1. The Building (Amendment) Regulations, SI 2001/3335 and
the publication of the 2002 editions of Approved Documents
L1 and L2 convey major improvements in energy performance
standards in the Building Regulations. However, as described
in the June 2000 consultation paper , these changes were
only the first of four stages of proposed improvements in
the requirements and associated approved guidance that were
expected to be introduced in the period up to around 2008.
In February 2003 however, the Energy White Paper (EWP) announced
the Government's aim of bringing the next major review of
the Building Regulations into effect in 2005. This paper
is an initial informal response from the Office of the Deputy
Prime Minister (ODPM) on the sorts of improvements that
could be achievable in the amendment now proposed for 2005.
2. Other factors that will influence this review are:-
a. The EU Directive on the Energy Performance of Buildings
(EPBD) , which requires transposition into UK law by January
2006
b. The need to consider how building design and construction
practice might need to adapt to the impacts of changing
climate. A separate Adaptation Strategy paper relative to
Part L is being prepared, and this will be used to inform
the Part L review.
3. Part 5 of the June 2000 consultation document set out
the thinking amongst members of the Building Regulations
Advisory Committee and the ODPM (DTLR as then was) on how
the suggestions collected during the 1998 consultations
might best be staged over time. This paper provides a first
update on that document, taking into account what has been
achieved in the implementation of Stage 1 and the new context
as set out in the EWP. It summarises the issues that are
being considered for the new review, and outlines the ranges
of performance standards that are being considered with
industry and other interested parties during the development
of amendment proposals.
Staging
4. In June 2000 the then "current thinking" was
outlined in terms of three possible further stages of revising
Part L.
Stage 2
5. This was defined as proposals for further guidance in
relation to those requirements introduced or amended in
Stage 1, and additional requirements and guidance material
on other measures - but not altering those in Stage 1. It
was envisaged that there would be a formal consultation
on the Stage 2 proposals, enabling a Stage 2 amendment about
a year after Stage 1.
6. Having reviewed the range of possible new requirements
that could be introduced at Stage 2, it was decided that
these do not warrant consultation and a new amendment of
Parts L1 and L2, and the associated Approved Documents so
soon. It was agreed that the possible new requirements should
instead be deferred to the Stage 4 consultation. Stage 2
is therefore limited to issuing supplementary technical
guidance. It is hoped that most of these can be introduced
during the remainder of 2003 by administrative action such
as amending the text in the 2002 editions of the Approved
Documents, by circular letters and through drawing attention
to supplementary guidance on the ODPM web site.
Stage 3
7. This was defined as a package of the suggestions arising
from the 1998 consultations that concerned buildings in
use, and whose implementation was therefore dependent on
amendments to the Building Act. It is not possible to define
whether or when the Building Act might be amended, so the
proposals were effectively placed in limbo.
8. In the meantime, the new EU Directive on the Energy Performance
of Buildings (EPBD) has been published, which requires transposition
into UK law by January 2006. The requirements of the Directive
are discussed later (paragraphs 10 et seq.), and will enable
some elements of the 1998 ideas for controlling buildings
in use to be assimilated into the Stage 4 package. It is
proposed to do this using powers in Section 2 of the Building
Act 1984, amended or supplemented as necessary using the
powers in the European Communities Act 1972.
Stage 4
9. This was envisaged as the next occasion for a comprehensive
review of the whole of the requirements of Part L and the
associated Approved Documents. In the June 2000 consultation,
it was envisaged that this would take place not less than
five years after the Stage 1 amendments and would therefore
not be implemented before April 2007. The EWP has brought
this date forward to late 2005, which means that formal
consultations on firm proposals will need to be carried
out during the summer of 2004.
The Directive
10. The Directive aims to promote the improvement of the
energy performance of new and existing buildings, taking
into account outdoor climate and local conditions as well
as indoor requirements and cost-effectiveness. Via a series
of Articles, it sets out requirements covering the following
issues
a. A methodology for calculating the energy performance
of buildings.
b. Setting energy performance standards for new and existing
buildings.
c. Requiring more consideration of low-carbon and zero-carbon
systems when constructing larger non-domestic buildings.
d. Introducing requirements for producing building energy
certificates whenever buildings are built, leased or sold.
e. Setting up an inspection system for boilers rated at
more than 20kW (or an information system that achieves similar
results).
f. Setting up a routine inspection system for air conditioning
systems of more than 12kW rated output.
11. Article 15 contains the timing obligations and requires
Member States (MSs) to implement the measures by 04 January
2006. As an exception to this, MSs may agree with the Commission
that implementation of the building certification and plant
inspection requirements can be delayed for up to three years
if they have insufficient qualified and/or accredited experts.
12. Because the issues surrounding implementation of the
Directive are broader than the aspects of building design
and construction covered by Part L, and because they apply
in Scotland and Northern Ireland as well as England and
Wales, a series of separate strategy papers will be published
in due course. The first example of this separate series,
which addresses the requirement to develop a national methodology
for the calculation of building energy performance for buildings
other than dwellings, was published on 15 September 2003
on the ODPM website .
The White Paper
13. The EWP was published on 24 February 2003. One of the
stated objectives is "to put ourselves on a path to
cut UK's CO2 emissions by some 60% by about 2050, with real
progress by 2020". Given the significant contribution
that buildings make to national CO2 emissions, building
energy efficiency standards will have to improve significantly
over the coming decades.
14. Specifically in relation to Building Regulations, the
EWP announced the intentions of:-
a. Raising standards over the next decade, learning lessons
from the standards in comparable European countries (Para
3.12)
b. Raising the standard required for new and replacement
boilers to SEDBUK classes A or B (Para 3.13). The Government
has since decided to bring this provision into effect by
01 April 2005.
c. Starting immediately on the next major revision of Part
L, with the aim of bringing this into effect in 2005 (Para
3.16).
d. Seeing how the enforcement system might be improved to
enable better correlation between design standards and as-built
performance (Para 3.20).
15. The performance standards published in Approved Documents
L1 and L2 give guidance on what is reasonable provision
for compliance with Parts L1 and L2 of Schedule 1 of the
Building Regulations. These standards have been based on
measures shown to be cost-effective over their service life,
taking account of the market prices for materials, labour
and fuel. Additionally, Government requires that the measures
are proportionate with other legislation bearing on the
construction industry, and should allow sufficient design
flexibility and avoid undue technical risk.
Carbon pricing
16. In the Stage 1 Review the Government included in its
Regulatory Impact Assessment (RIA) a qualitative assessment
of the environmental cost of carbon emissions.
17. Since then, the Government has published a comprehensive
review of quantitative estimates of the social costs of
carbon emissions . Government has accepted that for policy
development purposes, the social cost of carbon should be
factored into the cost benefit analysis. This social cost
is based on a figure of £70 per tonne of carbon emitted
(in 2000 price levels) , and that this value should be increased
at £1 per year thereafter before adjustments are made
to take account of general inflation . This additional social
cost, which arises whenever non-renewable fuels containing
carbon are used, will therefore be taken into account as
part of the future basis of setting Part L standards. This
will mean that more measures will be shown to be cost effective
than when using current market prices for the various fuels.
Present value calculation of cost-effectiveness
18. The Government uses the Discounted Cash Flow Analysis
Method to establish the costs and benefits of proposed measures
on an even basis - the "present value". To date
Government has used a 6% test discount rate to determine
present values. In the new edition of the Green Book published
by HM Treasury the test discount rate is 'unbundled' so
that the new rate of 3.5% reflects only one factor, the
social time preference rate. (The current rate of 6% implicitly
takes account of such other factors as risk, optimism bias,
and the cost of variability. The advice now is to deal with
these separately and explicitly - and, for the purposes
of regulatory impact assessments for the Building Regulations,
these other factors will now be excluded from the calculations.
19. The lower test discount rate means the present value
of avoiding longer-term environmental impacts will be more
significant by comparison with initial investment costs.
Higher building performance standards than could previously
be justified will therefore prove to be cost-effective.
Embodied energy
20. Embodied energy in building materials and building services
plant can represent a significant element of the lifecycle
energy budget of a building and the aim is to address this
in Building Regulations within the coming decade. Although
it is considered desirable that this energy and carbon burden
should be addressed however, it is considered that the analysis
procedures and supporting data are not yet sufficiently
developed for this to be considered in quantifiable terms
for the revision planned for 2005.
21. To take matters forward we therefore propose :-
a. to carry out a study on how sustainability indices could
be included in the Building Regulations,
b. where practicable, to include qualitative assessments
in the 2005 Regulatory Impact Assessment, and
c. to propose provisions for addressing embodied energy
in Part L (or as an additional issue covered by Regulation
7 (workmanship and materials)) when the accounting methods
and data are sufficiently well developed.
22. In the following sections, the various issues that are
being considered in this review are introduced, and ODPM's
current thinking on possible revisions to Part L are summarised.
This thinking will be developed further via discussion with
the BRAC Working Party, and with industry and other interests
via the Industry Advisory Groups (IAGs) and their specialist
working panels, prior to the formal public consultation
scheduled for the summer of 2004.
General
23. The Stage 4 (see paragraph 9) is now being developed
as the major revision envisaged in the EWP for 2005 - an
opportunity to consider further raising all the performance
standards currently in place, and possibly to introduce
new ones for both new build and work on existing buildings.
However, the overall aim continues to be to make the best
practicable contribution towards the Government's carbon
emission reduction policies whilst keeping the Regulations
proportionate, providing sufficient design flexibility,
and avoiding inappropriate technical risk.
24. The following paragraphs outline the areas under review,
grouped under a number of generic headings. As mentioned
at the start, further thinking in the light of informal
consultations with industry and other interests is required
before decisions are made about which new measures BRAC
might recommend Government should consult on next Summer,
and what standards they might recommend should be regarded
as reasonable provision for the conservation of fuel and
power.
25. During the course of the work, the references in the
two Approved Documents will be reviewed and updated where
possible, and new references added where appropriate.
Thermal bridging
26. Stage 1 raised the awareness of the importance of minimising
thermal bridges, and through associated publications, has
provided improved guidance to industry. The aim was to encourage
industry to develop its understanding of linear thermal
transmittances and their effects on energy consumption.
These effects are increasingly significant as overall fabric
losses and ventilation heat losses are reduced.
27. Industry provided a significant input into the development
of Robust Construction Details, which if implemented in
practice, should limit the effects of thermal bridging and
air leakage. Since the publication of the document on robust
details for dwellings and similar buildings, work has been
done on other types of construction (e.g. metal cladding
systems and curtain walling). It will be important to build
on this resource of good construction practice, and especially
to ensure compatibility between the thermal performance
guidance and the corresponding work on Robust Standard Details
for acoustic protection, following the recent revision of
Part E.
28. EN 14683 now provides the basis for quantifying the
effects of thermal bridging using linear thermal transmittances.
Consideration is therefore being given to taking account
of quantified thermal bridges in setting thermal standards
for the building envelope. This would allow improved design
details to be offset against poorer standards in the main
elements of construction, thereby increasing design flexibility.
However, all junction details would need to meet the temperature
criteria to avoid condensation problems.
29. Incorporating quantified thermal bridges would require
setting a specific quantified performance standard for thermal
bridges. This would either require the linear transmittances
to be calculated for all junctions, or be available from
a library of previously calculated values. This could be
achieved by updating the Robust Details catalogue with the
pre-calculated linear transmittance values, or adopting
a separate thermal bridge catalogue and software such as
that available through EuroKOBRA .
30. Given the increasing significance of thermal bridges,
the current thinking is that the effects of thermal bridges
should be quantified as part of the overall assessment of
whole building energy performance. However it is recognised
that simple ways of showing compliance and more comprehensive
guidance will both be needed.
Airtightness standards
31. It is suggested that airtightness standards (measured
as air permeability) need to be improved, and that different
standards should be set for the different types of buildings,
as suggested in CIBSE TM23 .
32. The degree to which the standards are raised must take
account of the need to comply with Part F in providing adequate
ventilation for health, and Part J in relation to air supply
for combustion appliances. A review of Part F is starting
in late 2003. For this reason, consideration of the airtightness
standards for naturally ventilated buildings must be correlated
with any changes to Part F.
33. The level of improvement that might be justified is
likely to be greater for the more energy intensive building
types (e.g. commercial buildings as opposed to industrial
ones, and balanced mechanically ventilated dwellings as
opposed to naturally ventilated ones).
34. Within the constraints mentioned above, it is considered
likely that substantially improved airtightness performance
standards for some building types could be justified in
the next (2005) amendment, with different standards being
set for different building types. The values in the following
table give an indication of the standards that might be
considered, the first two columns summarising the industry-developed
recommendations for Good and Best Practice as published
in TM23 in 2000.
Permeability in m3/h/m2 at 50 Pa
Type of new building TM23 Good practice TM23 Best practice
Current thinking
Dwellings - naturally ventilated 10 5 10 **
Dwellings with balanced whole house mechanical ventilation)
5 3 5
Offices and retail - naturally ventilated 7 3.5 10 **
Offices and retail with balanced mechanical ventilation
3.5 2 7
Industrial and warehouses 10 3.5 7
** Note - these values are subject to revision in the context
of the parallel review of Part F. The standard could be
improved if it is found that this would be unlikely to compromise
ventilation for health.
35. The final column in the table contains the airtightness
standards we suggest could be justified for adoption in
2005. We further suggest that less demanding performance
standards should probably be considered reasonable for refurbishment
works.
36. In addition we will be considering with DfES and NHS
Estates the possibilities for setting separate standards
for specialist building types like schools and hospitals.
Pressure testing
37. In order to continue to achieve further improvements
in the levels of airtightness found in practice, it is thought
that it would be beneficial to expand the application of
airtightness testing. There has been some confusion over
the implementation of the guidance in the 2002 ADL2. Consideration
is therefore being given to introducing a legal requirement
to carry out pressure testing of buildings. Our current
thinking on the requirements for testing different categories
of buildings is as follows:-
38. Dwellings - those builders that are not using Robust
Details and a third party quality assurance system would
need to demonstrate that sufficient airtightness has been
achieved via a pressure test. In addition, if tests to be
carried out during the next few months indicate that the
adoption of robust details is not delivering the required
standards (see paragraph 65), then pressure testing might
be required even if robust details have been adopted. In
all cases, testing would be done on a sample basis - perhaps
modelled on the sampling provisions set out in the new Part
E.
39. Other types of buildings with floor areas exceeding
200m2 should each be tested. (The current guidance is to
test buildings over 1000m2. The 200m2 threshold matches
the application area limit set in ADL2, 2002 for air conditioning.
It also roughly matches in with the Directive Article 9
threshold of 12kW cooling output, being equivalent to a
cooling load of 60W/m2.)
We currently think that both of these new requirements could
be implemented as part of the 2005 review
40. A PII project being led by the Air Tightness Testing
and Measurement Association is developing guidance on pressure
testing large buildings and is likely to deliver guidance
material that could be included or referred to in the next
edition of ADL2.
Improved correlation between design and as-built performance
41. There is a measure of concern that there is often significant
difference between the design assessment of energy performance
and the performance achieved in practice (see paragraph
d. Focusing attention on improved design details and site
supervision to improve the performance of thermal bridges
and airtightness might help to improve the correlation.
Other factors might include the robustness of assumptions
about such factors as gaps between insulation, timber fractions
etc.
42. The current thinking is that there are perhaps two approaches
to addressing this issue -
a. Increasing the type and frequency of pre-completion testing
to check that build quality matches the design intent, and
the attention that building control inspectors pay to see
that this is being done. This has implications for availability
of test equipment, competent testers and resources for building
control bodies etc.
b. Basing the performance standards on more realistic assumptions
about build quality. This would mean that to achieve a given
U-value, more insulation would be required to compensate
for the defects in typical construction. Builders who reasonably
demonstrate that their construction methods or systems deliver
better build quality than the standard could use this to
justify reducing insulation thickness. Such an approach
has been used in Sweden and it is understood that similar
provisions are in place in Holland
43. We propose to explore these two approaches to see how
best we could help improve the correlation between design
and as-built performance. As part of this we propose to
canvass the views of the BCBs and the experience from other
countries like Sweden and Holland.
Appliances
44. It is clear that in many building types, the energy
used by appliances (white and brown goods, business machines,
personal computers etc) represents a very significant proportion
of the energy budget and the carbon emissions. Currently,
Building Regulations do not address the performance of appliances,
although ODPM lawyers have advised that the powers available
in the Building Act do not preclude so doing.
45. We propose to explore this issue in close collaboration
with DEFRA's Market Transformation Team to see if Part L
is the most appropriate mechanism for introducing performance
standards for appliances and will report at a later date.
Swimming pools
46. Until now, Part L has only addressed those aspects of
building design that provide comfort and convenience for
normal occupant activities. In line with the aims of the
EWP, we are looking to see what other activities within
dwellings and other buildings might provide opportunities
to achieve reductions in carbon emissions. Swimming pools
and hot tubs (whether indoor or outdoor) are particularly
suited to the application of no/low carbon systems such
as solar hot water or CHP and can be significant users of
energy in respect of such issues as:
a. Insulation of the pool basin
b. Provision of pool covers
c. Pool water heating system efficiency
d. Ventilation heat recovery.
47. We are therefore giving consideration to whether standards
could be defined for swimming pools and hot tubs (and whether
they would yield worthwhile and cost-effective carbon savings).
Portable buildings
48. As indicated in the 2002 edition of ADL2 as amended
by the 12 February 2002 Circular Letter, special considerations
apply to buildings constructed from sub-assemblies that
have been manufactured prior to the implementation date
of the new standards, and have been obtained from a centrally
held stock or from disassembly of another building. In such
cases, for the 2005 edition of ADL2, we are thinking of
raising standards for reasonable provision to those set
out in the 2002 edition of Approved Documents L2.
Reference compliance method
49. In line with the requirements of the Energy Performance
Directive, we are proceeding with the thinking that came
out of the Stage 2 review that energy or carbon calculation
methods in SAP should be used as the basic method for establishing
what is "reasonable" - i.e. the test of compliance
with Part L1.
50. This approach provides the following benefits -
a. greater design flexibility than the Elemental Method.
b. avoidance of the somewhat arbitrary cut-offs at specific
numerical values in the Elemental Method, which can be inconsistent
with standard dimensions of insulation layers in practical
construction.
c. elimination of the need to define elemental standards
for linear thermal transmittances as part of the quantification
of thermal bridging. However this would require quantification
of all linear transmittances as part of the estimation of
heat loss.
51. We nevertheless think that an Elemental Method will
need to be retained to provide guidance on standards for
manufacturers and suppliers, and to cover extensions and
replacement work.
The effect of size and shape
52. One weakness of the existing compliance methods is that
they do not fully address the impact of built form, that
is to say building size and shape. Encouraging more compact
built forms would improve energy efficiency and reduce carbon
emissions, and help Planning Departments tasked with delivering
increased planning densities. We therefore propose to explore
in the coming months the feasibility of introducing requirements
for built form. Depending on progress, we may be able to
develop firm proposals for formal consultation prior to
the 2005 amendment, but the matter may have to be deferred
to the next revision in around 2010.
53. A practical consequence of introducing a built form
factor into these methods would mean that larger dwellings,
or ones that do not conform to optimum shapes, would be
more expensive to build. The significance of the factor
in calculating overall performance would therefore have
to be carefully balanced. However, recent work suggests
that overheating is likely to be a greater problem in small,
compact dwellings (see paragraph 67), and so this might
provide a self-balancing effect.
U-values
54. For new build, the aim is to express the reasonable
standard of provision for the whole building using the SAP
energy and/or carbon methods leaving designers to follow
their own inclinations on how best to achieve it, whilst
keeping within constraints of poorest acceptable U-values.
In establishing the whole-building performance standard
it will be necessary to analyse a range of house types constructed
to reasonable elemental standards. The following paragraphs
describe what those elemental standards might be. Smaller
builders may wish to continue using an elemental-based method,
and U-value standards will still be necessary for use in
alteration and extension work.
55. The first column of data in the following table shows
the standards set out in ADL1 (2002). The forward thinking
paper published in the June 2000 consultation document envisaged
that the U-values adopted by Stage 4 (see paragraph 9) could
be as given in the second data column of the table below.
The final two columns give the Best Practice and Advanced
standards as given in GIL 72 . The last three columns represent
significant improvements on current standards, but they
need to be considered if the EWP's challenging CO2 reduction
targets are to be met.
Indicative standards for fabric insulation ADL1 2002 2000
Forward Thinking GIL72 Best Practice GIL 72 Advanced Standard
Roofs 0.16-0.25 0.16 0.13 0.08
External walls 0.35 0.25 0.25 0.15
Ground floors 0.25 0.22 0.20 0.10
Average of all windows, doors and rooflights 2.0-2.2 1.80
1.80 1.50
56. Much attention has been given to the need to improve
the existing stock if the Kyoto targets are to be met. Such
attention is necessary, but dwellings built now will have
a service life well beyond 2050, and it is important that
they make a reasonable contribution to achieving the 2050
target. Consequently, the stock that is built between now
and 2050 has to be of the best practical standard.
57. Our current thinking is that for new dwellings, the
second and third columns in the above table should be the
starting point for establishing the standard of reasonable
provision for new dwellings for 2005, with the fourth column
being signalled as our current thoughts on standards for
around 2010.
58. We think that 2005 may be too soon to raise window standards
for replacement work because of handling and fabrication
issues associated with soft coat technologies, and the difficulties
associated with soft coating toughened glass. We therefore
think that for replacement windows, the performance standard
should be kept at the current level as set out in ADL1(2002),
(i.e. 2.0 W/m2K for wood and PVCU windows and 2.2 for metal
ones) - at least until the originally targeted 5 years period
between the 2002 implementation and the next revision of
Part L has passed (i.e. April 2007). However, we propose
that the improved standard would apply to new building work
immediately following the implementation date. This approach
should keep the costs of replacement windows at their current
level, thereby not discouraging homeowners from investing
in replacements. The period up to 2007 would allow industry
to expand their soft-coat production technologies as the
market for such windows expands.
59. More guidance needs to be given on what is reasonable
provision in replacement window work. For example, we think
that reasonable provision might include installing insulated
cavity closers.
60. We think that the guidance introduced in ADL1(2002)
that stated that such standards might not be appropriate
in some refurbishment situations, especially in relation
to historic buildings, should be retained. English Heritage
has published guidance on compliance with Part L , and it
is hoped that this might be reviewed and widened ahead of
2005.
61. Another issue for review is whether the trade-off allowed
by reduced window areas allows poorer opaque U-values than
is desirable. The EPBD requires that the standards should
be based on overall energy performance, and therefore it
might be argued that full trade-off should be allowed. This
view was adopted within ADL1(2002), with the only limit
on trade-off being set by establishing poorest allowable
U-values, and a caution about the need to achieve sufficient
daylighting. Given the current drive to improve standards,
it might be argued that U-values should never be significantly
poorer than a standard that is cost effective over the service
life of the element. Consequently, we are thinking that
the standards given in Table 3 of ADL1(2002) should be revised,
such that the U value of all element types (wall, roof etc)
should not be worse than a given threshold figure, both
in terms of individual elements, and in terms of whole dwelling
averages for that element type. We are thinking for instance
that the thresholds might be as given in the following table:-
Element Worst allowable U-value
of any individual element of the given type (W/m2K) Maximum
average U-value of all elements of the given type (W/m2K)
Roof 0.35 0.25
Exposed walls and floors 0.7 0.35
Wood / PVCU windows and glazed doors 3.3 ** 2.2
Metal windows and glazed doors 3.3 2.2
Unglazed doors 3.0 2.2
** We think that single glazed elements smaller than a certain
area might also be allowed
62. As with the current ADs, we think that the same standards
should be required for extension work as for new construction,
but that, excluding windows, doors and rooflights, reasonable
provision might be something less in alteration work (see
paragraph 92).
European window energy rating scheme (EWERS)
63. In the 2002 editions of ADL1 and ADL2 different U-value
standards were defined, dependent on framing material. This
was accepted in recognition of the greater solar benefit
from slimmer metal frames. The difference was based on a
generic difference rather than actual product standards.
We think it could be more effective for energy conservation
to use a product-rating scheme as the basis of assessing
performance. Therefore our current thinking is to adopt
EWERS, principally for the quality assured fundamental properties
(U-value, solar heat gain coefficient etc) that underpin
the rating, and which are required for use in the whole-building
calculation methods required by EPBD. The actual rating
may also be useful as a standard for replacement windows,
where an elemental approach is most useful.
64. By adopting the EWERS as the basis for standards in
the AD, industry should be encouraged to adopt the scheme
in sufficient numbers to make the scheme effective.
Airtightness
65. The levels of airtightness achieved in some new dwellings
is to be monitored over the next few months to help establish
whether the "Robust Details" published by TSO
in 2001 are delivering satisfactory As-Built performance.
If there is insufficient confidence that the standards mentioned
in paragraph 35 will be achieved in practice, then we would
consider introducing sample pressure testing of dwellings
in the 2005 amendment.
Robust Standard Details
66. We propose to review the existing robust details, to
add new ones to improve choice, and to cover more severe
weather exposure. We will also explore the possibility of
taking advantage of this opportunity to correlate and perhaps
merge the Part L RSDs with those produced for Part E compliance.
Control of overheating in dwellings
67. Some reservations were expressed during the Stage 1
consultation process that further increases in the levels
of insulation set out in ADL1(2002) might result in problems
of overheating and subsequent increase in domestic air conditioning.
A Partners in Innovation research contract sponsored by
DTI has investigated the validity of these concerns, and
is developing guidance aimed at limiting such problems.
The outcome of this work will be examined to establish overall
performance targets and see what specific guidance could
beneficially be included in ADL1.
68. Although levels of insulation do have an impact on overheating,
the major factors are solar gain, internal gain, ventilation
rate and thermal capacity. It is also clear that the smaller,
more compact dwellings are more prone to overheating, and
that to achieve the same comfort standard irrespective of
dwelling size would require relatively greater investment
in measures to limit overheating in small dwellings. Solar
control measures and appliance standards (see paragraph
44) are particularly relevant in this respect. This size
and shape trend is opposite to that relating to limiting
heat loss, and so this might enable the overall cost impact
of new standards to be approximately equalized across all
sizes and shapes of dwelling. We will be looking into the
possibility of introducing design standards (opening area,
solar control, building mass and ventilation provisions)
that will enable overheating to be limited through passive
means.
69. Even with such improved passive measures to control
overheating, the impact of changing climate could increase
the demand for domestic air-conditioning. We will therefore
be looking into the possibilities of setting minimum air
conditioning equipment efficiency standards for new dwellings
and for retrofit applications. The latter would require
air-conditioning systems in dwellings to be added to the
list of controlled services.
Heating systems
Central heating boilers
70. For domestic gas boilers serving space-heating systems,
the EWP has indicated that the standard for normal circumstances
will be increased to SEDBUK Band A or B (i.e. a seasonal
efficiency >= 86%), which is equivalent to a condensing
boiler. The Government has indicated that it wants this
higher standard brought into effect by 01 April 2005 so
that boilers can be removed from the prospective new Energy
Efficiency Commitment signalled in the EWP. We shall therefore
be developing proposals for an interim amendment timed to
come into effect on 01 April 2005, that revises the guidance
in ADL1 (2002). The aim is to consult on this as part of
the general consultation on Part L in the summer of 2004,
and then to fast-track the review and approval process to
enable the amendment to be published around February 2005.
71. Because the impact of improved heating system efficiency
is greatest the poorer the insulation standards of the house,
(longer heating season and greater heating demand), it could
be argued that higher standards should be set for replacement
boilers than for those included in new dwellings. However,
there is currently no real technical distinction between
boilers rated at SEDBUK A and SEDBUK B and so this may not
be practical.
72. We believe that lower SEDBUK standards will be justified
in some exceptional circumstances, especially for replacement
boilers in existing dwellings where there may be flueing
or condensate drain problems or other significant structural
and décor barriers and in dwellings away from the
gas grid or with solid or oil fuelling by choice. Industry
is working to identify these exceptional building situations
in terms of the practical difficulties and the extra overcosts
involved. In due course a paper will be presented making
recommendations on the cut-off point when the extra costs
make condensing boilers non-cost-effective, and hence the
standard of what would be reasonable provision post March
2005. As part of this however we would be looking to obtaining
best practical performance from non-condensing boilers.
We therefore think that, in addition to defining when non-condensing
boilers replacements are allowed, ADL1 should call for the
controls package to be upgraded to the standards applying
to new dwellings.
73. It will be necessary as part of this to introduce separate
provisions for different classes of boilers such as back
boilers, combi-boilers and central hot water storage units,
and boilers fired with LPG, oil, or solid fuel. Multi-fuel
solid fuel boilers will need particular consideration, given
the very different carbon intensity of the alternative fuels
(coal, wood and wood pellets).
74. We also think it essential to make reasonable provision
when microCHP units (or other new heating technologies)
are to be installed. As part of this process, SAP 2001 will
need to be updated to reflect the performance of mature
new technologies as well as to align it with the requirements
of the EPBD.
Local fires - secondary heating
75. In many dwellings, a local fire supplements the central
heating system, or provision is made via a chimney or flue
for a fire to be fitted by the occupier. It is thought likely
that the carbon emissions from such secondary heating systems
are considerable when viewed nationally. Consultees in the
past have therefore suggested that
a. secondary heating systems should be specifically required
to be efficient,
b. that the heat loss from permanently open flues should
be taken into account and
c. that poorer appliance performance should be compensated
for in some way.
76. We propose to investigate how compensation could be
made and the practicalities and enforcement issues arising
from such a measure. The requirements of the EPBD to move
to a compliance procedure based on an integrated building
performance method (likely to be based on SAP for dwellings)
seem likely to take account of this issue, because allowance
would have to be made for secondary heating systems and/or
chimneys and flues in the calculation procedure.
Other forms of heating in dwellings
77. We are looking into developing proposals for introducing
new performance standards and guidance for a wider range
of heating systems in dwellings including:-
a. Localised fires; as insulation standards improve, the
use of several local fixed heaters may become more common
instead of, rather than supplementary to, hot water central
heating. Consideration is being given to basing performance
requirements on recently published standards . We also propose
to consider what standards might apply to electric heaters,
which are 100% efficient at point of use, but usually involve
a higher carbon burden.
b. Domestic CHP - either microCHP units directly replacing
domestic boilers, or macroCHP (up to say 25kWe) in blocks
of flats for instance. Following the announcement of Government
supported trials of this technology and the goals for increasing
embedded generating capacity over the next 2 decades, small
scale CHP may well take a significant share of the future
market for replacement heating systems. Currently, the overall
carbon emissions from CHP units are compared with regular
boilers that meet the performance standards in ADL1. It
is expected that a new CHP seasonal efficiency index similar
(but not comparable with) SEDBUK will become available,
and it is hoped that this can be adopted for 2005.
Hot water services
78. As fabric insulation and airtightness standards improve,
the relative importance of efficient generation of hot water
and provisions for controlling its consumption increases.
We will investigate ways of setting standards for the efficiency
of hot water generation, distribution and use. In addition
to the existing guidance on central heating boilers with
HWS cylinders, we propose to introduce guidance on reasonable
provision when choosing COMBI boilers, multi-point instantaneous
water heaters and economising outlet taps and valves. The
on-going CEN activity aimed at developing a standard for
labelling of water heating systems will be a useful source
of information in this respect.
79. It is thought unlikely however that Part L of the Building
Regulations could be used to influence householders' demand
beyond making provisions for economic delivery at outlets.
In the Building Act 1984 there are powers enabling water
conservation measures to be introduced. ODPM will be considering
with DEFRA how these might be used.
80. It is proposed to investigate under what circumstances
solar hot water systems are cost-effective. It seems likely
that they will be found to be so for new dwellings with
favourable roof orientations. It may also be cost-effective
to require hot water replacement works, and the works involved
in installing replacement combi-boilers, to include provisions
for later connection of solar collector systems. Where systems
are shown to be cost effective, our current thinking is
that reasonable provision should include their installation
(or compensating for their omission by greater energy efficiency
measures elsewhere in the design).
81. The safe and effective installation of solar water heating
systems requires a degree of specialist expertise. We therefore
wish to include guidance in ADL1 on appropriate installation
and commissioning practice. In parallel with this we have
invited the industry to investigate with us the prospects
for a competent persons scheme.
82. The EWP encourages the greater uptake of renewable energy
systems, and so we will be exploring what guidance might
be appropriate for other types of building integrated renewable
energy technology. The most likely candidate is PV generating
systems , and as with solar hot water, where the economics
are favourable, consideration might be given to requiring
some PV provision, or at least making it practical to more
easily incorporate PV as a later retrofit. Either way, ADL1
will provide references to documents that give advice on
the selection and installation of various types of renewable
energy system.
Lighting
83. The guidance on lighting for dwellings will be reviewed
in the light of the perceived effectiveness of the 2002
standards. This is an area where further significant improvements
in efficiency are achievable, but where mechanisms such
as product rating schemes might be more effective.
84. Now that the domestic lighting industry has expanded
the available range of fittings that can accommodate energy
efficient lamps, we are thinking that it could be reasonable
to provide energy efficient fittings at more locations in
new dwellings. The guidance in the current ADL1 is based
on the 1995 edition of GIL20; that document has been updated,
and any new guidance will be correlated with the new edition
and any further relevant guidance.
85. Consideration is also being given to whether lighting
should be included in SAP as a further means of encouraging
energy efficient lighting, since by so doing, improved standards
of energy efficient lighting could be used to offset other
perhaps more expensive energy efficiency measures. This
would be in line with the option in the Annex to the EPBD.
Conservatories
86. The current exempt status for conservatories less than
30m2 is being considered by a separate Building Regulations
Advisory Committee (BRAC) working party, following consultations
that concluded on 29 March 2002.
87. A PiI project investigating the energy performance of
modern conservatory designs has been completed and is being
used to inform the on-going discussions. The results will
be used as the basis for setting performance standards in
a new guidance document addressing all the technical requirements
that apply. The main conclusions of the PiI work are that
reasonable energy performance can be achieved provided there
is effective thermal separation between the living space
in the dwelling and the conservatory, and the thermal performance
standards match the general elemental standards. The current
thinking is that, if conservatories have not been addressed
in the meantime by a separate Technical Guidance document
covering all aspects of conservatory design, ADL1 should
be extended to indicate that thermal separation from the
dwelling should be maintained, that the elements (opaque
wall, glazing etc) should comply with the elemental U-value
standards, but that they are not required to comply with
the standard area allowances. We would also think that some
form of solar protection system (e.g. roof blinds) and high
and low level vents to promote natural ventilation is also
reasonable provision for avoiding excessive summer overheating.
88. The technical guidance document referred to above will
only deal with conservatories that are thermally separated
from the attached dwelling. We are therefore thinking that
ADL1 may need to provide guidance on what is reasonable
provision for those situations where there is a permanent
opening between a highly glazed extension and the main accommodation.
Refurbishment of the existing stock
89. There are around twenty four million existing dwellings
and the average SAP Rating of this stock is around 44. New
dwellings built to the 1995 standards were achieving SAP
Ratings on average perhaps around 75, and those being designed
to the 2002 standards may be achieving SAP Ratings up to
around 90. However less than 200,000 new dwellings are being
built in the UK each year. Examining how further encouragement
can be given towards improving the average SAP Rating of
the existing stock is therefore seen to be a vital element
of this review.
90. The Building Regulations only apply when people propose
to carry out work. In deciding what measures are to be controlled
and what standards are considered reasonable, an important
consideration is the risk of dissuading people from improving
at all. The outcome of the Treasury's consultation on fiscal
measures to encourage investment in energy saving measures,
and DEFRA's programmes for supporting the activities of
the Energy Saving Trust will therefore be important considerations
in how far Building Regulations can move.
91. We propose to review the performance standards for windows,
boilers and hot water cylinders that were introduced in
ADL1 (2002) in the light of experience. It is thought that
these standards could be raised to keep them in line with
the provisions for new dwellings (although as discussed
in paragraphs 58 and 72, particular considerations might
apply to replacement windows and some replacement boilers).
In the light of the point made in paragraph 69, it could
be a prudent provision to add domestic air-conditioning
systems to the list of Controlled Services for dwellings.
92. The possibilities for widening the definition of material
alterations and stiffening the performance standards that
apply in these cases will be re-examined in an effort to
encompass more types of what are now considered to be maintenance
and repair work. We propose to investigate how the existing
guidance on material alterations and changes of use in paragraphs
2.6 and 2.8 of ADL1 can be widened to address more types
of work, such as replacing the weather resisting layers
of roofs. This could lead to a fundamental amendment of
what constitutes a material alteration, but as this would
have an impact wider than just Part L, it needs to be considered
in that wider context.
The Energy Performance of Buildings Directive
93. In line with the Directive Article 3, and with help
from Expert Panels, we shall be developing : -
a. the national methodology for calculating the energy performance
of buildings, and
b. a system for establishing reference performance levels
for the different types of buildings including multi-purpose
ones.
c. overall building energy performance standards in line
with Articles 4 to 6,
d. in relation to Article 5, provisions for considering
whether it is reasonable to provide low carbon and zero
carbon systems.
e. in accordance with Article 7, a system for requiring
the supply of building energy performance certificates for
new buildings and for those substantially refurbished,
f. the case for adopting either option (a) or option (b)
in Article 8, and, if option (a) is preferred, a system
for effecting boiler inspections under the powers in Section
2 of the Act.
g. In accordance with Article 9, a system for effecting
air conditioning inspections under the powers in Section
2 of the Act.
94. We shall also be participating with others in the development
of the systems for appointing suitably expert building energy
surveyors and boiler and air conditioning plant inspectors.
95. As indicated in paragraph 11, our strategies for developing
these new provisions will be published separately.
96. As discussed in paragraph 23, the aim of the Part L
revision is expected to be a substantial improvement in
energy efficiency standards in 2005 consistent with practical
and economic considerations. All elements of construction
work will be expected to make a contribution towards achieving
this improvement. Those elements of construction work for
which the 2002 Review introduced standards for the first
time are areas where we think significant advances in standards
might be possible, because the standards set in introducing
the requirement were especially cautious.
97. In parallel with the development of the overall building
energy performance standards mentioned above, we shall also
be considering improvements in the standards applicable
to elements of buildings (as currently set out in the elemental
standards). The aim is to substantially raise standards
in line with the overall energy performance methods as required
by the Directive. The setting of improved elemental standards
will help define the overall building performance standard,
and also enable builders engaged in small-scale alteration
and extension work to avoid detailed energy calculations.
Building envelope
U-values
98. We shall be considering how U-values can be further
improved, with the aim of keeping them generally in line
with those improvements applicable to dwellings (see paragraph
55). However, since the EPBD requires a move to whole building
standards, precise U-value targets are less significant.
We shall also be investigating whether it would be appropriate
to set different minimum performance standards dependent
upon the building type and/or construction method.
99. We have already begun a review of the provisions applicable
to buildings with low levels of heating as set out in paragraph
0.22 of ADL2(2002). The aim is to amend this as part of
the Stage 2 package (see paragraph 6).
Solar control
100. Consideration will be given to how best the solar control
requirements could be applied to window replacements. Current
thinking is that the solar overheating requirement might
be limited to apply only when new or larger openings are
being created, or when ACMV systems are being installed
at the same time as replacement glazing is being installed.
Display windows and glazed entrances
101. Currently, display windows are ill-defined but nevertheless
exempted from considerations when showing compliance with
Part L2. However, display windows can represent a significant
proportion of the façade area in (e.g.) retail and
leisure developments. We are therefore looking to develop
a more distinct definition of "display" window,
with the aim of introducing this definition as part of the
2005 review.
102. The relative impacts on heating, cooling and lighting
need to be better understood, along with the structural
and durability implications of large double glazed units.
We therefore propose to review the energy balance of display
windows in different contexts (corner shop, high street
store, car showroom, mall retail unit etc). The Scottish
Executive has also commissioned work in this area and we
shall be looking to pool our results. Following this analysis,
we will then consider whether the exemption should be removed
or modified, and make proposals for introducing new guidance
into ADL2. We think that some improvements may be possible
as part of the 2005 amendment, but more time will be needed
thereafter to complete this work.
Rooflights and ventilators
103. It has been suggested that non-opening rooflights typically
found in large-span buildings such as factory units, retail
sheds or leisure complexes might be classified as a separate
element type, with different U-value requirements and different
area allowances to those in Tables 1 and 2 of ADL2.
104. We are aware that the current provisions for trading
off in ADL2 paras 1.14 to 1.16 are causing difficulties
between developers and BCBs.
105. The performance standards and area allowances for rooflights
will be the subject of a major review, especially in relation
to the area allowances. The current 20% is considerably
greater than that used in conventional designs for many
building types. If any excess rooflight allowance is used
for trade-off purposes, it can create anomalies. This aspect
will be the subject of special review, so that while design
flexibility is maintained and the appropriate use of daylight
is encouraged, opportunities for excessive lowering of thermal
standards are eliminated from the compliance procedures
in the AD. The whole building performance approach to compliance
required by EPBD will help in this respect.
106. Roof ventilators (for smoke extraction or normal ventilation)
can have relatively poor thermal performance relative to
that of the opaque roof elements and their running gear
introduces thermal bridges and air leakage paths. Appropriate
standards of insulation and airtightness performance are
as yet undefined for such products, and these are likely
to be reviewed in conjunction with the non-opening rooflights
discussed above. The degree of insulation and airtightness
that might be appropriate has yet to be determined, but
it is thought that the presence or otherwise of opening
roof ventilators should not influence the required air permeability
standards.
Entrance and vehicle access doors
107. Building airtightness may be compromised by the use
of large unprotected entrance doorways. These may be closed
when air pressure tests are carried out, but open for much
of the time in practice. In hospital and industrial buildings
there is often the need to have doorways that enable frequent
traffic. However in hotter and colder climates it is normal
to protect entrances with draught lobbies (or similar) and
it is considered that provisions like these might now be
appropriate for normal application in England and Wales.
108. It has been suggested that the current guidance on
the minimum U-value standard for vehicle access doors is
somewhat impractical and this will be reviewed. The aim
is to revise the standard as part of the Stage 2 package
(see paragraph 6).
Heating system efficiency standards
109. For non-domestic heating plant, we propose to consider
improving the required standards of carbon intensity. Although
this will inevitably cover boiler performance standards,
consideration will also need to be given to system integration
issues, since these can have a significant impact on overall
performance.
110. As part of this, consideration is to be given to the
possibilities for developing a seasonal efficiency rating
similar to the SEDBUK, though it is recognised that there
is much greater variation in heating demand patterns and
operating regimes than is the case for dwellings. In many
non-domestic situations, there will be multiple boilers,
and so it is therefore planned to work with industry to
see how boiler selection and system design issues might
improve seasonal efficiency, with the aim of introducing
improved standards in 2005.
111. Additional guidance on reasonable provision for fuel
efficiency and controls for systems such as radiant or warm
air heaters is envisaged, but the extent of the advice will
depend on the availability of the proposed CEN standards.
Regular inspection of boiler plant
112. The EPBD offers member states two routes to achieving
this goal and discretion on which fuelling options trigger
the inspection requirement. There are options of an inspection
regime or a system of advice to users that will achieve
the same objective, namely delivering recommendations on
cost-effective improvements to, or replacements of, the
heating system to improve energy efficiency. The EPBD Article
allows that inspection systems can be limited to apply to
oil and solid fuelled installations or opened up to include
gas. As an urgent first step DEFRA are preparing a statement
of the merits and demerits of the options so that Ministers
can decide which is most appropriate for the UK.
113. If the decision is to go for option (a), the inspection
option, we will need to develop new legal requirements underpinned
by Section 2 of the Building Act, perhaps amended by the
European Communities Act.
114. As an adjunct to this issue, DEFRA will be investigating
how building owners might be encouraged or required to carry
out the improvement work recommended as a result of the
inspection.
Lighting
Efficacy
115. It is felt that significant improvements in the standards
for lamp efficacies, luminaire efficiency and lighting controls
might be practical for all building types. However, these
aspects of the design need to be balanced against issues
of lighting quality, especially following recent professional
guidance tending to increase the use of indirect lighting.
We propose to explore with industry how and to what extent,
the lighting efficiency standards can be improved and to
make proposals for amendments that could come into effect
in 2005 - and also to set outline targets for future reviews.
116. The move to the whole building energy performance approach
to compliance means that we will need to consider performance
standards related to the building and not just to lamps
or luminaires. This might require standards to be set in
terms of kWh/m2 per annum per hundred lux or similar, although
this would not interfere with designers' discretion to select
lighting intensities to suit occupiers' needs. A CEN working
group is already working in this area, and we will seek
to take benefit from their activities.
Lighting controls
117. BRE have developed further guidance on lighting controls
relating controls provision to the type of space/occupancy
combination. It is expected that this new guidance will
be published next year. It is envisaged that most, if not
all of it, will be referred to in the 2005 edition of Approved
Document L2 as reasonable provision for compliance. Lighting
controls will be an important element of a whole building
lighting energy target, and so the controls issues may well
be integrated with the approach described in the previous
paragraph.
118. CIBSE have just published a commissioning guide for
lighting control systems, and this will be referenced as
part of the revision of the current section 2 of ADL2.
Air conditioning and mechanical ventilation (ACMV)
System performance
119. The performance standards given in ADL2 (2002) for
buildings that are air-conditioned or mechanically ventilated
(ACMV) were equivalent to what was considered "typical"
performance in 1998. The application of ACMV in new and
existing buildings continues to expand rapidly (and may
accelerate should climate change effects become more manifest).
Higher standards for effective design and appropriate commissioning
are therefore being considered.
120. Because of the growth in multiple split systems that
can serve small individual rooms, our current thinking is
that the limit on application of the requirement should
be reduced. The present limit of 200 m2 was derived from
considerations of minimum lettable areas. The limit might
be reduced to say 100 m2, or might instead be based on considerations
of fan or refrigeration capacities. For example, the EPBD
requirement on inspection of air-conditioning systems covers
those systems with an output greater than 12kW, and there
may be benefit in having a consistent application limit.
Component benchmarks
121. We have found it impossible to apply the Carbon Performance
Rating Method to buildings other than offices because of
the variances of occupation and energy use in other types
of buildings, and the absence of national data (similar
to that in ECON 19 for offices) on which to base pass criteria.
We are therefore exploring the possibilities of component
benchmarking systems such as the specific fan power indices
already included in ADL2. Such benchmarks might be defined
for room air conditioners, central chillers and pumps etc.
122. For example, work is on going to explore the potential
of the Integrated Part Load Value (IPLV) approach. This
may well prove useful, especially if appropriate weighting
factors for UK climate and practice can be established.
This will help to address system integration issues as well
as component performance.
123. The IPLV recognises the importance of part-load efficiency,
and this issue will need to be addressed across all the
components that contribute to the energy performance of
ACMV systems.
Humidity control
124. The control of humidity can result in significant energy
consumption in some buildings. Evidence suggests that energy
is often wasted through over humidification in winter. To
that end, we propose to give consideration to how this should
be addressed via guidance in ADL2 on humidification methods
and humidity control systems. One concern would that the
more energy efficient technologies tend to require greater
maintenance effort; if maintenance regimes were poor in
practice, the risk of legionella problems might increase.
This risk will have to be factored in to the overall cost
benefit analysis.
125. Energy for dehumidification is implicit in the cooling
load, at least as far as normal comfort cooling systems
are concerned, and so no further action is required.
Regular inspection of air conditioning systems
126. In line with the EPBD, we will be developing proposed
legal requirements and technical guidance for reasonable
provision for regularly inspecting and reporting on air
conditioning systems rated at more than 12 kW. The guidance
might be included in ADL2 or could be published as perhaps
a CIBSE or FETA Technical Memorandum. CIBSE and FETA are
already working on this. This would be underpinned by deploying
dormant powers in Section 2 of the Building Act, perhaps
amended by the European Communities Act 1972.
Renewable energy systems
127. We are investigating how the Building Regulations can
address the requirement in the EPBD Article 5 to take into
account low-Carbon and Zero-Carbon technologies at the design
stage Various ways that have been suggested include
a. Setting the building energy performance standard based
on a proportion of the building's energy demand being generated
from an on-site renewable source. This would require designers
to include renewable or low-carbon energy systems as part
of the design, or else compensate via higher energy efficiency
standards in other aspects of the design. This approach
has the advantage of allowing market forces to determine
the most cost effective way of achieving carbon savings.
b. Setting a limit on the externally supplied power input
to the building, requiring buildings with high power demands
to have building integrated energy generation capacity.
This approach has been used in other countries (e.g. parts
of Switzerland), but has the disadvantage of being more
to do with building use than building design.
128. Further guidance is to be developed on the selection
and application of a number of low-carbon and zero-carbon
technologies that can be used as part of achieving the requisite
overall building carbon performance.
129. Where such no or low carbon technologies are installed,
we think that for the time being, such provisions should
not be used via trade-off to reduce the fundamental efficiency
of the building envelope or the building services systems.
Power factor correction
130. Low power factors can cause significant energy losses
in transmission systems. We propose to consider whether
the prospective overall building power factor can be assessed
at the design stage, and if and how it might be corrected
(at a component, system or whole building level). This will
be discussed with both the building industry and the utilities.
If the potential savings are found to be significant, we
will make proposals for introducing requirements in 2005.
This will depend on being able to set appropriate standards
and the practicalities of checking compliance.
131. There is also an issue for suppliers' networks of harmonic
distortions, but this is probably outside the scope of Part
L.
Other energy consuming services
132. There are some energy consuming services in buildings
that are not currently addressed by Part L2 (e.g. lifts
and other vertical transportation systems). We propose to
give consideration to whether setting efficiency standards
for such systems might deliver worthwhile carbon reductions.
Conservatories, atria and other sun spaces
133. Atria are common in many types of non-domestic buildings
and are often much larger than the present 30m2 threshold
of exemption granted to conservatories. We therefore propose
to further examine the possibilities for defining standards
of reasonable performance, and the guidance on its achievement
as given in ADL2 (2002). However, the move to a whole-building
based approach to compliance may mean that specific performance
standards for atria are not needed
Refurbishment of the existing stock
134. There were about 1.9 million business addresses in
England and Wales in 1994, each on average occupying about
650 m2 of building floor area. Total floor area is increasing
at about 2% per year. Building turnover (demolition and
replacement) is somewhat higher than for dwellings, so the
potential for energy performance improvement year on year
for the stock as a whole is somewhat better. In 2000, the
emissions of carbon from these buildings was about 21 million
tonnes , about 20% of the national total. Offices, shops,
hotels, industrial buildings and schools are the largest
contributors.
135. Extensive performance data and a common energy rating
system like the SAP for dwellings are presently unavailable
to assist consideration of this stock, but it is widely
held that its average performance is far short of that being
achieved by new build. The EPBD will in due course help
to improve this situation. However, even in the absence
of firm information, further improvement to the average
performance of the existing stock is seen to be a vital
element of the 2005 amendment
136. The Building Regulations only apply when people propose
to carry out work. In deciding what measures are to be controlled
and what standards are considered reasonable, an important
consideration is the possibility of dissuading people from
improving at all.
137. The performance standards for windows and the building
services installations that were introduced in ADL2 (2002)
will be reviewed in the light of experience. Where practical,
we will raise these standards to keep them in line with
the provisions for new buildings.
138. The possibilities for widening the definition of material
alterations and stiffening the performance standards that
apply in these cases will be re-examined with the aim of
encompassing more types of maintenance and repair work (see
the general discussion under paragraph 92).
Extensions
139. As with the current ADL2, we suggest that extension
work should continue to be required to meet the same standards
as for new-build.
140. The performance standards for windows, boilers and
building services introduced in ADL2 (2002) will be reviewed
in the light of experience. It is suggested that these standards
should be raised to keep them in line with the provisions
for new buildings (although as discussed in paragraph 58,
particular considerations might apply to replacement windows).
141. The possibilities for widening the definition of material
alterations and stiffening the performance standards that
apply in these cases will be re-examined in an effort to
encompass more types of what are now considered to be maintenance
and repair work. We propose to investigate how the existing
guidance on material alterations and changes of use in paragraphs
2.6 and 2.8 of ADL1 can be widened to address more types
of work.
