on a permanent 24 hour basis (as it would be in residential
projects) or whether is it working intermittently (as it might in a school or office project)
where the building is periodically unoccupied and where there is no need for the system
to be running continuously.
1.4.3 Special ‘Non-Domestic’ Worksheets
In addition to the above options that are chosen when setting up the PHPP file for the
project, there are other specific sheets that have to be filled in for non-domestic projects.
A non-exhaustive list of these is provided and described in outline below:
DESIGN GUIDELINES For Non-Domestic Passive House Projects
Plate 1.4.3.1 Electricity demand in non-domestic projects can be accurately calculated in the
PHPP software
•
•
Internal Heat Gains Non-Domestic, where it is possible, for example, to calculate
the average heat emitted per person by entering the number of occupants, their
utilisation pattern, their age category (up to 10 years old or greater than 10 years old)
and activity level (whether sitting or standing / doing light work). Internal heat gains
from electrical devices are summarised in the second section of this worksheet.
Use Non-Domestic, where individual user profiles can be entered which define
the typical use patterns in any given section of a building. Practical examples of
the kind of input in this worksheet include the typical starting and ending time
of occupation, number of occupied days per year, illumination level required and
average occupancy.
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SECTION 1 Introduction
Additional Software Analysis
In certain circumstances additional energy assessment and dynamic simulation
modelling might be required in parallel with PHPP analysis as part of the design process.
According to the Passivhaus Institut, however, this is mostly relevant in the case of
research work on ‘unusual’ building types calculated in PHPP for the first time including
swimming pools, for example, or when dealing with different climate zones. The amount
of input parameters is significantly higher for dynamic simulations, potentially leading
to incorrect outputs. Accordingly, the Passivhaus Institut recommends using stationary
assessment methods for most projects.
In special cases where additional assessment is warranted, examples of the kinds of
software used, as well as their functions, are listed below:
•
•
•
•
CFD Simulations, for example Fluent or Comis;
Simulation programs for subsoil heat exchangers, for example PHLuft or Gaea;
Daylight simulation software, for example based on Radiance (calculation engine –
‘Rechenkern’ in German);and
Dynamic building Simulation, for example Dynbil or Trnsys.
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1.5
CONTENTS
Passivhaus Standard and Building Energy Rating
The Passivhaus Standard and Building Energy Rating (BER) are different methods for
evaluating energy performance of buildings based on calculated energy consumption. The
Passivhaus Standard is a voluntary standard whereas BER is mandatory when new buildings
are constructed or when new and existing buildings are offered for sale or rent. Input
parameters and outputs are similar but specific definitions and the way in which the two
assessment methodologies calculate outputs can be significantly different. It should not
be expected that both tools would predict precisely the same energy consumption for any
given project, therefore. It is possible that a Passive House project might not achieve an A
rating according to BER, especially if the systems used for heating, cooling or ventilation are
primary energy intensive. Likewise, it is possible that a Passive House project could achieve
an A1 BER if there sufficient use of renewable energy technology.
The Non Domestic Energy Assessment Procedure (NEAP) is the methodology for
demonstrating compliance with specific aspects of Part L of the Building Regulations.
NEAP is also used to generate the BER and advisory report for new and existing non
domestic buildings. NEAP calculates the energy consumption and CO2 emissions
associated with a standardised use of a building. The energy consumption is expressed
in terms of kilowatt hours per square metre floor area per year (kWh/m2/yr) and the
CO2 emissions expressed in terms of kilograms of CO2 per square metre floor area per
year (kg CO2/m2/yr). NEAP allows the calculation to be carried out by approved software
packages or by the default calculation tool, Simplified Building Energy Model (SBEM) and
associated interface iSBEM, which is based on CEN standards and has been developed by
BRE on behalf of the UK Department of Communities and Local Government.
Some of the key differences between both the PHPP and NEAP inputs are highlighted
below:
Heating Times / Comfort Provision.
PHPP assumes comfort temperatures are maintained at all times throughout the heating
season of 205 days. NEAP calculates the energy demands of each space in the building
according to the activity within it. Different activities may have different temperatures,
operating periods and lighting requirements.
DESIGN GUIDELINES For Non-Domestic Passive House Projects
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SECTION 1 Introduction
Internal Temperature.
PHPP assumes 20oC throughout the entire building during the heating season. In NEAP
buildings can be divided into a number of activity areas e.g. an office building may
include a reception area, open plan office, cellular offices, circulation spaces and toilets.
The heating and cooling set points for open plan offices are 22oC and 24oC respectively.
The set back temperature set point is 12oC.
Building Geometry - Envelope.
PHPP uses external dimensions for determining the area of the elements forming the
envelope, therefore fabric heat loss will be amplified for a passive design as the external
elements, i.e. walls and roofs, will have a much greater thickness than standard buildings
because of the increased levels of insulation. In NEAP the floor area is calculated using
the internal horizontal dimensions between the internal surfaces of the external walls.
Building Geometry – Floor Area.
PHPP uses internal dimensions for the calculation of floor area as does NEAP. However,
PHPP excludes space taken up by items such as internal partition walls and chimneys and
treats the calculation of floor area differently where the ceiling height is less than 2m.
Included / Excluded Energy Consumption.
PHPP focuses on delivered energy for space heating with limiters for all other energy
consumption including white goods and water heating. NEAP focuses on primary energy
for space heating and cooling, ventilation, hot water, pumps, fans and lighting but does
not consider non-fixed electrical using appliances computers and office equipment
which can be responsible for significant primary energy use.
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Primary Heating System.
The approach taken for entering heating system efficiency differs in PHPP and NEAP,
most notably in the case of biomass boilers where a better result can be achieved using
PHPP. In NEAP the effective heat generating seasonal efficiency is calculated by adding
the heating efficiency credits, where applicable, to the heat generator seasonal efficiency.
The heat generator seasonal efficiency is the ratio of the useful heat output to the
energy input over the heating season.
Thermal Bridging.
PHPP uses external dimensions for thermal bridging calculations and it is also possible
to carry out visual analysis of whether linear thermal bridges occur. NEAP requires
information on the two types of thermal bridge; repeating and non-repeating.
Repeating thermal bridges should be taken into account when calculating the U-value
of a construction element. Non repeating thermal bridges can arise from a number
of situations, but NEAP is only concerned with those arising from junctions between
envelope elements, windows, and doors which are in contact with the exterior. For
each type of junction, you can enter a Psi value (W/mK) or leave the default values. For
junctions not involving metal cladding, you can also tick a box indicating whether or not
that type of junction complies with the relevant standards.
Primary Energy Factors.
PHPP only considers the non-renewable part of non-fossil fuels, e.g. processing and
transport and therefore the primary energy factor used for wood and pellets is 0.2. In
NEAP the primary energy includes the delivered energy, plus an allowance for the energy
“overhead” incurred in extracting, processing, and transporting a fuel or other energy
carrier to the building. NEAP uses a value of 1.1.
Occupancy.
In verification mode, PHPP uses 35 m²/person (can be overridden within limitations), e.g.
100 m2 = 2.86 people, 200 m2 = 5.71 people. In NEAP the occupancy is determined by the
activity assigned to each zone or part of the building. For an open plan office the people
density used in 0.11 per / m2 i.e. 100m2 = 11 people.
Product Accreditation Standards.
PHPP requires the substantiation of input data but is perhaps less prescriptive than NEAP
in terms of accreditation. An example of this that is particularly relevant to passive non
domestic buildings is mechanical ventilation heat recovery system data certified by the
Passivhaus Institut. The acceptance of certification data is likely to cause quite marked
differences between the outputs of the two methodologies.
DESIGN GUIDELINES For Non-Domestic Passive House Projects
15
2
Key Principles
DESIGN GUIDELINES For Non-Domestic Passive House Projects
CONTENTS
2.1
The Building Envelope
17
2.2
Orientation and Massing 26
2.3
Mechanical Systems
26
2.4
Shading
31
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SECTION 2 Key Principles
Many of the key principles presented in SEAI’s previous Passive House guidelines for
single family dwellings pertain to non-domestic projects. As presented in Section 1.2
above, however, there are a number of specific issues that need to be dealt with when
designing non-domestic Passive House projects. This Section will outline some of the key
aspects to be considered.
2.1
SECTION CONTENTS
CONTENTS
The designer must decide at the outset whether the basement will be cold or warm and
draw a continuous ‘red-line’ defining the thermal envelope. This will help to identify where
critical thermal bridges may arise and where additional detailing will be required. This advice
might sound somewhat obvious and therefore unnecessary, but experience has proven time
and time again that if basic fundamentals are overlooked at the early stages in the design
process, then costly mistakes can be made which could easily have been avoided.
The Building Envelope
2.1.1 Thermal Insulation and Thermal Bridging
Similar U-values to those recommended in the guidelines for single family dwellings
will be required for non-domestic projects, in the order of 0.15 W/(m2K). The precise
insulation levels required will ultimately depend on an analysis of the building design in
the PHPP software, so the above value should not be taken as any kind of ‘standard’ for
commercial Passive House projects. The key difference between non-domestic projects
and single family dwellings, however, is that the former often comprise more challenging
building elements not found in the latter, including the following, for example:
•
•
•
•
Basements (perhaps used for car parking, or for plant or storage);
Parapet walls;
Curtain wall systems (which might have externally ventilated rain screens); and
Warm non-ventilated roofs externally sealed for weather protection
Solutions have been developed for all or most of these design challenges as outlined
below.
2.1.1.1 Basements
When considering the insulation of basements, there are two choices, namely:
1. Create a thermal separation in the basement ceiling (i.e. create a cold’ basement
which would be quite appropriate for car parks, for example); and
2. Incorporate the basement into the thermal envelope, and insulate externally to that
basement (ie. create a ‘warm basement’ appropriate where it is used as part of the
habitable or used space and where normal indoor temperatures are required).
Plate 2.1.1.1.2 Definition of thermal envelope with a warm basement
Whether a cold or warm basement is used, both present their own challenges.
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Plate 2.1.1.1.1 Take the time to carefully define the extent of the thermal envelope early on in
the design process
Cold Basement – External Structure
In the case of a cold basement, a thermal break will be required in the external structural
envelope which overlaps with the layer of insulation fitted to the underside of the
basement ceiling. This thermal break can be provided using a variety of means, but is often
achieved using a continuous layer of insulating blocks, a variety of which are available such
as those depicted below . Consideration needs to be directed not just to the insulation
value of those products, but also to their load bearing strength which will generally need
to be high in projects which might involve several storeys. In the table below, it will be
noticed that with reducing vertical thermal conductivity, the thermal bridge effect is
lessened. However, in parallel with this, there is also a reduction in load bearing capacity.
In other words , thermally optimal products are not always the best considering structural
integrity. In some projects, the designers use a kind of hybrid system whereby a highly
efficient thermal break is created (for example using foamglass) with intermittent structural
support using concrete spuds as illustrated in the image across.
DESIGN GUIDELINES For Non-Domestic Passive House Projects
Plate 2.1.1.1.5 Hybrid thermal break used in masonry multi storey apartment projects.
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SECTION 2 Key Principles
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CONTENTS
Thermal Break Material
Thermal Conductivity
Horizontal
Vertical
Load Bearing (kN/m2) Psi value (W/mK)
Light concrete
0.088
0.286
2400
0.192
Lime-sandstone
0.33
0.33
1900
0.218
Porous concrete
0.21
0.21
1500
0.144
Light concrete
0.083
0.189
1200
0.129
Porous concrete
0.13
0.13
1000
0.086
Bricks
0.09
0.139
900
0.093
Foamglass
0.055
0.058
600
0.026
Porous concrete
0.09
0.09
400
0.053
Table reproduced with permission from the Passivhaus Institut, Darmstadt . Note that the thermal bridging (Psi) values above are
indicative only and not to be used for design purposes. Further, they relate to external junctions, as per the norm when calculating
heat losses for Passive House projects. The convention in Ireland using DEAP, on the other hand, is to calculate thermal bridging along
internal junctions which tend to be higher in heat transfer but shorter in length. Calculation of thermal bridges is an integral part of
the design of Passive House projects.
Cold basement – Internal Support Structures
Aside from the above details concerning the (external) building envelope, there will also
typically be internal elements connecting through the basement ceiling which support
the overall structure. Such support can be provided through walls or columns and the
choice between these can have a significant effect on thermal bridging as illustrated
below. The Passivhaus Institut presents the following scenarios regarding the thermal
breaks created by basement supports:
•
•
•
•
A reinforced concrete wall in the basement penetrating through the thermal
envelope with no thermal break will result in heat losses of +90% when compared to
an undisturbed basement ceiling.
Replacing the above continuous wall with reinforced columns at 6m grid intervals
would reduce the heat losses to +17% for 1 – 2% steel content and to +28% for 9%
steel content. This is clearly a marked improvement on the above continuous wall.
If the whole column is insulated down to ground level, the heat losses are further
reduced to +13%. This is the most efficient method of reducing thermal bridge
effects in cold basement scenarios.
Walls in the basement which are non-structural should be thermally separated from
the ceiling with low conductivity materials such as those presented in the earlier
table.
Plate 2.1.1.1.3 Defining the thermal envelope of a building with a cold unheated basement
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Plate 2.1.1.1.6 Re-inforced masonry walls penetrating cold basements ceilings will result in
Plate 2.1.1.1.7 Replacing a wall with Columns will help to reduce heat loss through thermal
significant thermal bridging
bridging
Source: Passivhaus Institut Dr. Wolfgang Feist - Protokollband Nr. 35
Source: Passivhaus Institut Dr. Wolfgang Feist - Protokollband Nr. 35
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Warm Basement
As illustrated the key challenge in achieving a warm basement is to completely externally
insulate the basement walls, foundation and floor slab .In this situation there is no need
to create a thermal break for internal support structures such as columns.
The feasibility of insulating underneath the building will depend on the foundation
design (whether strip foundation, or structural slab on grade), the load bearing pressure
of the soil and the sensitivity of the building to settlement. As highlighted by the
Passivhaus Institut, German regulations dictate that any insulating material used under
load bearing structures must display long term pressure resistance (total displacement
of insulation material ≤ 2% after 50 years). Some examples of materials used for this
purpose are included in the table below.
Material
Thermal Conductivity (W/mK)
Max Admissible Pressure (kN/m2)
High density expanded polystyrene
0.042
250
Crushed foam glass
0.14
180
Foam glass
0.05
380
Table reproduced with permission from the Passivhaus Institut, Damstadt
Plate 2.1.1.1.8 The thermal optimal solution is to use columns which are at least partially
insulated
Source: Passivhaus Institut Dr. Wolfgang Feist - Protokollband Nr. 35
DESIGN GUIDELINES For Non-Domestic Passive House Projects
Plate 2.1.1.1.9 Structural foamglass insulation for use under floor slabs
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SECTION 2 Key Principles
If external insulation is deemed not possible underneath the floor slab or foundation, it
might be required to insulated the basement internally. Care should be taken to avoid the
risk of condensation on the floor slab in such circumstances. When exploring all various
means of insulation, full thermal bridge and condensation risk analysis should be carried
out for each connection and the former input to the PHPP software so that heat losses
can be accurately calculated for the overall project.
2.1.1.2 Parapet Details
Treating parapet walls is similar in approach to that of cold basement walls, where the
choice is either to create a thermal break between the exposed ‘cold’ section of the
parapet wall, or alternatively, to fully clad the parapet wall externally with insulation as
depicted in the image across
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CONTENTS
2.1.1.3 Curtain Walls
Curtain walls are quite typically used in commercial Passive House projects, where the
external facade system is supported through the external insulation layer back to the
structural layer (which is often constructed of concrete). These curtain wall systems may
or may not have naturally ventilated external cladding or rain screens. The key issue for
consideration with curtain walls is the potential thermal bridge effect created by the fixings
used to support the external insulation or cladding system. The materials used for such fixings
as well as their anchoring method and frequency of use will determine the thermal bridge
effect created. Some examples of different kinds of systems used are illustrated below.
2.1.1.4 Non-Ventilated Warm Roofs
Most commercial Passive House projects will have flat or mono-pitch roofs of low
gradient which are completely waterproofed externally. In the case where these roofs are
of wooden construction and have no ventilated cavity over the insulation layer, it is vital
that an ‘intelligent’ vapour control layer is used on the warm side of the structure which
(a) minimises risk of condensation migrating into the structure and (b) if moisture does
enter the structure that it can migrate safely back out to the living space. This strategy
is being used at the WohnArt apartment development currently under construction in
Darmstadt, Germany.
2.1.2 Windows
The same thermal performance of glazing and frames as has been discussed in SEAI’s
Passive House Guidelines for single family dwellings is required for commercial projects,
namely:
•
•
•
Triple glazing with Ug (U-value of glazing) ≤ 0.8 W/(m2K) and Uf (U-value of frame) ≤
0.8 W/(m2K);
Ψ spacer (thermal bridge heat loss coefficient of the glazing spacer) ≤ 0.04 W/(mK) and
Ψ installation (thermal bridge heat loss coefficient of the installation detailing) ≤ 0.04 W/
(mK);and
g-value ( solar energy transmittance) 50 – 55%.
Plate 2.1.1.2.1 Parapet walls should be designed to avoid thermal bridging, in this case
externally insulation (Source :PHI)
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SECTION 2 Key Principles
What is interesting about the use of windows in non-domestic Passive House projects
is they tend to perform more functions than in single family dwellings, as discussed in
outline below:
•
•
•
•
•
Providing balanced high comfort in both summer and winter is especially
important in non-domestic projects such as schools or offices where students or
workers may have their desks located close to the window. Consider the case of a
conventional building, with a large radiator underneath a poorly insulated window
where the person is perhaps too hot when the radiator is on, and too cold when it
is off in the heating season. Such imbalances do not occur in Passivhaus Standard
buildings, and this is primarily due to the high performance of the glazing.
Night cooling is often required in commercial projects due to the high internal heat
loads (this is found to be especially the case with schools, for example). Openable
windows can play a significant role in cooling strategies, automatically opening at
night as controlled by thermostatic sensors.
Balancing day lighting requirements with glare avoidance is very important in
schools and office projects where large open windows bring daylight deep into
rooms but can also cause unwanted glare at people’s desks. External shading is
usually found in such projects to achieve the correct balance between these two
requirements (discussed in more detail below).
Reducing risk of overheating is also an important role of windows in non-domestic
projects, again assisted with the use of external blinds. It should be remembered that
the enhanced thermal performance of Passive House windows has the added benefit
in summer of reducing unwanted solar heat gains from outside.
Control of heating systems is also common place in non-domestic projects, where a
sensor is fitted to the window and which automatically shuts off the heating system
if the window is opened in order to conserve energy.
DESIGN GUIDELINES For Non-Domestic Passive House Projects
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CONTENTS
2.1.3 Air-tightness and Infiltration
It is a requirement for Passive House certification that the following level of air-tightness
is achieved:
•
≤ 0.6 air changes per hour using 50 Pascal over-pressurisation and under-pressurisation
testing (n50 ≤ 0.6 h-1).
In Ireland, air-tightness is tested and measured using q50 rather than n50 (required by the
Passivhaus Standard) and this has lead to some considerable confusion on projects in this
country. An overview of both measurement systems is provided below:
•
•
n50 is a measure of the air change rate in terms of volume of air moved per hour at
50 Pascal (the mean air leakage rate) divided by the internal volume of the building
((volume per hour) / volume) and expressed in the following format: n50 = X.X h-1.
q50 is a measure of the volume of air passing through the external envelope per hour
also at a pressure of 50 Pascal. It is a measure of permeability and is expressed in the
following format: q50 = X.X m3/h/m2 where m2 is a measure of the envelope based on
internal dimensions including the floor area.
It is possible to make a general comparison between n50 and q50. For most large buildings,
the area to volume ratio (A/V ratio) is approximately 0.5, whereas for small buildings,
the area to volume ratio is typically in the region of 1.0. Therefore, the n50 value of 0.6 air
changes per hour equates to an air permeability, q50, of 1.2 for large buildings (0.6/0.5)
and an air permeability of 0.6 for small buildings (0.6/1). If the building is very compact
(as recommended for Passive House buildings), the A/V ratio might even be lower than
that mentioned above, for example, 0.3. In that case, the n50 value of 0.6 air changes per
hour would approximately equate to an air permeability of 2m3/h/m2 (0.6/0.3). These
examples are provided for illustrative purposes only and should not be used as a basis for
definitive comparison of n50 and q50.
23
SECTION 2 Key Principles
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CONTENTS
aware of the detailing and high quality workmanship required. The number and length
of junctions that have to be detailed and sealed on-site is significantly greater for nondomestic projects than for single family dwellings, so there is a greater potential margin
for error. It is best practice to hold a project workshop for all parties involved to explain the
importance of achieving a high level of air-tightness. This will undoubtedly focus the minds
of the entire team and has been found to be strongly motivating especially for craftsmen.
The most common mistake made with inexperienced construction teams is that the airtightness test is performed too late in the construction process when opportunities to
find and fix leaks have passed. If at that stage the required level of air-tightness has not
been achieved, it will likely be very difficult, disruptive and expensive to get it right.
Some practical examples of frequent oversights in creating and achieving an airtight
envelope are listed below:
•
•
•
•
•
Plate 2.1.3.1. Use a blue marker to define precisely the air-tightness layer
In the early stages of design development, a blue marker should be used to trace an
unbroken line where the airtight envelope will be created. This same strategy (albeit
with a red marker) was recommended above in relation to identifying the exterior of the
thermal envelope. Such seemingly ‘elementary’ exercises will save a lot of headaches onsite at a later stage.
•
Entry and exit points for building services, including for example ducts for the
heat recovery ventilation unit, waste pipes and electrical cables;
Breaks in plastered masonry walls, such as can occur at sockets and other
electrical boxes located on external walls;
Not plastering to the floor, in the case of masonry buildings resulting in air leaks
behind the skirting boards;
Unplastered sections of external masonry walls, which can sometimes arise if wall
mounted mechanical services are fitted at an early stage of the construction process
ahead of the skim coat;
Not providing an internal service cavity in the case of timber frame projects and
where the airtight barrier is penetrated by a multitude of internal mechanical and
electrical services; and
Not installing an overlapping airtight membrane between different floors in
timber frame projects where the floor cassette is sandwiched between upper
and lower walls.
It will be seen later in these guidelines that this level of air-tightness is typically well
surpassed in completed non-domestic Passive House projects in continental Europe. There
is not the same level of experience in achieving such standards in Ireland, however, so
it is especially important that both the design team as well as the craftsmen are acutely
DESIGN GUIDELINES For Non-Domestic Passive House Projects
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Plate 2.1.3.3 In masonry construction where there is no service cavity, it is important to make
any penetrations for services as airtight as possible, in the above case used by bedding the
fixings into wet plaster
Plate 2.1.3.2 It would be impossible to make the above construction airtight – this is a result
of poor planning
Plate 2.1.3.4 Note how the rear of this fixing for wall mounted services was plastered in
advance of installation, ensuring air-tightness
DESIGN GUIDELINES For Non-Domestic Passive House Projects
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2.2
CONTENTS
Orientation and Massing
The low space heating and cooling demand achieved by the Passivhaus Standard is
determined not only by the thermal performance of the envelope as outlined above, but
also by the extent of solar heat gains as well as the overall compactness or massing of the
building. The ideal orientation and massing would be a compact building (with a surface
to volume ratio of < 0.4) with a south facing aspect in terms of glazing.
2.3
Plate 2.1.3.5 Providing an internal service cavity will ensure protection of the air-tightness
barrier in timber frame construction
Testing Procedures
Depending on the design of the building, it might make sense to test various sections
of the project on a phased basis as they arrive at the relevant stage in the construction
process, rather than waiting to carry out the very first test on the whole building.
Furthermore, due to the significantly larger volumes of commercial projects, the testing
equipment typically used for single family dwellings will be inadequate.
Air Infiltration at Entry Zones
The lobbies of non-domestic projects are typically used intensively. This can be limited
to peak times in the case of, say, offices and schools, but would be more evenly spread
throughout the day in the case of supermarkets or banks. It might be expected that the
use of entry and exit points compromises the performance of Passive House projects
due to drafts caused in the heating season. The Passivhaus Institut have completed
comprehensive research on the implications of additional infiltration arising at lobbies in
a case study school (the Kalbacher Höhe Primary School, Frankfurt), however, and found
that any additional heat losses are not significant1.
The PHPP 2007 handbook provides guidance on how to deal with heat losses at entry
zones in public buildings, recommending using an infiltration rate between 1.5m3 and
4.5m3 per person and event, the former for entrances with porch and door closers, the
latter without porch but still with closers.
1 Kah, O. and Pfluger, R.: Air change and energetic consequences of door opening processes in a school entry zone. Conference Proceedings for the
2007 International Conference on Passive Houses. Passivhaus Institut.
DESIGN GUIDELINES For Non-Domestic Passive House Projects
Mechanical Systems
The design of mechanical systems for commercial Passive House projects is influenced
by a huge variety of factors and providing specific or prescriptive recommendations is
outside the broad scope of these guidelines. As one can imagine, there is a vast array of
possibilities for heating, cooling, ventilating and providing hot water for non-domestic
Passive Houses. The intention in this section is to provide an overview of the most
common approaches used across the broad spectrum of non-domestic projects. Further
detail is provided later in Section 3 for a number of different building types and examples
of systems used in case study projects are described in Section 4.
Minimum Performance Standards
There are no prescribed minimum performance standards for mechanical systems used
in Passive House projects. However, the maximum thresholds set for both space heating
and cooling demand as well as primary energy demand will ensure that highly efficient
plant has to be used. A list of certified Passive House products can be found on the
Passivhaus Institut website (www.passiv.de – click on the tab ‘Certification’). In the case
of mechanical heat recovery ventilation units, if the equipment is not officially certified
by the Passivhaus Institut then the manufacturer’s stated efficiency has to be reduced by
12% in order to err on the safe side in terms of performance.
2.3.1 Heating
It is sometimes reported that Passive Houses require no heating whatsoever. However,
heating is in fact required in every Passive House (albeit much reduced compared to
conventional standards) and the design of the heating system, especially for non-domestic
projects, requires the specialist input of Mechanical and Electrical Engineers. The design of
the heating system should not be treated casually, therefore, as every Passive House project
must provide excellent comfort at all times in the worst possible weather.
26
SECTION 2 Key Principles
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A key factor to consider in designing the heating system for a commercial Passive House
project will be the space heating load, a measure of the output of the heat provision
system (for example a boiler) required to generate and distribute sufficient heat to maintain
internal temperatures of 20oC in the most challenging weather conditions (expressed in
Watts per m2). Taking an office measuring 10,000m2, for example, a typical Passive House
heat load might require a 100kW boiler (10,000m2 multiplied by 10W per m2). The heat load
is determined in PHPP by calculating the maximum possible difference (planning for worst
case scenario) between heat losses and heat gains. The software takes into account the
two contrasting weather conditions of (a) very cold yet clear sunny weather with high solar
radiation and (b) moderately cold but overcast and with little solar radiation.
The above diagram above does not take into account the impact of external and internal
relative humidity levels and the influence this has on the amount of useful heat that can
be recovered. The specific heat capacity of water is higher than air and the external relative
humidity levels in Ireland are generally higher all year round than in Central Europe.
The PHPP software also calculates the maximum heating load that is transportable in the
supply air and will indicate to the designer whether or not the mechanical ventilation
system can be used to deliver the required heat. As a rule of thumb, if the heat load is
below 10Watts per m2, then it is very likely that the ventilation system can be used. The
Excel sheet ‘Heating Load’ in PHPP will calculate whether it is possible to deliver the
required amount of heating simply through the ventilation air or whether an alternative
method (for example through radiators) would be required.
•
Heating Via the Ventilation System
If using the supply air to heat the building, then some kind of post-heater is required
to heat the air once it has passed through the heat recovery section of the mechanical
ventilation system. There are a number of options available in this regard, including the
following:
•
•
Water to air heat exchanger (the hot water can be heated using a combination of
solar and biomass or natural gas boilers, for example);
In-line electrical heat element; and
Heat pump.
If it is desired to have individual temperature control in each room (for example in each
classroom in the case of a school), then a thermostatically controlled post-heater would
be required at the point of entry of supply air to each room. This would significantly
increase the cost of the system.
Use of Radiators is OK
In Passive House projects it is not necessary to use the supply air to distribute heat
throughout the building. In visiting the case studies for these guidelines, the authors
were surprised to find that a number of the projects use conventional radiators to
provide the required space heating (most people do not associate radiators with Passive
Houses). The project designers in these cases emphasise that using such ‘traditional’
methods of heating are readily accepted by the occupants, provide flexible means of
managing temperature on a room by room basis and are relatively inexpensive to install.
It has also been pointed out that using such a traditional method of heating means that
the building can be kept warm even in circumstances where the heat recovery ventilation
system is not operating. Separating the heating and the ventilation system is especially
advantageous in schools because it enables the students and teachers to regulate the
heating of their individual classrooms.
Plate 2.3.1.1. Schematic of low heating is typically delivered using the mechanical heat
recovery ventilation system
Source: www.passivhaus.org.uk
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2.3.2 Cooling
2.3.3 Ventilation
When designing single family dwellings to the Passivhaus Standard, the PHPP software
will indicate on the Verification Sheet the likely frequency of overheating (defined as over
25oC). In Ireland’s climate, this is unlikely to be a significant problem for such small-scale
domestic projects and even if overheating does arise, the occupants can easily cool the
building by opening the windows at night or using the summer-bypass option in the
ventilation equipment. In the case of non-domestic Passive House projects, however,
some further consideration of the risk of overheating and the need for active cooling is
required.
The table below presents recommendations for ventilation of different building types
(offices, schools, sports halls and apartment living rooms) and compares the Chartered
Institute of Building Services Engineers (CIBSE) Design Guide A rates with those
recommended in the PHPP software. The units recommended by CIBSE are generally
litres per second per person (l/(s*P)) whereas the PHPP uses cubic metres per person per
hour (m3/(P*h)). In the table below, the CIBSE units l/(s*P) have been converted to m3/
(P*h) to enable direct comparison with the PHPP recommendations.
The critical difference between single family dwellings and some non-domestic projects
is the significant internal heat loads in the latter arising from people and / or equipment.
Consider a classroom with 25 students collectively generating 2kW of heat, combined
with 10m2 of south facing glass with a solar yield of another 2kW, totalling 4kW of ‘free
heat’. The same classroom might have transmission losses of just 0.5kW, eliminating the
need for any supplementary heating during class hours2. In fact, in this situation, the
temperature of the classroom may gradually rise during the day to a point where night
cooling is required in order to return classroom to normal comfort levels. Just as with
schools, offices also typically have to deal with significant internal heat loads not just
from occupants from also from computers, office equipment, servers and kitchens. In all
of the case study projects visited for preparation of these guidelines, no air conditioning
was used for cooling with perhaps with the exception for computer server rooms.
It can be seen for offices that there is relatively little difference between the CIBSE and
PHPP recommendations (36 and 30 m3/(P*h) respectively). For schools, however, the
PHPP recommendation is approximately half of that recommended by CIBSE but the
converse is true for sports halls, where the PHPP rate is approximately double that of
CIBSE. In the case of schools, research by the Passivhaus Institut has demonstrated that
providing 15 – 20 m3/(P*h) fresh air ensures good quality air as measured comparing
indoor CO2 concentrations to ambient CO2 levels. In the case of sports halls, a higher rate
is recommended by PHPP than by CIBSE to ensure very high indoor air quality for people
engaged in physical exertion. Lastly, concerning apartment living rooms, the unit ‘air
changes per hour’ (ACH) is used both by CIBSE as well as PHPP, the former recommending
a range of 0.4 to 1.0, the latter recommending an average of 0.4. It will be noticed that
for three of the four building types, PHPP recommends a lower air change rate. The
ventilation rates outlined above in existing Passive House schools may be regarded by
some observers as low. However, the following factors must be bourne in mind when
considering these rates: (a) carbon dioxide production by young people sitting in class
is lower than would be the case for adults engaged in normal daily activities – hence the
need for fresh air is less in schools (especially primary schools) (b) a one-hour intense
flushing ventilation phase both before school opens as well as on school closing is
typically used which greatly supplements the lower background ventilation; (c ) it has
been the practical experience in many Passive House schools that windows are left
open by teachers during breaks, even in the heating season, which also increase the
background ventilation rate; and (d) as presented elsewhere in this document (Figure
3.2.2.1) the air quality in Passive House schools is well proven. Irrespective of these
comments, a CO2 level of 700ppm is recommended as a maximum for good indoor air
quality and each system should be designed to deliver this for all building types.
2 A
xel, B. Benefits of the Passive House Standard in Schools: cost-effectiveness and user convenience. Conference Proceedings for the 2009
International Conference on Passive Houses. Passivhaus Institut.
DESIGN GUIDELINES For Non-Domestic Passive House Projects
28
SECTION 2 Key Principles
SECTION CONTENTS
CONTENTS
2.3.4 Hot water
Comparison of Ventilation Rates Recommended by CIBSE and PHPP
Building Type
Offices
Schools
Sports Hall
Apartment living rooms
Suggested CIBSE Air
Supply Rate
10 l/(s*P)
10 l/(s*P)
10 l/(s*P)
0.4 – 1.0 ACH
Conversion from CIBSE to
PHPP units
36 m3/(P*h)
36 m3/(P*h)
36 m3/(P*h)
Recommendation as per
PHPP
30 (m3/(P*h)
15 – 20 (m3/(P*h)
60 (m3/(P*h)
0.4 ACH
Source: CIBSE Environmental Design Guide A
Technical Guidance Document Part F of the 2009 Irish Building Regulations deals with
Ventilation and was published in early 2010. Section 1.2.3 of Part F deals with mechanical
ventilation with heat recovery in the residential sector and specifies the minimum of
either 5 l/s plus 4 l/s per person or 0.3 l/s per m2 of internal floor area. The rate of 5 l/s plus
4 l/s per person for a house with four persons converts to approximately 19m3 per person
per hour, which is 60% of the ventilation rate of 30m3 per person per hour recommended
in the Passivhaus Standard. Having said that, the above ventilation rate assumes an Air
Permeability of 5m3/(h.m2) which would typically be far exceeded in a Passive House. The
alternative method for calculating the ventilation rate using 0.3 l/s per m2 of internal floor
area would equate to 35m3 per person per hour for a 130m2 house for four persons (0.3
l/s X 3.6 (to convert to m3/h) = 1.08 m3 per hour x 130m2 = 140m3 per hour / four persons
= 35m3 per person per hour. This rate of ventilation is closer to the recommended rate
of 30m3 per person per hour in the Passivhaus Standard. Further recommendations are
provided for non-residential buildings in TGD Part F, referring to guidance found in CIBSE
documents such as that presented in the table above.
The demand for hot water in non-residential projects is generally much lower than that in
single-family dwellings due principally to their reduced hours of use as well as (typically)
no demand for either showering or bathing. The PHPP software recommends using the
default hot water consumption of just 12 litres per day per person in an office, compared
to twice that (25l/P*d) for residential projects. The Department of Education and Skills
in Ireland estimates that hot water consumption in primary schools is approximately
3l/P*d. Coupled with this reduced demand is the potentially very long circulation pipes
that would have to be used if a central thermal store is used, with distribution pipes to
outlying bathrooms. Combining low demand with a lengthy distribution system can
result in significant energy losses.
Avoiding Risk of Legionella
Legionella can result in bacterial contamination of domestic hot water and is therefore
a risk to human health. It grows best in temperatures of between 30oC and 45oC, so one
preventative solution is ‘thermal disinfection’ achieved by heating the water to at least
60oC every day. This will obviously result in considerable distribution and stand-by losses
which in turn increase the primary energy demand. Instant under-sink water heaters
operating on a timer basis practically eliminate circulation losses and also greatly reduce
risk of Legionella. Other technologies are also coming on the market, including special
membranes and UV-light are also options to consider.
Reducing losses
Distribution heat losses in hot water can be considerable if there is insufficient insulation
of the pipes, and only 45% of any losses can be used even if the pipes are placed inside
the thermal envelope. The thickness of insulation should generally be a minimum
of twice the nominal pipe diameter (Volume 28 of Research Group Cost Efficient
Passive Houses: Heat Transfer and distribution losses in Passive Houses. Passivhaus
Institut, Darmstadt 2004). Heat losses can be accurately calculated in the PHPP sheet
‘DHW+Distribution’ wherein the designer can enter pipe lengths and diameters, thickness
and thermal conductivity of insulation, location of pipes in relation to the thermal
envelope (whether inside or outside), design temperatures and storage losses.
DESIGN GUIDELINES For Non-Domestic Passive House Projects
29
SECTION 2 Key Principles
SECTION CONTENTS
CONTENTS
2.3.5 Lighting
2.3.6 Fire protection
Lighting typically accounts for up to 40% of the energy consumption of commercial
buildings, with inefficient lighting possibly adding to the risk of overheating and adding
to cooling requirement. The focus of the Passivhaus Standard is not just directed towards
space heating requirement, but also to Primary Energy Demand where the maximum
use is set at 120 kWh/(m2year). It is important to carefully consider the lighting strategy,
therefore, and to maximise the amount of natural daylighting where possible as
discussed previously. There are no minimum performance standards for lighting systems
in Passive House projects per se, as long as they do not contribute towards exceeding the
above primary energy threshold.
For all construction projects, fire protection is of paramount importance and the
separation of fire compartments must not be compromised by any Passive House
elements. The issue generally of greatest concern is the ventilation ducting which
may pass through different fire compartments and which must be designed in
order to prevent both spread of flame as well as smoke. There are various products
on the market presently which can be used to separate fire compartments, such as
fire-dampers which are triggered to close automatically either due to an increase in
temperature (at 72oC) or via external smoke detectors. Access to fire dampers has to
be ensured in order to enable periodic visual inspection and maintenance, so their
positioning has to be carefully considered.
The PHPP software has three input Excel sheets which deal with lighting requirements for
Passive House projects, with data being entered typically in the following sequence:
1. ‘Use Non-Dom’ sheet (dealing with use patterns for non-domestic projects) – in this
sheet the designer specifies the different room types in the building (for example,
offices, WS, circulation space, plant rooms), their hours of use, the illumination level
required and the height at which that illumination is delivered (for example desk
height = 08m);
2. ‘Electricity Non-Dom’ sheet (dealing with electricity for non-domestic projects) – in
this sheet the orientation and g-value of typical rooms is entered along with width
of windows and room dimensions which allows an estimation of daylight utilisation.
After this, the designer specifies the degree of lighting controls provided (whether
manual, automatic or using a bus system, with our without motion detectors). PHPP
then uses these data entries to estimate the electricity use for lighting as well as the
primary energy demand.
3. ‘IHG Non-Dom’ sheet (dealing with internal heat gains in non-domestic projects) –
this sheet is connected to the above sheet (Electricity Non-Dom) where the average
heat released internally from lighting requirements is specified (no-input required,
automatically brought forward from the above sheet).
DESIGN GUIDELINES For Non-Domestic Passive House Projects
Plate 2.3.6.1 Fire dampers are essential in ventilation ducting where there is separation
between different fire compartments
Shutters for cold smoke can also be used to prevent cross-flow of smoke if the central
ventilation unit is powered off. They are especially critical in multi-residential buildings
with a centralised ventilation system.
30
SECTION 2 Key Principles
2.4
SECTION CONTENTS
CONTENTS
Shading
External shading can be provided by either brise soleil or retractable blinds. The former
type present the advantage of having no moving parts (and therefore require less
maintenance) but they are not as effective as blinds in keeping out low level light
especially from the west and east. Furthermore, if optimally designed, they would differ
in their depth according to different orientations (for example, absent on the north
elevation and deep on west and east elevation). Such variation might be regarded by the
architects as detracting from the overall aesthetic of the building design.
The latter type of shading, retractable blinds, appear to be preferred in the German
Passive House office projects visited by the authors. They are designed according to the
following strategy:
•
•
•
•
•
Strike a balance between minimizing glare and overheating for office workers while
also maximizing natural day lighting and reducing primary energy consumption.
Not be so ‘sensitive’ or reactionary to external solar irradiation patterns such that
they are constantly moving up and down causing unnecessary irritation to the office
workers. Some systems have a delay mechanism such that they only change their
position after a predetermined phase of a given exterior condition.
They should be capable of varying the amount of light penetration at different
heights, for example fully closed at the bottom to eliminate glare at the desks and
workstation level, with more open towards the top allowing light penetrate deep
into the office.
It should be possible for the building occupants to override the system such that
they have control over their own workspace. It is typically in such instances, however,
that the building management system will return the blinds to the programmed
position after a certain period (for example two hours).
Linked to a wind monitoring station such that they retract in period of heavy wind in
order to avoid damage.
Plate 2.4.1 The shading blinds on this office building, when fully extended, remain open at
the top to allow daylight deep into the office but are closed at the bottom to reduce glare
at desk level
Plate 2.4.2(a) and (b) Retractable shading can be fitted to the external facade and controlled
either manually or automatically
DESIGN GUIDELINES For Non-Domestic Passive House Projects
31
SECTION 2 Key Principles
SECTION CONTENTS
CONTENTS
Plate 2.4.3 These retractable opaque blinds are restrained by guide wires but would have to
be carefully considered in windy or exposed locations
DESIGN GUIDELINES For Non-Domestic Passive House Projects
Plate 2.4.4 Shading can be provided which still provides filtered views of the surroundings
32
SECTION 2 Key Principles
SECTION CONTENTS
CONTENTS
There does appear to be difficulties with shading in some of the Passive House projects
visited in preparing these guidelines. In one project, the wind monitoring device was
programmed to retract the blinds at very low (too low) wind speeds. In another project,
the programming system was not working correctly and the shades were not reacting
adequately to external weather conditions. Despite such ’teething’ problems, however,
retractable shades appear to be working well on most projects.
A variation on the external retractable shade is a system whereby the shade (a perforated
metal foil) is located between the panes of glass. This system avoids any concerns about
wind damage but the cost differential would need to be careful analysed. If considering
using this system, ensure that the blinds pull from the bottom towards the top (and not
vice versa) to reduce glare at desk level as discussed above.
DESIGN GUIDELINES For Non-Domestic Passive House Projects
33
3
Key Guidance for Different
Building Types
DESIGN GUIDELINES For Non-Domestic Passive House Projects
CONTENTS
3.1
Offices
35
3.2
Schools
41
3.3
Gymnasia and Sports Halls
47
3.4
Apartment Complex
52
34
SECTION 3 Guidance for Different Building Types
3.1
Offices
3.1.1 Key Design Considerations
SECTION CONTENTS
CONTENTS
High risk of overheating
Whereas Passive House buildings are renowned mostly for their low heating energy
requirement, a key challenge in constructing Passive House office buildings is to avoid
the risk of overheating in summer, otherwise requiring active cooling. This is normally
caused by excessive areas of glazing without adequate shading. In addition, there are
significantly greater internal heat gains in offices compared to residential projects
resulting from high occupancy rates as well as computers, lighting and computer
servers which all generate heat. A Passive House office must not only be comfortable in
the heating season, but also in the ‘cooling’ summer season.
Flexibility of Layout
Many office projects are built speculatively and without prior knowledge of how
the building might be subdivided as tenants take occupancy. The impact that this
has for Passive House design is in the planning of the mechanical systems including
ventilation, heating and cooling, the layout of which should be designed in such a way
as to cater for different configurations that might be required. There should generally
be a sufficient number of ventilation units, for example, to cater for a large number of
sub-divisions.
Varied Occupational Patterns
Offices are typically used during normal working hours and outside of that might
well be completely empty. It is important to design the mechanical systems such
that they can automatically respond to these changing use patterns and reduce their
energy consumption when the building in not in use. One method of achieving this
is to install CO2 sensors which determine the volume of airflow in the ventilation
equipment. In the morning, as the offices become occupied, the sensors will increase
the rate of ventilation, and the opposite happens in the evening when the demand
for fresh air reduces.
Point Source Hot Spots
Plate 3.1.1.1 The proportion of glazing in office projects is optimised to create a balance
between maximising solar gains in winter and minimising risk of overheating in summer
DESIGN GUIDELINES For Non-Domestic Passive House Projects
Typically office buildings will require special rooms for computer servers which are at
risk if they overheat and thus must be kept cool. This places a high energy demand
for those spaces compared to the remainder of the building, albeit over a confined
floor area. Energy efficient methods for cooling server rooms must be an integral part
of the planning of Passive House office buildings, including the re-use of ‘waste’ heat
generated in such rooms elsewhere in the building.
35
SECTION 3 Guidance for Different Building Types
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CONTENTS
Fire Protection
There are special fire protection measures that are necessary for office buildings which
can affect the Passive House design approach. Most critically, fire protection of ventilation
ducting must be provided to minimise risk of spread of flame and smoke between
different fire compartments.
Shading
Shading is an essential factor in office buildings in order to prevent overheat through
solar gain. The proportion of glass to be used should be determined by day lighting
requirements (don’t build a glass house!). Otherwise, windows create a great challenge
for the building designer because they can lead to overheating in the summer and
excessive heat losses in winter. This applies even to triple glazed Passive House windows.
There is thus a balance to be held in deciding upon the proportion of glazing compared
to opaque elements.
Cooling
The Passive House envelope, which is highly insulated and highly airtight, requires much
less cooling than conventional construction. Concrete core activation is typically used in
Passive House office buildings, minimising the need for ‘active cooling’ (especially in the
relatively benign Irish climate).
Figure 3.1.1.1
Comparison of Built Passive House Projects
Comparison of Passive House and Conventional Office Construction
A comparison is made below between the primary energy use of standard airconditioned offices with those built to the Passivhaus Standard. In total, ‘standard’ offices
use approximately 3.5 times the amount of primary energy compared to Passive House
offices. There is a negligible difference between both approaches in terms of hot water
production, external ventilation and what are referred to as ‘other items’. There are very
significant differences in terms of air conditioning, lighting, computers and heating with
the standard office using 11 times, 8 times, 7 times and 4 times the amount respectively
compared to Passive House. The reason for the dramatic difference in terms of air
conditioning is not simply due to reduced solar gains through shading, but also reduced
internal heat gains arising from more efficient lighting and computers. A net benefit of
focusing on reducing the primary energy for lighting and computers, therefore, has a
considerable impact on the extent of cooling required.
DESIGN GUIDELINES For Non-Domestic Passive House Projects
A comparison of a selection of Certified Passive House offices is provided below to
illustrate the range of approaches that have been realised. The last of these represents
a refurbishment project, the others being new-build. Some of the key issues worth
considering for prospective projects are listed below:
•
•
•
The size of projects completed has steadily been increasing in recent years,
culminating in the Luteco Offices in Ludwigshafen, Germany, at almost 10,000m2
(Plate 3.1.1.2). There would appear to be no limit as to the size of office facility that
can be built to the Passivhaus Standard, therefore.
In terms of construction type, most (but not all) projects comprise a concrete shell,
some of which are clad with timber frame facades.
The cost of construction is regrettably not available for many of the projects. For
the two largest projects, however, that there was no additional cost in building to
the Passivhaus Standard compared to the conventional standard. Furthermore, it is
perhaps interesting to note that the refurbishment cost for the office in Tübingen
was in the order of €1,000 per m2.
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SECTION 3 Guidance for Different Building Types
SECTION CONTENTS
•
•
•
•
Plate 3.1.1.2 Entrance to the Luteco Offices in Ludwigshafen, Germany
DESIGN GUIDELINES For Non-Domestic Passive House Projects
CONTENTS
All of the projects reached impressive levels of air-tightness, many down as low as
n50 0.2 air changes per hour @ 50 Pascal, including the refurbished office building in
Tübingen (even though the limit for certification is somewhat higher at 0.6 ACH).
Space heat requirement for all projects is less than or equal to 15 kWh/(m2/a)
(delivered energy). There is a significant difference between the projects in terms of
primary energy requirement, some as low as 68 kWh/(m2/a) and with an average of
93 kWh/(m2/a).
Heating systems vary from project to project with most using either heat pumps or
condensing gas boilers.
Lastly considering U-values, the average for walls is in the order of 0.13 W/(m2K), with
0.18 W/(m2K) for floors and 0.11 W/(m2K) for roofs. It must be remembered that these
values are designed for cold Continent climates, so it is likely that less insulation
would be required in order to meet the Passive House Standard in Ireland (subject to
design and testing in PHPP).
Ludwigshafen Energon Ulm Stadl-Paura Unterhaching Bremen
Tübingen
refurbishment
Year of
construction
2007
2002
2003
1999
2001
2003
Treated floor
area
9,823
5,412m2
2000m2
1,074m2
902m2
838m2
Construction
type
Masonry
Masonry and
timber
Timber
Masonry and
timber
Masonry
Masonry
Construction
cost per m2
N/A
€1,300
N/A
N/A
Air-tightness
0.2/h
0.2/h
0.4/h
0.2/h
0.49/h
0.2/h
Space heat
requirement
(kWh/(m2/a)
(delivered
energy)
12
12
14
9.2
15
15
Primary
energy
requirement
(kWh/(m2/a)
102
68
N/A
96.4
N/A
107
Heating
/ cooling
method
Concrete core
- geothermal
probes.
Concrete
core - district
heating &
geothermal
for cooling
Geothermal
Condensing
gas boiler,
15kw
Central gas
boiler
Gas condensing
boiler with
radiators
U-value of
wall / floor /
roof (W/(m2K)
0.14 / 0.23 /
0.11
0.13 / 0.21 /
0.12
0.11 / 0.13 /
0.11
0.13 / 0.15 /
0.11
0.13 / 0.16 /
0.09
0.14 / 0.18 /
0.14
€967
Source: www.passivhausprojekte.de/projekte.php
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CONTENTS
3.1.2 Mechanical Systems
Ventilation
The table below is derived from EN 13779 and was summarised by PHD
(www.passivhaus-info.de) in preparation of their CEPH training material. In this table
different indoor air quality (IDA) levels are presented, from IDA 1 (excellent quality) to
IDA 4 (low quality). IDA 3 is regarded as sufficient for office projects, whereas IDA 4 is
regarded as adequate for schools. In any event, the quality of indoor air has firstly to be
agreed with the Client. It should be noted that typical concentrations of CO2 in outdoor
fresh air is approximately 400-500ppm, implying that IDA 3 below for offices would
achieve an indoor CO2 level of approximately 900 – 1500ppm.
Classification of Indoor Air Quality (IDA) According to CO2 levels in Non-Smoking Areas.
Classification if IDA
Fresh Air Flow
IDA 1 – Excellent Quality
>54m3/h/Person
Increase in CO2 compared to external fresh air
<400ppm
IDA 2 – High Quality
36 - 54m3/h/Person
400 – 600ppm
IDA 3 – Medium Quality
22 - 36m3/h/Person
600 – 1000ppm
IDA 4 – Low Quality
>22m3/h/Person
>1000ppm
Source: www.passivhaus-info.de
As highlighted above, the overall design of the ventilation system will be greatly affected
by whether a centralised (whole building) system is used or whether a decentralised
system is used. The latter would enable easy subdivision division of the building into
smaller letting units should this be required and thus guarantees greater flexibility of
building use in the future.
The ventilation system will typically be shut down when the offices are not in use, requiring
a pre-‘flushing’ phase prior to opening the next day to clear the air of any contaminants.
Further details on this flushing phase is provided later when dealing with schools.
Heating and Cooling
Heating and cooling of office projects is dealt with simultaneously in this section due to
their typically using the same system.
Plate 3.1.2.1 The decentralised ventilation system provides flexibility of internal layout options
DESIGN GUIDELINES For Non-Domestic Passive House Projects
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SECTION 3 Guidance for Different Building Types
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CONTENTS
Offices present a special case in terms of Passive House design due to the high internal
heat gains resulting from high occupancy rates and use of heat generating devices
such as computers and other electrical equipment and appliances. Internal heat gains
in offices and administrative buildings according to PHPP are approximately 3.5W/m2,
compared to just 2.1W/m2 for residential projects and 2.8W/m2 for schools. Only assisted
living residences, at 4.1W/m2, are specified in PHPP as having higher internal heat gains
than offices. As result of these high internal heat gains, the demand for space heating
tends to be relatively lower for office projects.
The choice of heating system is, ironically perhaps, typically determined by the optimal
method of cooling. There is little point in using traditional radiators for heating in the
winter if the same appliances cannot be used for cooling in the summer. In the case of
office projects, heating is thus often provided through a hydronic system of heating the
concrete floor slab(s) using geo-thermal earth probes which can then be used in reverse
in summer for cooling.
There should be no need for air-conditioning in Passive House office projects, except
perhaps for server rooms where temperatures of 16oC are typically required. It is best
to cluster the servers in one part of the building in order to minimise the number of
separate air-conditioning units required. In any event, the roof of a Passive House office
building will typically look quite barren compared to typical office buildings in terms of
the amount of air-conditioning kit involved, leaving more room for renewable energy
technology if deemed appropriate.
Figure 3.1.2.1
Offices built to the Passivhaus Standard can be cooled using a variety of means, whether
using air-conditioning (not at all common) or using a more typical Passive House
approach such as with fresh air at night. The above figure highlights the difference in
costs and performance of different cooling systems for an office of 10,000m2 built to the
Passivhaus Standard and can be summarised as follows:
•
•
•
DESIGN GUIDELINES For Non-Domestic Passive House Projects
Conventional air conditioning is by far the most expensive method of providing
cooling, in terms of energy consumption, maintenance and capital investment costs.
Concrete core cooling using a geothermal heat pump brings about very significant
savings in comparison to air conditioning but nevertheless does not bring about any
energy saving potential compared to the two methods presented below.
Night cooling using openable windows and cooling fresh air intake in earth tubes
requires marginally higher capital costs that concrete core cooling, but also achieves
significant savings.
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SECTION 3 Guidance for Different Building Types
•
SECTION CONTENTS
CONTENTS
Fresh air cooling using a reversible heat pump to cool the fresh air delivered in
a mechanical ventilation system was found to be the optimal system from an
economic perspective given the net savings over the lifetime of the building.
3.1.3 Shading
As mentioned in the introduction to this section on Passive House office projects, a
careful balance has to be held between (a) use of glass for solar gain in the heating
season to minimise space heat demand and (b) avoidance of overheating through
excessive solar gain in the summer. The optimal approach is to provide sufficient glazing
to achieve the space heating target of 15 kWh/(m2a) (delivered energy) whilst providing
some means of shading the windows in the summer to prevent overheating (defined as
greater than 25°C for more than 10% of the year. Retractable blinds are used extensively
in Continental Europe for this purpose, withdrawn when there is a low risk of overheating
and when solar gain can contribute positively towards the overall energy balance, and
extended to provide shading when there is a likelihood of overheating (Plate 3.1.3.1).
Shading mechanisms are most usually controlled by solar irradiation sensors as well as
wind anemometers, the latter retracting the blinds if structural damage to the blinds
is a risk. The automated control of external blinds can be designed to enable complete
control by office occupants if so desired. However, the automated controlling system
usually overrides manual settings after a prescribed period to ensure that an optimal
energy balance is maintained.
3.1.4
Building Management
Contemporary office developments are typically managed by sophisticated building
management systems, controlling lighting, ventilation, heating and cooling along with
other important functions. The Passivhaus Standard is no different in that regard, and
there are significant energy savings to be made with carefully programmed building
energy management systems. The primary objective in any Passive House project is to
maintain a balance between heat gains and losses, whilst also ensuring high indoor air
quality as well as thermal comfort. In the non-domestic sector, this balance can only be
realistically achieved through the use of relevant building management systems.
Plate 3.1.3.1 Shading mechanisms are most usually controlled by solar irradiation sensors
as well as wind anemometers, the latter retracting the blinds if structural damage to the
blinds is a risk.
DESIGN GUIDELINES For Non-Domestic Passive House Projects
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3.2
SECTION CONTENTS
CONTENTS
Schools
Plate 3.2.1.1 Internal heat gains from pupils is accounted for in the PHPP software
Plate 3.2.0 The renowned certified Passive House doors in the Aufkirchen Montessori School
3.2.1 Key Design Considerations
Internal Heat Gains
The key challenge in the design of Passive House schools is the very high occupancy
at certain times of the day and certain times of the year (Plate 3.2.1.1). Despite the
high number of occupants, however, the resulting substantial internal heat gains are
insufficient to provide heat for the entire school as there will not be students in all rooms
at all times.
DESIGN GUIDELINES For Non-Domestic Passive House Projects
Outside of the heating season, especially in spring and autumn, there is a risk that the
building might overheat if not designed correctly. The thermal comfort levels during the
summer months should be maintained so that internal temperatures do not exceed 250C
for more than 10%, (ideally 0%), of the occupancy time of the school. The frequency of
overheating is one of the outputs of PHPP in the verification sheet, and the designer can
adjust the design to achieve the above recommendation.
The Importance of Thermal Mass
Thermal mass is very important in schools, modulating temperature fluctuations which
might otherwise be significant. The Passivhaus Institut recommend that the total
effective, floor area specific, thermal storage capacity of room enclosure components
should be ceffective>150 Wh/m²K in relation to the class room floor area. This can be
achieved in a variety of ways and does not necessarily imply that the entire structure
need be constructed of heavy ‘massive’ materials. It is possible, for example, to use a
timber frame external shell combined with masonry floors and internal walls (so called
‘mixed’ construction). If the above thermal mass is not possible to achieve, alternative
additional cooling methods must be considered (see below).
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SECTION 3 Guidance for Different Building Types
In the graph below the beneficial effects of thermal mass in a school can be readily
appreciated. Whilst all three construction types are seen to fluctuate in response
to external conditions, the peaks in temperature in the lightweight construction
is noticeably higher than either mixed or solid construction. Using mixed or solid
construction in schools is beneficial, therefore, in terms of modulation of internal
temperatures.
SECTION CONTENTS
CONTENTS
The school will also feature standard low energy design systems which are standard on all
new Irish schools such as:
•
•
•
•
•
T5 lighting with daylight dimmers set to off and absence detech
Individual digital temperature room controls
Rainwater recovery
Low flush toilets
Percussion taps
Please visit www.energyeducation.ie for updates on the project and other DOES projects.
Complexity of room types and functions
Most schools have teaching spaces which are quite different to typical classrooms in
terms of internal heat gains as well as the need for fresh air ventilation. Such rooms would
include, for example, multi purpose rooms, learning support rooms, specialist subject
rooms, general purpose halls, libraries, computer rooms, laboratories (Plate 3.2.1.2) or
sports halls. The exact amount will vary from primary to post primary schools. This can be
overcome by specific ventilation and heating strategies for each of these room types.
Figure 3.2.1.1
(Source: Volume 33 of Passivhaus Institut Research group cost-efficient Passive Houses: Schools)
Easy to plan for Educational Spaces
The advantage presented by the scheduling of classrooms is that the occupancy of
different spaces is typically predictable. The occupancy is therefore known in advance
making it easier to plan the heating and ventilation system. It is more difficult to plan for
other spaces, however, such as staff rooms where occupancy varies throughout the day.
Plate 3.2.1.2 Schools typically have a variety of rooms with specific functions that need to be
carefully considered when designing the mechanical systems
DESIGN GUIDELINES For Non-Domestic Passive House Projects
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CONTENTS
3.2.2 Mechanical Systems
Ventilation Rates
In PHPP the typical ventilation rate used is 30m3 per person per hour. However, in the
case of schools, this is generally reduced to 15 to 20m3 per person per hour due to the
frequency of breaks during the day when the room is unoccupied. Such ventilation rates
will typically achieve CO2 concentrations of between 1,200 ppm and 1,500 ppm. This rate
of air exchange is significantly lower than for residential or offices buildings due to the
high density of occupation during school hours. Of course, a CO2 concentration of < 1,000
ppm would be better. Achieving such air quality would increase the ventilation rates
and therefore the electrical power used as well as increasing the size of plant, ducting
required and operational costs. It would also result in decreasing the relative air humidity
in winter. According to the Passivhaus Institut, it is the experience of Passive House
schools in Germany that the air quality is significantly higher than in conventional (nonmechanically ventilated) schools, but still not the absolute best as this would require
too much energy. In terms of efficiency of the heat recovery system, this should be at a
minimum of 80%, otherwise there would be significant heat losses during the heating
system.
Note that the above ventilation rate of 15 to 30m3 per person per hour should be
increased marginally for secondary schools where the average age of students is higher.
Fresh air ventilation only through opening windows is generally not provided in Passive
House schools. However, openable windows are generally recommended and sometimes
needed to prevent overheating.
Comparison of Window Ventilation with Mechanical Ventilation
A comparison study of ventilation using only manually openable windows compared
to that with mechanical ventilation is provided below (prepared by the Department of
Architecture, City of Frankfurt). As can be seen from the graphs below, the schools which
only use window ventilation tend to experience high level of CO2, and therefore lower
air quality. Schools with mechanical ventilation, on the other hand, experience much
reduced CO2 levels.
DESIGN GUIDELINES For Non-Domestic Passive House Projects
Figure 3.2.2.1 Comparing the effectiveness of window versus mechanical ventilation of schools
Periodic Switching off the Ventilation System
The schedule school days are 183 primary school and 167 post primary, they are
therefore left unoccupied for very long periods during which is it typical to switch off the
ventilation systems or operate it a much reduced levels (for example at night or during
the holiday season) in order to reduce primary energy consumption.
Best (Passive House) practice is to run the ventilation system in a kind of ‘temperaturethreshold-operation’ which involves ventilating the building at a reduced rate so that the
temperature never falls below 17°C. The Department of Education and Skills recommend
the heating frost protection system which uses pumps and heating systems to ensure 12°C
is maintained in order to protect the building fabric. Then, heating-up following closure
can be done relatively fast (1 hour), even when using supply air heating without radiators
(one hour pre-flushing is necessary anyway to allow for a sufficient ventilation to flush
all unwanted odours out of the school before the pupils arrive). If using this method for
heating-up the school, it is important to correctly dimension the heating load.
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Where the system is being shut down completely, it is important that there is an automated
system for complete drying of the air filters before the ventilation switches off so that there
is no risk of mould growth in the filters which might be moist with potential risk to human
health. This can be easily achieved by re-circulating the air at the end of each usage period.
The periodic switching off of the ventilation system is a fundamental difference between
residential projects where the system is in operation on a continuous basis. Operation
of ventilation rates at reduced levels during opening hours can also be controlled by
occupancy sensors, CO2 sensors or other air quality indicators.
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Separate Ventilation Systems
Schools will typically require separate ventilation systems according to different room
functions, as follows:
•
•
•
Classrooms, toilets, circulation spaces and common areas;
Staff rooms and servaries;
Science laboratories and fume cupboards.
Pre and Post ‘Flushing’
As suggested above, where the ventilation system is shut down (whether overnight, at
the weekend or during school holidays) it is beneficial to carry out what is referred to as
‘flushing’ for an hour or so before and after the operational period. This flushing requires
operating the ventilation systems at the maximum flow rate possible, drenching the
building with surplus fresh air at the beginning and end of the school day.
Filter Quality
Different quality of filters can be used depending on the specific application and the
separation rate required. In the table below, a filter classification is provided according to
EN 779 (collated by passivhaus-info.de). For hygienic reasons, a minimum F7 filter quality
should be used in the supply air duct
Filter Classification
Separation Rate (%)
Suitable Application
G1, G2 and G3
<65, 65 - <80 and 80 < 90
Coarse dust filter: Pre-filter for coarse and fine dust
G4
> 90
Passive House extract filter
F5 & F6
Fine particle filter: pre-filter for suspended particles
for use in restaurants, clinical rooms and clean rooms
F7, F8 and F9
Passive House fresh air filter
EU 10 – 17
> 85 to 99.99
Highest standards of air purity for operating theatres
and clean rooms
Fire Protection
The use of a centralized ventilation system may have implications for fire protection
measures. Therefore, it is best to keep the design of the ventilation system as simple as
possible, with minimal ducting connecting / interlinking different teaching spaces. It
would also be necessary to take into account acoustic issues, such as cross talking when
interlinking different teaching spaces with the ventilation system.
DESIGN GUIDELINES For Non-Domestic Passive House Projects
Plate 3.2.2.1 Fume cupboards in laboratories will need separate extract systems
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Heat Distribution
Research by the Passivhaus Institut on best practice European case studies has proven
that there should be no difficulty in heating schools through the supply air and that the
systems should be designed in such a manner that the flushing phase can heat-up the
building after periods when the building is unoccupied. In the case of the two Passive
House schools visited in preparation of these guidelines, both used traditional radiators
as their means of delivering additional heating to the classrooms. In both cases, the
radiators were not positioned under the windows. The recommendation of using such
‘traditional’ methods of heating will likely come as a surprise to many readers, but it has
been found that allowing the teacher direct control of the heating of individual rooms
using the all-familiar radiator is very successful. In the case of Passive Houses schools
these radiators have quite a low output and therefore and quite slim and are nonintrusive in terms of useable floor space.
Maximise Natural day lighting
Irish classrooms are typically 7m maximum deep plan and two storey therefore require
high windows to maximize the availability of natural day lighting for the whole room.
However, it is not necessarily recommended to have floor to ceiling glass throughout
as this could lead to over-heating through external solar gains. It is best to adopt a
moderate approach therefore and not use glazing excessively. Note: Department of
Education and Skills do not provide floor to ceiling glass but do require a daylight factor
of 4.5 in technology spaces.
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3.2.3 Shading
There are a number of considerations involved in designing a shading system for Passive
House classrooms, namely :
•
•
•
•
Minimise unwanted external solar heat gains in summer;
Maximise solar heat gains in the heating season;
Maximise natural daylighting; and
Minimise risk of glare and visual irritation.
In terms of control, it is best to employ a system that can be controlled directly by the
teacher in each room, for example roller blinds with an open weave factor of 5%.
3.2.4 Building Management
As with all Passive House projects, the simpler the mechanical systems used the easier
it will be to manage the operation of the building. Ideally the system should be set up
such that the principal can operate and control the ventilation and heating systems
independently.
As mentioned in the introduction, the key challenge concerning schools is to deal with
the variation in building occupancy as this has a significant effect on the ventilation rates
and heating system.
Avoiding Temperature Asymmetries
Night Cooling
It is important to avoid temperature asymmetries which can arise near the windows of
classrooms and this can be achieved by using high quality Passive House windows with
an overall combined U value for glass and frames of <0.85W/ (m2K) inclusive of installed
thermal bridges. Furthermore, while the Passive House Standard requires an n50 airtightness level of 0.6 ACH @ 50 Pascal, it is recommended to improve this to < 0.3 ACH @
50 Pascal if at all possible.
In order to maintain thermal comfort in periods of hot weather during the spring months
(ie. to minimise overheating) night cooling might occasionally be required. This can be
achieved using a variety of means. One mechanical method is to operate the ventilation
system using what is referred to as the ‘summer bypass’ where the cool night air is not
heated up by the exhaust air, but instead passes directly through the building. Another
method is to have openable windows or vents in the rooms which are thermostatically
operated, opening and closing during the night as required in order to achieve the required
temperature. Care needs to be taken that this method does not compromise any internal
alarm sensors that might be activated by moving elements in the interior. Note: Security at
the building would need to be taken into account with this approach.
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Comparison of Completed Passive House School Projects
The overview table below was prepared by the Architectural Department of the City of
Frankfurt and provides a useful overview of six new-build and one retrofit school project
completed up to 2005 in Continental Europe. Some key issues relating to Passive House
design are summarized in bullet form below:
•
•
•
•
•
•
•
The Passive House standard can be achieved irrespective of the size of the school.
All the new-build projects use a central ventilation system, with the retrofit
project using a decentralized system, likely due to difficulty in integrating ducting
throughout an existing school.
Just two of the projects deliver the space heat requirement through the ventilation
system, with the others using radiant heat (whether radiators or through the
concrete core).
Costs vary hugely from project to project, with an average build cost for the six
new-build projects of approximately €1,500 per m2. The cost of refurbishment of the
project at Baiersdorf was approximately €750 per m2, or 50% of the average cost of
new-build.
The level of air-tightness achieved varied from project to project, but the average for
the schools for which results are available is in the order of n50 0.3 ACH @ 50 Pascal.
Readers will note that this is considerably better than the requirement of 0.6 ACH @
50 Pascal required for Passive House Certification.
Larger schools tend to have lower surface to volume ratios which makes it easier to
achieve the Passivhaus Standard.
Lastly, reference to the U-values used is not that relevant to Ireland given that all of
these projects are built in climates with much colder winters. What is interesting,
however, and bearing in mind the above highlighted difference in climates that
U-values for the floors (new build) average at approximately 0.15W/ (m2K) and for
walls averaging at 0.17 W/ (m2K). It is likely that higher U-values (ie. > .15 W/ (m2K))
could therefore be used in Ireland which would not be too onerous in terms of cost.
The average U-value for roofs is found to be considerably lower at approximately
0.11W/ (m2K), highlighting that the insulation of the roof is considerably more critical
than the floors.
DESIGN GUIDELINES For Non-Domestic Passive House Projects
Notes on the above table:
The build cost above includes all structural elements, the building envelope and all
mechanical and electrical services (and does not include fit-out).
For U values, D = roof, W = wall and B = floor
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3.3
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Gymnasia and Sports Halls
3.3.1 Key Design Considerations
Preference for Two Temperature zones
The preferred temperature in a sports hall proper is between 180C or 190C. Higher
temperatures would be too warm given the high level of physical activity engaged in by
the users. The temperature in the changing rooms and showers, on the other hand, needs
to be warmer, perhaps as high as 220C. Differences in temperature can be achieved using
different means of delivering the required heating.
Plate 3.3.1.1 The ideal temperature in any gymnasium sport hall is 180C or 190C which is
marginally less than that used for the majority of Passive House projects, ie. 200C
DESIGN GUIDELINES For Non-Domestic Passive House Projects
Plate 3.3.1.2 Warmer temperatures are generally desired in changing rooms, ideally 190C.
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Requirement for Separate Ventilation Zones
Benefit of Thermal Mass
Just as the changing rooms and shower areas require higher temperatures than the
sports hall, so too do they require significantly higher air change rates in order to ensure
high air quality considering both moisture levels as well as odours from sports clothing
and footwear. Furthermore, the volume of space to be ventilated in the changing rooms
will be considerably smaller than that of the sports hall.
High thermal mass is beneficial in gymnasia in terms of modulating the effects of solar
gains and internal peak loads and will reduce temperature fluctuations more so than
would a light-weight construction. The effect of this is illustrated in the graph below.
The Passivhaus Institut notes that the benefit of high thermal mass in gymnasia is less
beneficial than in schools (due to the lower internal peak loads in the former).
Alternatively, sports hall ventilation can be used as supply air to changing rooms.
35
High insulation Reduces Vertical Temperature Stratification
30
25
Temperatur [°C]
In the case of conventionally insulated high spaces such as sports halls there can often
be pronounced vertical temperature stratification, equating to approximately 1oK per
1m height1. This results in a ‘heat cushion’ just below the ceiling which in turn can lead
to exaggerated heat losses through the roof. In the case of highly insulated Passivhaus
Standard buildings, on the other hand, very even temperatures are found to exist at all
heights. The CFD simulations prepared by the Passivhaus Institut below illustrate this effect.
20
15
Leichtbau
10
Mischbau
Massivbau
5
Taußen
0
18.7
Figure 3.3.1.1 Vertical cross-section through a simple sports hall heated with supply air from
the ventilation system. Temperature isolines are shown for a sports hall with a Passive House
building envelope (left) and another sports hall built to the German EnEV 2007 (‘low energy’)
standard (right). In the Passive House sportshall, temperature distribution is very even.
Assumptions: outside temperature 0°C; heating with supply air from the upper left
Source: Passivhaus Institut Dr. Wolfgang Feist – ‘Conditions and planning aspects of Passive House gymnasiums’. Oliver Kah,
Jürgen Schnieders in Conference Proceedings of 13th International Passive House conference, Frankfurt, Germany
19.7
20.7
21.7
22.7
23.7
24.7
25.7
Figure 3.3.1.2 room temperature over time for heavy construction, mixed construction, and
lightweight construction in a Passive House gymnaisum during a hot week.
External sun shades and night ventilation can be used to maintain comfortable
temperatures in the summer
Note: ‘Leichtbau’ = lightweight construction, ‘Mischbau’ = mixed construction and
‘Massivbau’ = thermally-massive construction
Source: Passivhaus Institut Dr. Wolfgang Feist – ‘Conditions and planning aspects of Passive House gymnasiums’. Oliver Kah,
Jürgen Schnieders in Conference Proceedings of 13th International Passive House conference, Frankfurt, Germany
1 Some of the specific recommendations in this text are derived from the paper titled Conditions and planning aspects of Passive House
gymnasiums, written by Oliver Kah and Jurgen Schnieders of the Passivhaus Institut and published in the Proceedings of the 13th International
Passive House Conference, 17th to 18th April 2009
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Speed of Construction
Sports halls and gymnasia are often built on the grounds of schools or universities where
disturbance by noise and vibration as well as health and safety concerns strongly favour
the use of a rapid construction approach, perhaps using off-site systemised techniques.
Cost Considerations
If it is being considered to use a sports hall for other purposes such as a community
centre or for occasional theatre or such-like events, a well designed acoustic system will
be required which would add significantly to the typical cost of construction.
3.3.2 Mechanical Systems
Sizing of Ventilation System
It is important to size the ventilation equipment appropriately to the typical demands by
users. Consider the case where sports halls are also used as community centres for public
gatherings. If the ventilation system is sized for potential full occupancy, say catering for 300
persons, the equipment required would be very substantial and would add a significant
cost to the project. Besides, such events might represent a small percentage of typical use.
In such instances, it would be possible to provide additional ventilation using zero energy
ventilation strategies such as openable windows which are triggered by Co2 levels. The
ventilation systems can therefore be sized for typical user numbers, perhaps in the range of
30 to 40 persons depending on the circumstances.
Plate 3.3.2.1 The windows in the top section of this glazed facade can be opened if necessary
to provide for cooling when needed
Single or Dual Ventilation Systems
An important distinction has to be made between the air exchange rates in the sports hall
section of the gymnasium and that in the changing and shower area. The former is typically
of very large volume, requires lower temperatures (perhaps 180C) and a modest air change
rate of perhaps 0.7 times per hour during use. The volume of the latter is considerably
smaller, but requires higher temperature (perhaps 220C) and much higher air exchange
rates, perhaps 5 to 10 times during their use, due to the high humidity. A choice has to be
made as to whether to use a single MHRV system covering both spaces (sometimes referred
to as ‘flow-through’) or to use two separate systems, one for each space.
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In the two Passive House Gymnasia visited by the authors, the former flow-through
system was used in the Kalbacher Höhe Primary School, Frankfurt, with the latter used in
the sports hall at Unterschleißheim. The advantage of the single system is that there are
likely to be cost savings in terms of mechanical plant. However, the air in the gymnasium
which is at 18oC might have to be heated up as it passes through to the changing area
or, if not, additional radiant heat provided to compensate for the flow-through of the
slightly cooler air. If the flow-through concept is used, it is important to consider any
requirements of fire regulations.
Positioning of Supply and Extract Grills
The positioning of the fresh air ducts in the sports hall must also be considered as
they are typically high ceilinged (7m at lowest point). In the Unterschleißheim project,
dynamic modelling carried out in the design phase suggests that the fresh air would
typically drop off gently from the point of entry, eventually hitting the floor perhaps five
to six metres from the ventilation grill. Accordingly, the fresh air grills in that project were
placed at approximately 2.5m above the floor with the extract air grills placed close to
floor level to provide maximum turnover of fresh air in the zone where people need it
most. In the sports hall at the Passive House Kalbacher Höhe Primary School, Frankfurt,
the fresh air is delivered at ground level and drawn through the hall through vents at a
higher mezzanine level.
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3.3.3 Shading and Glare Avoidance
The enjoyment of sports can be significantly compromised if there is too much glare
created by light of low incidence which typically arises on both east and west elevations
when the sun is lower in the sky. Shading might thus be required to reduce glare,
depending on the building design and orientation. Both of the gymnasia visited in the
preparation of these guidelines use a very clever strategy to avoid risk of glare, placing
the playing surface below ground level with the windows at (a higher) ground level
delivering light at an ideal position. The use of a semi-basement also helps to integrate
the taller sports hall into its surroundings which might be beneficial in terms of planning
considerations.
Excessive glazing on east and west elevations can also result in overheating, particularly
in summer, so shading may be required not only to reduce glare but also to reduce
overheating and the need for cooling. Micro-perforated blinds can be used to reduce
glare and overheating. Another possible strategy is to provide reflected light through
roof-lights with grills to avoid glare. Lastly, the colour of finishes used internally can
also have a great influence on day lighting (with brighter warmer colours reflecting
more natural light) which in turn will affect the degree of artificial lighting used and,
accordingly, the primary energy use of the building. The use of such design strategies will
be greatly determined by the specifics of the project design as well as site characteristics.
Plate 3.3.2.2 In this sports hall, fresh air is delivered at mid-height of the main hall, and
extracted at floor level
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Plate 3.3.3.2 Natural daylighting can also be provided through energy efficient rooflights,
coupled with bris-soleil to reduce overheating when the sun is high in the sky
Plate 3.3.3.1(a) and Plate 3.3.3.1(b) External shading can be extended or retracted to control
Plate 3.3.3.3 The internal wooden finish of this gymnasium was finished with a white wash to
glare for sports activities and to minimise risk of overheating
reflect more natural light within the building
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3.3.4 Building Management
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3.4
CONTENTS
Apartment Complex
Periodic Operation of the Ventilation System
The operational hours of the ventilation system needs to be carefully considered. It would
be a waste of energy to have the ventilation system running at full capacity when the
building is not occupied (as compared to a dwelling where the system runs 24/7). The
ventilation can thus be either shut down completely when the building is not occupied
or, preferably, can be run at a very low level reducing energy consumption whilst also
providing some minimum air change rate. When considering such strategies, great care
must be taken to ensure that there is no risk of mould growth in the filters. The risk of
this is higher if the system is completely shut down. The equipment can be automatically
programmed to completely dry the filters before shut down, eliminating any risk of
mould and therefore reduced air quality. Sports halls are typically used according to a
regular and predictable schedule and so the ventilation system can be programmed in
advance with minimal manual operation required.
Pre-Flushing
As recommended earlier in relation to schools, in cases where the ventilation system is
periodically turned off or reduced in terms of air change rates it is important to operate
a pre-flushing phase which will help to (a) freshen up the space in terms of indoor air
quality and (b) re-heat the building which might have dropped slightly in temperature.
Re-heating the building using such pre-flushing implies that the heat demand is
delivered through the MHRV and not through the use of radiators (which is also an
option that can be considered). This flushing phase should ideally provide at least 2
complete air changes prior to occupation.
Plate 3.4.0 In this development near Darmstadt, large apartment complexes are being built
to the Passivhaus Standard
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3.4.1 Key Design Considerations
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•
Passive House apartments differ from all the other building types presented in these
guidelines in so far as they are residential in function. The implications of this in terms of
Passive House design include the following:
•
•
•
•
•
They tend to be occupied on a 24 hour seven day a week basis, unlike schools
or offices which can be left vacant for extended periods. High thermal comfort and
good indoor air quality are thus required on a continuous basis.
Individual residents will expect to have complete control of the temperature
of their living space, as thermal comfort needs differ from person to person. This
contrasts with an office, school or shopping centre where an open plan arrangement
is more the norm and where the same temperature is generally delivered over the
entire complex. Apartment blocks thus require more temperature controls per m2
than other building types.
The treated floor area will be very significantly smaller compared to all other
project types, typically ranging between 65m2 and 125m2. The heated volume too
will be a fraction of that in commercial or public buildings, with lower ceilings and
less unused / common / void space. This can impact on such design aspects as
the sizing of ventilation equipment, for example (which will be much smaller for
individual units than it would be for a large office building).
On a practical level, the reduced floor area means there may be little room for bulky
plant, such as a large solar tank, or for storage of wood pellets for back-up heating.
Domestic hot water and space heating can be provided through a centralised
system, however, freeing up valuable floor space. Remember too that radiators
are typically not used in residential projects, maximising useable floor space and
removing clutter from beneath the windows.
Apartment blocks are occupied, and therefore ‘managed’, by lay-persons who will
typically have little knowledge of Passive House technology. This can have
implications in the first couple of years of occupancy for the maintenance of the
heat recovery ventilation equipment, for example, and the need to change the filters
periodically. There are solutions to this potential problem, however, such as having
a centralised ventilation system where the filters can be changed by the building
management company.
DESIGN GUIDELINES For Non-Domestic Passive House Projects
•
CONTENTS
The occupancy rates tend to be much lower than for offices and schools, with the
default used in PHPP at 35m2 per person. This tends to reduce potential internal heat
gains purely on the basis of heat generated by humans. This reduction, however,
must be balanced with a higher internal heat gain on average per m2 from the
operation of household appliances and the activities of day to day living, such as
cooking and washing. On balance, the internal heat gains in residential projects
would be marginally less than for schools and considerably less than for offices.
There tends not to be the same preference or demand for floor to ceiling glass as
there might be in an office or retail project, reducing potential risk of overheating
through unwanted solar gain. An added bonus of this is reduced heat transmission
losses through glazing.
Influence of Solar Gain on Space Heat Requirement
Depending upon the design of the apartment block, there might be individual living
units which do not have the benefit of solar gain in the heating season (for example
single aspect north facing apartments. While such units may well have the same
internal heat gains as their south facing counterparts, they will otherwise clearly be at
a disadvantage with regards to overall energy balance. This can be compensated with
increased insulation which will reduce transmission heat losses, or perhaps through
reducing the size of the units such that the internal heat gains on average per m2 of
treated floor area are higher than for larger units.
Inevitably there will be variation in the space heat requirement of different units with
different orientations. The same holds true in terms of the actual space heating energy
used by individual apartments, however, with some residents preferring it warmer than
others, some preferring to leave their windows open, some people being at home all
day long and others out during normal office hours. It is possible to test the influence of
variation in the temperature of neighbouring apartments in the Heating Load worksheet
in PHPP (Row 36 – ‘House/DU Partition Wall’ which is linked to Cell E26 in the Areas
worksheet). This is a useful exercise as it ensures that all units can maintain adequate
comfort even in periods when the neighbouring unit(s) might be colder as might occur
when the neighbours are on winter holiday and their heating is shut off. It can also be
used to test the influence of being located next to an unheated circulation space. The
PHPP software uses a default temperature difference for adjacent unheated spaces of
3oC which might be considered low but has been found to be adequate due to the high
thermal inertia causing temperatures to decrease very slowly. If the adjacent unit is an
existing poorly insulated building, a temperature difference of 5oC is recommended.
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Irrespective of whether individual apartments receive solar gain in the winter, they will
always be much more thermally efficient than a standalone detached single family
dwelling which suffers the same lack of external solar gains due to the reduced surface
area in apartments exposed to the elements.
Regarding design and certification of Passive House apartment projects, it is the entire or
overall project that is certified, rather than individual units as per certification criteria on
www.passiv.de/07_eng/phpp/Criteria_Residential-Use.pdf.
Maximise Natural Daylighting
In single aspect apartment developments (where a central corridor provides access on
both sides to individual apartment units), it is preferable to provide natural daylight
to circulation spaces which can also spill-over to the apartments. This will enhance the
quality of space for residents and also reduce primary energy consumption with artificial
lighting. The Passive House student accommodation complex in Vienna (need to get
the name of the Architects) provides a clever example of this, where large roof windows
provide daylighting to the corridors in each of the five floors through a series of light
shafts as depicted below.
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3.4.2 Mechanical Systems
Centralised versus Decentralised Space Heating and Domestic Hot Water Systems
The majority of non-domestic case studies presented in these guidelines use centralised
systems for heating, hot water and mechanical ventilation. In the case of apartments,
however, there is a choice to be made as to whether each individual apartment has their
own separate system (decentralised) or if a centralised system can be used.
A cost benefit analysis will help to determine whether or not it makes sense to use
centralised or decentralised mechanical systems. In continental Europe, district heating
is commonplace in which case centralised systems for space heating and domestic hot
water generally makes more sense due to the benefit of not requiring a boiler or storage
facilities on-site. District heating is less common in Ireland currently, however, so there is
not the same automatic presumption in favour of centralised systems.
Consider the scenario presented below between centralised versus decentralised heating
systems. In the case of a decentralised system, 50 individual heat generating devices (such
as a boiler or a heating coil) would be required, whereas a centralised system would require
just one or perhaps two or three modulating heat generating devices for different zones.
Heating system No. of apartments Treated floor area Heat Load
Design No. and size of boilers
required
Decentralised
50
100m2
10 W/m2
50 no. 1 kW heat generating devices
Centralised
50
100m
10 W/m2
1 no. 50 kW heat generating device
2
The following factors will have an influence on whether to use a centralised or
decentralised system for space heating:
•
Plates 3.4.1.1(a), (b) and (c) Light shafts in apartment blocks can be designed to provide
daylighting for both semi-private circulation space as well as private living space
•
DESIGN GUIDELINES For Non-Domestic Passive House Projects
Number of living units – the more units there are in an apartment complex, the
more economically viable it is to use a decentralised system (decisions in this regard
will be project specific). There may come a point with very large developments,
however, where the length of heating pipes is so great that there are significant heat
losses. In such cases, it would likely make sense to sub-divide the complex into a
number of different zones, each served by a separate modulating heat generating
device. Alternatively, the form or shape of the apartment complex might dictate the
number of devices to use. In an L-shaped development, for example, two might be
used each serving its own zone.
District heating – where available, a centralised heating system would likely make
more sense due to the potential to avoid the use of any boilers whatsoever in the project.
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•
•
Delivery of space heating – there is a choice to be made as to whether to deliver
the space heat requirement via a hydronic radiant system using radiators or under
floor heating (not common in Continental Europe) or, alternatively, using the
mechanical ventilation system. If using the latter system, there are further choices
to be made, including whether to use an electrical heat pump or a water to air
heat exchanger. A third choice can involve a hybrid system where radiant heat is
provided in the bathrooms (for example with a small radiator for extra comfort) in
combination with heat provided via the mechanical ventilation system. In all of the
above cases with the exception of where a heat pump is used in the mechanical
ventilation system, a centralised hydronic heating system is likely to be preferred.
These scenarios are presented in the table below. The advantage of using a heat
pump in combination with the mechanical ventilation is that there is no need for
any external hot water heating system. In this case, each apartment can have total
and independent control over its own heating system using, for example a socalled ‘compact unit’ which incorporates a DHW tank, the mechanical heat recovery
ventilation system and a heat pump for heating both DHW as well as heating the air
passing around the apartment when needed.
Heat exchangers – if a centralised heating system is being used, heat exchangers
will be required irrespective of whether the means of delivering that heat is via
radiators, under floor heating of warm air systems.
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Space heating system
Options for space heat delivery
Likely preferred scenario
1. Hydronic system for radiant
heat
Radiators or under floor heating
Centralised
2.Mechanical ventilation system
Water to air heat exchanger
Centralised
Electric - typically air to water heat pump
Decentralised
Radiant heat in the bathroom and
elsewhere using the mechanical
ventilation system
Combination of both centralised and
decentralised
3. Hybrid (combination of
hydronic and mechanical
ventilation)
Be aware that option to use individual air source heat pumps must be carefully
considered in light of relatively poor efficiencies and the resulting large primary energy
overhead.
Domestic Hot Water
The PHPP software uses a default value of 25 litres per person per day for consumption
of domestic hot water in residential projects (compared with 12 litres per person per day
for office projects). As with space heating demand, the supply of DHW can be provided
on a centralised or decentralised basis and using a variety of means of production,
including a boiler, heat pump or solar collectors. If using a solar collector system, the
Passivhaus Institut recommends designing a system to provide approximately 50% of the
anticipated annual demand. While it is technically possible to size a system to provide a
higher contribution, the usability of the excess produced in summer is fairly restricted.
The recommendation provided in PHPP is to specify approximately 0.5m2 of south facing
solar collectors per person, with a storage tank of 50 litres per person.
Centralised versus Decentralised Mechanical Heat Recovery Ventilation
There are much more factors to consider in choosing between centralised versus
decentralised mechanical ventilation systems compared to the above discussion on
space heating and domestic hot water. The latter tend to be used predominantly, but
there are situations where a centralised system might be considered, the advantages of
which are listed below:
Plate 3.4.2.1 Compact units such as that depicted above are well suited to apartment
projects where space might be limited for more bulky plant
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•
•
•
Centralised management – with a centralised approach, the entire ventilation
system for all living units can be managed and maintained at one location and by
one suitably qualified person. This removes the responsibility on individual home
owners to maintain their own system, including the periodic replacement or cleaning
of filters. This scenario might be especially relevant in social housing projects or in
student accommodation or hostels where there might not be the same interest on
the part of the occupants to change the filters when needed. There is some concern
in the case of social housing apartment projects that residents might even turn off
the ventilation equipment as a means to saving money on electricity. A centralised
system would remove any risk of this happening.
Potential space saving in individual apartments – heat recovery ventilation
systems for apartments will tend to be quite small in size (some of which can even be
placed in a ceiling void) but nevertheless do occupy space which might otherwise be
saved if a centralised system were used. Any space saving in individual apartments
must be considered in light of the significant amount of space needed for a large
centralised system, however. The efficiency of smaller MHRV units is improving over
time and the advantages concerning space saving is likely to diminish as new and
improved products come on the market.
Reduced primary energy consumption – A single MHRV system for multiple living
units will use less primary energy than multiple individual systems. This is especially
the case for very small living units (such as student accommodation facilities) where
the individual air flow volumes might be very low and where one large plant could
easily provide the needs for the entire complex.
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Plate 3.4.2.2 Decentralised MHRV system in apartment ceiling void during construction
Plate 3.4.2.3 Bulky centralised MHRV systems require considerable floor space
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The disadvantages of a centralised MHRV system may well outweigh the advantages, as
listed below:
•
Fire compartmentalisation – if a centralised mechanical ventilation systems is used,
there must be special fire protection measures in order to eliminate risk of spread of
flame or smoke between each living compartment (depicted below). Such measures
can significantly increase the cost of the overall system.
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3.4.3 Shading
The Passive House design considerations for apartments in respect to shading will
generally be quite similar to that recommended for single family dwellings. However,
in situations where an apartment has just one external façade, there will be probably
be a need to maximise the proportion of glazing in order to provide sufficient day
lighting for the residents. The area of glazing must, of course, be considered in respect
of maximising solar gain and natural daylighting while also minimising overheating and
transmission heat losses. The PHPP analysis will guide the designer into optimising these
considerations.
It is often easier to accommodate shading to apartment complexes than it is to other
building types such as offices or schools due to the typical need for balconies as amenity
space or for external access on dual aspect units (see examples below).
Plate 3.4.2.4 Fire compartmentalisation devices in centralised ventilation systems
•
•
Additional controls – despite their being a centralised MHRV plant, each individual
homeowner must still be given control of their system such that they can alter the
flow rate depending on their needs (for example, low rate when they are on holidays,
high rate if they have a lot of guests or otherwise medium in normal circumstances).
The cost of providing these controls might well offset any savings made on using one
centralised plant.
Sound attenuation – there is likely to be an increased complexity in the design of
the system to ensure that sound does not travel between individual living units,
adding further to the cost of the system.
Plates 3.4.3.1 Balconies often serve dual purpose in providing both access to external space as
well as providing shading to south-facing windows
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In situations where balconies are not possible or appropriate, there are other means of
providing shading such as using blinds which have been shown earlier in relation to
offices (but which are not commonplace in Ireland), or using external shutters such as on
the Vienna student accommodation complex depicted below.
In many situations, there will not be a need for any shading and this will be accurately
predicted by the PHPP analysis.
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3.4.4 Building Management
Management of apartment buildings is considerably different to that of, for example,
offices or schools insofar as they are used as accommodation for families or individuals
on a 24 hour basis. Each living unit must generally provide individual control of the
key services required for optimising comfort, including space heating and mechanical
ventilation. It has been explained earlier that these services can be provided either on a
centralised or decentralised basis, with the former placing responsibility for management
and maintenance with the facility manager and the latter being operated directly by the
occupant. In the case of social housing or student accommodation, it might be beneficial to
use a centralised system that is managed by a third party, whereas private accommodation
might well be best managed by the home owners. In any event, the management of
Passive House apartments will tend to be simpler than for public buildings such as schools
or offices due to the lower internal heat gains and their use on a 24 hour basis (without the
need for shutting down systems at night such as happens in offices and schools).
The key design challenge for management of Passive House apartment buildings is to
make the operation of the Passive House extremely simple for the homeowner. The controls
should be user friendly. The control depicted below, for example, allows the homeowner to
set the temperature of the apartment as well as the ventilation rate and will also indicate
when the filters need to be changed and if there is a high concentration of C02.
Plates 3.4.3.2(a) and (b) Sliding copper shutters manually operated from inside add a
dynamic character to this Passive House student accommodation complex in Vienna city
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Circulation Space
An important issue to consider in apartment buildings is the maintenance and
management of circulation spaces. In many projects, stairwells and lift shafts are left
out of the Passive House envelope and are treated as external areas in terms of heating
and ventilation (this is true also in some Passive House office buildings). In other words,
they are neither heated nor mechanically ventilated. If this strategy is employed, it is
crucial that the adjoining accommodation space is thermally separated from these other
‘cooler’ spaces in order not to create thermal bridging, drafts or exaggerated heat losses.
This approach will not suit every project, but it should be considered as an option at
the concept design stage as it will reduce considerably the energy use of the overall
development. Due to the compactness of apartment buildings, such unheated spaces
tend not to get too cold and so are regarded as acceptable buffer zones by the residents.
Common Areas
Plate 3.4.4.1 Typical control unit for MHRV in an apartment which will inform the home
owner when the filter needs to be replaced
DESIGN GUIDELINES For Non-Domestic Passive House Projects
In many apartment buildings there will be common areas (such as reception space,
toilets, lobbies, corridors, crèche, meetings rooms and leisure facilities) which will need to
be heated, lit and mechanically ventilated using systems separate to that of the individual
residences. These spaces must all provide a high level of thermal comfort and good air
quality. It is best to cluster such spaces if at all possible (whether horizontally beside
each other, or vertically above and below each other) so that the heating and ventilation
services can be provided on an efficient zoned basis. This will reduce the number of
individual mechanical systems that have to be maintained and managed. Some of
these spaces will be infrequently used, and the ventilation system can be controlled by
presence detectors or by a Co2 sensor instead of them constantly operating and wasting
energy. In such spaces, it might be preferable to provide the back-up heating required
using radiators which are familiar to most people and are easily controlled to provide an
instant boost of temperature if required.
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Completed Case Study Projects
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4.1
Energon Offices, Ulm
61
4.2
Lu-Teco Offices Ludwigshafen
66
4.3
Montessori School, Aufkirchen, Munich
70
4.4
Kalbacher Höhe Primary School, Frankfurt 74
4.5
Irish Prototype Passive House School
78
4.6
Tesco Supermarket, Waterford
81
4.7
Wohn Sinn apartments, Kranichstein, Darmstadt
86
4.8
St. Franziskus Church and Community Centre, Linz, Austria
90
4.9
Sports Hall and Community Centre, Unterschleißheim
93
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4.1
CONTENTS
Energon Offices, Ulm
4.1.1 Motivations for project
This office building is one of the largest Passive House projects in the world,
measuring 6,000m2, and located in the Science Park II on the outskirts of the city of
Ulm in southeastern Germany. It was completed in 2003. The Client in this instance
was very conscious of corporate social responsibility and also wanted to project
a green image. The concept for a Passive House emerged as the clear winner in a
design competition which was won by Architect Stephan Oehler.
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4.1.2 Key design features
Contemporary Facade
The building is designed in a compact triangular shape (Figure 4.1.2.1 (plan) and Figure
4.1.2.2 (section)) consisting of three curving facades (Plate 4.1.2.1) with a central atrium
(Plate 4.1.2.2). The facades curve in section also (Plate 4.1.2.3), creating a relaxed massing.
Whilst the external wall system is constructed of timber frame, it is finished with metal
cladding which gives a high-tech contemporary appearance, entirely suited to the
innovative research and development work that is carried out there.
Contemporary and kinetic facade
Unlike many modern offices which comprise floor to ceiling windows throughout, the
proportion of glazing to opaque façade is tightly controlled in this building to optimize
the balance between maximizing natural daylighting and minimizing overheating and
the need for cooling. A dynamic external shading system helps to keep the building cool
and changes the appearance of the building throughout the day. The offices on each
floor have a single aspect either with an external window or an internal window opening
onto the atrium.
Figure 4.1.2.1 (plan)
Figure 4.1.2.2 (section)
Plate 4.1.2.1
Plate 4.1.2.2
Plate 4.1.2.3
Plate 4.1.3.1
4.1.3 Mechanical Systems
Dynamic shading system
As has been discussed in Section 2 above, the principal challenge for most offices is to
minimise the cooling load due to overheating in summer by a combination of internal
heat gains and external solar gains. The highly insulated envelope, triple-glazing and
airtight construction go a long way to reduce unwanted external heat gains. However,
a clever shading system is also used on this project which reduces unwanted solar gain.
The shading is automatically controlled by solar irradiation sensors on each facade. When
fully extended, the shades are partially open at the top but fully closed at the bottom
(Plate 4.1.3.1). This strategy provides natural light at a high level deep into the office,
whilst also eliminating glare at the desk level. The automated system can be overridden
by the office occupants, but will revert to the optimally programmed position after a predetermined time (in this case two hours).
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Concrete Core conditioning (CCC) using geothermal boreholes
This office building is cooled using a series of 40 geo-thermal boreholes which deliver
‘cool’ water (18°C) to the concrete floors at each level. The ground temperate at an
average of 10°C cools the circulating water to 15°C which in turn is mixed with warm
water to 18°C before entering the concrete core so that there is no risk of condensation.
The cooling demand for the entire office is provided just by one 3.5kW pump (Plate
4.1.3.2) used to power the concrete cooling system.
Minimal heating requirement
In terms of heating, if the external temperature is greater than 5°C, there is no need for
active heating. If the external temperature goes between 5°C and –5°C, the waste heat
from the server rooms and kitchen extract is sufficient to heat the entire building. If the
external temperature goes below –5°C heating is provided by connection to the district
heating system.
Plate 4.1.3.2
Plate 4.1.3.3
Ventilation strategy
The fresh air demand for this building is so huge (28,000m3/hour at full occupancy,
reduced to 4,000m3/ hour when unoccupied) that it is possible to walk upright inside the
air intake duct! The majority of fresh air is delivered centrally to the atrium space which
also serves internal offices (Plate 4.1.3.3) through louvered vents (Plate 4.1.3.4). Offices
located on the external facade have their own ‘active’ decentralised supply. All extract air
from the building is drawn from the central corridors at each floor.
Plate 4.1.3.4
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4.1.4 Perceived Benefits of the Passive House Standard
The energy savings being experienced at this project are hugely impressive. Heating and
cooling costs for conventional buildings in this region are approximately €10 to €15 per
m2 per year. In the case of this office, however, the cost is between €2 to €3 per m2 per
year, representing a saving of approximately 80%. The total build cost for the office was
approximately €1,650/m2 which is 20% less than the average cost for offices at the time
when it was built.
“The payback from this project
was from day 1 – the owner will
never build ‘normal’ again”
4.1.5 Lessons learned and guidance for future projects
This building was originally designed for a single occupant, with a staff complement of
400 persons all engaged in typical office duties. As a result of this, the design consisted
of a single heating and cooling zone for the entire building. In practice, the building is
used by a number of different companies, some of which are engaged in research and
development with the result that different floors have different heating and cooling
loads. A more flexible system with separate cooling and heating zones would thus be
advisable in future projects.
The wind speed sensor controlling the external shading has tended to be a little overly
‘sensitive’, retracting the shades when perhaps they could safely be left extended. Lastly,
the air handling system used by the kitchen and canteen represents approximately
one third of the total air volume for the building. In the future, perhaps there will be
more efficient means by which kitchens can be ventilated as a proportion of the entire
building (Plate 4.1.5.1). In some non-domestic projects, the kitchens are used only for
reheating food that has been cooked elsewhere and which may not require separate
air-handling systems. In cases where a fully operational kitchen is required, then separate
heat recovery is important perhaps using an induction hood (which works with lower
volumetric flow rates).
Plate 4.1.5.1
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Factual summary overview:
Project type
Office
Treated floor area in PHPP
5,692m2
Annual heat requirement (delivered energy)
PHPP = 12.5 kWh/(m²a)Measured = 17 kWh/(m²a)
Year of construction
2003
Project Team
Architects
Stefan Oehler, Bretten Ebok Tubingen, FP7 Stuttgart
Mechanical Engineers / Building Services Planning
Ebok Tubingen, FP7 Stuttgart
Other important design team members
Passivhaus Dienstleistung GmbH
Construction Details
Construction type (for example, timber frame, concrete…)
Concrete skeleton with timber frame facade
Exterior wall U value insulation thickness and type
0.13 W/(m²K), 350mm of mineral wool type Roof U value insulation thickness and type
0.12 W/(m²K), 400 – 700mm of cellulose
Floor U value insulation thickness and type
0.22 W/(m²K), polyurethane
Glazing details
Ug = 0.7 W/(m²K)
g-value = 50%
Ventilation Details
Air-tightness
n50 = 0.20h
Ventilation equipment used
Air is preheated in earth tube (42% efficient) and heat
recovery from waste air is 64% efficient
Ventilation rate:
Centralised distribution of fresh air through the atrium
Means of controlling ventilation rate
Time clock
Design Heating (and Cooling) System and Renewable Energy
Heat load per m2
Unknown
Type of back-up heating system used
District heating powering a concrete core heating
system (26oC)
Cooling load per m2
Unknown
Method of cooling used
Chilled concrete floor powered from geothermal tubes
(18oC)
Domestic hot water production
From district heating (only required in the kitchen)
Renewable energy production
Photovoltaic panels producing 850 kWh per year
Construction and Energy Costs
Cost of construction (not including cost of land)
€1,680 / m2
Estimate on additional (‘extra’) costs over conventional cost
for construction
Lower! Approximately 80% of ordinary office buildings
Typical annual energy costs (only for space heating and / or
cooling)
€2.50 / m2
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4.2
CONTENTS
Lu-Teco Offices Ludwigshafen
4.2.1 Motivations for project
The office facility based near the banks of the Rhine in Ludwigshafen is the largest
Passive House building in the World, measuring approximately 10,000m2 in floor
area (Plate 4.2.1.1).
Photo 4.2.1
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4.2.2 Key design features
Overall form
These offices consist of three blocks each connecting to a lateral spine on the northern
side (Figure 4.2.2.1 (plan) and 4.2.2.2 (section) and Plate 4.2.2.1 and Plate 4.2.2.2). Two
south facing courtyard spaces are created between the three blocks (Plate 4.2.2.3), with
green canopies protect the south-facing glazed areas from overheating. This design
strategy reduces the area of south facing glass and creates overshadowing for a high
proportion of the windows, reducing unwanted solar gain.
Flexible occupancy layout
This office was purposely designed in order to cater for different tenancy occupation
arrangements. Mechanical services were installed so that each floor could be subdivided
in a number of layouts while still ensuring that individual tenants would have control of
the ventilation, heating and cooling of their own space. This flexible approach is critically
important when designing office buildings.
4.2.2.2 (section)
Cost efficient finishes
The overriding influence on the planning of this project was achieving the Passive House
standard within the budget of a typical office block. The design team focused on investing in
energy efficient design rather than on exorbitant finished and materials. That said, the quality
of finished is very high and there is no sign of compromise having been made anywhere.
Plate 4.2.2.2
Figure 4.2.2.1 (plan)
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Plate 4.2.2.1
Plate 4.2.2.3
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4.2.3 Mechanical Systems
Geothermal concrete heating and cooling
Each of the three blocks are heated and cooled in a similar way to the Energon offices
described above using ground source heat pumps located in the basement. Each of the
heat pumps is served by 13 boreholes.
Decentralised ventilation system
In terms of the mechanical ventilation system, a decentralised approach was used on
this project, different to that used in the Energon building which was centralised. The
ventilation equipment for each space is positioned on an external wall, and can be
identified externally by the intake and extract vents (Plate 4.2.3.1). The ducting system
was left exposed in most of the office spaces (Plate 4.2.3.2) to reduce costs and to
facilitate easy access if required.
Plate 4.2.3.2
The air flow rate in each office is controlled automatically by CO2 sensors, eliminating the
need for manual or time-clock control.
Server rooms
The only air conditioning required in the building is for the server rooms. The amount of
cooling units involved is a tiny fraction of that typically required for conventional airconditioned offices (Plate 4.2.3.3).
Vacuum insulation panels and solar shading
Plate 4.2.3.1
Plate 4.2.3.3
Plate 4.2.3.4
Plate 4.2.3.5
Very thin yet highly efficient vacuum insulation panels were used in the glazing section
of the exterior fabric to the rear of the housing for the retractable shading device (Plate
4.2.3.4). Above this is a high level shallow window with no shading (allowing light to
penetrate deep into the office). Below this, the glazed section can be protected from
excessive solar gain by variable louvered shading. The operation of the louvers is
automatically programmed by an external solar sensor (Plate 4.2.3.5).
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4.2.4 Perceived Benefits of the Passive House Standard
4.2.5 Lessons learned and guidance for future projects
The Lu-Teco offices are fully occupied, despite the trend in the region for vacancy
rates as high as 25%. The offices were constructed at no additional cost compared to
conventional build, yet save approximately €150,000 per year on heating and cooling
costs. Without doubt, therefore, the project has been a commercial success and this is
primarily due to the Passive House standard being adopted from the very outset.
Factual summary overview:
Project Description
Project type
Office
Treated floor area in PHPP
9,823m2
Annual heat requirement (delivered energy)
PHPP = 12 kWh/(m²a)
Year of construction
2007
Project Team
“Our tenants love to see the
oil price rising!”
Architects
Architekturbüro Lutz Laier
Mechanical Engineers / Building Services Planning
IBB Büro Baumgartner
Other important design team members
Passivhaus Institut
Construction Details
Construction type
Masonry
Exterior wall U value insulation thickness and type
0.137 W/(m²K), 200mm of 0.035 W/(mK) insulation conductivity Roof U value insulation thickness and type
0.113 W/(m²K), 300mm of insulation
Floor U value insulation thickness and type
0.226 W/(m²K), 160mm of 0.044 W/(mK) insulation conductivity Window frame details
Uf = 0.9 W/(m²K)
Glazing details
Ug = 0.6 W/(m²K)
g-value =50% Ventilation Details
Air-tightness
n50 = 0.20/h
Ventilation equipment used
Vallox equipment, heat recovery 75% efficient
Average air change rate
Decentralised system (each zone 200 – 300m2)
Means of controlling ventilation rate
Decentralised system controlled by CO2 sensors
Design Heating (and Cooling) System and Renewable Energy
Heat load per m2
10W/m2
Type of back-up heating system used
3 geothermal heat pumps, each with 13 boreholes
Cooling load per m2
Unknown
Method of cooling used
Chilled concrete floor, additional cooling achieved through
shading
Domestic Hot Water production
Centralise hot water system not provided due to low usage
Renewable energy production
Photovoltaic panels producing XXXXkWh per year
Construction and Energy Costs
Cost of construction (not including cost of land)
XXXX € / m2
Estimate on additional (‘extra’) costs over
conventional cost for construction
X%
Typical annual energy costs (only for space heating
and / or cooling)
XXXX € / m2
Miscellaneous
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CONTENTS
Montessori School, Aufkirchen, Munich
4.3.1 Motivations for project
This project is located on the outskirts of the community of Aufkirchen, a short
distance to the east of Munich Airport. The Clients were aware of the Passive
House standard and had visited some projects in the Netherlands after which they
were convinced of achieving that standard.
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4.3.2 Key design features
The principal architect for this project, Gernot Vallentin, aimed to create a Passive House
school which was simple in design and detailing, yet also dynamic and highly expressive
and, most importantly, could be built at no greater cost than a conventional school.
Each of these objectives was achieved with ease as will be seen from the description and
images below.
In terms of overall massing, a compact form was sought which would maximise energy
efficiency. In terms of aesthetics, however, a rolling green roof which connects at both
ends with the surrounding landscape as well as a curving plan provided the overall
concept for the building (Figure 4.3.2.1, Figure 4.3.2.2 and Plate 4.3.2.1). As a result of
the above design approach, every classroom room is a different shape creating a strong
sense of identity for individual classes.
Figure 4.3.2.1
Figure 4.3.2.2
The architect approached the building design using the classic principles of Passive
House, orientating the longest axis of the building to the south. Classrooms in this two
storey school face to the south, with corridors, utility rooms and toilets to the north
(Figure 4.3.2.2 and Plate 4.4.2.2). From the very outset the overriding objective was to
keep the design and detailing very simple, therefore minimizing cost of construction.
Thermal mass is achieved using an internal masonry skeleton clad with a timber frame
exterior shell.
An interesting design feature of this school is the individual external stairs provided
from each of the first floor classrooms directly to the school garden below (Plate 4.3.2.3).
Incorporating these stairs resulted in very significant savings in terms of fire protection
measures that would otherwise be required. Note: Strategies such as this need to be
verified for compliance with Building Regulations in force in each jurisdiction.
Plate 4.3.2.1
Plate 4.4.2.2
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Natural daylighting is provided to internal circulation space through four massive west
facing rooflights (Plate 4.3.2.4 and Plate 4.3.2.5).
4.4.3 Mechanical Systems
The mechanical systems required for this school cost approximately €150,000 less
than would be required for a conventional school. The money saved was invested on
upgrading the windows to Passivhaus Standard as well as additional insulation.
Heating is provided by a combined heat and power (CHP) unit (Plate 4.3.3.1), the smallest
available on the market, in combination with a condensing gas boiler. The heat is
delivered to the classrooms using conventional radiators, not something you see in every
Passive House. The principal advantage of using radiators was the ease of control by the
teacher in each classroom.
Plate 4.3.2.4
Plate 4.3.2.5
Plate 4.3.3.1
Plate 4.3.3.2
Plate 4.3.3.3
Plate 4.3.3.4
In terms of ventilation, each room is provided with fresh air through a long ceiling grill
which is positioned overhead the transition from what is the main body of the classroom
to a project work space and cloak room (Plate 4.3.3.2). The extract air is drawn from the
cloakroom area which helps to keep the air in the room dry on wet days when outdoor
clothes might be damp. This extract air is drawn out through a combination of a ceiling
grill directly to the MVHR unit (‘active’) as well as ‘passively’ through an opening to the
central corridor (Plate 4.3.3.3). Using the latter technique, all of the classrooms ventilate
through the open space to be extracted at a central point.
A dual shading system is provided on the floor to ceiling glazing in each of the
classrooms. The function of the external shading is primarily to reduce potential
overheating, whereas the internal blinds are used to prevent unwanted glare for students
(Plate 4.3.3.4).
4.3.4 Perceived Benefits of the Passive House Standard
The key benefits for the owners and occupants of the school is the high level of comfort
and air quality, not to mention the significant cost savings from reduction of energy use.
The mechanical systems were designed so that teachers have full control of the air flow,
temperature and daylighting in their classrooms. They thus feel ‘connected’ with and in
control of the building.
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“The students no longer
complain about the building,
they only complain about
the teachers! :-)
School Principal
CONTENTS
Project Fact file
Project Description
Project type
School
Treated floor area in PHPP
3,275m2
Annual heat requirement (according to PHPP) (delivered energy) PHPP = 12kWh/(m²a)
Year of construction
2004
Project Team
Architects
Architekturbüro Vallentin | 84405 Dorfen
Architekturbüro Grotz, 85435 Erding
Walbrunn Architekten , 85461 Emling
Reinhard Loibl, 85345 Freising
Mechanical Engineers / Building Services Planning
Ing. Büro Lackenbauer Building Physics planning
Fraunhofer Institut, 83607 Holzkirchen Construction Details
4.3.5 Lessons learned and guidance for future projects
Construction type
Mixed construction (timber and masonry)
Exterior wall U value insulation thickness and type
0.176 W/(m²K), 280mm of cellulose insulation The Architect is very satisfied with the overall design concept of compact form, southern
orientation and simple detailing. There were some difficulties initially with the automated
control of the external shading system resulting in occasional overheating. This school
was one of the first Passive House schools in Germany (the first was built in Bremen) and
as such was somewhat experimental in its design. It was designed and built according
to principles of Passive House schools developed by the Passivhaus Institut, is working
extremely well, and the occupants are very happy with its performance. The use of
thermal massing internally has prevented any need for active cooling. In summary,
this project perfectly demonstrates that Passive House projects can be comfortable,
expressive and affordable to build.
Roof U value insulation thickness and type
0.102 W/(m²K), 406mm of cellulose insulation
Floor U value insulation thickness and type
0.146 W/(m²K), 120mm +120 mm of XPS insulation
Window frame details
Uf = 0.805 W/(m²K)
Glazing details
Ug = 0.75 W/(m²K)
g-value = 51% Ventilation Details
Air-tightness
n50 = 0.09/h
Ventilation equipment used
Robatherm manufacturer, rotationswärmetauscher
– 8000 m³ machine
Average air change rate
30 m³/h x person when occupied
15 m³/h x person when not occupied
Means of controlling ventilation rate
Manual setting
Design Heating (and Cooling) System and Renewable Energy
Heat load per m2
9,9 W/m2
Type of back-up heating system used
Combined heat and power unit (12 kW+5 kW
electric)+ gas-fuelled condensing boiler (60 kW)
Cooling load per m2
Not required
Domestic hot water production
Combined heat and power unit
Renewable energy production
Nil
Construction and Energy Costs
DESIGN GUIDELINES For Non-Domestic Passive House Projects
Cost of construction (not including cost of land)
€1,587 / m2
Estimate on additional (‘extra’) costs over conventional cost for
construction
Nil
Typical annual energy costs (only for space heating and / or
cooling)
1.92 € / m2
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4.4
CONTENTS
Kalbacher Höhe Primary School, Frankfurt
4.4.1 Motivations for project
During a design competition held for primary schools in the Frankfurt Region in 2000
/ 2001, a decision was taken to build three schools to the Passive House Standard.
Ahead of construction, a cost benefit analysis by both the school board as well as the
municipal authorities concluded that the additional cost to achieve the Passive House
Standard over and above a ‘low energy standard’ was likely to be in the order of 5.3%
which would be amortised over a 10 to 20 year period. This project at Riedberg was
opened in November 2004 and is reported as the first primary school in Germany
built to the Passive House Standard (Plate 4.4.1.1 and Plate 4.4.1.2).
Plate 4.4.1.1
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Plate 4.4.1.2
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4.4.2 Key design features
The project comprises a primary school, kindergarten and gymnasium with full
commercial kitchen and cafeteria. There are 16 classrooms serving 400 primary school
children, with an additional 120 children in the kindergarten and an adult complement of
approximately 50. The two storey building is designed in a south-facing horseshoe form
enclosing a central courtyard and playground (Figure 4.4.2.1 and Plate 4.4.2.1).
4.4.3 Mechanical Systems
Ventilation
The ventilation system when fully operational delivers approximately 8,000m3 per hour
costing in the region of €500 per year to operate. The ventilation system is only operated
during the heating season, which is in the order of 100 days during the year. Outside of this,
the MVHR is shut down (with the exception of toilets which have no openable windows)
in order to reduce primary energy consumption with fresh air being provided through
openable windows and openable vents. The air exchange rate during full occupancy is
2/h. In rooms which are infrequently used (such as staff rooms or the hall) CO2 or mixed
gas sensors control the volumetric flow regulator (Plate 4.4.3.1). Similar to the Aufkirchen
Montessori School, a centralised air exhaust system through the corridors is used.
Figure 4.4.2.1
Plate 4.4.2.1
Plate 4.4.3.1
Plate 4.4.3.2
Summer night cooling
Classrooms have high internal (25 students) and external thermal loads (15m2 of glazing
with 15% irradiation producing 60 – 80 W/m2). The heat thus has to be stored during the
day, and dissipated during the night. Each classroom is fitted with two thermostatically
controlled night air flaps (Plate 4.4.3.2) which open when required and direct airflow into
the corridors and up through roof windows. These flaps (measuring 1m2 per classroom
and opening if the temperature exceeds 260C) provide night air cooling and can be used
in combination with active night cooling using the ventilation system running with the
summer bypass in operation. Furthermore, the extract ducts terminate at a high point in
the building and can be left open to create a ‘passive’ stack effect.
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Heating system
Two 60kW wood pellet boilers are used to supply the heating for the entire complex
(Plate 4.4.3.3). The system consumes 25 tonnes of pellets per year, and the ash has to be
emptied just once annually. A simple system of small but high temperature radiators is
used in all the classrooms to provide any backup heating required. These radiators were
curiously described to MosArt as a ‘placebo’ whereby the teachers from day one feel
confident that they could control the temperature just as they like in each of the rooms.
Circulation spaces are heated only through the exhaust air passing from the classrooms. If
the windows are opened, the radiators are automatically switched off via a thermostat.
Lighting
The building uses a clever central lighting control system whereby the lights in all
classrooms are automatically turned off at the end of each lesson. It has been the
experience of the building managers that the students and teachers often don’t bother
to turn on the lights again when they return to the room, reducing primary energy
consumption.
External blinds
External blinds are provided to each classroom which are automatically controlled. The
positioning of the blinds can be temporarily overridden using a key switch. When the
blinds are fully extended, the upper one third remain open to provide natural light deep
into the room.
Plate 4.4.3.3
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4.4.4 Perceived Benefits of the Passive House Standard
The high performance glazing provides high comfort even at the window without the
need for a radiator next to the window. The promoters of this schools project maintain
that better learning conditions are created for the students as well as enhanced working
conditions for the teachers.
“The heating system was broken
for one week and nobody
realised it”
4.4.5 Lessons learned and guidance for future projects
The use of a centralised exhaust air system resulted in an increase in fire safety and noise
control measures which increased the cost of the project. In the future, the designers of
the project say that they would likely use an exhaust air duct system to each classroom
which may be more economical.
CONTENTS
Project Fact file for Kalbacher Höhe School, Frankfurt
Project Description
Project type
Primary school, kindergarten and gymnasium
Treated floor area in PHPP
8,000m2
Annual heat requirement (according to PHPP as well as
measured if available) (delivered energy)
PHPP = 15 kWh/(m²a)
Year of construction
2003 - 2004
Project Team
Architects
Architekturbüro 4a, Stuttgart
Mechanical Engineers / Building Services Planning
ICRZ, Hochbauamt Stadt Frankfurt, Ingenieurbüro Rösch,
SHL Planungsbüro
Other important design team members
Passivhaus-Institut and Transsolar
Construction Details
Construction type
Masonry
U value and insulation type and thickness used in exterior
0.17 W/(m²K), 280mm of mineral fibre insulation
wall
U value and insulation type and thickness used in roof
0.11 W/(m²K), 300mm of insulation
U value and insulation type and thickness used in floor
0.21 W/(m²K), 20mm sound insulation, 100mm of EPS
insulation, 12.5mm plasterboard and 40mm clay pebbles
Window frame details
Uf = 0.8 W/(m²K)
Glazing details
Ug = 0.6 W/(m²K)
g-value = 45% Ventilation Details
Air-tightness
n50 = 0.46/h
Ventilation equipment used
Menerga manufacturer
Average air change rate
2/h
Design Heating (and Cooling) System and Renewable Energy
Heat load per m2
10.5 W/m2
Type of back-up heating system used
Two 60 kW pellet boilers
Cooling load per m2
Not required
Method of cooling used
Night cooling achieved through night flaps
Domestic Hot Water production
Heated using the central heating system. Student
bathrooms only have cold water. User facilities > 30m
from the central heating system use electric water heaters
Renewable energy production
8 kWp of photovoltaic panels
Construction and Energy Costs
DESIGN GUIDELINES For Non-Domestic Passive House Projects
Cost of construction (not including cost of land)
€1,110 / m2 net
Estimate on additional (‘extra’) costs over conventional
cost for construction
5.3%
Typical annual energy costs (for space heating and / or
cooling)
€1.46 / m2
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CONTENTS
4.5Irish Prototype Passive House School Research and
Demonstration projects
4.5.1 Motivations for project
The Department of Education and Skills (DOES) has a proven track record in
achieving energy efficiency in their schools buildings programme, including
pioneering and exemplar projects such as the Tullamore and Raheen National
Schools. The DOES builds all its schools to exceed the current Part L of the Building
Regulations, with primary schools achieving an A3 BER and post primary achieving
B1 as a minimum setting a high standard for public buildings in Ireland and
advancing research and development of cost effective low energy construction.
In 2009, the DOES Planning and Building unit, inhouse architects and engineers
in Tullamore commenced as part of their overall energy research program
developing plans and designs for two primary schools to be constructed to
passive house principles.
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4.5.2 Key design features
The key design feature of the school is that it is based on a modular footprint that can
be easily expanded from a four classroom school to a six classroom school (Figure
4.5.2.1). Considering specifically the Passive House aspect, the building form (of the
four classroom school) is compact and in terms of orientation, there is a clear bias in the
positioning of the classrooms towards the southeast which will maximise solar gains as
well as natural daylighting during the heating season (Figure 4.5.2.2). Less frequently
used rooms as well as circulation spaces and plant rooms are logically positioned on the
northern side. While there is some stepping in terms of footprint, overshadowing will be
minimal.
4.5.3 Mechanical Systems
Figure 4.5.2.1
As has been discussed above under general design guidance for schools, thermal mass
is important in order to modulate temperature fluctuations and to minimise overheating
arising from significant internal gains. The construction method proposed for the school
comprises traditional masonry concrete floors and walls, with the former to be externally
insulated.
A centralised mechanical heat recovery ventilation system will be used to deliver the
recommended 30m3 per person per hour, achieving an average air change rate when
occupied of 1 per hour for the entire volume. The ventilation system will only be used
during school hours, plus a ‘flushing phase’ of one hour before and after closing. Rooms
that require extraction of air (such as WCs) are evenly spread around the building which
will make it easier to achieve a ‘whole-building’ integrated ventilation system.
A wood pellet boiler is proposed for the heating system, to be delivered through
radiators located in each of the rooms. Using radiators will enable hands-on control of
the heating of individual classrooms by the teachers and has been found to work well
in many completed Passive House schools in Continental Europe and this is a standard
feature in all Irish schools.
4.5.4 Perceived Benefits of the Passive House Standard
Using a building management system with significant monitoring these schools will be
used as living experiments to test various means of heating, cooling and ventilating for
future developments in Ireland.
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Figure 4.5.2.2
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4.5.5 Lessons learned in the Design Process
Factual summary overview (Table)
As part of the design process for these passive house schools, a number of alternative
construction scenarios were tested in PHPP to identify the most economical basis for
achieving the Passivhaus Standard concerning space heating demand and primary energy
demand. These scenarios were tested for the two contrasting Irish climate datasets included
in PHPP, namely for Dublin Airport and Birr in County Offaly and are presented below.
• Initial sketch: 120mm phenolic insulation and 225mm Rockwool in roof, 160mm
phenolic insulation on external walls and 160mm phenolic insulation in the floor,
with triple glazing throughout;
• Option 1: Extra 75mm Rockwool in roof, extra 40mm insulation on the walls
• and extra 40mm insulation in the floor, with double glazing throughout (overall
U-value 1.6W/m2K);
• Option 2: As above, except 300mm EPS under floor insulation;
• Option 3: As above, except triple glazing in clerestory (roof windows) in classrooms;
• Option 4: As above, with all windows in classrooms being triple glazed; and
• Option 5: As above, with all windows triple glazed and doors double glazed.
Key performance criteria calculated using the PHPP are listed in Table 1 below, illustrating
how the different scenarios would likely perform. For the purposes of this analysis, the interior
temperature is set at 190C, and night cooling is achieved using passive window ventilation.
Table 1: Comparative Performance of Alternative Scenarios (X/Y where X = Dublin Airport
climate data and Y = Birr climate data)
Space Heat Demand
kWh/(m2a)
Primary Energy Demand
kWh/(m2a)
Heating load
(W/m2)
Initial sketch
10 / 15
35 / 36
11 / 11
Option 1
18 / 23
37 / 38
14 / 14
Option 2
17 / 22
37 / 38
14 / 14
Option 3
15 / 20
37 / 38
13 / 13
Option 4
13 / 18
36 / 37
13 / 13
Option 5
8 / 12
35 / 36
11 / 11
Project Description
Project type
Passive House Primary School
Treated floor area in PHPP
816 m2
Annual heat requirement (according to PHPP) (delivered
energy)
PHPP = 15 kWh/(m²a)
Anticipated Year of construction
2010
Construction Details
Construction type
Externally insulated masonry walls and floor with timber
roof structure,
Exterior wall U value insulation thickness and type
0.133 W/(m²K), 150mm of phenolic insulation Roof U value insulation thickness and type
0.087 W/(m²K), 120mm of phenolic insulation over
300mm of mineral fibre Floor U value insulation thickness and type
0.90 W/(m²K), 250mm of phenolic insulation
Window frame details
Majority of windows double-glazed at Uf = 1.60 W/(m²K),
8 no. clerestory windows with Uf = 0.79 W/(m²K)
Glazing details
Majority of windows double-glazed at Ug = 1.30 W/(m²K)
and g-value = 64%, 8 no. clerestory windows with Ug =
0.50 W/(m²K) and g-value = 55% Ventilation Details
Air-tightness
n50 = 0.60/h (target)
Ventilation equipment used
To be confirmed post tender award
Average air change rate
1.00 /h when occupied
0.45/h average over 24 hours
Means of controlling ventilation rate
To be confirmed post tender award
Design Heating (and Cooling) System and Renewable Energy
Heat load
11W/m2
Type of back-up heating system used
Wood pellet boiler (size to be confirmed)
Cooling load per m2
8W/m2
Method of cooling used
Night cooling to be provided through ventilation system
Domestic hot water production
Wood pellet boiler
Renewable energy production
Photovoltaic panels being considered
Construction and Energy Costs
Cost of construction (not including cost of land)
Unknown at time of print
Estimate on additional (‘extra’) costs over conventional
cost for construction
Unknown at time of print
Typical annual energy costs (only for space heating and
/ or cooling)
Projected at approximately €1 / m2
As can be seen from the results in the above table, all options easily satisfy the
requirements for primary energy demand. However, only the initial Sketch as well as
Option 5 would achieve the Passivhaus Standard for space heat demand according to
both the Dublin Airport and Birr climates. If only referring to the Dublin Airport climate,
Option 3 and Option 4 would also achieve the required standard.
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4.6
CONTENTS
Tesco Supermarket, Waterford
4.6.1 Motivations for project
The Tesco store in Tramore, County Waterford, was completed in October 2008
and is the first Certified Passive House retail outlet in the World (Plate 4.6.1.1).
This project is an important case study, therefore, as it demonstrates the diversity
of building project types that can be built to the Passive House Standard. The
design and development of this Passive House supermarket was identified as the
next logical step for the supermarket chain who have been innovating for some
considerable time in terms of energy efficiency of their stores. The strategy being
deployed is to test which measures are most cost effective on pilot stores and
then apply those measures onto existing stores. The Tramore prototype is the 18th
such ‘experiment’ for this retailer worldwide. It is important to highlight that the
decision to ‘go passive’ was made post-planning, so, for example, the orientation of
the building is not ideal with regards to solar gain.
Plate 4.6.1.1
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4.6.2 Key design features
The Tesco supermarket in Tramore provides just a few hints of its eco-credentials at first
glance, including the micro-generator wind turbine, the externally exposed timber frame
and cladding and the massive roof lights (Plate 4.6.2.1). Aside from these, the store is very
similar in appearance to any other in the same chain across Ireland. What lies beneath,
however, are all the traits of typical Certified Passive House projects including tripleglazed windows, highly insulated building fabric, air-tight envelope, optimal daylighting
and low energy appliances. The glazed façade addressing the car park is north facing and
thus would not generate any solar gain during the heating season. Efforts were made to
reduce the extent of heat loss along this elevation through using 6m wide solid walls on
either side as well as a 1.2 m opaque section running along the top of the entire façade.
Otherwise for marketing purposes, the maximum amount of glass was used which also
provides a high level of day lighting along the cashier line (Plate 4.6.2.2). Six very large
roof lights provide natural daylight to the store interior, reducing the degree of artificial
daylighting required (Plate 4.6.2.3 and Plate 4.6.2.4). The exposed interior structural
elements are all laminated timber beams which are unusual in such buildings and create
a rather distinct character (Plate 4.6.2.5).
DESIGN GUIDELINES For Non-Domestic Passive House Projects
Plate 4.6.2.1
Plate 4.6.2.3
Plate 4.6.2.2
Plate 4.6.2.4
Plate 4.6.2.5
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4.6.3 Mechanical Systems
The highest energy demand in a large retail outlet such as that at Tramore is for chilling
of fridge and freezer units, equating to approximately 40% of the total energy use (Plate
4.6.3.1). There was a significant focus in this project to introduce innovative measures
to reduce this energy demand, therefore. Carbon dioxide refrigeration was used (a first
application of this technology in commercial retail for Ireland) which uses CO2 as the main
refrigerant. The use of this gas is carbon neutral (and thus does not affect the primary
energy calculations in PHPP) and the specific design application of this technology at
Tramore, consumes 15% less electrical energy than conventional 404A HFC refrigerant
systems. The electrical demand for the fridge cabinets was further reduced by replacing
conventional 32 Watt fan motors with 7 Watt EC motors along with low energy LED
lighting and trim heater control. And all the while, these innovations pass unnoticed to
the shoppers. The mechanical plant required for cooling is placed external to the building
envelope in order that it (the plant) does not contribute towards internal heat gains
inside the store which in turn would require additional cooling (Plate 4.6.3.2).
Plate 4.6.3.1
Lighting too consumes a high proportion of the electrical demands of a retail outlet (in
the region of 25% of total energy use). The strategy developed for lighting of the main
sales area in this case involved using T5 lamps (which are currently the most energyefficient lighting devices) combined with a DALI (Digital Addressable Lighting Interface)
bus system which allows for intelligent control. Artificial lighting thus actively responds
to the availability of natural daylight delivered either through the south-facing facade or
the large roof lights. Low energy LED lights were used in the fridge cabinets.
Plate 4.6.3.2
Retail outlets are often open on a 24 hour basis, and their front doors are constantly
opening and closing with resulting heat losses. Electric hot air curtains are typically used
at the front door to keep the cold air from entering the shop. In this case, however, the
warm air system is driven by a more efficient hot water system generated by the CCHP
or tri-generation plant). An ideal solution would have been to use a large revolving door
but this was not practicable on this site. Instead, a purpose designed external lobby was
introduced to allow for a buffer zone between external and internal doors (Plate 4.6.3.3).
The 2007 PHPP handbook gives some guidance (Page 86) on air infiltration loses arising
in such situations, estimated to be in the order of 1.5m3 to 4.5m3 per person and event.
Plate 4.6.3.3
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In addition to the above energy saving mechanical plant, a roof mounted photovoltaic
system (Plate 4.6.3.4) contributes electrical energy to partially power the check-out tills
and the wind turbine located in the car park provides power for the LED sign at the front
entrance. Furthermore, a tri-generation unit for production of electricity, heating and
cooling is used on the site, running on natural gas (neither the PV nor the tri-generation
unit are required for the Passivhaus Standard).
In terms of the design of the thermal envelope, the store owners required three different
temperature zones according to their function, namely 160C in the bulk storage area, 190C
in the sales area and 200C in the back-of-house offices. The concrete floor in each of these
three zones thus had to be isolated in order to prevent thermal bridging and resulting
risk of uncontrolled heat losses to the (cooler) bulk storage area.
Lastly, considering air-tightness, the average achieved for conventional Tesco stores
is 3.0m3/hr/m2. In the case of the Tramore store, the Passive House n50 requirement of
0.6ACH @ 50 Pascal equates approximately to q50 of 2.7 m3/hr/m2 which was exceeded to
the level of 2.4 m3/hr/m2. It should always be the objective of building as tight as possible,
and not ‘just’ to the threshold set by the Passivhaus institut.
4.6.4
Plate 4.6.3.4
Perceived Benefits of the Passive House Standard
The average primary energy consumption for Tesco stores in Ireland is approximately
69 kWh/ (m2/a) . This has been reduced by 40% in the Tramore store, to approximately
43 kWh/ (m2/a), saving almost 100,000 kWh of energy per year. If this amount of energy
reduction were feasible over the entire chain of stores in Ireland (consisting of some 115
stores), the savings in terms of CO2 as well as operational costs would be very significant.
There has also been a positive spin-off in terms of consumer reaction to the many ecofeatures in the store, assisted by the interactive digital display board in the entrance area
(Plate 4.6.4.1).
Plate 4.6.4.1
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“This store is very comfortable to
work in, it is like being at home in
your own sitting room”
Quotation from the Store manager
4.6.5 Lessons learned and guidance for future projects
The Tesco Passive House project cost approximately 5% more than conventional stores.
As explained earlier, this store was not originally designed as a Passive House, and it
would have been more cost effective to do so right from the outset. Areas where possible
additional savings could be made for future stores would be to locate the chilled and
frozen products in a separate insulated room (like an ‘ice cave’) and reducing the area of
expensive triple glazing. Lastly, the detailing and design consultancy required for this
project (which represents a very small proportion of the above costs) would be reduced
for future projects.
CONTENTS
Project Description
Project type
Supermarket
Treated floor area in PHPP
3,972.2m2
Annual heat requirement (delivered energy)
PHPP = 15 kWh/(m²a)
Year of construction
2008
Project Team
Architects
Joseph Doyle Architects, Dublin
Mechanical Engineers / Building Services Planning
White Young Green, Belfast
Other important design team members
Passivhaus Institut
Principal Construction Contractors
Manning & Son Ltd., Dublin
Construction Details
Construction type
Timber Frame
Exterior wall U value insulation thickness and type
0.18 W/(m²K), 150mm prefabricated wall panel filled with PIR
foam, aluminium coating (lambda = 0.025 W/(mK))
Roof U value insulation thickness and type
0.15 W/(m²K), 100mm prefabricated roof panel filled with PIR
foam, lambda = 0,025
80mm prefabricated roof panel (PUR-foam - lambda = 0.030
W/(mK))
Floor U value insulation thickness and type
Perimeter insulation only, due to the large size of the building:
ground below building acts as a heat storage. 100mm
insulation, lambda value = 0.04 W/(mK) at perimeter only:
Equivalent u-value = 3.69 W/(m²K)
Window frame details
Uf = 1.1/1.8/2.5 W/(m²K)
Uw-value 1.08 is the mean value of all vertical and horizontal
windows and glass doors.
Glazing details
Ug = 0.6 W/(m²K)
g-value = 43% Ventilation Details
Air-tightness
n50 = 0.31/h
Ventilation equipment used
Klingenberg plate heat exchanger with Klingenberg rotary
wheel.
Average air change rate
Means of controlling ventilation rate
0.30/h when occupied
CO2 sensor
Design Heating (and Cooling) System and Renewable Energy
Heat load per m2
14.9 W/m2
Type of back-up heating system used
Gas-fired Tri-generation (heating, electricity, cooling)
Cooling load per m
Space cooling = 0 W/m2, Fridges are cooled with CO2
refrigerants
2
Method of cooling used
Domestic Hot Water production
Gas-fired Tri-generation
Renewable energy production
40 photovoltaic panels producing approximately 8,450 kWh
per year
Construction and Energy Costs
DESIGN GUIDELINES For Non-Domestic Passive House Projects
Cost of construction (not including cost of land)
Not available
Estimate on additional (‘extra’) costs over
conventional cost for construction
5%
Typical annual energy costs (only for space heating
and / or cooling)
Yet to be verified
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4.7
CONTENTS
Wohn Sinn apartments, Kranichstein, Darmstadt
4.7.1 Motivations for project
This apartment development is located a very short distance from where the first
ever Certified Passive House project was completed in 1992, at Kranichstein near
Darmstadt in Germany. The first phase of the Wohn Sinn project was initiated in
2003, comprising 39 apartments, and was judged to be so successful that a second
phase of 34 apartments was built in 2008. A similar project is currently underway
adjacent to the Wohnsinn project involving approximately 44 apartments which
will be completed in 2010.
The concept for the project was developed over a number of years with the key
objective of creating a diverse yet socially integrated community of households
of different life stages (considering age and size of family unit) as well as income
levels. And it would appear that this ‘social experiment’ has been very successful.
As a practical example of the benefits of living in such a neighbourhood, it
was envisaged that families with young children could call upon their elderly
neighbours from time to time to assist with child minding when the need arises.
Some families purchased their homes, whereas others rent them privately while
others rent with some welfare assistance from the Government.
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4.7.2 Key design features
The development consists of a three storey south-facing U-shaped layout with some of
the units two storey and others single storey (Figure 4.7.2.1, Plate 4.7.2.1 & Plate 4.7.2.2).
All of the upper levels are accessed off shared terraces which connect to a lift at the
northeast corner. The entire development is thus barrier free in terms of access. All of the
homes are dual aspect, with the two north-south blocks having east and west facades,
and the connecting east -west block having south and north facing facades. All of the
homes located off the ground floor have terraces, many of which have been planted and
provide a valuable private and communal amenity (Plate 4.7.2.3).
The corners of the apartment blocks are cleverly used for community purposes, including
a day room winter garden (Plate 4.7.2.4) and library to the northwest, sauna, guest
apartments and kids den to the northeast and meeting rooms to the southwest.
In the central courtyard is located a well landscaped mound which disguises an
underground ‘bunker’ style room which is used by the community to store food items
and bulky non-perishables that require cooler temperatures than would be provided in
the Passive House apartments (Plate 4.7.2.5).
Figure 4.7.2.1
Plate 4.7.2.1
Plate 4.7.2.2
Plate 4.7.2.3
Plate 4.7.2.5
Plate 4.7.2.6
The development is just a few hundred metres from an electric tram line which connects
with the nearest urban settlement at Darmstadt just a short journey to the southwest
(Plate 4.7.2.6).
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4.7.3 Mechanical Systems
The apartments are heated through the ventilation system using a water to air heat
exchanger connected to a district heating system. The district heating is provided by a
local incinerator plant (located just a few kilometres from the project (Plate 4.7.3.1)) and
the calculation of primary energy demand from this is calculated in a dedicated Excel
sheet in the PHPP software titled ‘District Heat’.
The avoidance of needing radiators for heating results in space saving which is appreciated
by the homeowners. The exception to this rule is found in the bathrooms where a small
radiator is used to provide additional comfort and to help with clothes drying.
Each apartment has a separate heat recovery ventilation system, so every household has
direct control of their own mechanical system. There are three levels of air exchange rate;
namely low, which is used when the units are left unoccupied during holidays, normal, for
everyday use, and high, when there is a need for greater air change rate such as during a
party or family gathering.
Plate 4.7.3.1
There is no individual metering of heating energy used in the apartments as this was
felt to be too expensive given the low space heating demand. Instead, each household
is charged a flat rate per square metre on an annual basis for all their heating needs.
Consumption of domestic hot water is, however, metered.
All residents have the option to invest in the photovoltaic power plant located on the
roof of the apartment complex, which provides an annual return on investment of 3 - 4%
(Plate 4.7.3.2).
Plate 4.7.3.2
An adjacent apartment neighbourhood is currently under construction and provides
a very useful case study to see the form of construction that is used. The structural
envelope of the building is, in this case, masonry which is externally insulated in high
density polystyrene (Plate 4.7.3.3). The windows are fitted in advance of the external
insulation in order to ensure that an airtight connection between the frame and the shell
is achieved. The external insulation is then fitted to provide partial cover of the window
frame which reduces any heat losses through thermal bridging.
The mechanical heat recovery ventilation units are discretely fitted to the underside
of the ceiling over the entrance hallway (Plate 4.7.3.4) and the drain for condensate is
cleverly connected to the cistern for the toilets providing an easy means of disposal.
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Plate 4.7.3.3
Plate 4.7.3.4
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4.7.4 Perceived Benefits of the Passive House Standard
The benefits typical to Passive House projects all apply to residents at this facility,
including low heating cost, high thermal comfort, excellent indoor air quality,
bright living spaces and an overall sense of well being attributed to the high level of
sustainability. There is an additional and important social benefit in this project that can
be attributed directly towards the Passive House Standard, however. The formation of
sub-committees to assist in helping the residents to familiarise themselves with living in
Passive Houses has contributed to a stronger sense of community spirit. The community
is clearly very proud of its achievement in developing what is an excellent model of
sustainable living with the Passive House Standard being at the core.
“The first phase of this apartment
complex was so successful that it was
extended just a few years later”
Quotation from the owners / tenants / users
4.7.5 Lessons learned and guidance for future projects
In the early days of the project, it took people a while to become accustomed to the
subtleties of living in a Passive House. Some families were in the habit of leaving windows
open during the heating season, for example, and most were unfamiliar with the use
of heat recovery ventilation and the periodic changing of filters. These issues were
addressed through the formation of a number of neighbourhood groups who provided
advice and assistance to those that needed it. One of these groups visits each household
once a year to remind them to change the filters, for example.
If the temperature in the apartment drops, as might happen over a two week vacation
during the heating season, for example, it can take a while (about one day) to bring
the home up to a comfortable temperature again. This is because the primary heating
method is through the use of warm air through the ventilation system. If radiators or
underfloor heating was used, the re-heating of homes would be much quicker. This
doubling up of systems, however, (ie. ventilation system plus hydronic heating system)
would have increased the cost of construction.
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CONTENTS
Project Description
Project type
Apartment
Treated floor area in PHPP
3.885 m2 WohnSinn1, 3.097m² WohnSinn2
Annual heat requirement (according to PHPP as well as
measured if available) (delivered energy)
PHPP = 15 kWh/(m²a)
Year of construction
2002/2003 WohnSinn1, 2007/2008 WohnSinn2
Project Team
Architects
faktor10 GmbH, Petra Grenz, Darmstadt
Mechanical Engineers / Building Services Planning
WohnSinn1: Norbert Stärz, Pfungstadt
WohnSinn 2: Hans Baumgartner, Mörlenbach
Other important design team members
Passivhaus Institut, Darmstadt for WohnSinn 1
Principal Construction Contractors
WohnSinn1: Tichelmann & Barillas, Darmstadt
WohnSinn2: Büro bauart, Lauterbach, Darmstadt
Construction Details
Construction type
Concrete core made with prefabricated elements with
facade comprising a timber frame structure
Exterior wall U value insulation thickness and type
0.12 W/(m²K), either 300mm Styropor insulation on
concrete elements or 300mm Isofloc in the timber frame
elements
Roof U value insulation thickness and type
0,12 W/(m²K), either 300mm Styropor or 400mm Isofloc
Floor U value insulation thickness and type
0.11 W/(m²K), 300mm perimeter insulation
Window frame details
Uf = 0.78 W/(m²K)
Glazing details
Ug = 0.6 W/(m²K)
g-value = 50%
Ventilation Details
Air-tightness
n50 = 0.35/h
Ventilation equipment used
Vallox KWL 90, 75% efficient
Average air change rate
0.4/h when occupied
0.25 – 0.3/h when not occupied
Means of controlling ventilation rate
Manually controlled
Design Heating (and Cooling) System and Renewable Energy
Heat load per m2
10W/m2
Type of back-up heating system used
Fernwärme aus städtischem BHKW (Gas)
Cooling load per m2
N/A
Method of cooling used
N/A
Domestic Hot Water production
District heating + 25m² thermal solar collectors (used on
WohnSinn2)
Renewable energy production
250m2 of photovoltaic panels installed in 2009 –
productivity not yet determined Jahr 2009
Construction and Energy Costs
Cost of construction (not including cost of land)
1.100 € / m2– WohnSinn1
€1,230 / m²– WohnSinn2
Estimate on additional (‘extra’) costs over conventional
cost for construction
10%
Typical annual energy costs (only for space heating)
€3.60 / m2 including maintenance (not metered, flat rate
independent of actual use)
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4.8
CONTENTS
St. Franziskus Church and Community Centre, Linz, Austria
4.8.1 Motivations for project
The main motivation for the construction of this church and community centre
(completed in 2004) was “to protect as far as possible the resources of the World and
God’s creation in line with the teachings of St. Francis of Assisi without a significant
loss in comfort”. The aspiration was to create a building which has a net positive
effect on the environment through the production of renewable energy right on
the site. The project involved not only the construction of a new Church, but also
refurbishment of an existing community facility.
Figure 4.8.1.1: Plan of Church and
Community Centre
DESIGN GUIDELINES For Non-Domestic Passive House Projects
Figure 4.8.1.2: Southeast Elevation
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4.8.2 Key design features
The main part of the church proper was designed in a contemporary form, consisting of
a mostly opaque cube with a glazed section on the south façade which continues in the
roof bringing light from above (Plate 4.8.2.1, Plate 4.8.2.2 and Plate 4.8.2.3). The opaque
elements on the southern façade consist of photovoltaic cells which visually serve
as a mirror, reflecting the surrounding gardens and integrating the building into it’s
surroundings (Plate 4.8.2.4). The altar is located north of centre within the church, with a
separate sacristy to the west and a glazed wall identifying a contemplative space to the
east. The church combines with separate meeting and social rooms to cater for multiple
functions for the local community (Plate 4.8.2.5).
4.8.3 Mechanical Systems
Plate 4.8.2.1
Plate 4.8.2.2
The principal challenge in building a church to the Passive House Standard is the
extended periods of time when the building is unoccupied. To deal with this, the external
fabric of the church was insulated to such a high degree that the unheated room
temperature never drops below 120C in the even the coldest days of winter (at the time
of the authors visiting this project, the external temperature was a numbing minus 250C).
During the design development stage, a separate calculation and simulation was carried
out for the building by a specialist firm (GMI) to optimize and test the building shell and
ventilation in terms of insulation, temperature consistency and air flow energy efficiency.
The back-up heating for the church and community centre is a wood boiler which
delivers the heating both through the ventilation system as well as through hydronic
means. The heat load of the church is quite high for a Passive House and this could not be
delivered through the ventilation system.
Plate 4.8.2.3
The use of the church is generally scheduled in advance and so the heating system can
easily be programmed to deliver the optimal temperature at the times required. An
automated shading system comprising a retractable internal canopy is used in both the
ceiling and south facing glazed section to reduce any risk of overheating.
The ventilation system is turned off when the building is not occupied and is
automatically regulated by a C02 sensor.
The opaque southern façade is constructed of photovoltaic cells and there are additional
cells located on the roof (measuring in total 200m2) which generate approximately
15,000kWh per year. Hot water is delivered by 35m2 of solar collectors.
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Plate 4.8.2.4
Plate 4.8.2.5
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4.8.4 Perceived Benefits of the Passive House Standard
The parish identifies itself intensely with this new construction type and sees in it as
a contemporary way to implement the message of St. Francis (Plate 4.8.4.1). All future
churches in the district of Linz will be built with a heavy focus on ecology and economy.
CONTENTS
4.8.5
Lessons learned and guidance for future projects
The construction of the building was and still is an experiment and many elements and
building parts were used in a prototype like fashion. There is still a certain degree of fine
tuning carried out to optimise the energy efficiency.
2. Project Fact file
Completion of the church would not have been possible without the input of the local
parish community and the evolution of the project was characterized by different parties
learning from each other and by developing solutions through ‘collective building’.
This building is described locally
as ‘God’s Power Station’
Quotation from the owners / tenants / users
Project Description
Project type
Church and community centre, partially retrofitted
Treated floor area in PHPP
1,320 m2
Annual heat requirement (delivered energy)
PHPP = 17.03 kWh/(m²a)
Year of construction
2004
Project Team
Architects
Architekten Luger & Maul ZT Gesellschaft OEG
Mechanical Engineers / Building Services Planning
GMI Bernhard Gasser
Schulgasse 22
A 6850 Dornbirn
Construction Details
Construction type
Timber frame with timber cladding
Exterior wall U value insulation thickness and type
0.119 W/(m²K), 350mm of rockwool Roof U value insulation thickness and type
0.084 W/(m²K), 300mm of EPS
Plus 60mm of rockwool Floor U value insulation thickness and type
0.120 W/(m²K), 300mm of EPS Glazing details
Ug = 0.68 W/(m²K)
g-value = 53% Ventilation Details
Air-tightness
n50 = 0.12/h
Ventilation equipment used
MHRV with 85% efficiency and capable of delivering
10,150m3/h
Means of controlling ventilation rate
Combination of CO2 sensor and clock timer
Design Heating (and Cooling) System and Renewable Energy
Heat load per m2
45W/m2 (the reason this is so high as it also includes the
refurbished section of the community centre)
Type of back-up heating system used
wood boiler 85 kW
Cooling load per m2
Method of cooling used
Air circulation with earth heat exchanger
Domestic hot water production
35m² solar collectors
Renewable energy production
200m2 of photovoltaic panels producing 15,000kWh per year
Construction and Energy Costs
Cost of construction (not including cost of land)
2,250 € / m2
Estimate on additional (‘extra’) costs over
conventional cost for construction
Unknown
Typical annual energy costs (only for space heating
and / or cooling)
Unknown
Plate 4.8.4.1
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4.9
CONTENTS
Sports Hall and Community Centre, Unterschleißheim
4.9.1 Motivations for project
This project was the first Passive House sports hall in Germany. It is located
adjacent to a school in the town of Unterschleißheim, a short distance to the
northeast of Munich. The brief was to design a building which would primarily
serve the needs of the adjacent school (Figure 4.9.1.1), but also be available for use
to private sports clubs in the local community as well as serving as a community
centre for local events including occasional film screenings and theatre. This
building is thus a multi-purpose facility.
Figure 4.9.1.1: The Sports Hall (in dark green) connects to the adjacent school (below in the
above sketch) and creates a courtyard aligned with a church in the distance
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4.9.2 Key design features
The sports hall was designed to achieve a clear and simple spatial organization,
responding to a strong visual axis created by a church in the middle-distance (Plate
4.9.2.1). Both of the longitudinal facades are entirely glazed thus creating an easy
transition from outside to inside (Plate 4.9.2.2). The facility is entered via a foyer at ground
level which takes up the entire width of the hall and acts as a spectator stand during
sports events (Plate 4.9.2.3). The playing surface is located one level below as depicted
in the sectional drawing (Figure 4.9.2.1). It is possible therefore to look outwards and
inwards via the fully glazed facades of the ground floor.
In terms of structural elements, the building comprises a post-and-beam arrangement
based on a modular design which facilitated pre-fabrication of much of the project. The
roof is supported by a series of laminated timber beams tapering towards the ends and
supported by visually lightweight posts (Plate 4.9.2.4). The overall impression created is
of a lightweight floating roof, despite the fact that it conceals approximately 400mm of
mineral wool insulation!
Plate 4.9.2.1
Plate 4.9.2.2
Plate 4.9.2.3
Figure 4.9.2.4
The quality of detailing in this building is impressive, with all services and utilities neatly
integrated behind the internal finish of three-layer pine panels (Plate 4.9.2.5) which have
been glazed in white to reduce the need for artificial lighting.
Figure 4.9.2.1: The foyer provides an elevated view over the sunken sports area
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Figure 4.9.2.5
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4.9.3 Mechanical Systems
The mechanical heat recovery ventilation system was designed to cater for two different
zones, the first comprising the shower area which needs warmer temperatures and
a higher air change rate, the second in the open sports hall and foyer which needs
lower temperatures and a much reduced air change rate (due to the large volume). The
supplementary heating required is provided via a renewable energy district heating
system (using a geothermic power plant). Window sizing was guided by daylight
simulations which strike to achieve a balance between providing sufficient light for the
users of the sports hall, whilst also minimising use of artificial lighting. Roof windows are
also provided which supplement daylighting but which have louvers which can be used
to minimise risk of overheating from solar gain (Plate 4.9.3.1).
4.9.4 Perceived Benefits of the Passive House Standard
The Architect for this project is keen to emphasise that building design must be guided
by strong architectural and urban place-making concepts first and foremost, with
principles of Passive House playing a secondary role. The combination of these elements
has been successfully achieved in this project. The Passive House concept has created a
building of extremely low energy use, high comfort levels and superb indoor air quality.
”When you are outside you are
drawn inside, and when you are
inside you are drawn outside”
Plate 4.9.3.1
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4.9.5 Lessons learned and guidance for future projects
In the design of this project, there was much discussion between the Design Team and
the Local Authorities on the sizing of the ventilation system. Due to the fact that the
building was to be used not just for small groups playing sports, but also for community
events (such as concerts), the Design Team were initially requested to size the ventilation
system to cater for the latter larger occupation pattern. However, this would have
required very significant ventilation equipment that would only be used occasionally.
The solution to this challenge was achieved by providing large openable windows which
are used to supplement the MHRV when required. This hybrid system of mechanical and
natural ventilation has worked well in practice.
CONTENTS
Factual summary overview
Project Description
Project type
Gymnasium
Treated floor area in PHPP
1,000m2
Annual heat requirement (delivered energy)
PHPP = 14 kWh/(m²a)
Year of construction
2003
Project Team
Architects
P S A Pfletscher und Steffan Mechanical Engineers / Building Services Planning
Ingenieurbüro Bauer, Herr Veeh Other important design team members (eg.
Passivhaus Institut or others?)
Passivhaus Institut
Construction Details
Construction type
Timber frame
Exterior wall U value insulation thickness and type
0.088 W/(m²K), 400mm of mineral wool insulation
Roof U value insulation thickness and type
0.094 W/(m²K), 400mm of mineral wool insulation Floor U value insulation thickness and type
0.155 W/(m²K), 240mm of perimeter insulation Window frame details
Uf = 0.91 W/(m²K)
Glazing details
Ug = 0.6 W/(m²K)
g-value = 50% Ventilation Details
Air-tightness
n50 = 0.20/h
Ventilation equipment used
Menerga Resolair machine, delivering 3,000m3/h
Average air change rate
Different ventilation rates used for showering area (high air
change rate) and for the sports hall (moderate)
Means of controlling ventilation rate
Manual setting and time clock
Design Heating (and Cooling) System and Renewable Energy
Heat load per m2
11W/m2
Type of back-up heating system used
Hybrid system of geothermal heat pumps and district heating
Cooling load per m2
Not required
Method of cooling used
Not required
Domestic hot water production
District heating provided via a geothermic renewable energy
source
Renewable energy production
Not applicable
Construction and Energy Costs
DESIGN GUIDELINES For Non-Domestic Passive House Projects
Cost of construction (not including cost of land)
€2,400 / m2 net
Estimate on additional (‘extra’) costs over
conventional cost for construction
Unknown
Typical annual energy costs (only for space heating
and / or cooling)
Unknown
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CONTENTS
Sustainable Energy Authority of Ireland
Wilton Park House
Wilton Place
Dublin 2
Ireland
t +353 1 808 2100
f +353 1 808 2002
e [email protected]
w www.seai.ie
Sustainable Energy Authority of Ireland
Renewable Energy Information Office
Unit A, West Cork Technology Park
Clonakilty
Co Cork
t +353 23 8863393
f +353 23 8863398
e [email protected]
w www.seai.ie
The Sustainable Energy Authority of Ireland is financed
by Ireland’s EU Structural Funds Programme co-funded
by the Irish Government and the European Union
DESIGN GUIDELINES For Non-Domestic Passive House Projects
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