If you would like further information on this subject you can read all about it here.

If you would like further information on this subject you can read all about it here.
Technical Handbook - Domestic
Technical Handbook - Domestic
Table of Contents
Technical Handbook - Domestic ........................................................................... 1
6. Energy ....................................................................................................... 2
6.0 Introduction ...................................................................................... 2
6.1 Carbon dioxide emissions ............................................................... 9
6.2 Building insulation envelope .......................................................... 16
6.3 Heating system ............................................................................. 30
6.4 Insulation of pipes, ducts and vessels ........................................... 41
6.5 Artificial and display lighting .......................................................... 43
6.6 Mechanical ventilation and air conditioning ................................... 45
6.7 Commissioning building services .................................................. 48
6.8 Written information ........................................................................ 49
6.9 Energy performance certificates .................................................... 51
6.10 Metering ...................................................................................... 55
Annex 6.A Compensating U-values for windows, doors and
rooflights .............................................................................................. 55
Annex 6.B Compensatory approach - heat loss example .................... 56
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Technical Handbook - Domestic
Energy
6.0 Introduction
6.0.1 Background
Within Scottish building regulations, improvements in energy standards have been
made over many years, culminating in 2007 with the move to a carbon dioxide
emission based methodology for assessing carbon and energy performance in
new buildings.
In 2007, Scottish Ministers convened an expert panel to advise on the
development of a low carbon building standards strategy to increase energy
efficiency and reduce carbon emissions. This resulted in The Sullivan Report –
‘A Low Carbon Building Standards Strategy for Scotland’. A key recommendation
of this Report is staged improvements in energy standards in 2010 and 2013,
with the aim of net zero carbon buildings (emissions for space heating, hot water,
lighting and ventilation) in 2016/17, if practical.
The Climate Change (Scotland) Act 2009 http://www.legislation.gov.uk/
asp/2009/12/pdfs/asp_20090012_en.pdf creates a statutory framework for delivery
of greenhouse gas emissions reductions in Scotland. The Act sets an interim
target of a 42% reduction in emissions (compared to 1990) by 2020, and an 80%
reduction target for 2050. Annual targets will be set in secondary legislation by 1
June 2010. The high level measures required in each sector to meet Scotland’s
statutory climate change targets, for 2022 and in the long term, are set out in the
Scottish Government’s Climate Change Delivery Plan http://www.scotland.gov.uk/
Publications/2009/06/18103720/0. This includes recommendations for the delivery
of low carbon new buildings.
The construction sector has a major role to play in this respect. Emissions from
the burning of fossil fuels are contributing to climate change, with energy use in
buildings a significant source of such emissions. Increased energy efficiency and
promotion of renewable energy are therefore an important element of Scotland’s
strategy to tackle climate change.
To deliver buildings that are more energy efficient and have fewer carbon dioxide
emissions, a greater emphasis is needed on the overall effect that design and
specification choices, construction and commissioning of new work can have on
building performance.
6.0.2 Aims
The intention of Section 6 is to ensure that effective measures for the conservation
of fuel and power are incorporated dwellings and buildings consisting of dwellings.
In addition to limiting energy demand, by addressing the performance of the
building fabric and fixed building services, a carbon dioxide emissions standard
obliges a designer of new buildings to consider dwellings design in a holistic way.
Improvements set out within this section will result in a greater need to consider
the benefits which localised or building-integrated low carbon equipment (LCE)
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Technical Handbook - Domestic - Energy
(e.g. photovoltaics, solar water heating, combined heat and power and heat
pumps) can make towards meeting standards. Although the focus is primarily on
lowering carbon dioxide emissions from dwellings in use, the measures within this
section also reduce energy demand and continue to ensure that, for new homes
and new building work, use of energy and fuel costs arising from this are both
minimised.
Guidance also recognises issues relevant to requirements within Article 5 of
the EU Directive 2002/91/EC http://europa.eu/legislation_summaries/other/
l27042_en.htm on the Energy Performance of Buildings (EPBD) and Article
13 of the EU Directive 2009/28/EC on the promotion of the use of energy from
renewable sources.
The standards and guidance given in this section are intended to achieve an
improvement, reducing emissions by approximately 30% compared to the 2007
Standards. However nothing here prevents a domestic building from being
designed and constructed to be even more energy efficient and make greater use
of low carbon equipment (LCE).
6.0.3 General guidance
This section addresses the carbon dioxide emissions and energy performance of
all domestic buildings (houses, flats and maisonettes) and ancillary buildings. In
respect of dwellings, all parts of a building intended to form part of the dwelling
should be within an insulation envelope.
This section should be read in conjunction with all the guidance to the Building
(Scotland) Regulations 2004 but in particular Section 3 Environment has a close
affiliation with energy efficiency, regarding:
a. heating of dwellings
b. ventilation of domestic buildings
c. condensation
d. natural lighting
e. combustion air and cooling air for combustion appliances
f. drying facilities and
g. storage of woody biomass.
Other than where qualified in the limitations to individual functional standards,
the standards and guidance within this section apply, irrespective of the intended
lifespan or the potential to relocate a building:
• to dwellings
• to ancillary and subsidiary accommodation to dwellings (some of which may
be stand-alone buildings), that are to be heated (excepting heating rated at
2
a maximum of 25 W/m floor area, installed solely for the purpose of frost
protection)
• to stand-alone buildings that are heated (see paragraph below) and
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Technical Handbook - Domestic - Energy
• to work on existing buildings (see paragraph below).
Heated stand-alone buildings - in 2007, the EU Directive 2002/91/EC on the
energy performance of buildings led to the introduction of the category of ‘standalone building’, a definition of which is available within Appendix A of the Technical
2
Handbooks. The Directive exempts such buildings, where less than 50m in floor
area, from both the need to use a methodology to calculate energy performance
(Standard 6.1) and also the production of an Energy Performance Certificate
(Standard 6.9). The defined term includes not only detached buildings, but also
thermally divided parts of a building with separate heating shut-down control.
2
Stand-alone building that are less than 50m in floor area must still comply with
Standards 6.2 to 6.8 (6.10 not being applicable to domestic buildings). The
guidance to Standard 6.2 recommends that the insulation envelope of such a
building should achieve the level of performance applicable to an extension.
Common examples of stand-alone buildings that could be less than 50m² include:
a heated stair enclosure associated with a block of flats; a heated summerhouse
ancillary to a dwelling; and a conservatory attached to a new or existing dwelling.
Work on existing buildings - as for other standards within Scottish building
regulations, the energy standards apply to conversions and also work on existing
buildings, such as extensions, conservatories, alterations and replacement work.
However in some situations, individual standards may not apply or guidance on
compliance with the standards may differ for such work. The latter is usually to
recognise constraints that arise when working with existing buildings.
It is advisable, in the first instance, to check the functional standard as sometimes
a limitation removes certain classes of this type of work. Where not excepted by
a limitation to a standard, the provisions of the standard will apply in full to the
new work on the existing building, other than where proposed works are wholly
categorised as a conversion, where the standard in question may be met as far
as is reasonably practicable. This is identified in the introduction to the guidance
supporting each standard.
6.0.4 U-values
Thermal transmittance (U-value) is a measure of how much heat will pass through
one square metre of a structure when the temperature on either side differs by one
degree Celsius. It is expressed in units of watts per square metre per degree of
2
temperature difference (W/m K).
Measurements of U-values should be made in accordance with BS EN ISO
8990:1996 - ‘Thermal insulation. Determination of steady-state thermal
transmission properties. Calibrated and guarded hot box’. In calculation, thermal
bridging may be disregarded where the difference in thermal resistance between
2
bridging and bridged material is less than 0.1m K/W. For example, normal mortar
joints need not be taken into account in calculations for brickwork, but should be
taken into account for lightweight insulating blockwork.
Taking into account guidance from BRE publication BR 443:2006 ‘Conventions
for U-value calculations’ http://www.brebookshop.com/, individual U-values of
building elements forming the insulation envelope can be established by a number
of methods, including:
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Technical Handbook - Domestic - Energy
a. by using insulation to a thickness derived from manufacturers’ data relating to
2
thermal conductivities (W/m.K) and thermal transmittances (U-values: W/m K)
certified by a notified body
b. by calculation, taking into account thermal bridging effects of, e.g. timber joists,
structural and other framing and normal bedding mortar, by using the Combined
Method set out in BS EN ISO 6946:2007 or CIBSE Guide Section A3, 2006
Edition or
c. for floors adjacent to the ground and basements, by using the method set out in
BS EN ISO 13370: 2007 or CIBSE Guide Section A3, 2006 Edition
d. for windows, doors and rooflights, by using BS EN ISO 10077-1: 2006 or BS EN
ISO 10077-2: 2003 and, for rooflights, BS EN ISO 12567-2: 2005.
6.0.5 Thermal conductivity
The thermal conductivity (the #-value) of a material is a measure of the rate
at which that material will transmit heat and is expressed in units of watts per
metre per degree of temperature difference (W/m.K). Establishing the thermal
conductivity of materials in a building element forming part of the insulation
envelope will enable the thermal transmittance of the element to be calculated.
Measurements of thermal conductivity should be made in accordance with BS
EN 12664: 2001, BS EN 12667: 2001 or BS EN 12939: 2001. There are a wide
range of technical publications which give the thermal conductivity of common
construction materials but, where available, preference should be given to values
that are certified by a notified body. Additional guidance given in BRE publication
BR 443: 2006 should also be followed.
6.0.6 Thermal transmittance through separating elements
Previously, thermal transmittance through separating walls or separating floors
between 2 dwellings or between a dwelling and other heated parts of the same
building (e.g. between a flat and a protected zone with space heating) was not
assessed. Accommodation on both sides of the separating element was expected
to be at a similar temperature when the dwellings or buildings are occupied.
This is no longer always the case. Whilst ‘no loss’ may still be assumed for
solid walls, research has identified previously unanticipated heat losses from air
movement in cavity separating walls. This ‘thermal bypass’ is now identified in both
calculation methodology and guidance to Standard 6.1, guidance to Standard 6.2
and within the revised ‘Accredited Construction Details (Scotland) 2010’.
6.0.7 Buffering effects on the insulation envelope
If a dwelling or part of a building consisting of dwellings is separated from an
unheated enclosed area, (e.g. solid waste storage accommodation, a porch,
garage, protected zone or underground car park) the U-values of the walls/floors
(including doors and translucent glazing) may be calculated by:
a. disregarding the buffering effects and treating the element as if it is directly
exposed to the outside
b. using the relevant formulae within SAP 2009
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Technical Handbook - Domestic - Energy
c. following the procedure in BS EN ISO 6946: 2007 or
d. following the procedure in BS EN ISO 13789: 2007.
6.0.8 Roofs that perform the function of a floor
A roof of a dwelling or building consisting of dwellings that also performs the
function of a floor or similar load-bearing surface (e.g. an access deck, escape
route, roof garden or car park), should be considered as a roof for the purpose of
assessment within this section.
6.0.9 Conservatories and atria
A conservatory allows natural light and natural ventilation to be ‘borrowed’ through
glazing and ventilators into adjacent rooms of a dwelling. In view of this, a large
area of translucent material is required in the conservatory fabric to ensure that
such rooms are not adversely affected. The definition of conservatory in appendix
A of the Technical Handbooks should be read in conjunction with the SAP 2009
document. Further guidance is given on how the standards apply to conservatories
in clauses 6.1.7, 6.2.12, and 6.3.14.
In a dwelling with an atrium, it should be assumed that the atrium is to gain heat
transfer from the surrounding building. The continuity of the insulation envelope
occurs at the roof level (usually predominantly glazed with translucent material)
and the atrium is considered to be a heated part of the dwelling.
6.0.10 Performance of fixed building services
Unless otherwise identified in text, guidance given in support of Standards 6.3 to
6.6 continues to follow the recommendations developed for the Domestic Building
Services Compliance Guide http://www.planningportal.gov.uk produced by the
Department for Communities and Local Government. This is intended to allow
standardisation of the specification and expected performance of fixed building
services throughout the UK. The Guide also provides helpful supplementary
information that may assist designers in the installation and commissioning of
services to delivering optimum operating efficiency.
Additional information on the use of a range of low carbon equipment (LCE), such
as solar thermal systems, photovoltaic panels and heat pumps, and application
within building regulations can be found on the Technical Pages of the Building
Standards Division website http://www.scotland.gov.uk/Topics/Built-Environment/
Building/Building-standards/profinfo/techguide/.
6.0.11 Calculation of areas
When calculating areas for the purposes of this section and in addition to
regulation 7, schedule 4, the following should be observed:
2
a. all areas should be measured in square metres (m ), unless stated otherwise in
this guidance
b. the area of a floor, wall or roof is to be measured between finished internal
faces of the insulation envelope, including any projecting bays and in the case
of a roof, in the plane of the insulation
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Technical Handbook - Domestic - Energy
c. floor areas are to include stairwells within the insulation envelope and also nonuseable space (for example service ducts)
d. the area of an opening (e.g. window or door) should be measured internally
from ingo to ingo and from head to sill or threshold.
6.0.12 Latest changes
The 2010 edition of Section 6 incorporates a large number of changes whilst
retaining the existing methodology introduced in 2007. The majority of these
changes relate to improvement in specified performance to deliver the intended
30% reduction in carbon dioxide emissions. A full summary of changes can be
found on the Technical Handbooks page of the Building Standards Division section
of the Scottish Government website http://www.scotland.gov.uk/Topics/BuiltEnvironment/Building/Building-standards/publications/pubtech.
The key changes that have been made to the standards and guidance since 1 May
2009:
• Standard 6.1 - standard updated to reflect changes to Standard 6.9. No effect on
guidance.
• SAP 2009 now used to calculate carbon dioxide emissions.
• Clause 6.1.2 – comprehensive revisions of fuel package table and associated
notes to deliver 30% aggregate improvement on Target Emissions Rates.
• Clause 6.2.1 - improved fabric backstops for new buildings; proposal to address
performance of cavity separating walls.
• Clause 6.2.3 - revised guidance on limiting non-repeating thermal bridging &
revision of current Accredited Construction Details document.
• Clause 6.2.4 - expanded guidance on limiting uncontrolled air infiltration,
including reference to Standard 3.14 where very low infiltration rates proposed.
• Clause 6.2.5 - introduction of airtightness testing regime.
• Clause 6.2.7 - improved U-values for conversion of heated buildings (aligned
with non-domestic guidance).
• Clause 6.2.8 - expanded guidance on how to address energy performance in
conversion of older and traditional buildings.
• Clause 6.2.9 - improved fabric backstops for extensions; alternative approach
for highly-glazed extensions; improving existing buildings - guidance on
constructing extensions to better U-values where existing building fabric values
are poor.
• Clause 6.2.12 - improved U-value for glazing in conservatories, irrespective of
area.
• Standard 6.3 – 6.6 - comprehensive revision of guidance on heating
lighting, cooling and ventilation systems, efficiencies and controls. Guidance
remains based upon UK recommendations (developed by the Department of
Communities and Local Government).
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Technical Handbook - Domestic - Energy
• Standard 6.4 - limitation within standard on cooled pipes or ducts in domestic
buildings removed.
• Standard 6.5 - standard extended to include lighting in common areas of
domestic buildings.
• Clause 6.5.1 - increased percentage of energy efficient lighting; revised
minimum efficacy; new clause on common areas.
• Clause 6.5.2 - new clause on efficiency of external lighting.
• Standard 6.6 - standard extended to include ventilation and cooling systems in
domestic buildings.
• Clause 6.6.2 - new clause on efficiency of air conditioning systems.
• Clause 6.6.3 - new clause on efficiency of mechanical ventilation systems.
• Standard 6.8 - standard extended to cover ventilation and cooling systems in
domestic buildings.
6.0.13 Relevant legislation
Reference should be made to UK legal requirements enforcing Article 13 of the
Energy End-Use Efficiency and Energy Services Directive 2006/32/EC http://
europa.eu/legislation_summaries/energy/energy_efficiency/l27057_en.htm. When
building work is carried out to an existing building with a floor area of more than
2
1000m or a new building is constructed, the energy supply companies providing
services to such buildings should be notified.
Directive 2009/28/EC http://europa.eu/legislation_summaries/energy/
renewable_energy/en0009_en.htm promotes the use of energy from renewable
sources, including promotion within national legislation. It establishes a common
framework for the use of energy from renewable sources in order to limit
greenhouse gas emissions, including establishment of national action plans and
targets which set the share of energy from renewable sources for 2020.
6.0.14 Certification
Scottish Ministers can, under Section 7 of the Building (Scotland) Act 2003,
approve schemes for the certification of design or construction for compliance with
the mandatory functional standards. Such schemes are approved on the basis that
the procedures adopted by the scheme will take account of the need to co-ordinate
the work of various designers and specialist contractors. Individuals approved to
provide certification services under the scheme are assessed to ensure that they
have the qualifications, skills and experience required to certify compliance for
the work covered by the scope of the scheme. Checking procedures adopted by
Approved Certifiers will deliver design or installation reliability in accordance with
legislation.
The Certification of Design (Section 6 – Energy) for domestic Buildings scheme
has been approved by Scottish Ministers to confirm compliance with Section 6.
Details area available on the certification pages of the Building Standards Division
website http://www.scotland.gov.uk/Topics/Built-Environment/Building/Buildingstandards/profinfo/cert.
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Technical Handbook - Domestic - Energy
6.1 Carbon dioxide emissions
Mandatory Standard
Standard 6.1
Every building must be designed and constructed in such a way that:
a. the energy performance is estimated in accordance with a
methodology of calculation approved under regulation 7(a) of the
Energy Performance of Buildings (Scotland) Regulations 2008 and
b. the energy performance of the building is capable of reducing carbon
dioxide emissions.
Limitation:
This standard does not apply to:
a. alterations and extensions to buildings, other than alterations and
extensions to stand-alone buildings having an area less than 50 square
metres that would increase the area to 50 square metres or more, or
alterations to buildings involving the fit-out of the building shell which is the
subject of a continuing requirement
b. conversions of buildings
c. non-domestic buildings and buildings that are ancillary to a dwelling that are
stand-alone having an area less than 50 square metres
d. buildings, which will not be heated or cooled, other than by heating provided
solely for the purpose of frost protection or
e. limited life buildings which have an intended life of less than 2 years.
6.1.0 Introduction
Standard 6.1 focuses on the reduction of carbon dioxide emissions arising
from the use of heating, hot water and lighting in a new dwelling. The guidance
sets an overall level for maximum carbon dioxide emissions in buildings by
use of a methodology which incorporates a range of parameters that influence
energy use. This means that, for new dwellings, a designer is obliged to consider
energy performance as a complete package rather than looking only at individual
elements such as insulation or boiler efficiency - a ‘whole dwelling approach’ to
energy, which offers a significant degree of design flexibility.
For the majority of new buildings, Standard 6.1 has the greatest influence on
design for energy performance. Standards 6.2 to 6.10, in the main, recommend
benchmark and backstop levels to be achieved for individual elements or systems.
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Technical Handbook - Domestic - Energy
To achieve compliance with Standard 6.1 it will be necessary to improve on these
backstop levels or incorporate additional energy efficiency measures, such as low
carbon equipment (LCE).
Directive 2009/28/EC http://europa.eu/legislation_summaries/energy/
renewable_energy/en0009_en.htm promotes the use of energy from renewable
sources. Where the building design will include use of renewable energy for
heating, Article 13 of the Directive recommends, amongst other measures,
consideration of use of the following:
• for biomass equipment, conversion efficiencies of 85%
• for heat pumps, those that fulfil the minimum requirements of eco-labelling
established in Commission Decision 2007/742/EC of 9 November 2007
establishing the ecological criteria for the award of the Community eco-label to
electrically driven, gas driven or gas absorption heat pumps and
• for solar thermal systems, those that are subject to EU standards, including
eco-labels and other technical reference systems established by the European
standardisation bodies.
Directive 2010/31/EU http://eur-lexhttp//.europa.eu/LexUriServ/LexUriServ.do?
uri=OJ:L:2010:153:0013:0035:EN:PDF requires that, for all new buildings, the
technical, environmental and economic feasibility of high-efficiency alternative
systems (such as decentralised energy supply systems using renewable energy,
co-generation, district or block heating/cooling and heat pumps) are considered
and taken into account in developing proposals.
This should be documented and available for verification purposes and a
statement should therefore accompany the building warrant application.
Further information on this process is available in the guidance note EPC 10
- 'Consideration of high-efficiency alternative systems in new buildings'. http://
www.scotland.gov.uk/Topics/Built-Environment/Building/Building-standards/
enerperfor
Conversions - in the case of conversions as specified in regulation 4, this
standard does not apply.
6.1.1 Dwellings
Objective - the calculated carbon dioxide emissions (measured in kilograms per
square metre of floor area per annum) for the proposed dwelling, the dwelling
emissions rate (DER), should be less than or equal to the target carbon dioxide
emissions for a ‘notional dwelling’, the target emissions rate (TER).
Summary of procedure - in order to establish the target carbon dioxide emissions
rate (TER) for the ‘notional dwelling’ (i.e. a dwelling of the same size, shape and
'living area fraction' as the proposed dwelling), the dimensions and 'living area
fraction' of the proposed dwelling and a set of standard values are input into
the methodology. To calculate the emissions for the proposed dwelling (DER) a
second calculation is carried out where the proposed values are input into the
methodology. An alternative way of meeting Standard 6.1 which avoids the use of
the calculation methodology is to design to the set of values used for the ‘notional
dwelling’. This elemental approach is described in clause 6.1.6.
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Technical Handbook - Domestic - Energy
The Government’s Standard Assessment Procedure for Energy Rating of
Dwellings (SAP 2009) http://www.bre.co.uk/sap2009/page.jsp?id=1642 is the
calculation tool used with the methodology which conforms with the European
Directive 2002/91/EC http://europa.eu/legislation_summaries/other/l27042_en.htm
and is approved to calculate the energy performance and the carbon dioxide
emissions of an individual dwelling. At all stages, the conventions in the SAP
document should be read in conjunction with the specific guidance given in the
clauses to this section.
Non-domestic use within dwellings - some new dwellings may incorporate
surgeries, consulting rooms, offices or other accommodation of a floor area
not exceeding 50m² in aggregate, used by an occupant of the dwelling in a
professional or business capacity. Where this occurs, the accommodation should
be considered as a part of the dwelling.
6.1.2 Setting the target carbon dioxide emissions level
To set the target carbon dioxide emissions level, (i.e. the level that should not be
exceeded, the TER), refer to the table to this clause. The package of measures
for the fuel type for the main space heating of the proposed dwelling is selected.
This package of measures is used in the methodology and no improvement factors
are applied. In addition, this ‘notional dwelling' is to have the same size, shape
(including floor, roof, exposed wall areas and storey heights) and 'living area
fraction' as the proposed dwelling. These terms are explained in SAP 2009.
Software vendors providing BRE - approved SAP 2009 software http://
www.bre.co.uk/ will incorporate a function that, with ‘Scotland’ selected,
automatically generates the target CO2 emissions level once the fuel type is
selected and the ‘notional dwelling’ dimensions and 'living area fraction' have been
input into the programme.
Measures to calculate target carbon dioxide emissions for the 'notional
dwelling'
The measures identified in this table are set to deliver on aggregate, 30% fewer
carbon dioxide emissions than the 2007 Standards. Whilst it is possible to
construct a dwelling using one of the packages of measures (see clause 6.1.6),
this table is provided for the purpose of setting the target emission rate (TER) for
the ‘notional dwelling'.
Table 6.1 Main space heating system fuel [1] [2]
Element or Gas
LPG
Oil
Electricity Biomass [3]
system
(Package 1) (Package 2) (Package 3) (Package 4) (Package 5)
Walls
U = 0.19
U = 0.19
U = 0.19
U = 0.19
U = 0.19
Floors
U = 0.15
U = 0.15
U = 0.15
U = 0.15
U = 0.15
Roofs
U = 0.13
U = 0.13
U = 0.13
U = 0.13
U = 0.13
U = 1.5
U = 1.5
U = 1.5
U = 1.5
Openings [4] U = 1.5
Allowance
for thermal
bridging [5]
0.08 x total 0.08 x total 0.08 x total 0.08 x total 0.08 x total
exposed
exposed
exposed
exposed
exposed
surface area surface area surface area surface area surface area
Open flues
None
One
One
11
None
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Technical Handbook - Domestic - Energy
Element or Gas
LPG
Oil
Electricity Biomass [3]
system
(Package 1) (Package 2) (Package 3) (Package 4) (Package 5)
Heating
system
(pump in
heated
space) [10]
Gas boiler
room sealed
fan flued,
90.2%
efficiency
LPG boiler
room sealed
fan flued,
90.2%
efficiency
Oil boiler
room
sealed fan
flued, 93%
efficiency
Air to water
heat pump
[6]
Heating
system
controls
Programmer Programmer Programmer Programmer
+room
+room
+room
+room
thermostat thermostat thermostat thermostat
+TRVs
+TRVs
+TRVs
+Boiler
+Boiler
+Boiler
interlock
interlock
interlock
+weather
+weather
+weather
compensationcompensationcompensation
+delayed
+delayed
+delayed
start
start
start
Programmer
+room
thermostat
+TRVs
+weather
compensation
+ delayed
start
Hot water
(HW)
system
Stored HW
(from boiler)
separate
time control
for space
and water
heating
Stored HW
(from boiler)
separate
time control
for space
and water
heating
Stored HW Stored HW
(from boiler) by electric
separate
immersion
time control
for space
and water
heating
Stored HW
(from boiler)
separate
time control
for space
and water
heating
Secondary
space
heating
none
10% closed
wood logburning
room heater
[7]
10% closed 10% electric none
wood logburning
room heater
[7]
Solar
thermal
system
Yes [8]
Yes [8]
Yes [8]
Yes [8]
Wood
pellet boiler
HETAS
approved
Yes [8]
Table 6.2 For the 'notional dwelling' in addition all of the
following applies in every fuel type
Windows, doors and rooflights
area 25% of total floor area [9]
Orientation
all glazing orientated east/west
Shading
average overshading
Number of sheltered sides
2
Chimneys
none
Ventilation system
natural ventilation with intermittent
extract fans. 4 for dwellings with floor
2
area more than 80 m , 3 for smaller
dwellings
Air infiltration through building fabric
7m /m h at 50 Pa
Hot water cylinder (combined cylinder
with 75 litre solar store)
150 litre cylinder insulated with 50mm of
factory applied foam (cylinder in heated
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Technical Handbook - Domestic - Energy
space); cylinder temperature controlled
by thermostat
Primary water heating losses (where
applicable)
primary pipework insulated
Low energy light fittings
100% of fixed outlets
Thermal mass parameter
The value identified for the proposed
building should be used
2
Party wall heat loss (applicable to cavity 0.2 W/m K
separating walls)
Notes:
1. Where a multi-fuel appliance is proposed, assessment of both TER and DER
should be based upon the fuel option with the highest carbon factor (e.g. multifuel stove capable of burning coal or wood is assessed as solid mineral fuel).
Where heat is supplied to a dwelling from more than one source, through a
generation mix (e.g. community heating using both oil and biomass where heat
is provided from both sources simultaneously), the primary heating element
within the TER should be calculated pro rata, on the basis on the basis of the
identified fuel mix. The same mix should be used in calculation of the DER,
including any pro rata contribution made by solutions such as CHP. This does
not apply where heat demand can be provided solely from one of the identified
generating sources, in which case other identified heat sources should be
considered as back-up systems and excluded from the assessment.
2. Where solid mineral fuel is proposed for the main space heating system, the
TER should be calculated using the values identified for oil as a fuel (package
3). This will require improvements in performance within the DER specification
for compliance.
3. The biomass column should be used not only where biomass fuel is to be used
but also for biogas, large scale waste combustion from boilers and waste heat
from power stations.
4. U is the average U-value of all openings (windows, doors, rooflights) based on
2
one opaque door 1.85 m of U =1.5, any other doors fully glazed. For windows,
doors etc a frame factor of 0.7, light transmittance of 0.80 and solar energy
transmittance of 0.63 are assumed.
5. For the purposes of setting the TER, a y-value of 0.08 is identified, which
assumes construction using the principles set out in the BSD document
‘Accredited Construction Details (Scotland) 2010' (http://www.scotland.gov.uk/
topics/built-environment/building/building-standards). In determining the DER,
guidance on designing to limit heat loss from non-repeating thermal bridges is
given in clause 6.2.3.
6. For calculation of the TER, radiators should be identified as the distribution
system (seasonal performance factor 1.75).
7. The closed wood log-burning room heater should be capable of burning wood
only, not multi-fuel.
8. Evacuated tube (collector efficiency ##= 0.6, heat loss coefficient a1 = 3),
oriented between SE and SW, pitch not more than 45º from horizontal, solar
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Technical Handbook - Domestic - Energy
powered circulation pump. Panel size for TER calculation, rounded to the
2
nearest 0.1 m , determined as follows:
2
Dwelling area < 100m : 0.75 + (0.0375 x total floor area)
2
Dwelling area > 100m : 4.3 + (0.002 x total floor area)
2
2
For dwellings smaller than 35m , a panel size of 2m should be used in the TER
calculation.
9. If total exposed facade area is less than 25% of the floor area, the area of
windows, doors and roofs should be taken as the area of the total exposed
facade area.
10.For gas and oil, boiler efficiency values for the specific notional dwelling are
SEDBUK (2005). Equivalent values for SEDBUK (2009) are Natural gas and
LPG-89%, oil-90%.
6.1.3 Calculating carbon dioxide emissions for the
proposed dwelling
The second calculation involves establishing the carbon dioxide emissions for the
proposed dwelling (DER). To do this the values proposed for the dwelling should
be used in the methodology i.e. the U-values, air infiltration, heating system, etc.
The exceptions to entering the dwelling specific values are:
a. it may be assumed that all glazing is orientated east/west
b. average overshading may be assumed if not known. 'Very little' shading should
not be entered
c. 2 sheltered sides should be assumed if not known. More than 2 sheltered sides
should not be entered
d. where secondary heating is proposed, if a chimney or flue is present but no
appliance installed the worst case should be assumed i.e. a decorative fueleffect gas appliance with 20% efficiency as secondary heating. If there is no
gas point, an open fire with 37% efficiency should be assumed as secondary
heating burning solid mineral fuel for dwellings outwith a smokeless zone and
smokeless solid mineral fuel for those that are within such a zone.
All other values can be varied, but before entering values into the methodology,
reference should be made to:
• the back-stop U-values identified in guidance to Standard 6.2 and
• guidance on systems and equipment within Standards 6.3 to 6.6.
6.1.4 Buildings with multiple dwellings
Where a building contains more than one dwelling (such as a block of flats or
terrace of houses) the average carbon dioxide emissions for the proposed block
or terrace (DER) may be compared to the average target CO2 emissions (TER) for
the ‘notional block or terrace'.
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Technical Handbook - Domestic - Energy
The average emissions for the block or terrace is the floor-area-weighted average
for all the individual dwelling emissions, i.e:
{(emissions1 x floor area1)+(emissions2 x floor area2)+(emissions3 x floor area3)+
…..)} ÷ {(floor area1+ floor area2 + floor area3) + …..}.
The degree of flexibility which is provided by averaging out building emissions
should be used carefully. It is not intended that one or more dwellings are superinsulated (in a building consisting of dwellings) so that another may be constructed
with a high percentage of glazing.
6.1.5 Common areas in buildings with multiple dwellings
Communal rooms or other areas in blocks of dwellings (which are exclusively
associated with the dwellings) should be assessed either by:
a. using the guidance to Standard 6.1 for non-domestic building or
b. ensuring that the glazing does not exceed 25% of the total communal floor area
of the building; and the U–values, thermal bridging, air infiltration values equal
or better those given for the gas 'notional dwelling' (package 1 in the table to
clause 6.1.2).
2
However where the common areas are less than 50m in total these rooms or
areas may be treated as a stand-alone building and are not therefore subject to
Standard 6.1.
6.1.6 A simplified approach
Where a dwelling is designed to one of the packages of measures in the table to
clause 6.1.2, it can be considered to reduce carbon dioxide emissions to the same
level as by use of the methodology, calculating and comparing DER with TER.
In using a package of measures east/west orientation, average overshading and 2
sheltered sides may be assumed for the proposed dwelling.
The simplified approach may still be used where there are minor deviations of
input values that will clearly achieve the same or a better level of emissions. For
example:
• a thermal mass parameter value of 'medium' should be assumed
• a boiler with a higher SEDBUK efficiency
• a ground source heat pump instead of an air source heat pump
• where secondary heating forms part of the TER calculation, a secondary space
heating system of equal or better performance (e.g. a closed, biomass-burning
room heater)
• area of openings between 20% and 25% of total floor area (windows, doors,
rooflights, and roof windows)
3
2
• a declared air infiltration of 7m /m .h at 50Pa or lower
• a hot water cylinder with a declared heat loss figure (BS 1566-1: 2002) not
exceeding 2.11kWh/day.
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Technical Handbook - Domestic - Energy
This simplified approach should not be used where there is any deviation from
values in the table which will result in higher CO2 emissions. An example is if the
dwelling has more than 4 extract fans or windows of a poorer U-value. Likewise, if
some elements offer poorer performance and others offer higher performance, the
simplified approach should not be used.
This approach should also not be used where there is a likelihood of high internal
temperature in hot weather or where air-conditioning is proposed. Reference
should be made to the guidance to Standard 6.6.
Note that an Energy Performance Certificate (EPC) will still be required, on
completion of the dwelling, to meet Standard 6.9.
6.1.7 Conservatories and stand-alone buildings
2
Conservatories of less than 50m in area are stand-alone buildings, thermally
separated from the dwelling. A dwelling to which one is attached should be
assessed as if there was no conservatory proposed.
2
For conservatories and other ancillary stand-alone buildings of 50m or more the
guidance and methodology for non-domestic buildings should be followed.
6.2 Building insulation envelope
Mandatory Standard
Standard 6.2
Every building must be designed and constructed in such a way that an
insulation envelope is provided which reduces heat loss.
Limitation:
This standard does not apply to:
a. non-domestic buildings which will not be heated, other than heating
provided solely for the purpose of frost protection
b. communal parts of domestic buildings which will not be heated, other than
heating provided solely for the purpose of frost protection or
c. buildings which are ancillary to dwellings, other than conservatories, which
are either unheated or provided with heating which is solely for the purpose
of frost protection.
6.2.0 Introduction
The levels set out in the guidance to this standard are robust back-stops and these
are necessary for the following reasons:
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Technical Handbook - Domestic - Energy
• to help reduce energy demand (particularly where use of low carbon equipment
(LCE) may reduce carbon dioxide emissions but not energy consumption) and
• to ensure that a good level of fabric insulation is incorporated, especially to
construction elements that would be difficult and costly to upgrade in the future.
Non-repeating thermal bridging at the junctions of building elements and
around openings in the building envelope form part of the calculation of energy
performance in the Standard Assessment Procedure (SAP 2009, see clause
6.1.1). Heat loss through such junctions, if poorly designed and constructed, can
contribute significantly to the overall heat loss through the insulation envelope.
Limiting infiltration - as fabric insulation levels improve, the heat lost through
uncontrolled infiltration of air through the building envelope (air permeability)
becomes proportionally greater. For example, in a typical 1960s house with nondraughtstripped windows 20% of the total heat could be lost through air infiltration
and ventilation. If the same house was upgraded to 2002 levels of fabric insulation
but no attempt made to reduce the air infiltration then the losses from infiltration
could represent up to 40% of total heat losses. Limiting infiltration, whilst providing
controllable ventilation, is therefore essential if both energy efficiency and good
indoor air quality are to be achieved.
Conversions - in the case of conversions, as specified in regulation 4, the
building as converted shall meet the requirements of this standard in so far as
is reasonably practicable, and in no case be worse than before the conversion
(regulation 12, schedule 6).
6.2.1 Maximum U-values
Area-weighted average U-values - column (a) of the table below sets out robust
backstop measures. In most cases, meeting Standard 6.1 will result in even better
levels of thermal insulation unless the design of a dwelling involves extensive use
of building-integrated or localised low carbon equipment (LCE).
Individual element U-values - localised areas of the same building element may
be designed to give a poorer performance, providing the average U-value for all
elements of the same type is maintained by designing the rest of the element to
a more demanding level. An example of this would be a meter box set into an
external wall. These localised areas should have a U-value no worse than the
figures given in column (b) of the table below. This is particularly important with
regard to the control of condensation (see Section 3 Environment). Repeating
thermal bridges (e.g. timber studs in a timber frame wall) should not be considered
as an individual element in this respect, as these are already taken into account
within a BS EN ISO 6946: 2007 U-value calculation.
Common area - for communal areas refer to clause 6.2.13.
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Technical Handbook - Domestic - Energy
Table 6.3 Maximum U-values for building elements of the
insulation envelope
Type of element
(a) Area-weighted
average U-value (W/
2
m K) for all elements of
the same type
(b) Individual element U2
value (W/m K)
Wall [1]
0.25
0.70
Floor [1]
0.20
0.70
Roof
0.18
0.35
Windows, doors and
rooflights
1.8
3.3
Additional information
1. Excluding separating walls and separating floors between heated areas where
thermal transmittance need not be assessed, provided measures to limit heat
loss arising from air movement within the cavity separating wall (see below).
Cavity separating walls - recent research has established that previously
unanticipated heat loss can arise via air movement, within a cavity separating
wall, from heated areas to points outwith the insulation envelope. To limit this
heat loss a separating wall cavity should have effective perimeter sealing around
all exposed edges and in line with insulation layers in abutting elements which
separate the dwelling from another building or from an unheated space this allows
a U-value of 0.2 to be assigned to such walls. Further reduction in heat loss can
be achieved where the cavity separating wall is also fully filled with a material that
limits air movement.
In addressing this issue, regard should be paid to the need to limit noise
transmission (see Section 5 Noise).
Information on reducing heat loss from air movement in a cavity separating
wall can be found in the Building Standards Division document ‘Accredited
Construction Details (Scotland) 2010’ http://www.scotland.gov.uk/Topics/BuiltEnvironment/Building/Building-standards/profinfo/techguide/
6.2.2 Areas of windows, doors and rooflights
Due to the target method set by carbon dioxide emissions Standard 6.1, there is
no need for guidance on minimum or maximum area for windows, doors, rooflights
and roof windows in new dwellings.
The methodology for establishing compliance with Standard 6.1 considers
conflicting energy issues of heat loss versus solar gain and natural lighting
versus artificial lighting. In certain cases, where there is a desire to have a large
proportion of glass it may be difficult to demonstrate compliance with Standard
6.2. In such cases, innovative solutions will need to be considered. All relevant
Standards and guidance should be considered, including Standard 6.6, on
avoiding high internal summer temperatures.
Guidance on alterations, extensions and conversions is provided in clauses 6.2.6
to 6.2.13.
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Technical Handbook - Domestic - Energy
Common areas - for communal areas refer to clause 6.2.13.
6.2.3 Limiting heat loss through thermal bridging
As insulation values of new buildings improve, the need to limit heat loss through
thermal bridging becomes increasingly important. Incorrect detailing at design
stage or poor construction work can have a significant adverse effect on building
performance.
The insulation envelope of any heated building should be designed and
constructed to limit heat loss through thermal bridging. The key areas of concern
are:
• repeating thermal bridging within building elements and
• non-repeating thermal bridging at the junction between building elements and at
the edges of building elements where openings in the envelope are formed.
Whilst repeating thermal bridges are taken into account in the BS EN ISO 6946:
2007 U-value calculation, a separate assessment of non-repeating thermal
bridging should be carried out for new buildings which are subject to Standard 6.1.
Advice and further information on assessment of the effects of thermal bridging
can be found in BRE Information paper IP 1/06 – 'Assessing the effects of thermal
bridging at junctions and around openings'http://www.brebookshop.com/
A value for non-repeating thermal bridging, which should be input into SAP 2009,
can be determined in one of the following ways:
2
a. a conservative default y-value of 0.15 W/m /K may be assumed or
b. where construction is in accordance with the BSD document 'Accredited
Construction Details (Scotland) 2010' http://www.scotland.gov.uk/topics/builtenvironment/building/building-standards an assessed value can be calculated
simply, using the  (psi) value of each junction (provided in the document) and
the lengths of the thermal bridging element of each junction or
c. a y-value derived from numerical modelling of individual  (psi) values
calculated in accordance with BS EN ISO 10211: 2007 ‘Thermal bridges
in building construction - heat flows and surface temperatures - detailed
calculations’. Guidance on this process is given in BR 497, ‘Conventions For
Calculating Linear Thermal Transmittance and Temperature Factors’ http://
www.brebookshop.com/.
Further commentary on this process and use of other published documents
providing sources of pre-calculated values can be found within ‘Accredited
Construction Details (Scotland) 2010’ http://www.scotland.gov.uk/Topics/BuiltEnvironment/Building/Building-standards.
6.2.4 Limiting uncontrolled air infiltration
To limit heat loss, any heated building should be designed to limit uncontrolled
air infiltration through the building fabric. This is done by providing a continuous
barrier that resists air movement through the insulation envelope and limits
external air paths into each of the following:
• the inside of the dwelling or building consisting of dwellings
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Technical Handbook - Domestic - Energy
• the ‘warm’ side of insulation layers
• spaces between the component parts of exposed building elements, where such
parts contribute to the thermal performance of the element.
Using a target-based methodology for new buildings in Standard 6.1 (carbon
dioxide emissions), a reduction in uncontrolled infiltration will allow greater design
flexibility in the application of other energy performance measures. The infiltration
3 2
rate used for the TER calculation is 7m /m .h @ 50 Pa (see clause 6.1.2). Whilst
no backstop value is set for uncontrolled infiltration, it is recommended that
3 2
buildings are designed to achieve a value of 10m /m .h @ 50 Pa or better to allow
a balanced approach to managing building heat loss.
Designing and constructing a building in accordance with the principles set out
in BSD's document 'Accredited Construction Details (Scotland) 2010' http://
www.scotland.gov.uk/topics/built-environment/building/building-standards will
assist in limiting air infiltration. Due to the contribution of both detailing and
workmanship, it remains difficult to achieve a specified air infiltration rate with
any degree of accuracy. To ensure the dwelling will deliver the intended thermal
performance without adversely affecting air quality, air tightness testing should be
undertaken to verify as-built air infiltration rates (see clause 6.2.5).
Limiting air infiltration to improve energy performance should not compromise
ventilation required for:
• the health of the occupants of the building (Section 3)
• the removal of moisture from building fabric (Section 3)
• the safe operation of combustion appliances (Section 3) and
• any smoke control system (Section 2).
3
2
Lower air infiltration rates, of less that 5m /m .h @ 50 Pa, may give rise to
problems with internal air quality and condensation. Accordingly, where design
infiltration rates are proposed below this rate, reference should be made to
additional measures needed to ensure air quality under Standard 3.14, on
provision of ventilation within dwellings.
Common areas - in building consisting of dwellings, common areas which need
particular consideration to limit air infiltration include common stair entrances
and shafts which extend through most of the floors (e.g. lift and common stair
enclosures).
6.2.5 Air-tightness testing
Low air infiltration rates will contribute to energy performance but should not be
so low as to adversely affect the health of occupants or the building fabric. There
is, therefore, a need to establish building performance by test, to demonstrate
compliance in both these respects.
Evidence from testing of dwellings, constructed to the 2007 Accredited
Construction Details (Scotland), and of similar constructions elsewhere in the UK,
3 2
indicates that air-tightness levels of 5 to 7m /m .h @ 50 Pa are readily achievable
and can be exceeded unintentionally. Air-tightness testing should be carried out
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Technical Handbook - Domestic - Energy
on new buildings to ensure that air infiltration rates deliver both the stated design
level under this guidance and minimum levels of ventilation needed (see Section 3
Environment).
In order to allow the capacity of the testing industry to grow in Scotland, the need
to carry out infiltration testing is being phased in as follows:
• For building warrant applications made on or after 1 May 2011 - testing of flats
and maisonettes only and
• For building warrant applications made on or after 1 October 2011 – testing of all
dwelling types.
Frequency of testing dwellings - as a baseline, testing of completed dwelling
should be carried out on 1 in 20 dwellings or part thereof. The verifier may,
however, request that the frequency of testing be varied, as considered
appropriate to reasonable enquiry and in response to previous test results within a
development.
In larger developments, it is advisable to test more than one example of the same
dwellings type, completed at different stages in the overall development, to help
establish consistency in quality of construction.
In smaller developments, the proportion of dwellings tested may need to increase,
dependent on the range of type and form of dwellings present, to ensure a
representative sample is taken.
Normally for a development of one dwelling, an air-tightness test should be
carried out as it will not be possible to obtain comparative data on the quality of
construction from similar dwellings. Alternatively, for any single dwelling, or any
3 2
number of dwellings where a default design value of 15m /m .h @ 50 Pa is stated
in demonstrating compliance under Standard 6.1, testing need not be carried out.
Test methods - testing should be in accordance with BS EN 13829: 2001 –
‘Thermal performance of buildings - determination of air permeability of buildings
- fan pressurisation method’. Practical advice on procedure for pressure testing is
given in the ATTMA publication ‘Measuring Air Permeability of Building Envelopes’
http://www.attma.org/.
Testing should be carried out by persons who can demonstrate relevant,
recognised expertise in measuring the air permeability of buildings. This should
include membership of a professional organisation which accredits its members as
competent to test and confirm the results of testing.
6.2.6 Conversion of unheated buildings
A building that was originally designed to be unheated has, in most instances,
the greatest void to fill in terms of energy efficiency. Heating such buildings will
adversely affect energy efficiency and because of this, the most demanding of
measures are recommended when conversion occurs.
Where conversion of an unheated building (e.g. a barn) or part of a dwelling is to
be carried out, the building should achieve the same standards to those for an
extension to the insulation envelope by following the guidance in clauses 6.2.9
and 6.2.10. This same approach should be taken for the conversion of buildings
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Technical Handbook - Domestic - Energy
2
with heating rated at a maximum of 25W/m floor area and installed solely for the
purposes of frost protection.
Conversion of part of a dwelling - examples of work which involve conversion of
part of a dwelling are: changing a roof space, an unheated garage or a deep solum
space into an apartment:
• in the case of a roof space, this will usually involve extending the insulation
envelope to include, the gables, the collars, a part of the rafters and the oxters,
as well as any new or existing dormer construction. The opportunity should be
taken at this time to upgrade any remaining poorly performing parts of the roof
which are immediately adjacent to the conversion, for example, insulation to
parts of the ceiling ties at the eaves
• in the case of an unheated garage, this will usually involve extending the
insulation envelope to include, the existing floor, perimeter walls and the roof/
ceiling to the new habitable part and
• in the case of a deep solum space, this will usually involve extending the
insulation envelope to include, the solum/existing floor and perimeter walls to the
new habitable part.
6.2.7 Conversion of heated buildings
In the case of a building that was previously designed to be heated, the impact
on energy efficiency as a result of the conversion, may be either negligible, none
whatsoever or in some circumstances even an improvement.
A less demanding approach than identified in clause 6.2.6 is recommended which
at the same time still ensures that some overall improvements are being made to
the existing building stock.
Where an extension or conservatory is formed and/or alterations are being made
to the building fabric at the same time as the conversion, the guidance given in
clauses 6.2.9 to 6.2.12 should also be followed.
U-values - where conversion of a heated building is to be carried out, the existing
insulation envelope should be examined and upgraded following the table below:
Table 6.4 Maximum U-values for building elements of the
insulation envelope
Type of element
(a) Area-weighted
average U-value (W/
2
m K) for all elements of
the same type
(b) Individual element U2
value (W/m K)
Wall [1] [2]
0.30
0.70
Floor [1] [2]
0.25
0.70
Roof [1]
0.25
0.35
Where new and
replacement windows,
doors and rooflights are
installed [3][4]
1.6
3.3
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Technical Handbook - Domestic - Energy
Additional information:
1. Where upgrading work is necessary to achieve the recommended U-values,
reference should be made to 'Reconstruction of elements' in clause 6.2.11 and
more demanding U-values achieved, where reasonably practicable.
2. Excluding separating walls and separating floors between heated areas where
thermal transmittance need not be assessed, provided measures to limit heat
loss arising from air movement within a cavity separating wall are made (see
clause 6.2.1).
3. The total area of windows, doors and rooflights, should not exceed 25% of the
floor area of the dwelling created by conversion. Alternatively, a compensatory
approach should be taken.
4. Windows with a window Energy rating of Band C or better may also be used
(www.bfrc.org) http://www.bfrc.org/.
6.2.8 Conversion of historic, listed or traditional
buildings
With historic, listed or traditional buildings, the energy efficiency improvement
measures that should be invoked by conversion can be more complex.
Whilst achieving the values recommended in clause 6.2.7 should remain the aim,
a flexible approach to improvement should be taken, based upon investigation of
the traditional construction, form and character of the building in question and the
applicability of improvement methods to that construction. Provisions under other
legislation (e.g. planning consent for listed buildings or those within conservation
areas, where there is a need to maintain character, form or features) are also
relevant.
For all buildings, it would be advisable to consider the feasibility of upgrading fabric
to at least the U-values given in column (c) in clause 6.2.9 (individual element Uvalues). In many cases, specialist advice will be helpful in making an assessment
to ensure that, in improving energy efficiency, there is no other, adverse effect to
the building fabric.
Accordingly, each building will have to be dealt with on its own merits.
Improvements to the fabric insulation of the building will often depend on factors
such as whether or not improvement work can be carried out in a non-disruptive
manner without damaging existing fabric (for example, insulating the ceiling of
an accessible roof space), or whether potential solutions are compatible with the
existing construction.
In certain cases, buildings are given historic or listed status because of specific
features present in certain parts of the building. In these circumstances, it may be
possible to make greater improvements to other less sensitive areas.
In all cases the ‘do nothing’ approach should not be considered initially. Innovative
but sympathetic and practical solutions to energy efficiency, which are beyond the
scope of this guidance, can often result in an alternative package of measures
being developed for a building. For example, carbon dioxide emissions can be
reduced without affecting building fabric through improvements to the heating
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Technical Handbook - Domestic - Energy
system (refer to Standards 6.3 and 6.4), the lighting system (refer to Standard
6.5) or incorporation of low carbon equipment (such as a biomass boiler or heat
pump). Consultation on such matters at an early stage with both the verifier and
the planning officer of the relevant authority is advised.
6.2.9 Extensions to the insulation envelope
Extension of a building is not subject to Standard 6.1. In view of this, measures
to limit energy demand and carbon dioxide emissions rely primarily upon the
performance of the new building fabric.
As the majority of construction work for an extension will be new, there will seldom
be the need to consider construction to a lesser specification as is sometimes
the case for conversions and alterations. The exception to this is at the junction
between existing and new, for example the need for proprietary metal ‘wall starter’
ties where the existing brickwork stops and new cavity blockwork begins. However
other building standards should still be met with regard to such transitional
construction elements.
U-values - unlike a new building, an extension to an existing building will not
commonly benefit from the provision of an efficient heating system or low carbon
equipment (LCE). Therefore, fabric U-values should improve on the new build
backstops identified in clause 6.2.1 to limit CO2 emissions and energy demand to
an equivalent level.
Accordingly, where the insulation envelope of a dwelling or a building consisting of
dwellings is extended, the new building fabric should be designed in accordance
with one of two levels of elemental U-values for walls, floors, roof, windows, doors
and rooflights, as shown in the table below.
The applicability of particular maximum U-values for new works is determined
by the energy performance of the existing building, assessing external wall and
roof elements. Where a building has external walls with a U-value poorer than 0.7
and a roof with a U-value poorer then 0.25, then the more demanding U-values
in column (a) should be applied to the extension. Where existing wall and roof
elements already meet or, as part of the works, will be upgraded to meet U-values
of 0.7 and 0.25 respectively, the U-values in column (b) can be applied to the
extension.
Table 6.5 Maximum U-values for building elements of the
insulation envelope
Type of element
Wall [2]
Area-weighted average U-Value (W/
2
m K) for all elements of the same
type
(a)where UValues for wall
and roof of the
existing dwelling
are poorer than
0.7 [1] and 0.25
respectively
(b) where
parameters for
column (a) do not
apply
0.19
0.22
24
(c) Individual
element U-Value
2
(W/m K)
0.70
Technical Handbook - Domestic - Energy
Type of element
Area-weighted average U-Value (W/
2
m K) for all elements of the same
type
(c) Individual
element U-Value
2
(W/m K)
(a)where UValues for wall
and roof of the
existing dwelling
are poorer than
0.7 [1] and 0.25
respectively
(b) where
parameters for
column (a) do not
apply
0.15
0.18
0.70
Pitched roof
0.13
(insulation between
ceiling ties or
collars)
0.15
0.35
Flat roof or pitched 0.15
roof (insulation
between rafters or
roof with integral
insulation)
0.18
0.35
Windows, doors,
rooflights
1.6 [4]
3.3
Floor [2]
1.4 [3]
Additional information:
1. The Building Standards (Scotland) Amendment Regulations 1982, came into
force on 28 March 1983, introduced thermal insulation for an exposed wall
2
broadly equivalent to 0.7W/m K.
2. Excluding separating walls and separating floors between heated areas where
thermal transmittance need not be assessed, provided measures to limit heat
loss arising from air movement within a cavity separating wall are made (see
clause 6.2.1).
3. Windows with a Window Energy Rating of Band A may also be used
www.bfrc.org http://www.bfrc.org/.
4. Windows with a Window Energy Rating of Band C or better may also be used
www.bfrc.org http://www.bfrc.org/.
The U-values (area weighted average U-values) for column (b) of the table to this
clause are summarised in the diagram below. The extension is the shaded portion,
the existing dwelling is in elevation behind.
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Technical Handbook - Domestic - Energy
Figure 6.1 U-values for building elements of insulation envelope
Area of windows, doors and rooflights - where the insulation envelope of a
domestic building is extended, the area of windows, doors, rooflights and roof
windows should be limited to 25% of the floor area of the extension plus the area
of any openings built over and removed as a result of the extension work. This
figure may be exceeded if the compensatory approach, below, is adopted.
Varying U-values - Compensatory approach - the U-values for the elements
involved in the work may be varied provided that the area-weighted overall U-value
of all the elements in the extension is no greater than that of a ‘notional’ extension.
The ‘notional’ extension should be the same size and shape as one designed to
the elemental U-values in the table above with the area of windows, doors and
rooflights taken as 25% of the total extension floor area (plus equivalent area of
'built over openings'). An example of this approach is given in annex 6B.
Alternative approaches for highly-glazed extensions - where SAP data is
available for the existing dwelling, it may be practical to provide a revised SAP
calculation to demonstrate compliance of a dwelling, as proposed, including
extension, as part of the enlarged dwelling, using the target-based methodology
(DER not more than TER) set out in guidance to Standard 6.1 (carbon dioxide
emissions). This option will generally only be viable where both extension and
dwelling are built to the same, current edition of the standards.
6.2.10 Thermal bridging and air infiltration for existing
buildings
Where works are to alter, extend or convert a building, the elements of the work
should follow the guidance in clauses 6.2.3 and 6.2.4 and reference should be
made to the principles set out in BSD's document 'Accredited Construction Details
(Scotland) 2010'. It should be noted that Standard 6.1 does not apply to this type
of work unless the designer chooses to use the methodology identified in guidance
3
to Standard 6.1, as noted in clause 6.2.9. In such cases, a default value of 10m /
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Technical Handbook - Domestic - Energy
2
m .h @ 50 Pa, can be assumed or the testing of the extension carried out as
identified in clause 6.2.5.
In addition, the recommendations within the Building Research Establishments
(BRE) Report 262 'Thermal insulation, avoiding risks' 2002 edition can be followed.
6.2.11 Alterations to the insulation envelope
For alterations it is more than likely that the existing construction will be from a
different era, in building regulation terms. In many instances each building will
need to be considered on its own merits. Some of the guidance given in this
clause is written in specific terms, but in certain cases (e.g. historic, listed or
traditional buildings), it may be necessary to adopt alternative energy efficiency
measures which relate to the amount of alteration work being undertaken.
Extending the insulation envelope - alterations that involve increasing the floor
area and/or bringing parts of the existing building that were previously outwith
the insulation envelope into the heated part of the dwelling are considered as
extensions and/or conversions (regulation 4, schedule 2) and reference should be
made to the relevant guidance clause for such work.
2
Infill of small openings - the infill of an existing opening of approximately 4m
or less in the building fabric should have a U-value which matches at least that of
the remainder of the surrounding element. In the case of a wall or floor however it
2
2
should not be worse than 0.70W/m K, and for a roof, not worse than 0.35W/m K.
Infill of large openings - the infill of an existing opening of greater area (than
2
approximately 4m ) in the building fabric should have a U-value which achieves
those in column (b) of the table to clause 6.2.9. Another way would be to follow the
guidance in the paragraph above, but compensate for the energy efficiency deficit
by improving the overall U-value of other parts of the insulation envelope.
Insulation envelope formed from internal elements - where the alteration
causes an existing internal part or other element of a building to form the insulation
envelope, that part of the building (including any infill construction) should have
U-values which achieve those in column (b) of the table to clause 6.2.9. This will
most likely occur where a part of a building is permanently removed as a phase of
the alteration work. Another approach would be to follow the guidance given for
'infill of small openings' above, but compensate for the energy efficiency deficit by
improving the overall U-value of other parts of the insulation envelope. Where this
occurs at a boundary, no upgrading need be carried out if the element is a wall
that is exclusively the property of the adjoining building.
Where windows, doors and rooflights are being created or replaced, they
should achieve the U-value recommended in column (b) of the table to clause
6.2.9. A compensating approach may be used and an example of this is given
in annex 6A. For secondary glazing, an existing window, after alteration should
2
achieve a U-value of about 3.5W/m K. Where the work relates only to 1 or 2
replacement windows or doors, to allow matching windows or doors be installed,
the frame may be disregarded for assessment purposes, provided that the centre
2
pane U-value for each glazed unit is 1.2W/m K or less.
Areas of windows, doors and rooflights - where additional windows, doors and
rooflights are being created, the total area (including existing) of these elements
should not exceed 25% of the total dwelling floor area.
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Technical Handbook - Domestic - Energy
In the case of a heated communal room or other area (exclusively associated with
the dwellings), it should not exceed 25% of the total floor area of these rooms/
areas.
Reconstruction of elements - where the build-up of an element forming part of
the insulation envelope is to be altered or dismantled and rebuilt, the opportunity
should be taken to improve the level of thermal insulation. Column (b) of the
table to clause 6.2.9 gives benchmark U-values and in many cases these can be
achieved without technical risk, within the constraints of the existing construction.
It is recognised however that certain constructions are easier to upgrade than
others. A building that was in a ruinous state should, after renovation, be able to
achieve almost the level expected of new construction. It may not however be
reasonably practicable for a dwelling, which is in a habitable condition, to have
its internal space significantly reduced in area or height in order to accommodate
insulation; or for excessive enabling alterations to be caused by the fitting of
external thermal insulation, unless the owner/occupier of the dwelling intends
that these changes are to be made. Other building standards and the impact that
they will have when upgrading thermal insulation should be taken into account.
In the majority of cases however after an alteration of this nature to the insulation
envelope, a roof should be able to achieve at least an average U-value of 0.35 and
2
in the case of a wall or floor, 0.70W/m K.
Further guidance on this subject can be found on the Energy Saving Trust website
(http://www.energysavingtrust.org.uk/).
Thermal bridging and air infiltration - when alterations are carried out, attention
should still be paid to limiting thermal bridging at junctions and around windows,
doors and rooflights and limiting air infiltration (clause 6.2.10). As far as alterations
are concerned, only the work that forms the alteration and the impact of that work
on the existing building need be considered.
6.2.12 Conservatories
Conservatories are a common addition to many dwellings. Traditionally used as an
ancillary space, occupied for part of the year, conservatories are now often used
year-round leading to an increased heating demand. Accordingly, such buildings
should, like other heated stand-alone buildings, be constructed to limit energy
demand and reduce CO2 emissions.
Some smaller conservatories can be exempt from both building warrant and
2
building standards (see Section 0). Conservatories of 50m or more are subject to
Standard 6.1 of the non-domestic guidance.
Thermal division - a conservatory should be thermally divided from a dwelling,
being outwith the insulation envelope of the dwelling. The dividing elements (e.g.
wall, door, window) should have U–values equal or better than the corresponding
exposed elements in the rest of the dwelling.
U-values - although conservatories are attached to dwellings, they are standalone buildings. Where not exempt, a conservatory (heated or unheated) should
be built to the same maximum U-values as any other new work, as listed in
columns (b) and (c) of the table in clause 6.2.9, with the exception that glazing and
framing elements forming the walls or roof of a conservatory are unlimited in area
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2
and should have a maximum area-weighted average U-value of 2.0W/m K and a
2
maximum individual element U-value of 3.3W/m K.
Varying U-values Compensating U-values for windows, doors and rooflights
2
- individual U-values for the glazed and framing elements may exceed 2.0W/m K
provided that the average U-value for all the glazed and framing elements is no
2
greater than 2.0W/m K. An example of this approach is given in annex 6A.
Thermal bridging and air infiltration - in order to limit air infiltration and thermal
bridging at junctions and around windows, doors and rooflights, guidance in clause
6.2.10 should be followed.
If using the BSD document: 'Conservatories' http://www.scotland.gov.uk/topics/
built-environment/building/building-standards/publications/pubtech/techconserv/
these issues will be considered to have been taken into account. Draught
stripping for windows and doors which are part of the thermal division between
the conservatory and the dwellingshould be of a similar standard as the exposed
windows and doors elsewhere in the dwelling.
6.2.13 Stand-alone buildings
Thermal division of a stand-alone building from the remainder of a dwelling or
domestic building is explained in clause 6.2.12.
2
For heated stand-alone buildings of less than 50m , the fabric values identified
in columns (b) and (c) of the table to clause 6.2.9 and clause 6.2.10 should be
followed. U-value recommendations should be met, though it should be noted
that the area of glazing is not limited. This allows, for example, a dwelling to be
extended to create a highly-glazed stand-alone building such as a sunroom, with
glazing in excess of the limits identified in clause 6.2.9.
2
Stand-alone buildings of 50m or more are subject to Standard 6.1. Reference
should be made to clause 6.1.7 and use of the non-domestic calculation
methodology to assess carbon dioxide emissions.
Common areas - where the total area of a communal room or other heated
2
accommodation associated with a block of dwellings is less than 50m , these
rooms or accommodation should also be treated as a stand-alone building.
Elements (including dividing elements) should have U-values equal to or better
than those chosen for the rest of the building, as determined in conjunction with
the methodology in Standard 6.1. As part of a new building, the area of windows,
doors, rooflights and roof windows in these rooms or accommodation should be
limited to 25% of the total floor area of these common areas.
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Technical Handbook - Domestic - Energy
6.3 Heating system
Mandatory Standard
Standard 6.3
Every building must be designed and constructed in such a way that the
heating and hot water service systems installed are energy efficient and
are capable of being controlled to achieve optimum energy efficiency.
Limitation:
This standard does not apply to:
a. buildings which do not use fuel or power for controlling the temperature of
the internal environment
b. heating provided solely for the purpose of frost protection or
c. individual solid-fuel or oil-firing stoves or open-fires, gas or electric fires or
room heaters (excluding electric storage and panel heaters) provided as
secondary heating in domestic buildings.
6.3.0 Introduction
In the design of domestic buildings, the energy efficiency of the heating plant is
an important part of the package of measures which contributes to the overall
dwelling carbon dioxide emissions. In practice the backstop levels given in this
guidance for appliance efficiencies and controls will normally be exceeded to
achieve compliance with Standard 6.1 for new buildings.
This guidance refers to main heating systems for dwellings. Both the primary
heating and secondary heating systems are taken account of in SAP 2009.
When the guidance in Section 3 Environment on heating requirements for
dwellings is considered along with Standard 6.1, central heating (rather than using
several individual appliances as primary heating) will usually be the most practical
way to satisfy the standards.
Directive 2009/28/EC promotes the use of energy from renewable sources. Where
the dwelling design will include use of renewable energy for heating, Article 13 of
the directive recommends, amongst other measures, consideration of use of the
following:
• For biomass equipment, conversion efficiencies of 85%.
• For heat pumps, those that fulfil the minimum requirements of eco-labelling
established in Commission Decision 2007/742/EC of 9 November 2007
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Technical Handbook - Domestic - Energy
establishing the ecological criteria for the award of the Community eco-label to
electrically driven, gas driven or gas absorption heat pumps.
• For solar thermal systems, those that are subject to EU standards, including
eco-labels and other technical reference systems established by the European
standardisation bodies.
Conversions - in the case of conversions, as specified in regulation 4, the
building as converted shall meet the requirements of this Standard in so far as
is reasonably practicable, and in no case be worse than before the conversion
(regulation 12, schedule 6).
6.3.1 Gas and oil wet central heating efficiency
Boilers and appliances installed in a dwelling or building consisting of dwellings
should have minimum appliance efficiencies as set out below:
Table 6.6 Efficiency of gas and oil wet central heating boilers
and appliances
Heating system
Efficiency
Gas central heating boilers (natural gas SEDBUK (2005) [1] 90% or
or LPG)
SEDBUK (2009) 88%
Oil central heating boilers
SEDBUK (2005) [1] 90% or
Conventional boilers
SEDBUK (2009) 88%
Combination boilers
SEDBUK (2005) or (2009) [1] 86%
Gas or oil (twin burner) range cooker
central heating boilers
75% [2] (gas)
80% [2] (oil)
Gas fired fixed independent space
heating appliances used as primary
space heating
63% gross
Oil fired fixed independent space
heating appliances used as primary
space heating
60% gross
Additional information:
1. Seasonal Efficiency of Domestic Boilers in the UK. If the SEDBUK rating
of an appliance is not dated, it should be assumed to be a 2005 value
(www.sedbuk.com http://www.sedbuk.com/ www.boilers.org.uk http://
www.boilers.org.uk/).
2. Information on seasonal efficiency of range cookers is declared at
(www.rangeefficiency.org.uk http://www.rangeefficiency.org.uk/).
Vented copper hot water storage vessels associated with the system should meet
the heat loss and heat exchanger requirements in BS 1566-1: 2002.
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6.3.2 Solid fuel wet central heating efficiency
The appliance efficiency should be at least that required for its category as
designated by the Heating Equipment Testing Approval Scheme (HETAS) (http://
www.hetas.co.uk/) as given in the table below:
Table 6.7 Efficiency of solid fuel central heating appliances
Category
Appliance type
Efficiency (gross
calorific value)
D
Open fires with high
output boilers
63%
F
Room heaters and stoves 67% (mineral fuels and
with boilers
logs)
70% (wood pellets – part
load)
75% (wood pellets –
nominal load)
G
Cookers with boilers
65% (mineral fuels)
55-60% (wood fuels)
J
Independent boilers
(batch-fed) wood logs
75%
Independent boilers
(batch-fed) multi-fuel
65% (mineral fuels)
75% (wood logs)
Independent boilers
(automatic feed)
anthracite
70% up to 20.5kW
Independent boilers
(automatic feed) wood/
pellets/chips
75% nominal load
75% above 20.5kW
70% part load
Vented copper hot water storage vessels associated with the system should meet
heat loss and heat exchanger requirements in BS 1566-1: 2002 or BS 3198: 1981.
6.3.3 Electric wet central heating efficiency
Electric flow boilers should be constructed to meet the requirements of the Low
Voltage Directive and Electromagnetic Compatibility Directive, preferably shown
by a third party electrical approval e.g. British Electrotechnical Approvals Board
(BEAB) or similar. Vented copper hot water storage vessels associated with the
system should meet BS 1566: 2002 or BS 3198: 1981.
For the most efficient use of electrical supplies it is recommended that an electric
flow boiler is used to provide space heating alone, with the bulk of the hot water
demand of the dwelling being supplied by a directly heated water heater utilising
'off-peak' electricity tariffs.
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Technical Handbook - Domestic - Energy
6.3.4 Heat pump systems efficiency (warm and hot water)
All heat pumps are at their most efficient when the source temperature is as high
as possible, the heat distribution temperature is as low as practicable and pressure
losses are kept to a minimum.
When designing a heating system, the following operational provisions should be
applied:
Table 6.8 Heat pump systems efficiency minimum efficiency:
Heat Pump Systems
System
Supply temperatures
Underfloor heating
30ºC - 40ºC (new systems)
30ºC - 55ºC (existing systems)
Radiators – high efficiency radiators
with high water volume should be
utilised
40ºC - 55ºC
Fan coil units
35ºC - 45ºC
Domestic hot water
60ºC - 65ºC
Additional information:
1. A supplementary method of water heating should be provided if the heat
pump is not capable of supplying water at these temperatures during normal
operation.
Electrically driven heat pumps should have a coefficient of performance, calculated
using the procedures identified in BS EN 14511 series of standards, of not less
than:
• 2.2 when used for space heating or
• 2.0 when used for heating domestic hot water.
Electrically driven heat pump systems should also have a notional Seasonal
Performance Factor (SPF) not less than the relevant value identified under clause
C.3 of BS EN 15450: 2007.
Reference can be made to the DECC/Carbon Trust Energy Technology List
(http://etl.decc.gov.uk/etl/about/) for assistance in identifying equipment with this
recommended performance.
A water distribution system should be arranged for reverse return operation or
arranged with a low loss manifold system to maximise efficiency.
6.3.5 Dry central heating systems efficiency
Gas fired warm air systems
For a new gas-fired warm air system, the appliance should meet the
recommendations of BS EN 778: 2009 or BS EN 1319: 1999, depending on the
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Technical Handbook - Domestic - Energy
design of the appliance. The system should be installed in accordance with the
recommendations in BS 5864: 2004. Where a gas-fired circulator is incorporated in
the warm-air unit to provide domestic hot water, it should be of a type that is able
to deliver full and part load efficiency at least equal to that recommended by BS
EN 483: 2000.
Heat pump warm air systems
Refer to guidance in clause 6.3.4 on warm water systems. Minimum clearances
adjacent to all airflow paths, as recommended by the manufacturer, should be
maintained. For ground to air and water to air systems constant water flow should
be maintained through the heat pump.
6.3.6 Solar water heating efficiency
Solar water heating has low or zero carbon dioxide emissions and low or no
associated running costs and is inherently energy efficient. Reference may be
made to BS EN 12975: 2006 for information on collector performance for systems.
Location and orientation for optimum energy efficiency and to avoid overshading
should be considered and SAP 2009 takes account of these issues in order to
meet Standard 6.1.
The effective solar storage volume of a system should be:
2
• at least 25 litres (or equivalent heat capacity) per net m of the solar collector
absorber area or
• a volume (or heat equivalent heat capacity) which is equivalent to at least 80%
of the daily hot water demand (Vd) as defined by SAP 2009.
A heat exchanger between a solar primary and secondary system should provide
2
2
not less than 0.1m or equivalent of heat exchanger area per net m of solar
collector absorber area.
The electrical input power of a primary pump in a solar system should be rated at
not more than 50W or 2% of the peak thermal power of the collector, whichever is
the higher.
6.3.7 Micro combined heat and power efficiency
This guidance covers micro-combined heat and power (micro-CHP) systems with
an electrical output less than 5kWe. It is recommended that the system should be
heat-led and capable of exporting electricity to the grid, and controlled in such a
way as to avoid heat dumping.
The maximum Heating Plant Emission Rate (HPER) of a micro-CHP system
(measured in kgCO2/kWh) can be determined by dividing the carbon factor of the
fuel used by the minimum efficiency, given in clause 6.3.1, for an appliance using
that fuel. For example, for a gas CHP system, this would be 0.23 kgCO2/kWh.
The system HPER should be calculated using the Annual Performance Method
for micro-CHP systems that have been tested according to PAS 67 - ‘Laboratory
test to determine heating and electrical performance of heat led micro-generation
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Technical Handbook - Domestic - Energy
packages primarily intended for heating dwellings’. Appendix N of SAP 2009
(http://www.bre.co.uk/sap2009/page.jsp?id=1642) provides further information on
assessment of micro-CHP.
6.3.8 Efficiency of heating system circulators
Stand-alone, glandless heating system circulators and water pumps should be
rated at a minimum of Band C in respect of energy efficiency, in accordance
with the Europump Labelling Scheme. Further information is available at
www.bpma.org.uk/.
6.3.9 Controls for wet space heating and hot water
systems
Independent time and temperature control of heating and hot water circuits should
be provided along with a boiler interlock (refer to table below) to ensure that the
boiler and pump only operate when there is a demand for heat.
Small dwellings - zone controls are not considered necessary for single
apartment or other small dwellings.
2
For large dwellings with a floor area over 150m independent time and
temperature control of multiple space heating zones is recommended. Each zone
2
(not exceeding 150m ) should have a room thermostat, and a single multi-channel
programmer or multiple heating zone programmers. For hot water systems in large
dwellings, more than one hot water system should be considered e.g. a separately
controlled second hot water cylinder or heat source or a separate distribution
system from the same cylinder.
A hot water system (other than for combi boilers with storage capacity 15 litres or
less) should have controls that will switch off the heat when the water temperature
required by the occupants has been achieved and during periods when there is
no demand for hot water. For hot water central heating systems this thermostat
should be interconnected with the other controls which are needed to form a boiler
interlock.
The following tables summarise minimum recommendations for controls for
space and hot water gas, oil, electric and solid fuel ‘wet’ central heating systems
(radiators, convectors):
Table 6.9 Controls for combis, CPSU boilers, electric boilers
Type of control
Means to achieve
Boiler control
Boiler interlock
Automatic bypass valve [1][2]
Time control
Time switch (7 day for space heating)
Full programmer for electric
Room temperature control
TRVs (all radiators except in rooms with
room thermostats or where 'heat bleed'
required), Room thermostat(s)
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Technical Handbook - Domestic - Energy
Additional information:
1. As advised by boiler manufacturer in conjunction with any requirements for a
minimum pipe length.
2. An electric flow boiler should be fitted with a flow temperature control and be
capable of modulating the power input to the primary water depending on space
heating conditions.
Table 6.10 Controls for other boilers
Type of control
Means to achieve
Boiler control
Boiler interlock (for solid fuel as advised
by manufacturer)
Automatic bypass valve [1]
Time control
Full programmer (7 day for space and
hot water) [2]
Room temperature control
as above table
Cylinder control
Cylinder thermostat plus 2 port valves or
a 3 port valve [3]
Separately controlled circuits to cylinder
and radiators with pumped circulation
Pump control
Pump overrun timing device as required
by manufacturer
Additional information:
1. As note 1 to first table.
2. For solid fuel the level of sophistication of time controls should be selected to
be compatible with the appliance. The highest levels should only be used for
appliances with automatic ignition.
3. A zone valve is not recommended for a thermal store.
An alternative to the controls shown in the tables above would be a boiler
management control system.
Information and explanations of the various controls and heating types can be
found on the Energy Saving Trust website and in SAP 2009.
Solid fuel boilers
Hot water systems - these should be thermostatically controlled to reduce the
burning rate of the fuel, by varying the amount of combustion air to the fire. For
safety reasons, a suitable heat bleed (slumber circuit) from the system should be
formed - for example, a gravity fed radiator without a TRV or a hot water cylinder
that is connected independent of any controls. For hot water systems, unless the
cylinder is forming the slumber circuit, a thermostatically controlled valve should
be fitted, provided that the appliance manufacturer’s requirements for dealing with
excess heat created during a pump over-run are met.
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Technical Handbook - Domestic - Energy
Gas or oil (twin burner) range cooker central heating boilers
An appliance with 2 independently controlled burners (one for cooking and one for
the boiler) is recommended.
Gas and oil fired fixed independent space heating appliances
Each appliance should be capable of providing independent temperature control
in areas with different heating needs. This could be independent or in conjunction
with room thermostats or other appropriate temperature sensing devices.
Hot water underfloor heating
The controls described below should be fitted to ensure safe system operating
temperatures:
a. separate flow temperature high limit thermostat should be used for warm water
systems connected to any high water temperature heat supply and
b. mixed systems containing both radiators and underfloor heating, connected to
a common high water temperature supply operating at more than 60ºC should
be provided with a separate means of reducing the water temperature to the
underfloor heating system.
Minimum recommendations for room temperature, time and boiler controls are:
Table 6.11 Controls for underfloor heating
Type of control
Means to achieve
Room temperature control
Thermostats for each room (adjacent
rooms with similar functions may share
[1])
Weather compensating controller
Time control
Automatic setback of room temperature
during unoccupied periods/at night time
Boiler control
Boiler interlock
Additional information:
1. Bathrooms or en-suites which share a heating circuit with an adjacent bedroom
provide heat only when the bedroom thermostat is activated. In such cases,
the bathroom or ensuite areas should be fitted with an independent towel rail or
radiator.
Heat pumps hot water systems
Heat pump unit controls should include:
a. control of water temperature for the distribution system
b. control of water pumps (integral or otherwise)
c. defrost control of external airside heat exchanger (for air to water units)
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Technical Handbook - Domestic - Energy
d. control of outdoor fan operation (for air to water units)
e. protection for water flow failure
f. protection for high water temperature
g. protection for high refrigerant pressure and
h. protection for external air flow failure (on air to water units).
External controls - controls which are not integral to the unit should include:
• room thermostat to regulate the space temperature and interlocked with the heat
pump unit operation and
• timer to optimise operation of the heat pump.
6.3.10 Controls for dry space heating and hot water
systems
Small dwellings/large dwellings - zone controls are not considered necessary
for single apartment or other small dwellings. For large dwellings with a floor
2
area over 150m , independent time and temperature control of multiple space
2
heating zones is recommended. Each zone (not exceeding 150m ) should have a
room thermostat, and a single multi-channel programmer or multiple heating zone
programmers.
Electric storage heaters
Electric storage heater controls should include:
a. charge control: there should be automatic control of input charge, able to detect
the internal or external temperature and adjust the charging of the heater
accordingly and
b. temperature control: heaters should have manual controls for adjusting the rate
of heat release from the appliance. This may take the form of an adjustable
damper or some other thermostatically controlled means.
Panel heaters
Time and temperature control should be provided using:
• a programmable time switch and thermostat integral to the appliance or
• a separate time switch and separate room thermostats.
Electric warm air systems
Time and temperature control should be provided either integral to the heater or
external, using either:
• a time switch/programmer and room thermostat or
• a programmable room thermostat.
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Technical Handbook - Domestic - Energy
Gas fired warm air systems (without water heating)
Time and temperature control should be provided using:
• controls outwith the heater: time switch/programmer and room thermostat, or
programmable room thermostat or
• controls integrated with heater: time-switch/programmer and room temperature
sensor linked to heater firing and fan speed control.
Electric underfloor heating
The guidance relating to hot water underfloor heating should be followed
(disregarding the boiler interlock). For electric storage, direct acting systems and
under-tile systems programmable room timer/thermostats with manual over-ride
feature room controls are recommended for all heating zones, with air and floor (or
floor void) temperature sensing capabilities to be used individually or combined. A
storage system should have anticipatory controllers installed controlling low tariff
input charge with external temperature sensing and floor temperature sensing.
A manual override facility should be available for better user control. Controls for
storage systems with room timer/thermostats should take advantage of low tariff
electricity except where the system has anticipatory controllers controlling low tariff
input charge with external temperature and floor temperature sensing.
Heat pumps warm air systems
In addition to the controls that are not integral to the unit for heat pump hot water
systems (refer to clause 6.3.9) and the controls (b) to (h) for such systems, warm
air system controls should include:
• control of room air temperature (integral or otherwise) and
• control for secondary heating (if fitted) (on air to air systems).
6.3.11 Controls for combined warm air and hot water
systems
The first paragraph of the above clause provides guidance on zones for small and
large dwellings. However the following controls should be provided in all cases:
a. independent time control of both the heating and hot water circuits (achieved by
means of a cylinder thermostat and a timing device, wired such that when there
is no demand for hot water both the pump and circulator are switched off)
b. pumped primary circulation to the hot water cylinder
c. a hot water circulator interlock (achieved by means of a cylinder thermostat and
a timing device, wired such that when there is no demand from the hot water
both the pump and circulator are switched off) and
d. time control by the use of either:
• a full programmer with separate timing to each circuit
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Technical Handbook - Domestic - Energy
• two or more separate timers providing timing control to each circuit
• a programmable room thermostat(s) to the heating circuit(s) or
• a time switch/programmer (two channel) and room thermostat.
6.3.12 Controls for solar water heating
To ensure the safe and efficient operation of a system, controls should be provided
to:
a. optimise the useful energy gain from the solar collectors into the system’s
storage vessel(s)
b. minimise the accidental loss of stored energy by the solar hot water system,
whether originating from solar collectors, cold intake or auxiliary heat sources
c. ensure that hot water produced by auxiliary heat sources is not used when
adequate grade solar pre-heated water is available
d. provide a means of control consistent with the solar system being inherently
secure against the adverse affects of excessive primary temperatures and
pressures
e. ensure where possible that, where a separate DHW heating appliance is preheated by a solar system, no extra heat is added if the target temperature is
already satisfied from the solar pre-heat and
f. inform the end user of the system’s correct function and performance at all
times.
6.3.13 Work on existing buildings
The guidance in the above clauses also relates to:
• space heating/hot water system alterations or installations (including new
or replacement appliances) for conversions and extensions to the insulation
envelope and
• where alterations are being made to an existing heating/hot water system or a
new or replacement heating/hot water system is being installed in an existing
dwelling (or building consisting of dwellings). For example thermostatic radiator
valves should be installed to all new radiators in an extension even when the
heating is from an existing boiler.
For example, thermostatic radiator valves should be installed to all new radiators in
an extension even when the heating is from an existing boiler.
Part system - if a heating and/or hot water system is being replaced in part, the
guidance in the above clauses should be followed but only as it affects the new
or replaced components of the system. Such alterations should not allow the
heating system as a whole to be downgraded in terms of energy efficiency or
compromised from a safety point of view.
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Condensing boilers - there may be exceptional circumstances which make
it impractical or uneconomic to install a condensing boiler as recommended in
the guidance to clause 6.3.1. This can be shown by following the criteria set
out in the 'Guide to Condensing Boiler Installation Assessment Procedure for
Dwellings (Scotland)' (http://www.scotland.gov.uk/Topics/Built-Environment/
Building/Building-standards/publications/pubtech/techcondboilinstall). Where this
occurs the minimum SEDBUK efficiencies are: mains natural gas 78%, LPG 80%,
oil 85%, oil combi 82%. Alternatively a replacement back boiler with a SEDBUK of
3 percentage points less than the above recommended figures may be installed.
In addition existing gas and oil systems with semi-gravity circulation should be
converted to fully pumped systems.
For historic, listed or traditional buildings the guidance in the above clauses
should be referred to taking into account circumstances. In many cases heating
system improvements will be more feasible than any other energy efficiency
measures such as improving wall insulation. Therefore systems which go beyond
these minimum backstop levels may help offset the deficiency in other areas of
energy efficiency and in carbon dioxide emissions terms.
6.3.14 Conservatories
As a conservatory which is heated will be inefficient in energy terms, the general
guidance to occupiers is that they should be heated as little as possible. In view of
the fact that heating is often desired particularly at the start and end of the heating
season, any conservatory with heating installed should have controls that regulate
it from the rest of the dwelling e.g. a thermostatic radiator valvue (TRV) to each
radiator.
6.4 Insulation of pipes, ducts and vessels
Mandatory Standard
Standard 6.4
Every building must be designed and constructed in such a way that
temperature loss from heated pipes, ducts and vessels, and temperature
gain to cooled pipes and ducts, is resisted.
Limitation:
This standard does not apply to:
a. buildings which do not use fuel or power for heating or cooling either the
internal environment or water services
b. buildings, or parts of a building, which will not be heated, other than heating
provided solely for the purpose of frost protection or
c. pipes, ducts or vessels that form part of an isolated industrial or commercial
process.
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6.4.0 Introduction
Thermal insulation to heating pipes and ducts and hot water storage vessels will
improve energy efficiency by preventing:
• uncontrolled heat loss or heat gains from such equipment and
• an uncontrolled rise in the temperature of the parts of the building where such
equipment is situated.
Conversions - in the case of conversions, as specified in regulation 4, the
building as converted shall meet the requirements of this standard in so far as it
is reasonably practicable, and in no case be worse than before the conversion
(regulation 12, schedule 6).
6.4.1 Insulation of pipes and ducts
Warm air ducts and hot water pipes serving a space heating system should be
thermally insulated against uncontrolled heat loss unless the use of such pipes
or ducts always contribute to the heating demands of the room or space. In some
cases this will not be necessary where pipe and duct runs occur just behind the
internal wall or ceiling linings of the insulation envelope. This will not only address
energy conservation issues but will also assist with frost protection. Further
information on this subject is contained in BR 262, Thermal Insulation Avoiding
Risks http://www.brebookshop.com/.
Hot water pipes to appliances - pipes that are used to supply hot water to
appliances within a domestic building should be insulated against heat loss. This is
to conserve heat in the hot water pipes between frequent successive draw-offs. All
pipes of a solar water heating primary system should be insulated.
Insulation for such pipes and ducts may be provided by following the guidance on
insulation thickness given in BS 5422: 2009. The selection of insulation thickness
should be representative of both environmental conditions and fluid temperatures
within the pipes or duct, in question. For example, reference can be made to the
2001 edition of BS 5422 for insulation to pipework within unheated areas.
The building design should be considered at an early stage to ensure the complete
insulation of pipe and ducts where such services pass through or around structural
building components.
6.4.2 Insulation of vessels
A hot water storage vessel should be insulated against heat loss. Vented copper
hot water storage cylinders should comply with the heat loss recommendations
within BS 1566-1: 2002. Vessels themselves should be identified as having a
23
standing heat loss (kWh/day) of not more than 1.15 x (0.2 + 0.051 V / ) where V is
the declared volume of the vessel.
In addition to guidance within clause 6.4.1, other pipework that connects to the
vessel, including any vent pipe or primary flow and return should also be insulated
from their point of connection to the vessel to a distance of about 1m or to where
they pass into the building fabric.
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Insulation should not compromise the safe operation of the system and of any
safety devices fitted including, on unvented cylinders, the visibility of warning
discharges.
6.4.3 Work on existing buildings
Where a new or replacement boiler or hot water storage vessel is installed, or
where existing systems are extended, new or existing pipes that are accessible or
exposed as part of the work should be insulated as for new systems. Replacement
hot water storage vessels should be insulated as for a new vessel and should be
identified as having a standing heat loss (kWh/day) of not more than 1.28 x (0.2 +
23
0.051 V / ), where V is the declared volume of the vessel.
It is recognised that complete insulation will sometimes not be possible, where
such services pass through or around structural building components, floor joists,
for example, or where existing systems are wholly or partially retained as part of
conversion works. In such cases, insulation should be fitted as for new systems as
far as is reasonably practicable.
6.5 Artificial and display lighting
Mandatory Standard
Standard 6.5
Every building must be designed and constructed in such a way that the
artificial or display lighting installed is energy efficient and is capable of
being controlled to achieve optimum energy efficiency.
Limitation:
This standard does not apply to:
a. process and emergency lighting components in a building or
b. alterations in dwellings or a building ancillary to a dwelling.
6.5.0 Introduction
Artificial lighting can account for a substantial proportion of the electricity used
within a building. Appropriate lighting design (including use of natural daylight) can
reduce carbon dioxide emissions and running costs, and can also reduce internal
heat gains.
Advice on use and specification of low-energy lighting is available from the Energy
Saving Trust (http://www.energysavingtrust.org.uk/). This includes documents
such as GIL 20 – ‘Low energy domestic lighting’ and CE61 – ‘Energy efficient
lighting - guidance for installers and specifiers’.
In respect of this standard:
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Technical Handbook - Domestic - Energy
• fixed light fittings include only the main light sources to a room and not display
or feature lighting such as picture lights, kitchen wall cupboard lights, over
mirror lights. A light fitting may contain one or more lamps and a group of lamps
operated by the same switch could be counted as one fitting, e.g. A pair of wall
lights
• low energy light fittings should include the provision of lamps/bulbs.
Conversions - in the case of conversions, as specified in regulation 4, the
building as converted shall meet the requirements of this standard in so far as
is reasonably practicable, and in no case be worse than before the conversion
(regulation 12, schedule 6).
6.5.1 Fixed internal lighting
Whilst lighting generally represents a relatively small proportion of energy use
in the home, this aspect of domestic energy demand can be limited simply and
effectively, at very little cost, through the use of energy efficient light fittings and
lamps.
Accordingly, a minimum of 75% of the fixed light fittings and lamps installed within
a dwelling should be low energy type, with a luminous efficacy at least 45 lumens/
circuit watt, for example tubular fluorescent and compact fluorescent fittings
(CFL’s).
These fittings may be either:
• dedicated fittings which will have a separate control gear and will only take low
energy lamps (e.g. pin based lamps) or
• standard fittings supplied with low energy lamps with integrated control gear
(e.g. bayonet or Edison screw base lamps).
Lighting to common areas of domestic buildings should follow the guidance
above for dwellings with the following exception:
• all fixed light fittings and lamps provided to corridors, stairs and other circulation
areas should be low energy type. Controls to such lighting, to enable safe use of
the areas in question, are identified in guidance to Standard 4.6.
6.5.2 Fixed external lighting
Where fixed external lighting is installed, such as to enable safe use of external
areas when natural light levels are not sufficient or for security during the hours of
darkness, measures should be taken to prevent wasteful use of energy by such
fittings.
Fixed external lighting should either:
• be rated at not more than 100 lamp-watts per light fitting with automatic control
by both movement detection (e.g. PIR) and photocell to ensure operation only
when needed or
• have fittings with an efficacy of at least 45 lumens per circuit-watt, with
automatically control by photocell to ensure operation only when needed.
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In addition to the above, manual switching may be provided to override operation
of automatic controls.
6.6 Mechanical ventilation and air
conditioning
Mandatory Standard
Standard 6.6
Every building must be designed and constructed in such a way that:
a. the form and fabric of the building minimises the use of mechanical
ventilating or cooling systems for cooling purposes and
b. ventilating and cooling systems installed are energy efficient and are
capable of being controlled to achieve optimum energy efficiency.
Limitation:
This standard does not apply to buildings which do not use fuel or power for
ventilating or cooling the internal environment.
6.6.0 Introduction
It is not desirable that dwellings or buildings consisting of dwellings have airconditioning systems or use mechanical ventilation systems for cooling purposes,
as this leads to increased energy use and higher carbon dioxide emissions. In
view of this, guidance is intended to promote designs that avoid the need for
such systems in dwellings. However where such systems are installed, which
should generally only be a consideration when working with existing buildings, a
performance specification to limit energy use is set out.
With the drive to reduce carbon dioxide emissions and limit energy demand
in buildings, the need arises to consider efficient use of mechanical systems,
including ventilation. Accordingly, guidance is now offered on power consumption
and controls of such systems and on the efficiency of systems that incorporate
heat recovery.
Conversions - in the case of conversions, as specified in regulation 4, the building
as converted shall meet the requirement of this standard in so far as is reasonably
practicable, and in no case be worse than before the conversion (regulation 12,
schedule 6).
6.6.1 Form and fabric of the building
Reduce overheating - in order to minimise any need for mechanical ventilation
for cooling or air-conditioning due to high internal temperatures in hot weather the
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following issues should be considered with regard to the form and the fabric of the
dwelling:
a. proportion of translucent glazing taking into account the need for daylighting
and artificial lighting (Section 3 Environment and Standard 6.5)
b. orientation of translucently glazed areas
c. solar shading or other solar control measures where areas of the external
building fabric are susceptible to solar gain
d. natural ventilation (including night cooling) and
e. thermal mass.
Further information is available in the Energy Saving Trust publication
CE129 - 'Reducing Overheating - A Designer's Guide' (http://
www.energysavingtrust.org.uk/).
Poor cross ventilation/high proportion of translucent glazing - where a
dwelling has little or no cross ventilation (e.g. flats with all external windows/
rooflights on one southerly elevation which is orientated between due east and due
west) or a high proportion of translucent glazing:
a. the dwelling should be designed to avoid high internal temperature (refer to
advice above) and
b. it should be shown by calculation that the ‘likelihood of high internal temperature
in hot weather’ in the dwelling is ‘not significant, slight or medium’. The
recommended method to assess this is Appendix P to SAP 2009 (http://
www.bre.co.uk/sap2009/page.jsp?id=1642). The intention is to avoid the
situation where a dwelling occupier installs mechanical cooling or airconditioning at a later date.
Where a mechanical cooling system is to be considered for a dwelling:
a. the dwelling should first be designed to avoid any need for a cooling system
(refer to advice above)
b. then the ‘likelihood of high internal temperature in hot weather’ should be
assessed using Appendix P of SAP 2009.
If the 'likelihood of high internal temperature' is 'not significant, slight or medium' an
air-conditioning system should not be installed.
6.6.2 Efficiency of air conditioning systems
Where a need for cooling is identified which cannot be addressed by the measures
identified in clause 6.6.1 and installation of air conditioning or similar non-passive
cooling is proposed, controls and system efficiency should minimise additional
energy demand, as follows:
• air-cooled air conditioners working in cooling mode should have an Energy
Efficiency Rating greater than 2.4
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• water-cooled air conditioners working in cooling mode should have an Energy
Efficiency Rating greater than 2.5
• fixed air conditioners should have an energy efficiency classification equal to
or better than Class C in Schedule 3 of the labelling scheme adopted under
The Energy Information (Household Air Conditioners) (No. 2) Regulations, SI
2005/1726 and
• controls should prevent the operation of simultaneous heating and cooling within
any area of the building.
6.6.3 Efficiency of mechanical ventilation systems
Energy demand arising from the use of mechanical ventilation should be limited to
ensure efficient operation. Specific fan power (SFP) for domestic extract systems
should be no greater than the values noted below:
Table 6.12 Maximum Specific Fan Power
Extract type
SFP
intermittent extract ventilation;
continuous supply ventilation
0.5 W/l/s
continuous extract ventilation
0.7 W/l/s
continuous supply and extract with heat 1.5 W/l/s
recovery ventilation[1]
Additional information:
1. The heat recovery efficiency of a mechanical ventilation and heat recovery
(MVHR) system should be 70% or more.
The design and installation of ductwork design can have a significant effect on
the effectiveness of a ventilation system. Further guidance on basic good practice
in installation and commissioning of ventilation systems can be found on the
Technical Guidance page of the Building Standards Divisions website (http://
www.scotland.gov.uk/Topics/Built-Environment/Building/Building-standards/
profinfo/techguide).
Reference should also be made to Section 3 Environment for the provision of
ventilation to buildings.
Advice on the selection of systems can be found in the Energy Saving Trust
document GPG 268 – ‘Energy efficient ventilation in housing - a guide for
specifiers’ (http://www.energysavingtrust.org.uk/).
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6.7 Commissioning building services
Mandatory Standard
Standard 6.7
Every building must be designed and constructed in such a way that
energy supply systems and building services which use fuel or power
for heating, lighting, ventilating and cooling the internal environment
and heating the water, are commissioned to achieve optimum energy
efficiency.
Limitation:
This standard does not apply to:
a. major power plants serving the National Grid
b. the process and emergency lighting components of a building
c. heating provided solely for the purpose of frost protection or
d. energy supply systems used solely for industrial and commercial
processes, leisure use and emergency use within a building.
6.7.0 Introduction
Commissioning in terms of this section means, raising the building services
systems covered by this guidance from a level of static completion to full
working order and achieving the levels of energy efficiency that the component
manufacturers expect from their product(s). Commissioning however, should also
be carried out with a view to enabling the safe operation of the installation.
Although there is no requirement within Section 6 for minimum efficiency levels
of either, building-integrated or localised energy supply systems (e.g. diesel
generators, micro wind turbines or photovoltaic arrays), there is a need for
commissioning to be carried out to enable efficient use, unless they are exempt
under schedule 1, regulation 3. Major power plants which serve a number of
buildings (e.g. housing estates) and only export surplus electricity to the National
Grid will also need to be commissioned, unless exempt in terms of schedule 1,
regulation 3.
Conversions - in the case of conversions, as specified in regulation 4, the building
as converted shall meet the requirement of this standard (regulation 12, schedule
6).
6.7.1 Inspection and commissioning
A heating, hot water service, ventilating or cooling system and any decentralised
equipment for power generation in a dwelling or other area of a building
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consisting of dwellings should be inspected and commissioned in accordance with
manufacturers’ instructions to enable optimum energy efficiency.
6.8 Written information
Mandatory Standard
Standard 6.8
The occupiers of a building must be provided with written information by
the owner:
a. on the operation and maintenance of the building services and energy
supply systems and
b. where any air-conditioning system in the building is subject to
regulation 17, stating a time-based interval for inspection of the
system.
Limitation:
This standard does not apply to:
a. major power plants serving the National Grid
b. buildings which do not use fuel or power for heating, lighting, ventilating and
cooling the internal environment and heating the water supply services
c. the process and emergency lighting components of a building
d. heating provided solely for the purpose of frost protection
e. lighting systems in a domestic building or
f. energy supply systems used solely for industrial and commercial
processes, leisure use and emergency use within a building.
6.8.0 Introduction
Correct use and maintenance of building services equipment is essential if the
benefits of enhanced energy efficiency are to be realised from such equipment.
The intention of this standard is to make the information that will help achieve this
available to the occupier of the building.
Although there is no requirement within Section 6 for minimum efficiency levels
of either, building-integrated or localised energy supply systems (e.g. diesel
generators, micro wind turbines or photovoltaic arrays), there is a need for user
and maintenance instructions to enable efficient use, unless they are exempt
under schedule 1, regulation 3.
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Major power plants which serve a number of buildings (e.g. housing estates) and
only export surplus electricity to the National Grid will also need to have user and
maintenance instructions, unless exempt in terms of schedule 1, regulation 3.
Conversions - in the case of conversions, as specified in regulation 4, the building
as converted shall meet the requirement of this standard (regulation 12, schedule
6).
6.8.1 Written information
Written information should be made available for the use of the occupier on the
operation and maintenance of the heating, ventilation, cooling and hot water
service system, any additional low carbon equipment installations and any
decentralised equipment for power generation to encourage optimum energy
efficiency. If an air conditioning system is installed in a dwelling the guidance to
regulation 17 should be followed.
6.8.2 Work on existing buildings
Where alterations are carried out to building services on a piecemeal basis, the
alterations may not result in optimum energy efficiency being attained for the
whole system. In this case a list of recommendations which would improve the
overall energy efficiency of the system should be provided.
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6.9 Energy performance certificates
Mandatory Standard
Standard 6.9
Every building must be designed and constructed in such a way that:
a. an energy performance certificate for the building is affixed to the
building and *
b. the energy performance certificate is displayed in a prominent place
within the building.
Limitation:
a. this standard does not apply to buildings which do not use fuel or power for
controlling the temperature of the internal environment
b. this standard does not apply to non-domestic buildings and buildings that
are ancillary to a dwelling that are stand-alone having an area less than 50
square metres
c. this standard does not apply to conversions, alterations and extensions to
buildings other than alterations and extensions to stand-alone buildings
having an area less than 50 square metres that would increase the area to
50 square metres or more, or alterations to buildings involving the fit-out of
the shell which is the subject of a continuing requirement
d. this standard does not apply to limited life buildings which have an intended
life of less than 2 years
e. Standard 6.9(c) only applies to buildings with a floor area of more than
500 square metres, into which members of the public have an express or
implied licence to enter, and which are visited by members of the public on
at least a weekly basis.
* Standard 6.9(b) removed by the Building (Scotland) Amendment Regulations
2008 http://www.legislation.gov.uk/ssi/2008/310/contents/made
6.9.0 Introduction
Article 12 of Directive 2010/31/EU http://eur-lex.europa.eu/LexUriServ/
LexUriServ.do?uri=OJ:L:2010:153:0013:0035:EN:PDF on the Energy Performance
of Buildings requires that, when buildings or building units are constructed, sold or
rented out, an energy performance certificate (EPC) http://www.scotland.gov.uk/
Topics/Built-Environment/Building/Building-standards/enerperfor or a copy thereof
is shown to the prospective new tenant or buyer and handed over to the buyer or
new tenant. Standard 6.9 ensures the continued presence of such information for
buyers and tenants by also making EPCs fixtures within buildings.
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EPCs must be produced in an independent manner and be carried out by
qualified/accredited experts. With the exception of EPCs produced in relation to
a building warrant applied for before 9 January 2013, EPCs must be produced
by members of an Approved Organisation. Scottish Ministers have appointed
a number of Approved Organisations (AO) to deliver certification services,
with each AO following an Operational Framework which is published on
the Building Standards Division website. Information on this framework and
Approved Organisations can be found at www.scotland.gov.uk/epc. http://
www.scotland.gov.uk/Topics/Built-Environment/Building/Building-standards/
enerperfor
Scottish Ministers have directed local authorities to apply Standard 6.9 (a) to
existing buildings using Section 25 (2) of the Building (Scotland) Act 2003. The
direction limits the description of the buildings to which this standard applies
to those that are being sold or rented out, in support of duties imposed by
The Energy Performance of Buildings (Scotland) Regulations 2008. http://
www.legislation.gov.uk/ssi/2008/309/contents/made
Definitions in application of this standard 'energy performance certificate' has
the same meaning as given in The Energy Performance of Buildings (Scotland)
Regulations 2008. http://www.legislation.gov.uk/ssi/2008/309/contents/made
Guidance leaflets are available on the BSD website (http://www.scotland.gov.uk/
Topics/Built-Environment/Building/Building-standards/publications/pubepc)
explaining the action that building owners need to take in order to comply.
Conversions - in the case of conversions, as specified in regulation 4 Standard
6.9 does not apply.
6.9.1 Calculating the carbon dioxide emissions for a
certificate
The EU Directive allows energy performance to be reflected in one or more
numeric indicators. For this to be done in a transparent manner that is meaningful
in terms of Scottish building regulations, the measure to be used is carbon dioxide.
Simplified approach - the certification must be carried out using the Directive
compliant methodology and the calculation tool which was used to assess
compliance with Standard 6.1. In most cases SAP 2009 (http://www.bre.co.uk/
sap2009/page.jsp?id=1642) will have been used for the new dwelling. However
if the simplified approach referred to in clause 6.1.6 has been adopted for the
new dwelling, the construction specification is well enough defined to allow the
certificate to be generated using the simplified approach embedded in SAP
software.
Use of actual values - for the purpose of establishing a rating for the energy
performance certificate for a new dwelling, the values and specifications used to
obtain building warrant (as varied by any subsequent amendments to warrant)
should be adopted. Where a domestic building contains multiple dwelling, a rating
is required for each individual dwelling. However for certification purposes the
rating may be recalculated with the percentage of low energy lighting and the
type of heating as installed. Note, there will be no need to assume 10% electric
secondary heating if secondary heating is not present.
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2
Non-domestic use within dwellings - accommodation up to 50m used by
an occupant of a dwelling in their professional or business capacity should be
considered as a part of the dwelling.
6.9.2 Information to be provided for buildings
The energy performance certificate must display the following information:
• the postal address of the building for which the certificate is issued
• a unique reference number (other than for an EPC produced in support of a
building warrant applied for before 9 January 2013)
• the date of the assessment
• the date of the certificate
• the dwelling type
• the type of assessment used for certification
• the conditioned floor area of the building
• the main heating and fuel type
• a primary energy indicator
• the current and potential energy efficiency rating expressed on seven band
scale representing the following bands of running costs; A, B, C, D, E, F and G,
where A = excellent and G = very poor
• the current and potential environmental impact rating expressed on a seven
band scale representing the following bands of carbon dioxide emissions; A, B,
C, D, E, F and G, where A = excellent and G = very poor
• a list of the top applicable recommendations for cost-effective improvements
• a statement indicating that more detailed information on the recommendations
made in the EPC is contained in the recommendations report and
• a statement to the effect that the EPC must be affixed to the building and not to
be removed unless it is replaced with an updated version.
The recommendations report, which must accompany the EPC, but which does
not have to be affixed to the building, includes the following additional information:
• a summary of the energy performance related features of the dwelling
• estimated energy costs (based upon standard use patterns) and
• a list of all improvements identified for the dwelling and further information on
each measure.
An example of the EPC and recommendations report is available on the Building
Standards Division website .
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Cost-effective improvement - there are only limited cost-effective, low-cost,
energy efficiency improvements that can be made to a new dwelling (when no
other work is proposed) such as upgrade insulation in an accessible roof space
or fit low energy lamps throughout the dwelling. Measures presented on the
certificate and recommendations report must meet Scottish building regulations,
relevant to the individual dwelling and should be technically feasible.
Additional advice - a piece of advice that is worthwhile including is that a
conservatory (where one is installed) is only an energy efficiency benefit to the
dwelling if it remains unheated and is not mechanically cooled.
The recommendations report may give additional advice on protected energy
costs and improvements that are cost-effective only when additional work is being
carried out e.g. providing insulation when replacing flat roof coverings.
Some experts providing certificates may wish to add extra value and give
additional advice to their clients. All of this is welcome, but in every case,
such information should be clearly explained in the addendum section of the
recommendations report and be accompanied by advice on relevant warrants and
building regulations. Sources of further energy saving advice and funding options
are also noted in the recommendations report.
6.9.3 Location of an energy performance certificate
The energy performance certificate should be indelibly marked and located in a
position that is readily accessible, protected from weather and not easily obscured.
A suitable location could be in a cupboard containing the gas or electricity meter or
the water supply stopcock.
6.9.4 Conservatories and other stand-alone buildings
For conservatories and for other ancillary stand-alone buildings of less than
2
50m floor area, an energy performance certificate need not be provided.
2
For those buildings of a floor area of 50m or more, the guidance in the nondomestic Technical Handbook should be followed and an additional certificate
supplementing the one for the dwelling should be provided.
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6.10 Metering
Mandatory Standard
Standard 6.10
Every building must be designed and constructed in such a way that
each building or part of a building designed for different occupation is
fitted with fuel and power meters.
Limitation:
This standard does not apply to:
a. domestic buildings
b. district or block heating systems where each part of the building designed
for different occupation is fitted with heat meters or
c. heating fired by solid fuel or biomass.
6.10.0 Introduction
This standard does not apply to domestic buildings as fuel providers e.g. gas
companies, provide meters to dwellings to enable correct charging for fuel used by
the customer.
Annex 6.A Compensating U-values for
windows, doors and rooflights
6.A.0 Introduction
This annex gives guidance on how to calculate the average U-values for windows,
doors and rooflights and supports the guidance to Standards 6.1 and 6.2. It may
be used with the elemental methods provided and, in particular:
• the simplified approach in the guidance to Standard 6.1, where it is not possible
to input the individual U-values for all the windows, doors and rooflights for the
proposed new dwelling into the methodology (usually SAP 2009) and
• for work on existing domestic buildings, namely, conversions, extensions,
replacements, alterations, and conservatories (clauses 6.2.6 to 6.2.12).
Individual windows, doors or rooflights may have U-values that exceed the
relevant area-weighted average U-values identified in guidance provided that the
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average U-value calculated for all the windows, doors and rooflights is no greater
than that relevant U-value.
The example which follows below illustrates how this trade-off can be calculated.
6.A.1 Example of trade-off between windows, doors and
rooflights
2
A proposed new semi-detached house has a total window area of 17.8m
2
(including frames) and a total door area of 3.8m . It is proposed to use 2 external
2
quality timber finished fire doors with a U-value of 1.9W/m K.
In order to meet Standards 6.1 and 6.2, the additional heat loss due to the use
of the poorer external doors should be compensated for by more demanding Uvalues in the windows and/or rooflights so that the average overall U-value of such
2
elements does not exceed 1.8W/m K (see table to clause 6.2.1).
2
Specifying windows with a U-value of 1.5W/m K can achieve this requirement, as
shown by the following calculation:
Table 6.13 Average U-value calculation
2
Element
Area
2
(m )
U-value (Wm K)
Rate of heat loss (W/K)
Windows
16.9
x
1.5 [1]
=
25.5
Doors
3.8
x
1.9
=
7.22
Rooflights
0.9
x
1.8 [1]
=
1.62
Total
21.6
34.19
Additional information:
1. Note that although the windows and rooflights have the same U-value, for the
2
purpose of calculation the rooflight value is 0.3W/m K poorer due to inclination
from the vertical plane (see BR 443 - 'Conventions for U-value Calculations'
http://www.brebookshop.com/).
2
This gives an average U-value of 34.19 ÷ 21.6, or 1.58W/m K. The windows,
doors and rooflights can therefore be considered to follow the objectives of the
requirement for the insulation envelope.
Annex 6.B Compensatory approach heat loss example
6.B.0 Introduction
This annex gives an example of the compensatory approach for use in the design
of conversions, extensions and alterations. This is likely to be of use where there
is a need to specify one or more constructions with a U-value higher than the
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Technical Handbook - Domestic - Energy
recommended maximum area-weighted average U-values given in either column
(a) or (b) of the table to clause 6.2.9.
The example given in this instance is for an attic conversion, however the same
principles apply to extensions and substantial alterations.
Note that this method cannot be used in conversions, if recommended U-values
are only being met as far as is reasonably practicable.
A single compensatory approach calculation can be carried out to cover separate
areas of work to an existing dwelling provided the same assessment criteria
(maximum U-values, etc) are applicable to each area of work.
6.B.1 Example: alteration to create rooms in a roof space
Note - in this example, the fabric performance of the existing building allows use of
the values within column (b) in the table to clause 6.2.9.
Compensatory approach example - it is proposed to form two rooms in the roof
space of an existing single storey dwelling. The extra floor area created (including
2
opening for stairway) will be 36.4m . A plan and section of the proposed layout is
shown in the figure below. A key part of the design is to create as much headroom
as possible below the new coombe ceilings. The existing rafters are only 150mm
deep therefore it is difficult to achieve the recommended elemental U-value of
0.18 (see column (b) in the table to clause 6.2.9), without using branders or having
an excessive thickness of insulated ceiling lining. The principal compensatory
measure will be to highly insulate the attic walls that occur directly below the
lowest part of the coombes. The existing gables will be provided with insulated
internal wall lining to improve the U-value where the insulation envelope now
2
occurs. The four no. 1.5m rooflights installed have timber frames. The floor that
will be formed at the line of the existing ceiling ties is wholly within the insulation
envelope and is therefore disregarded for the purposes of this calculation.
Procedure:
• The internal exposed surface areas of each of the elements of the proposed
building insulation envelope that have different area weighted U-values are
calculated.
• The heat loss for the proposed attic is calculated using proposed U-values for
building elements, which may be higher or lower than those recommended in
column (b) of the table to clause 6.2.9. The percentage area of windows/doors/
rooflight area as proposed may also be greater or less than 25%.
• The heat loss for a ‘notional attic’ (i.e. an attic the same size and shape as the
proposed attic but with its area of window/doors/ rooflights taken as a maximum
25% of the floor area) is calculated using the U-values in column (b) in the table
to clause 6.2.9.
• Finally, the heat loss calculated for the proposed attic should be less than or
equal to that for the 'notional' one.
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Technical Handbook - Domestic - Energy
Figure 6.2 Attic Example
6.B.2 Proposed attic
Then calculate the rate of heat loss from the proposed attic as follows:
Table 6.14 Data for proposed attic alteration
Exposed element Exposed
surface area
2
(m )
Proposed U2
value (W/m K)
Rate of heat loss
(W/K)
Gables
19.0
x
0.30
= 5.70
Attic walls
14.0
x
0.20
= 2.80
Ceiling at collars
14.0
x
0.15
= 2.10
Coombe ceiling
22.0
x
0.32
= 7.04
Rooflights
6.0 (16.5%)
x
1.6
= 9.60
Total rate of heat loss
= 27.24
6.B.3 'Notional attic'
Then calculate the rate of heat loss from the 'notional attic' as follows:
Table 6.15 Data for 'notional' attic alteration
Exposed element Exposed
surface area
2
(m )
Column (b) U2
value (W/m K)
Rate of heat loss
(W/K)
Gables
19.0
x
0.22
= 4.18
Attic walls
14.0
x
0.22
= 3.08
Ceiling at collars
14.0
x
0.15
= 2.10
Coombe ceiling
18.9
x
0.18
= 3.40
Rooflights
9.1 (25%)
x
1.6
= 14.56
Total rate of heat loss
= 27.32
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Technical Handbook - Domestic - Energy
6.B.4 The comparison
From the above comparison, the rate of heat loss from the proposed attic (27.24)
is less than that from the 'notional attic' (27.32). Proposals will comply.
6.B.5 Additional insulation work
The existing dwelling is of an age where there was no insulation provided in the
roof space at the time of the original construction. Guidance on ‘reconstruction of
elements’ within clause 6.2.11 recommends that where an element forming part of
the insulation envelope is to be altered or dismantled and rebuilt, the opportunity
should be taken to improve the level of thermal insulation.
In this example, there is no technical risk or other reason which prevents the level
ceiling at the eaves of the roof (see X on the section) being upgraded to achieve
a U-value of 0.15 as noted in column (b) of the table to clause 6.2.9. This would
therefore be required as part of the proposed works.
59
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