ONLINE VERSION

The Building Regulations 2010

L1B
Conservation of fuel and power

APPROVED
DOCUMENT
L1B Conservation of fuel and power
in existing dwellings

In effect from 1 October 2010

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ONLINE VERSION
in
 ONLINE VERSION
MAIN CHANGES IN THE Main changes made by the
2010 EDITION 2010 and 2011 amendments
1. This Approved Document L1B came into force This 2010 edition, incorporating the further
on 1 October 2010 in support of the Building 2010 amendments reflects the changes made
and Approved Inspectors (Amendment) as a result of the Building Regulations 2010;
Regulations 2010, SI 2010 No. 719. The main Building Approved inspector etc Regulations
changes to the legal requirements and the and the Building (Amendment) Regulations
supporting guidance in this edition of 2011. The changes mainly reflect regulation
Approved Document L1B are as follows: number changes as a result of re-ordering. There
have been no amendments to the substantive
Changes in the legal requirements requirements in Schedule 1(i.e. Parts A to P) of
2. The exemption from the energy efficiency the Building Regulations.
provisions for extensions consisting of a Please note the simplification of the definition
conservatory or porch is amended to grant of ‘room for residential purposes’ in regulation
the exemption only where any existing walls, 2 of the Building Regulations 2010 and the
windows or doors are retained, or replaced if amendment of the definition of “renovation”
removed, and where the heating system of in regulation 2(1) of the Building (Amendment)
the building is not extended into the Regulations 2011. Please also note that L1(c) has
conservatory or porch. now become regulation 40.
3. The list of work in Schedule 4 (work that
need not be notified to building control) is Main changes made by the 2013
amended to include the installation of
thermal insulation in a roof space or loft amendments
space where this is the only work carried out The main changes, which apply only to
and the work is not carried out to comply England*, are:
with any requirement in the Building • To take account of a recast of the European
Regulations. Energy Performance of Buildings Directive
Changes in the technical guidance • Materials and workmanship guidance updated
4. In this Approved Document the guidance is • Updated references to third party guidance
generally based upon an elemental approach
to demonstrating compliance, with additional • Introduction of doorset energy ratings
guidance that provides greater flexibility. The
main technical changes comprise a general Main changes made by the 2016
strengthening of energy efficiency standards amendments
that are considered reasonable for work on
thermal elements, controlled fittings and Changes reflect alterations to the regulations,
controlled services in existing dwellings. principally withdrawal of Regulations 29 to
33 of the Building Regulations 2010 and their
5. Amended guidance is given for historic and replacement by Regulation 7A of the Energy
traditional buildings which may have an Performance of Buildings (England and Wales)
exemption from the energy efficiency Regulations 2012 and changes in wording of
requirements or where special considerations Regulations 24, 25, 26, 26A, 27 and 27A of the
apply. Building Regulations 2010. There are no technical
6. Amended guidance is given where an changes.
extension is a conservatory or porch that is
not exempt from the energy efficiency Main changes made by the 2018
requirements.
amendments
7. The guidance for the renovation of a thermal
element through the provision of a new layer Changes all references to the Domestic Building
or through the replacement of an existing Services Compliance Guide 2013 edition to the
layer has been expanded. Domestic Building Services Compliance Guide
2013 edition with 2018 amendments.
8. Guidance is provided for swimming pool
basins (walls and floor) in existing dwellings.

*This approved document gives guidance for compliance with the Building Regulations for building
work carried out in England. It also applies to building work carried out on excepted energy buildings in
Wales as defined in the Welsh Ministers (Transfer of Functions) (No 2) Order 2009.

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 ONLINE VERSION L1B
Contents
PAGE PAGE

Section 1: Introduction 2 Section 5: Guidance on thermal elements 16

What is an Approved Document? 2 THE PROVISION OF THERMAL ELEMENTS 16
Consideration of technical risk 2 U-values 16
How to use this Approved Document 2 Continuity of insulation and airtightness 17
Where you can get further help 3 Major renovation 17
Responsibility for compliance 3 RENOVATION OF THERMAL ELEMENTS 17
RETAINED THERMAL ELEMENTS 18
Section 2: The requirements 4
LIMITATION ON REQUIREMENTS 5 Section 6: Consequential improvements to
energy performance 19
Section 3: General guidance 6
Section 7: Providing information 20
Key terms 6
Types of work covered by this Appendix A: Work to thermal elements 21
Approved Document 7
Appendix B: Documents referred to 24
Dwellings within the scope of the
energy efficiency requirements 7
Appendix C: Standards referred to 25
Dwellings exempt from the energy
efficiency requirements 7 Index 26
Notification of work covered by the
energy efficiency requirements 8
Materials and workmanship 10
The Workplace (Health, Safety and
Welfare) Regulations 1992 10
Section 4: Guidance relating to
building work 11
THE EXTENSION OF A DWELLING 11
Reference method 11
Optional approaches with more
design flexibility 11
Conservatories and porches 11
Swimming pool basins 12
MATERIAL CHANGE OF USE AND
CHANGE OF ENERGY STATUS 12
Material change of use 12
Change of energy status 12
Option providing more design flexibility 13
WORK ON CONTROLLED FITTINGS
AND SERVICES 13
Controlled fittings 13
Controlled services 14
COMMISSIONING OF FIXED BUILDING
SERVICES 14

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Section 1: Introduction
What is an Approved Document? with any other applicable requirements of
building regulations.
1.1 This Approved Document, which takes
effect on 1 October 2010 has been approved 1.6 There are Approved Documents that give
and issued by the Secretary of State to provide guidance on each of the Parts of Schedule 1 and
practical guidance on ways of complying with the on regulation 7. A full list of these is provided at
energy efficiency requirements (see Section 2) the back of this document.
and regulation 7 of the Building Regulations 2010
(SI 2010/2214) for England and Wales. Regulation Consideration of technical risk
2(1) of the Building Regulations defines the 1.7 Building work to existing dwellings must
energy efficiency requirements as the satisfy all the technical requirements set out
requirements of regulations 23, 25A, 25B, 26, 28 in regulations 23, 22 and 28 of, and Schedule 1
and 40 and Part L of Schedule 1. The Building to, the Building Regulations. When considering
Regulations 2010 are referred to throughout the the incorporation of energy efficiency measures
remainder of this Document as ‘the Building in dwellings, attention should also
Regulations’. be paid in particular to the need to comply with
1.2 The intention of issuing Approved Documents Part B (fire safety), Part C (site preparation and
is to provide guidance about compliance with resistance to contaminants and moisture), Part E
specific aspects of building regulations in some (resistance to the passage of sound), Part F
of the more common building situations. They (ventilation), paragraph G3 (hot water supply and
set out what, in ordinary circumstances, may be systems), Part J (combustion appliances and fuel
accepted as reasonable provision for compliance storage systems) and Part P (electrical safety)
with the relevant requirement(s) of building of Schedule 1 to the Building Regulations, as
regulations to which they refer. well as Part L. The adoption of any particular
energy efficiency measure should not involve
1.3 If guidance in an Approved Document unacceptable technical risk of, for instance,
is followed there will be a presumption of excessive condensation. Designers and builders
compliance with the requirement(s) covered by should refer to the relevant Approved Documents
the guidance. However, this presumption can be and to other generally available good practice
overturned, so simply following guidance does guidance to help minimise these risks.
not guarantee compliance; for example, if the
particular case is unusual in some way, then How to use this Approved Document
‘normal’ guidance may not be applicable. It is
also important to note that there may well be 1.8 This Approved Document is subdivided
other ways of achieving compliance with the into seven sections as detailed below. These
requirements. There is therefore no obligation sections are followed by supporting appendices.
to adopt any particular solution contained in This introductory section sets out the general
this Approved Document if you would prefer context in which the guidance in this Approved
to meet the relevant requirement in some Document must be considered.
other way. Persons intending to carry out
building work should always check with their Section 2 sets out the relevant legal requirements
building control body, either the local authority contained in the Building Regulations.
or an approved inspector, that their proposals Section 3 contains general guidance, including
comply with building regulations. the definition of key terms, the types of building
1.4 It is important to note that this Approved work covered by this Approved Document,
Document, as well as containing guidance, also the types of building work that are exempt,
contains extracts from the Regulations. Such procedures for notifying work, materials and
regulatory text must be complied with as stated. workmanship and health and safety issues.
For example, the requirement that fixed building Section 4 gives guidance on reasonable
services must be commissioned (regulation 44) provision for various types of building work.
is a regulatory requirement. There is therefore no
flexibility to ignore this requirement; neither can Section 5 deals with the particular case of work
compliance with this particular regulation be to thermal elements.
demonstrated via any route other than that set Section 6 gives guidance in support of the
out in regulation 44. requirement for consequential improvements
1.5 The guidance contained in this Approved for buildings over 1,000 m2.
Document relates only to the particular Section 7 describes the information that should
requirements of the Building Regulations that the be provided to occupiers to help them achieve
document addresses (set out in Section 2). reasonable standards of energy efficiency in
However, building work may be subject to more practice.
than one requirement of building regulations. In
such cases the work will also have to comply

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INTRODUCTION ONLINE VERSION L1B
1.9 In this document the following conventions • if your query is of a highly technical nature,
have been adopted to assist understanding and you may wish to seek the advice of a
interpretation: specialist, or industry technical body, for
the relevant subject.
a. Texts shown against a green background are
extracts from the Building Regulations 2010
(SI 2010/2214) or Building (Approved Responsibility for compliance
Inspectors etc.) Regulations 2010 (SI 2010/2215) 1.11 It is important to remember that if you
and set out the legal requirements that relate are the person (e.g. designer, builder, installer)
to compliance with the energy efficiency carrying out building work to which any
requirements of building regulations. As stated requirement of building regulations applies you
previously, there is no flexibility in respect of have a responsibility to ensure that the work
such text; it defines a legal requirement, not complies with any such requirement. The building
guidance for typical situations. It should also owner may also have a responsibility for ensuring
be remembered that, as noted above, compliance with building regulation requirements
building works must comply with all the other and could be served with an enforcement notice
applicable requirements of building regulations. in cases of non-compliance.
b. Key terms are defined in paragraph 3.1 and
are printed in bold italic text.
c. Details of technical publications referred to
in the text of this Approved Document will be
given in footnotes and repeated as references
at the end of the document. A reference to a
publication is likely to be made for one of two
main reasons. The publication may contain
additional or more comprehensive technical
detail, which it would be impractical to
include in full in the Approved Document but
which is needed to fully explain ways of
meeting the requirements; or it is a source of
more general information. The reason for the
reference will be indicated in each case. The
reference will be to a specified edition of the
document. The Approved Document may be
amended from time to time to include new
references or to refer to revised editions
where this aids compliance.
d. Additional commentary in italic text appears
after some numbered paragraphs. This
commentary is intended to assist understanding
of the immediately preceding paragraph or
sub-paragraph, or to direct readers to
sources of additional information, but is not
part of the technical guidance itself.

Where you can get further help

1.10 If you do not understand the technical
guidance or other information set out in this
Approved Document and the additional detailed
technical references to which it directs you, there
are a number of routes through which you can
seek further assistance:
• the Government website:
www.gov.uk;
• if you are the person undertaking the building
work, you can seek assistance either from
your local authority building control service or
from your approved inspector (depending on
which building control service you are using;
• persons registered with a competent person
self-certification scheme may be able to get
technical advice from their scheme operator;

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L1B ONLINE VERSION
Section 2: The requirements
2.1 This Approved Document, which takes
effect on 1 October 2010, deals with the energy
efficiency requirements in the Building
Regulations. Regulation 2(1) of the Building
Regulations defines the energy efficiency
requirements as the requirements of regulations
23, 25A, 25B, 26, 28 and 40 and Part L of
Schedule 1. The energy efficiency requirements
relevant to this Approved Document, which deals
with existing dwellings, are those in regulations
23, 28 and 40 of, and Part L of Schedule 1 to,
those Regulations and are set out below.

Requirements for the renovation or replacement of thermal

elements – Regulation 23
(1) Where the renovation of an individual thermal element—
(a) constitutes a major renovation; or
(b) amounts to the renovation of more than 50% of the
element’s surface area;
the renovation must be carried out so as to ensure that
the whole of the element complies with paragraph L1(a)(i) of
Schedule 1, in so far as that is technically, functionally and
economically feasible.
(2) Where the whole or any part of an individual element is
proposed to be replaced and the replacement—
(a) constitutes a major renovation; or
(b) (in the case of part replacement) amounts to the
replacement of more than 50% of the thermal element’s surface
area;
the whole of the thermal element must be replaced so as to
ensure that it complies with paragraph L1(a)(i) of Schedule 1,
in so far as that is technically, functionally and economically
feasible.

Consequential improvements to energy performance

Regulation 28
(1) Paragraph (2) applies to an existing building with a total
useful floor area over 1000 m2 where the proposed building
work consists of or includes—
(a) an extension;
(b) the initial provision of any fixed building services; or
(c) an increase to the installed capacity of any fixed
building services.
(2) Subject to paragraph (3), where this paragraph applies,
such work, if any, shall be carried out as is necessary to ensure
that the building complies with the requirements of Part L of
Schedule 1.
(3) Nothing in paragraph (2) requires work to be carried out if
it is not technically, functionally or economically feasible.

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 ONLINE
THE REQUIREMENTS VERSION L1B

Requirement Limits on application

Schedule 1 – Part L Conservation of fuel and power

L1. Reasonable provision shall be made for the conservation of
fuel and power in buildings by:
(a) limiting heat gains and losses—
(i) through thermal elements and other parts of the
building fabric; and
(ii) from pipes, ducts and vessels used for space
heating, space cooling and hot water services;
(b) providing fixed building services which—
(i) are energy efficient;
(ii) have effective controls; and
(iii) are commissioned by testing and adjusting as
necessary to ensure they use no more fuel and power than is
reasonable in the circumstances; and
Regulation 40 providing to the owner sufficient information
about the building, the fixed building services and their
maintenance requirements so that the building can be operated
in such a manner as to use no more fuel and power than is
reasonable in the circumstances.

LIMITATION ON REQUIREMENTS
2.2 In accordance with regulation 8 of the
Building Regulations, the requirements in Parts A
to D and F to K (except for paragraphs G2, H2
and J7) of Schedule 1 to the Building Regulations
do not require anything to be done except for the
purpose of securing reasonable standards of
health and safety for persons in or about buildings
(and any others who may be affected by buildings
or matters connected with buildings).
2.3 Paragraph G2 is excluded as it deals with
water efficiency and paragraphs H2 and J7 are
excluded from regulation 8 because they deal
directly with prevention of the contamination of
water. Parts E and M (which deal, respectively,
with resistance to the passage of sound, and
access to and use of buildings) are excluded
from regulation 8 because they address the
welfare and convenience of building users. Part L
is excluded from regulation 8 because it addresses
the conservation of fuel and power.
2.4 In addition, regulation 4(2) of the Building
Regulations states that where the work is being
carried out in order to comply with regulation 23
(requirements relating to renovation or replacement
of a thermal element), regulation 22 (requirements
relating to a change of a building’s energy status)
or regulation 28 (consequential improvements
to energy performance), and is not a material
alteration, it need comply only with the requirements
of Part L.

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L1B ONLINE VERSION
Section 3: General guidance
Key terms Fixed building services means any part of, or
any controls associated with—
3.1 The following are key terms used in this
document: (a) fixed internal or external lighting systems (but
not including emergency escape lighting or
BCB means Building Control Body: a local specialist process lighting);
authority or an approved inspector.
(b) fixed systems for heating, hot water, air
Building envelope in relation to a building conditioning or mechanical ventilation; or
means the walls, floor, roof, windows, doors,
roof windows and roof-lights. (c) any combination of systems of the kinds
referred to in paragraph (a) or (b);
Commissioning means the advancement of
a fixed building service following installation, Major renovation means the renovation of a
replacement or alteration of the whole or part building where more than 25% of the surface area
of the system, from the state of static completion of the building envelope undergoes renovation.
to working order by testing and adjusting as
necessary to ensure that the system as a whole Room for residential purposes means a room, or
uses no more fuel and power than is reasonable in a suite of rooms, which is not a dwelling-house or a
the circumstances, without prejudice to the need flat and which is used by one or more persons to
to comply with health and safety requirements. live and sleep and includes a room in a hostel, an
For each system commissioning includes hotel, a boarding house, a hall of residence or a
setting-to-work, regulation (that is testing and residential home, but does not include a room in a
adjusting repetitively) to achieve the specified hospital, or other similar establishment, used for
performance, the calibration, setting up and patient accommodation.
testing of the associated automatic control
systems, and recording of the system settings ‘Renovation’ in relation to a thermal element
and the performance test results that have been means the provision of a new layer in the thermal
accepted as satisfactory. element (other than where that new layer is
provided solely as a means of repair to a flat
Consequential improvements means those roof) or the replacement of an existing layer, but
energy efficiency improvements required by excludes decorative finishes, and ‘renovate’ shall
regulation 28. be construed accordingly.
Controlled service or fitting means a service or Simple payback means the amount of time it
fitting in relation to which Part G (sanitation, hot will take to recover the initial investment through
water safety and water efficiency), H (drainage energy savings, and is calculated by dividing
and waste disposal), J (combustion appliances the marginal additional cost of implementing an
and fuel storage systems), L (conservation of fuel energy efficiency measure by the value of the
and power) or P (electrical safety) of Schedule 1 annual energy savings achieved by that measure
to the Building Regulations imposes a requirement. taking no account of VAT. When making this
calculation the following guidance should be used:
Dwelling means a self-contained unit, including
a house or a flat, designed to be used separately a. the marginal additional cost is the additional
to accommodate a single household. (Rooms for cost (materials and labour) of incorporating
residential purposes are not dwellings so Approved (e.g.) additional insulation, not the whole cost
Document L2B applies to work in such buildings.) of the work;
Energy efficiency requirements means the b. the cost of implementing the measure should
requirements of regulations 23, 25A, 25B, 26, be based on prices current at the date the
28 and 40 of, and Part L of Schedule 1 to, the proposals are made known to the BCB and
Building Regulations. be confirmed in a report signed by a suitably
qualified person;
energy performance certificate means a
c. the annual energy savings should be
certificate which complies with regulation 7A of
estimated using SAP 20121;
the Energy Performance of Buildings (England
and Wales) Regulations 2012. d. for the purposes of this Approved Document,
the energy prices that are current at the time
In respect of existing dwellings the applicable of the application to building control should
requirements consist of Part L and regulations be used when evaluating the annual energy
23, 38 and 40. savings. Current energy prices can be obtained
from the DECC website2.

www.bre.co.uk/sap2012.
1

www.gov.uk/government/organisations/department-of-energy-climate-
2

change/about/statistics#energy-price-statistics.

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 ONLINE
General guidance VERSION L1B
Thermal element is defined in regulation 2(3) d. the replacement or renovation of a thermal
of the Building Regulations as follows: element (Section 5);
2(3) In these Regulations ‘thermal element’ e. the major renovation of a building.
means a wall, floor or roof (but does not include
windows, doors, roof windows or roof-lights) 3.4 Where the activities include building work
which separates a thermally conditioned part of in a dwelling that is part of a mixed-use building,
the building (‘the conditioned space’) from: account should also be taken of the guidance in
Approved Document L2B in relation to those
a. the external environment (including the parts of the building that are not dwellings,
ground); or including any common areas.
b. in the case of floors and walls, another part of It should be noted that dwellings are defined
the building which is: as self-contained units. Rooms for residential
i. unconditioned; purposes are not dwellings, and so Approved
Document L2B applies to them.
ii. an extension falling within class VII in
Schedule 2; or
Dwellings within the scope of the
iii. where this paragraph applies, conditioned
to a different temperature, energy efficiency requirements
and includes all parts of the element between the 3.5 The energy efficiency requirements of
surface bounding the conditioned space and the the Building Regulations apply only to buildings
external environment or other part of the building which are roofed constructions having walls and
as the case may be. which use energy to condition the indoor climate.
For dwellings the requirements will apply to:
2(4) Paragraph 2(3)(b)(iii) only applies to a building
which is not a dwelling, where the other part of • the erection of a dwelling (guidance on this is
the building is used for a purpose which is not given in Approved Document L1A);
similar or identical to the purpose for which the • the extension of a dwelling other than some
conditioned space is used. extensions falling within Class VII in Schedule
2 to the Building Regulations; or
Note that this definition encompasses the walls
and floor of a swimming pool basin where this is • the carrying out of any building work to or in
part of an existing dwelling. connection with an existing dwelling or an
extension to an existing dwelling.
Types of work covered by this
Approved Document Dwellings exempt from the
3.2 This Approved Document is intended to
energy efficiency requirements
give guidance on what, in ordinary circumstances, 3.6 There are two exemptions from the energy
may be considered reasonable provision for efficiency requirements that may apply to
compliance with the requirements of regulation building work to existing dwellings or extensions
23 and 28 of, and Part L of Schedule 1 to, the to existing dwellings:
Building Regulations for those carrying out a. Buildings which are:
building work to existing dwellings. In addition it
gives guidance on compliance with regulations • listed in accordance with section 1 of
25A, 27, 43 and 44 of the Building Regulations the Planning (Listed Buildings and
and 20(1), 20(2) and 20(6) of the Approved Conservation Areas) Act 1990;
Inspectors Regulations 2010. • in a conservation area designated in
Buildings exclusively containing rooms for accordance with section 69 of that Act; or
residential purposes such as nursing homes, • included in the schedule of monuments
student accommodation and similar are not maintained under section 1 of the Ancient
dwellings, and in such cases Approved Monuments and Archaeological Areas
Document L2B applies. Act 1979.
3.3 In particular, this Approved Document gives For these buildings the exemption applies only
guidance on compliance with the energy efficiency to the extent that compliance with the energy
requirements where the following occurs: efficiency requirements would unacceptably
a. the construction of an extension (see alter the character or appearance of such
paragraphs 4.1 to 4.9); existing dwellings. Guidance on these buildings
is given in paragraphs 3.7 to 3.14 below.
b. a material change of use, or a change to the
building’s energy status, including such work b. Carports, covered yards, covered ways and
as loft and garage conversions (paragraphs some conservatories or porches attached to
4.11 to 4.16); existing dwellings. Guidance on these is
given at paragraphs 3.15 and 3.16 below.
c. the provision or extension of a controlled
service or controlled fitting (paragraphs
4.17 to 4.37);

Approved Document L1B Conservation of fuel and power

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L1B ONLINE
GENERAL GUIDANCE VERSION
Historic and traditional buildings which may 3.12 Particular issues relating to work in historic
have an exemption buildings that warrant sympathetic treatment and
where advice from others could therefore be
3.7 As mentioned above in paragraph 3.6a, the
beneficial include:
following classes of buildings have an exemption
from the energy efficiency requirements where a. restoring the historic character of a building
compliance would unacceptably alter the that has been subject to previous
character or appearance of the buildings. inappropriate alteration, e.g. replacement
windows, doors and rooflights;
a. listed buildings;
b. rebuilding a former historic building (e.g.
b. buildings in conservation areas; and
following a fire or filling a gap site in a terrace);
c. scheduled ancient monuments.
c. making provisions enabling the fabric of historic
Historic and traditional buildings where buildings to ‘breathe’ to control moisture and
special considerations may apply potential long-term decay problems.
3.8 There are three further classes of buildings 3.13 In assessing reasonable provision for energy
where special considerations in making reasonable efficiency improvements for historic buildings of
provision for the conservation of fuel or power the sort described in paragraphs 3.7 and 3.8, it is
may apply: important that the BCB takes into account the
advice of the local authority’s conservation officer.
a. buildings which are of architectural and The views of the conservation officer are
historical interest and which are referred to as particularly important where building work requires
a material consideration in a local authority’s planning permission and/or listed building consent.
development plan or local development
framework; 3.14 Other classes of buildings to which special
considerations apply are usually non-domestic in
b. buildings which are of architectural and character, and so are covered in ADL2A and ADL2B.
historical interest within national parks, areas
of outstanding natural beauty, registered Conservatories and porches
historic parks and gardens, registered 3.15 Regulation 21 of the Building Regulations
battlefields, the curtilages of scheduled exempts some conservatory and porch extensions
ancient monuments, and world heritage sites; from the energy efficiency requirements. The
c. buildings of traditional construction with exemption applies only for conservatories or porches:
permeable fabric that both absorbs and • which are at ground level;
readily allows the evaporation of moisture.
• where the floor area is less than 30 m2;
3.9 When undertaking work on or in
connection with a building that falls within one • where the glazing complies with Part K 4 of
of the classes listed above, the aim should be to Schedule 1;
improve energy efficiency as far as is reasonably • where the existing walls, doors and windows
practicable. The work should not prejudice the in the part of the dwelling which separates
character of the host building or increase the risk the conservatory are retained or, if removed,
of long-term deterioration of the building fabric replaced by walls, windows and doors which
or fittings. meet the energy efficiency requirements; and
3.10 The guidance given by English Heritage3 • where the heating system of the dwelling is
should be taken into account in determining not extended into the conservatory or porch.
appropriate energy performance standards for
building work in historic buildings. 3.16 Where any conservatory or porch does
not meet all the requirements in the preceding
In addition English Heritage has produced detailed paragraph, it is not exempt and must comply
technical guidance on how to implement specific with the relevant energy efficiency requirements
energy efficiency measures. (See list of available (see paragraphs 4.8 and 4.9 below).
guidance documents at http://www.english-
heritage.org.uk/professional/advice/advice-by- Notification of work covered by
topic/climate-change/energy-efficiency/.)
the Energy Efficiency requirements
3.11 In general, new extensions to historic or
traditional dwellings should comply with the 3.17 In most instances in order to comply with
standards of energy efficiency as set out in this the Building Regulations it will be necessary to
Approved Document. The only exception would notify a BCB before the work starts. Where you
be where there is a particular need to match choose to use the local authority and any work
the external appearance or character of the relates to the common parts of a block of flats,
extension to that of the host building (see this must be by deposit of full plans. For other
paragraph 4.2). existing dwellings this could be either in the form
of a deposit of full plans or by a building notice.
There is no set procedure where the BCB is an
3
Energy Efficiency and Historic Buildings, English Heritage, 2011 Approved Inspector provided they have been
http://www.english-heritage.org.uk/publications/energy-efficiency- notified at least 5 days before work starting.
historic-buildings-ptl/.

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General guidance VERSION L1B
3.18 In certain situations, however, you do not Work which need not be notified
need to notify a BCB:
3.23 Schedule 4 to the Building Regulations
a. Where the work is being carried out by a sets out types of work where there is no requirement
person registered with a relevant competent to notify a BCB that work is to be carried out.
person self-certification scheme listed in These types of work are mainly of a minor nature
Schedule 3 to the Building Regulations, no where there is no significant risk to health, safety
advance notification to the BCB is needed or energy efficiency. Note that the health, safety
(see paragraphs 3.19 to 3.22). and energy efficiency requirements continue to
apply to these types of work, and that only the
b. Where the work involves an emergency repair,
need to notify a BCB has been removed. In addition,
e.g. to a failed boiler or a leaking hot water
where only non-notifiable work is carried out by a
cylinder, in accordance with regulation 12(7)
member of a competent person self-certification
of the Building Regulations there is no need
scheme there is no requirement for a certificate
to delay making the repair in order to make
of building regulations compliance to be given to
an advance notification to the BCB. However,
the occupier or the BCB.
in such cases it will still be necessary for the
work to comply with the relevant requirements 3.24 The types of non-notifiable work in
and to give a notice to the BCB at the earliest Schedule 4 relevant to the energy efficiency
opportunity, unless an installer registered under requirements of the Regulations are:
an appropriate competent person scheme
a. In a heating, hot water, ventilation or air-
carries out the work. A completion certificate
conditioning system, the replacement of any
can then be issued in the normal way.
part which is not a combustion appliance
c. Where the work is of a minor nature as (such as a radiator, valve or pump) or the
described in the schedule of non-notifiable addition of an output device (such as a
work (Schedule 4 to the Building Regulations), radiator or fan) or the addition of a control
the work must still comply with the relevant device (such as a thermostatic radiator valve).
requirements but need not be notified to the However, the work will remain notifiable
BCB (see paragraphs 3.23 to 3.25). whenever commissioning is possible and
necessary to enable a reasonable use of fuel
Competent person self-certification schemes and power (see paragraphs 4.30 to 4.37).
3.19 It is not necessary to notify a BCB in b. The installation of a stand-alone, self-
advance of work which is to be carried out by contained fixed heating, hot water, ventilation
a person registered with a competent person or air-conditioning service. Such services
self-certification scheme listed in Schedule 3 to must consist only of a single appliance and
the Building Regulations. In order to join such a any associated controls, and must not be
scheme a person must demonstrate competence connected to, or form part of, any other fixed
to carry out the type of work the scheme covers, building service. Examples of non-notifiable
and also the ability to comply with all relevant services would be a fixed electric heater, a
requirements in the Building Regulations. mechanical extractor fan in a kitchen or
3.20 Where work is carried out by a person bathroom, and a room air-conditioning unit.
registered with a competent person scheme, However, if any of the following apply, the
regulation 20 of the Building Regulations 2010 work will remain notifiable building work:
and regulation 20(1) of the Building (Approved i. the service is a combustion appliance;
Inspectors etc) Regulations 2010 require that the
occupier of the building be given, within 30 days of ii. any electrical work associated with the
the completion of the work, a certificate confirming installation is notifiable;
that the work complies fully with all applicable iii. commissioning is possible and would
building regulation requirements. There is also a affect the service’s energy efficiency (see
requirement to give the BCB a notice of the work paragraphs 4.30 to 4.38);
carried out, again within 30 days of the completion
of the work. These certificates and notices are iv. in the case of a ventilation appliance, the
usually made available through the scheme operator. appliance is installed in a room containing
a natural draught open-flued combustion
3.21 BCBs are authorised to accept these appliance or service, such as a gas fire
certificates and notices as evidence of compliance which uses a chimney as its flue.
with the requirements of the Building Regulations.
Local authority inspection and enforcement c. Installation of thermal insulation in a roof space
powers remain unaffected, although they are or loft space where this is the only work carried
normally used only in response to a complaint out and the work is not carried out to comply
that work does not comply. with any requirement in the Building Regulations,
i.e. the work is carried out voluntarily.
3.22 A list of authorised self-certification schemes
and the types of work for which they are authorised 3.25 Schedule 4 also sets out what types
can be found at www.communities.gov.uk of electrical installation work in dwellings are
non-notifiable. Full information on this is given
in Approved Document P.

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General guidance VERSION
Materials and workmanship
3.26 Any building work which is subject to the
requirements imposed by schedule 1 to the
Building Regulations shall be carried out in
accordance with regulation 7. Guidance on
meeting these requirements on materials and
workmanship is contained in the Approved
Document to support regulation 7.
3.27 Building Regulations are made for specific
purposes, primarily the health and safety, welfare
and convenience of people and for energy
conservation. Standards and other technical
specifications may provide relevant guidance to
the extent that they relate to these considerations.
However, they may also address other aspects
of performance or matters which, although they
relate to health and safety etc., are not covered
by the Building Regulations.
3.28 When an Approved Document makes
reference to a named standard, the relevant
version of the standard to which it refers is the
one listed at the end of the publication. However,
if this version has been revised or updated by the
issuing standards body, the new version may be
used as a source of guidance provided it
continues to address the relevant requirements of
the Regulations.

The Workplace (Health, Safety and

Welfare) Regulations 1992
3.29 The Workplace (Health, Safety and
Welfare) Regulations 1992, as amended, apply to
the common parts of flats and similar buildings if
people such as cleaners, wardens and caretakers
are employed to work in these common parts.
These Regulations contain some requirements
which affect building design. The main requirements
are now covered by the Building Regulations,
but for further information see Workplace health,
safety and welfare, Workplace (Health, Safety and
Welfare) Regulations 1992, Approved Code of
Practice and guidance, HSE publication L24, 1996.
3.30 Where the requirements of the Building
Regulations that are covered by this Approved
Document do not apply to dwellings, the
provisions may still be required in the situations
described above in order to satisfy the Workplace
Regulations.

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 ONLINE VERSION L1B
Section 4: Guidance relating to building work
THE EXTENSION OF A DWELLING Area-weighted U-value method
4.5 One way of complying would be to
Reference method show that the area-weighted U-value of all the
Fabric standards elements in the extension is no greater than that
of an extension of the same size and shape that
4.1 Reasonable provision would be for the complies with the fabric standards referred to in
proposed extension to incorporate the following: paragraph 4.1 and the opening area standards
a. newly constructed thermal elements that in paragraph 4.2. Any fixed building service
meet the standards set out in paragraphs 5.1 provided or extended as part of constructing
to 5.6; the extension should follow the guidance in
paragraphs 4.24 to 4.37.
b. doors, windows, roof windows and rooflights
that meet the standards set out in paragraphs The area-weighted U-value is given by the
4.19 to 4.23; following expression:

c. improvements to fabric elements that are to {(U1  A1)  (U2 x A2)  (U3 x A3)  …)}
become thermal elements, following the 4 {(A1  A2  A3  …)}
guidance in paragraphs 5.6 to 5.11. Whole dwelling calculation method
Area of windows, roof windows and doors 4.6 Where even greater design flexibility is
4.2 In most circumstances reasonable required, reasonable provision would be to use
provision would be to limit the total area of SAP 2012 to show that the calculated carbon
windows, roof windows and doors in extensions dioxide (CO2) emission rate from the dwelling
so that it does not exceed the sum of: with its proposed extension is no greater than for
the dwelling plus a notional extension built to the
a. 25 per cent of the floor area of the extension; standards of paragraphs 4.1 to 4.3. The openings
plus in the notional extension should conform with
b. the total area of any windows or doors which, paragraph 4.2 with door area set equal to the
as a result of the extension works, no longer door area of the proposed extension, with the
exist or are no longer exposed. remainder of the openings being classified as
windows. The data in SAP 2012 Appendix S
As a general guide, if the area of glazing is much can be used to estimate the performance of the
less than 20 per cent of the total floor area, some elements of the existing building where these
parts of the extension and especially the part of are unknown.
the dwelling it covers may experience poor levels
of daylight, resulting in increased use of electric Approved Document C gives limiting values for
lighting. Areas of glazing greater than 25 per cent individual elements to minimise condensation risk.
may be acceptable, especially if this is required to 4.7 If, as part of achieving the standard set out
make the extension consistent with the external in paragraph 4.6, upgrades are proposed to the
appearance or character of the host building. existing dwelling, such upgrades should be
In such cases and where practical, either the implemented to a standard that is no worse than
U-value of the window should be improved set out in the relevant guidance contained in this
relative to the standard set out in paragraph Approved Document. The relevant standards for
4.1b, or other compensating measures applied improving retained thermal elements are as set
following the guidance set out in paragraphs out in column (b) of Table 3.
4.4 to 4.7.
Where it is proposed to upgrade the original
Heating and lighting in the extension building, the standards set out in this Approved
Document are cost-effective and should be
4.3 Where a fixed building service is implemented in full. It will be worthwhile
provided or extended as part of constructing the implementing them even if the improvement is
extension, reasonable provision would be to greater than necessary to achieve compliance.
follow the guidance in paragraphs 4.24 to 4.37. In some cases, therefore, the standard of the
extended dwelling may be better than that
Optional approaches with more required by paragraph 4.6 alone. Paragraph 4.7
design flexibility sets limits on design flexibility and ensures that
no cost-effective improvement opportunities are
4.4 The approach set out in paragraphs 4.1 traded away.
to 4.3 is somewhat prescriptive. The following
paragraphs offer more flexible approaches to Conservatories and porches
demonstrating that reasonable provision has
been made. These alternative approaches allow 4.8 Where the extension is a conservatory
some elements of the design to be relaxed or porch that is not exempt from the energy
through compensating measures elsewhere. efficiency requirements (see paragraphs 3.15

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work
and 3.16 above), then reasonable provision Change of energy status
would be to provide:
4.12 A change to a building’s energy status is
a. Effective thermal separation between the defined in regulation 2(1) as:
heated area in the existing dwelling, i.e.
the walls, doors, and windows between any change which results in a building becoming
the dwelling and the extension, should be a building to which the energy efficiency
insulated and draught proofed to at least requirements of these Regulations apply, where
the same extent as in the existing dwelling. previously it was not.
b. Independent temperature and on/off controls 4.13 The requirements relating to a change
to any heating system installed within the to energy status are in regulation 22:
extension. Any fixed building service installed
within the extension should also conform to the Where there is a change in a building’s energy
standards set out in paragraphs 4.24 to 4.37. status, such work, if any, shall be carried out
to ensure that the building complies with the
c. Glazed elements should meet the standards applicable requirements of regulation 40 and
set out in Table 1 and opaque elements Part L of Schedule 1.
should meet the standards set out in Table 2.
However, the limitations on total area of 4.14 In this regulation ‘building’ means the
windows, roof windows and doors as set building as a whole or parts of the building that
out at paragraph 4.2 above do not apply. have been designed or altered to be used
separately.
4.9 Removing, and not replacing, any or all of
the thermal separation between the dwelling and For example, this could occur where a previously
an existing exempt extension, or extending the unheated building, or parts of the building that
dwelling’s heating system into the extension, have been designed or altered to be used
means the extension ceases to be exempt (see separately, were to be heated in future, or where
paragraphs 3.15 and 3.16 above). In such a previously exempt building were no longer
situations, the extension should be treated as a within the exempted categories. A material
conventional extension and reasonable provision alteration (regulation 3(2) and (3)) may result
would be to demonstrate that the extension in a change in buildings energy status.
meets the guidance set out in paragraphs 4.1 4.15 In normal circumstances, reasonable
to 4.7 above. provision where there is a material change of
use or a change to the building’s energy status
Swimming pool basins would be:
4.10 Where a swimming pool is being provided a. Where controlled services or fittings are
in a building, the U-value of the basin (walls and being provided or extended, to meet the
floor) should be not worse than 0.25 W/m2.K as standards set out in paragraphs 4.17 to 4.37.
calculated according to BS EN ISO 133704. If the area of openings in the newly created
Design consideration should be taken with dwelling is more than 25 per cent of the total
regards to compressive creep, insulation boards floor area, either the area of openings should
not being fully supported and the effects of point be reduced to be not greater than 25 per cent,
loading. Care should be taken to avoid thermal or the larger area should be compensated for
bridging particularly around basin wall and floor in some other way using the procedure
junctions with foundations. described in paragraph 4.16.
b. Where the work involves the provision of a
MATERIAL CHANGE OF USE AND thermal element, to meet the standards set
out in paragraphs 5.1 to 5.6.
CHANGE OF ENERGY STATUS
For the purposes of Building Regulations, provision
Material change of use means both new and replacement elements.
4.11 Material changes of use (see regulation 5 c. Where any thermal element is being
of the Building Regulations) covered by this retained, to upgrade it following the guidance
document are where, after the change: given in paragraphs 5.11 to 5.13.
a. the building is used as a dwelling, where d. Where an existing window (including roof
previously it was not; window or rooflight) or door which separates
a conditioned space from an unconditioned
b. the building contains a flat, where previously space or the external environment has a
it did not; or U-value that is worse than 3.3 W/(m2.K), to
c. the building, which contains at least one provide replacement units following the
dwelling, contains a greater or lesser number guidance in paragraphs 4.19 to 4.23.
of dwellings than it did previously.
4
BS EN ISO 13370 Thermal performance of buildings – Heat transfer
via the ground – Calculation methods [2007 incorporating corrigendum
March 2009].

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GUIDANCE RELATING I N E VWORK
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Option providing more design 4.20 U-values shall be calculated using the
methods and conventions set out in BR 4435,
flexibility and should be based on the whole unit (i.e. in the
4.16 To provide more design flexibility, SAP case of a window, the combined performance of
2012 can be used to demonstrate that the total the glazing and frame). The U-value of the
CO2 emissions from all the dwellings in the window can be calculated for:
building as it will become are no greater than if a. the smaller of the two standard windows
each dwelling had been improved following the defined in BS EN 14351-16; or
guidance set out in paragraph 4.15.
b. the standard window configuration set out
in BR 443; or
WORK ON CONTROLLED
c. the specific size and configuration of the
FITTINGS AND SERVICES actual window.
4.17 Controlled services or fittings are The U-value of the door can be calculated for:
defined in regulation 2 as follows:
a. the standard size as laid out in BS EN 14351-
Controlled service or fitting means a service or 1; or
fitting in relation to which Part G, H, J, L or P of
b. the specific size and configuration of the
Schedule 1 imposes a requirement;
actual door.
Controlled fittings SAP 2012 Table 6e gives values for different
window configurations that can be used in the
4.18 In the context of this Approved Document, absence of test data or calculated values.
the application of the term controlled fitting to a
window, roof window, rooflight or door refers to a 4.21 The U-values for roof windows and
whole unit, i.e. including the frame. Consequently, rooflights given in this Approved Document are
replacing the glazing whilst retaining an existing based on the U-value having been assessed
frame is not providing a controlled fitting, and with the roof window or rooflight in the vertical
so such work is not notifiable and does not have position. If a particular unit has been assessed
to meet the Part L standards, although where in a plane other than the vertical, the standards
practical it would be sensible to do so. Similar given in this Approved Document should be
arguments apply to doors, where the controlled modified by making an adjustment that is
fitting refers to the complete doorset (leaf plus dependent on the slope of the unit following
frame). Replacing a door leaf whilst retaining the the guidance in BR 443.
existing frame is not notifiable and does not have
to meet the Part L standards, although where
practical it would be sensible to do so. Table 1 Standards for controlled
4.19 Where windows, roof windows, rooflights fittings1
or doors are to be provided, reasonable provision Fitting Standard
in normal cases would be the installation of
Window, roof WER Band C or better
draught-proofed units whose performance is no window or rooflight2 (see paragraph 4.22), or
worse than given in Table 1. In addition, insulated U-value 1.6 W/(m2.K)
cavity closers should be installed where Doors with >60% of Doorset Energy Rating (DSER) Band
appropriate. Where the windows or fully glazed internal face glazed E or better (see paragraph 4.22), or
external pedestrian doors are unable to meet the U-value 1.8 W/(m2.K)
requirements of Table 1 because of the need to Other doors DSER Band E or better (see paragraph
maintain the external appearance of the façade 4.22), or U-value 1.8 W/(m2.K)
or the character of the building, such fittings Notes:
should meet a centre pane U-value of 1.2 W/(m2.K), 1. Since the U-values are determined for standard configurations (see
where the centre-pane U-value is defined as the paragraph 4.20), the effects of Georgian bars and/or leaded lights
U-value determined in the central area of the can be ignored.
glazing unit, making no allowance for edge 2. For the purposes of checking compliance with this table, the true
U-value based on aperture area can be converted to the U-value
spacers or window frame. As an alternative, based on the developed area of the rooflight. Further guidance
single glazing should be supplemented with on evaluating the U-value of out-of-plane rooflights is given in
low-e secondary glazing. In this latter case, the Assessment of thermal performance of out-of-plane rooflights,
NARM Technical Document NTD 2 (2010). See http://www.narm.
weather stripping should be on the secondary org.uk/uploads/pdfs/NARM-TAOOPR-030311.pdf.
glazing to minimise condensation risk between
the primary and secondary glazing. Where 4.22 The calculation of Window Energy
enhanced performance requirements (e.g. wind Rating (WER) and the Doorset Energy Rating
load, safety, security or acoustic attenuation) (DSER) are set out in the GGF Guide to the
require thicker glass to be used, reasonable Calculation of Energy Ratings for Windows,
provision would be demonstrated if the window
unit with the equivalent standard glazing 5
BR 443 Conventions for U-value calculations, BRE, 2006.
thickness can be shown to comply. 6
BS EN 14351-1 Windows and doors – Product standard, performance
characteristics. Windows and external pedestrian doorsets without
resistance to fire and/or smoke leakage characteristics [2006 (+AMD 1:2010)].

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work
Roof Windows and Doors7. The guide provides electrical output that is not less than the
different procedures for windows, roof windows, original installation.
external pedestrian doors and patio/French/
4.28 When replacing a heating appliance,
sliding/folding doors. BCBs may accept a WER
consideration should be given to connecting
and/or DSER declaration from a certification
to any existing local heat networks. If the work
scheme that provides a quality assured process
involves pipework changes, consideration should
and supporting audit trail from calculating the
be given to providing capped off connections to
performance of the window through to installation
facilitate subsequent connection to a planned
as evidence of compliance. Notwithstanding the
local heat network.
suggested performance values set out in Table 1,
guidance on energy efficient windows is available 4.29 If a particular technology is not covered
from the Energy Saving Trust8. in the Domestic Building Services Compliance
Guide, reasonable provision would be demonstrated
4.23 If a window is enlarged or a new one
by showing that the proposed technology gives
created, then the area of windows, roof windows,
a performance that is no worse than a reference
rooflights and doors should not exceed 25 per
system of the same type whose details are given
cent of the total floor area of the dwelling unless
in the Guide.
compensating measures are included elsewhere
in the work.
COMMISSIONING OF FIXED
Controlled services BUILDING SERVICES
4.24 Whenever a fixed building service is
extended or provided, reasonable provision 4.30 Paragraph L1(b)(iii) of Schedule 1 to the
would be demonstrated by following the Building Regulations requires fixed building
guidance set out in the Domestic Building services to be commissioned by testing and
Services Compliance Guide9. The Guide covers adjustment as necessary to ensure that they use
the following services: no more fuel and power than is reasonable in the
circumstances. In order to demonstrate that the
a. heating and hot water systems (including heating and hot water systems have been
insulation of pipes, ducts and vessels; adequately commissioned, regulation 44 states:
b. mechanical ventilation; 44 Commissioning
c. mechanical cooling/air-conditioning; (1) This regulation applies to building work in
d. fixed internal lighting; relation to which paragraph F1(2) of Schedule 1
imposes a requirement, but does not apply to
e. fixed external lighting; the provision or extension of any fixed system for
f. renewable energy systems. mechanical ventilation or any associated controls
where testing and adjustment is not possible.
4.25 The efficiency claimed for the fixed building
service should be based on the appropriate test (2) This regulation applies to building work in
standard as set out in the Domestic Building relation to which paragraph L1(b) of Schedule 1
Services Compliance Guide and the test data imposes a requirement, but does not apply to
should be certified by a notified body. It would be the provision or extension of any fixed building
reasonable for BCBs to accept such data at face service where testing and adjustment is not
value. In the absence of such quality-assured possible or would not affect the energy efficiency
data, BCBs should satisfy themselves that the of that fixed building service.
claimed performance is justified. (3) Where this regulation applies the person
4.26 When replacing an existing appliance, carrying out the work shall, for the purpose of
the efficiency of the new appliance should not ensuring compliance with paragraph F1(2) or
be significantly less than the efficiency of the L1(b) of Schedule 1, give to the local authority a
appliance being replaced. If the replacement notice confirming that the fixed building services
involves a fuel switch, then the relative carbon have been commissioned in accordance with a
emissions associated with the new and existing procedure approved by the Secretary of State.
fuels should be considered when assessing the (4) The notice shall be given to the local authority–
reasonableness of the proposed new appliance.
The Domestic Building Services Compliance Guide a. not later than the date on which the notice
contains the detailed guidance on this issue. required by regulation 16(4) is required to be
given; or
4.27 If a renewable energy generator such
as a wind turbine or photovoltaic array is being b. where that regulation does not apply, not more
replaced, the new system should have an than 30 days after completion of the work.

7
Guide to the Calculation of Energy Ratings for Windows, Roof Windows
and Doors, GGF, 2013.
8
www.energysavingtrust.org.uk/Insulation/Windows.
9
Domestic Building Services Compliance Guide, DCLG, 2013
incorporating 2018 amendments.

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4.31 Reasonable provision would be to prepare 4.36 Where an approved inspector is the BCB,
a commissioning plan, identifying the systems the notice of completion of commissioning
that need to be tested and the tests that will be should generally be given to the approved
carried out. The notice required by regulation 44 inspector within 5 days of the completion of
should confirm that the commissioning plan has work. However, where the work is carried out
been followed and that every system has been by a person registered with a competent person
inspected in an appropriate sequence and to a scheme (see paragraph 3.19 to 3.22), the notice
reasonable standard and that the test results must be given within 30 days. Where the
confirm that performance is reasonably in installation of fixed building services which
accordance with the design requirements. require commissioning is carried out by a
person registered with a competent person
4.32 Not all fixed building services will need to
scheme the notice of commissioning will be
be commissioned. With some systems adjustment
given by that person.
is not possible as the only controls are ‘on’ and
‘off’ switches. Examples of this would be some 4.37 Until the BCB receives the commissioning
mechanical extraction systems or single fixed notice it cannot be reasonably satisfied that Part L
electrical heaters. In other cases commissioning has been complied with and consequently is
would be possible but in the specific circumstances unlikely to be able to give a completion/final
would have no effect on energy use. certificate.
Fixed building services which do not require
commissioning should be identified in the
commissioning plan, along with the reason
for not requiring commissioning.
4.33 Where commissioning is carried out it
must be done in accordance with a procedure
approved by the Secretary of State. For heating
and hot water systems the approved procedures
are set out in the Domestic Building Services
Compliance Guide. For ventilation systems,
an approved procedure would be to follow
the guidance in the Domestic Ventilation
Compliance Guide10.
4.34 Commissioning is often carried out by the
person who installs the system. In other cases it
may be carried out by a subcontractor or by a
specialist firm. It is important that whoever carries
it out follows the relevant approved procedure in
doing so.
4.35 Where a building notice or full plans have
been given to a local authority BCB, the notice of
completion of commissioning should be given to
that BCB within 5 days of the completion of the
commissioning work. In other cases, for example
where work is carried out by a person registered
with a competent person scheme (see paragraphs
3.19 to 3.22), it must be given within 30 days.

10
Domestic Ventilation Compliance Guide, DCLG, 2010.

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L1B ONLINE VERSION
Section 5: Guidance on thermal elements
5.1 New thermal elements must comply with
Part L1(a)(i) of Schedule 1 to the Building
Regulations. Work on existing thermal elements
must comply with regulation 23 of the Building
Regulations which states:

Requirements for the renovation or replacement of thermal

elements – Regulation 23
(1) Where the renovation of an individual thermal element—
(a) constitutes a major renovation; or
(b) amounts to the renovation of more than 50% of the
element’s surface area;
the renovation must be carried out so as to ensure that
the whole of the element complies with paragraph L1(a)(i) of
Schedule 1, in so far as that is technically, functionally and
economically feasible.
(2) Where the whole or any part of an individual element is
proposed to be replaced and the replacement—
(a) constitutes a major renovation; or
(b) (in the case of part replacement) amounts to the
replacement of more than 50% of the thermal element’s
surface area;
the whole of the thermal element must be replaced so as to
ensure that it complies with paragraph L1(a)(i) of Schedule 1,
in so far as that is technically, functionally and economically
feasible.

THE PROVISION OF THERMAL Table 2 Standards for new thermal

ELEMENTS elements
U-values Element1 Standard W/(m2.K)2
Wall 0.28
5.2 U-values shall be calculated using the
methods and conventions set out in BR 443. Pitched roof – insulation at ceiling level 0.16

5.3 Reasonable provision for newly constructed Pitched roof – insulation at rafter level 0.18
thermal elements such as those constructed Flat roof or roof with integral insulation 0.18
as part of an extension would be to meet the Floors3 0.224
standards set out in Table 2.
Swimming pool basin 0.25
5.4 Reasonable provision for those thermal Notes:
elements constructed as replacements for 1. ‘Roof’ includes the roof parts of dormer windows, and ‘wall’
existing elements would be to meet the standards includes the wall parts (cheeks) of dormer windows.
set out in Table 2. 2. Area-weighted average values.
3. A lesser provision may be appropriate where meeting such a
standard would result in a reduction of more than 5% in the
internal floor area of the room bounded by the wall.
4. A lesser provision may be appropriate where meeting such a standard
would create significant problems in relation to adjoining floor levels.
The U-value of the floor of an extension can be calculated using the
exposed perimeter and floor area of the whole enlarged dwelling.

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 O N L elements
Guidance on thermal INE VERSION L1B
Continuity of insulation and 5.8 Where a thermal element is subject to a
renovation through undertaking an activity listed
airtightness in paragraph 5.7a or 5.7b, the performance of the
5.5 The building fabric should be constructed whole of the thermal element should be
so that there are no reasonably avoidable thermal improved to achieve or better the relevant
bridges in the insulation layers caused by gaps U-value set out in column (b) of Table 3, provided
within the various elements, at the joints between the area to be renovated is greater than 50% of
elements, and at the edges of elements such the surface of the individual thermal element
as those around window and door openings. or constitutes a major renovation where more
Reasonable provision should also be made to than 25% of the surface area of the building
reduce unwanted air leakage through the new envelope undergoes renovation.
envelope parts. The work should comply with all 5.8A In relation to the renovation of individual
the requirements of Schedule 1, but particular thermal elements, when assessing the proportion
attention should be paid to Parts F and J. of the surface area that is to be renovated, the
5.6 A suitable approach to showing the area of the thermal element should be assessed
requirement has been achieved would be to as the area of each individual thermal element,
adopt Accredited Construction Details at not the area of all the elements of that type in
www.gov.uk. the building. The area of each individual thermal
element should also be interpreted in the context
It is impractical to expect thermal bridge and of whether the element is being renovated from
temperature factor calculations for work in inside or outside, e.g. if removing all the plaster
existing buildings. finish from the inside of a solid brick wall, the
area of the element is the area of external wall
Major renovation in the room. If removing external render, it is the
5.6A Major renovation means the renovation of area of the elevation in which that wall sits.
a building where more than 25% of the surface This means that if all the roofing on the flat roof
area of the building envelope undergoes of an extension is being stripped down, the
renovation. When assessing whether the area area of the individual element is the ‘roof area’
proportion constitutes a major renovation of a of the extension, not the ‘total roof area’ of the
building, the surface area of the whole of the dwelling. Similarly, if the rear wall of a single
external building envelope should be taken into storey extension is being re-rendered externally,
account i.e. external walls, floor, roof, windows, then the rear wall of the extension should be
doors, roof windows and rooflights. upgraded to the standards of Table 3 column
(b), even if the renovation affected less than 50%
RENOVATION OF THERMAL of the total area of the building elevation when
viewed from the rear. If plaster is being removed
ELEMENTS from a bedroom wall, the relevant area is the area
5.7 For the purposes of this Approved Document, of the external wall in the room, not the area of
renovation of a thermal element through: the external elevation which contains that wall
section. This is because the marginal cost of dry-
a. the provision of a new layer means either of lining with insulated plasterboard rather than plain
the following activities: plasterboard is small.
i. Cladding or rendering the external surface When a building undergoes a major renovation
of the thermal element; or this may represent an opportunity to consider and
ii. Dry-lining the internal surface of a take into account the technical, environmental
thermal element. and economic feasibility of installing high-
efficiency alternative systems.
b. the replacement of an existing layer means
either of the following activities: 5.9 If achievement of the relevant U-value set
out in column (b) of Table 3 is not technically or
i. Stripping down the element to expose the functionally feasible or would not achieve a
basic structural components (brick/ simple payback of 15 years or less, the element
blockwork, timber/metal frame, joists, should be upgraded to the best standard that is
rafters, etc.) and then rebuilding to technically and functionally feasible and which
achieve all the necessary performance can be achieved within a simple payback of no
requirements. As discussed in paragraph greater than 15 years. Guidance on this approach
3.9, particular considerations apply to is given in Appendix A.
renovating elements of traditional
construction; or 5.10 When renovating thermal elements, the
work should comply with all the requirements in
ii. Replacing the water proof membrane on Schedule 1, but particular attention should be
a flat roof. paid to Parts F and J.

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L1B GUIDANCE ONO N L I NELEMENTS
THERMAL E VERSION
RETAINED THERMAL ELEMENTS Examples of where lesser provision than column
(b) might apply are where the thickness of the
5.11 Part L of Schedule 1 to the Building additional insulation might reduce usable floor
Regulations applies to retained thermal area of any room by more than 5 per cent or
elements in the following circumstances: create difficulties with adjoining floor levels, or
a. where an existing thermal element is part of where the weight of the additional insulation
a building subject to a material change of use; might not be supported by the existing structural
frame.
b. where an existing element is to become part of
the thermal envelope where previously it was 5.13 When upgrading retained thermal
not, e.g. as part of a loft or garage conversion elements, the work should comply with all
where the space is now to be heated. the requirements in Schedule 1, but particular
attention should be paid to Parts F and J.
5.12 Reasonable provision would be to upgrade
those thermal elements whose U-value is worse
than the threshold value in column (a) of Table 3
to achieve the U-values given in column (b) of
Table 3 provided this is technically, functionally
and economically feasible. A reasonable test of
economic feasibility is to achieve a simple
payback of 15 years or less. Where the standard
given in column (b) is not technically, functionally
or economically feasible, then the thermal
element should be upgraded to the best
standard that is technically and functionally
feasible and delivers a simple payback period of
15 years or less. Generally, this lesser standard
should not be worse than 0.7 W/(m2.K).

Table 3 Upgrading retained thermal elements

Element1 (a) Threshold U-value W/(m2·K)8 (b) Improved U-value W/(m2·K)8

Wall – cavity insulation2 0.70 0.55

Wall – external or internal insulation 0.70

3
0.30

Floor4,5 0.70 0.25

Pitched roof – insulation at ceiling level 0.35 0.16

Pitched roof – insulation between rafters 0.35 6

0.18

Flat roof or roof with integral insulation 0.35

7
0.18

1 ‘Roof’ includes the roof parts of dormer windows and ‘wall’ includes the wall parts (cheeks) of dormer windows.
2 This applies only in the case of a wall suitable for the installation of cavity insulation. Where this is not the case, it should be treated as ‘wall – external or
internal insulation’.
3 A lesser provision may be appropriate where meeting such a standard would result in a reduction of more than 5% in the internal floor area of the room
bounded by the wall.
4 The U-value of the floor of an extension can be calculated using the exposed perimeter and floor area of the whole enlarged building.
5 A lesser provision may be appropriate where meeting such a standard would create significant problems in relation to adjoining floor levels.
6 A lesser provision may be appropriate where meeting such a standard would create limitations on head room. In such cases, the depth of the insulation
plus any required air gap should be at least to the depth of the rafters, and the thermal performance of the chosen insulant should be such as to achieve
the best practicable U-value.
7 A lesser provision may be appropriate if there are particular problems associated with the load-bearing capacity of the frame or the upstand height.
8 Area-weighted average values.

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 ONLINE VERSION L1B
Section 6: Consequential improvements to
energy performance
6.1 Regulation 28 of the Building Regulations
may require additional work to be undertaken to
make an existing building more energy efficient
when certain types of building work are proposed.
6.2 This requirement arises in existing buildings
with a total useful floor area of over 1,000 m2
where the proposed work consists of:
a. an extension;
b. the initial provision of any fixed building
service (other than a renewable energy
generator);
c. an increase to the installed capacity of any
fixed building service (other than a
renewable energy generator);
6.3 Consequential improvements should
only be carried out to the extent that they are
technically, functionally and economically feasible.
6.4 Only a relatively small number of existing
dwellings will exceed 1,000 m2 in size. Where there
is doubt the BCB can be consulted for advice.
6.5 Technical guidance on achieving compliance
with regulation 28 is not given in this Approved
Document but where the regulation applies it is
available in Approved Document L2B.

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L1B ONLINE VERSION
Section 7: Providing information
7.1 On completion of the work, in accordance
with regulation 40, the owner of the dwelling
should be provided with sufficient information
about the building, the fixed building services
and their operating and maintenance
requirements so that the dwelling can be operated
in such a manner as to use no more fuel and
power than is reasonable in the circumstances.
This requirement applies only to the work that
has actually been carried out, e.g. if the work
involves replacing windows, there is no obligation
on the contractor to provide details on the
operation of the heating system.
7.2 Where the work involves the provision of a
new heating system, a way of complying would
be to provide a suitable set of operating and
maintenance instructions aimed at achieving
economy in the use of fuel and power in terms
that householders can understand in a durable
format that can be kept and referred to over the
service life of the system(s). The instructions
should be directly related to the particular
system(s) installed as part of the work that has
been carried out.
7.3 Without prejudice to the need to comply
with health and safety requirements, any
instructions should explain to the occupier of the
dwelling how to operate the system(s) efficiently.
This should include:
a. the making of adjustments to timing,
temperature and flow control settings;
b. what routine maintenance is needed to
enable operating efficiency to be maintained
at a reasonable level through the service
live(s) of the system(s).

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Appendix A: Work to thermal elements
1  Where the renovation of an individual thermal
element constitutes a major renovation; or
amounts to the renovation of more than 50% of
the element’s surface area, an opportunity exists
for cost-effective insulation improvements to be
undertaken at marginal additional cost. This
appendix provides guidance on the cost-
effectiveness of insulation measures when
undertaking various types of work on a
thermal element.
2  Table A1 sets out the circumstances and the
level of performance that would be considered
reasonable provision in ordinary circumstances.
When dealing with existing dwellings some
flexibility in the application of standards is necessary
to ensure that the context of each scheme can
be taken into account while securing, as far as
possible, the reasonable improvement. The final
column in Table A1 provides guidance on a
number of specific issues that may need to be
considered in determining an appropriate course
of action. As part of this flexible approach, it will
be necessary to take into account technical risk
and practicality in relation to the dwelling under
consideration and the possible impacts on any
adjoining building. In general the proposed works
should take account of:
a. the requirements of any other relevant parts
of Schedule 1 to the Building Regulations;
b. the general guidance on technical risk relating
to insulation improvements contained in
BR 26211;
c. for buildings falling within the categories set
out in paragraphs 3.7 to 3.8, the guidance
produced by English Heritage.
Where it is not reasonable in the context of the
works project to achieve the performance set out
in Table A1 the level of performance achieved
should be as close to this as practically possible.
3  Table A1 incorporates, in outline form, examples
of construction that would achieve the proposed
performance, but designers are free to use any
appropriate construction that satisfies the energy
performance standard, so long as they do not
compromise performance with respect to any
other part of the Building Regulations.
4  General guidance is available from such
sources as the Energy Saving Trust and relevant
British Standards.

11
BR 262 Thermal insulation: Avoiding risks, BRE, 2002.

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L1B O N Lelements
Work to thermal INE VERSION
Table A1 Cost-effective U-value targets when undertaking renovation works to
thermal elements
Proposed works Target U-value Typical construction Comments (reasonableness,
W/(m2.K) practicability and cost- effectiveness)

Pitched roof constructions12

Renewal of roof covering – No 0.16 Provide loft insulation – Assess condensation risk in roof space and
living accommodation in the roof 250 mm mineral fibre or make appropriate provision in accordance
void – existing insulation (if any) at cellulose fibre as quilt with the requirements of Part C relating
ceiling level. No existing insulation, laid between and across to the control of condensation. Additional
existing insulation less than ceiling joists or loose fill or provision may be required to provide access
50 mm, in poor condition, and/ equivalent to and insulation of services in the roof void
or likely to be significantly
disturbed or removed as part
of the planned work

Renewal of roof covering – Existing 0.16 Top up loft insulation to at Assess condensation risk in roof space and
insulation in good condition and least 250 mm mineral fibre make appropriate provision in line with the
will not be significantly disturbed or cellulose fibre as quilt requirements of Part C relating to the control
by proposed works. Existing laid between and across of condensation. Additional provision may
insulation thickness 50 mm or more ceiling joists or loose fill be required to provide insulation and access
but less than 100 mm or equivalent. This may be to services in the roof void
boarded out
Where the loft is already boarded out and
the boarding is not to be removed as part of
the work, the practicality of insulation works
would need to be considered

Renewal of the ceiling to cold loft 0.16 Provide loft insulation – Assess condensation risk in roof space and
space. Existing insulation at ceiling 250 mm mineral fibre or make appropriate provision in accordance
level removed as part of the works cellulose fibre as quilt with the requirements of Part C relating
laid between and across to the control of condensation. Additional
ceiling joists or loose fill provision may be required to provide insulation
or equivalent. This may be and access to services in the roof void
boarded out
Where the loft is already boarded out and
the boarding is not to be removed as part
of the work, insulation can be installed from
the underside but the target U-value may
not be achievable

Renewal of roof covering – 0.18 Cold structure – Insulation Assess condensation risk (particularly
Living accommodation in roof (thickness dependent on interstitial condensation), and make
space (room-in- the-roof type material) placed between appropriate provision in accordance with
arrangement), with or without and below rafters the requirements of Part C relating to the
dormer windows control of condensation (Clause 8.4 of
Warm structure – Insulation BS 5250:2002 and BS EN ISO 13788:2002
placed between and above
rafters Practical considerations with respect to an
increase in structural thickness (particularly
in terraced dwellings) may necessitate a
lower performance target

Dormer window constructions

Renewal of cladding to side walls 0.30 Insulation (thickness Assess condensation risk and make
dependent on material) appropriate provision in accordance with the
placed between and/or requirements of Part C
fixed to outside of wall
studs. Or fully external
to existing structure
depending on construction

Renewal of roof covering – Follow guidance on Assess condensation risk and make
improvement to pitched or appropriate provision in accordance with the
flat roofs as appropriate requirements of Part C

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 ON
Work to thermal LINE
elements VERSION L1B
Table A1 Cost-effective U-value targets when undertaking renovation works to
thermal elements
Proposed works Target U-value Typical construction Comments (reasonableness,
W/(m2.K) practicability and cost- effectiveness)

Flat roof constructions

Renewal of roof covering – Existing 0.18 Insulation placed between Assess condensation risk and make
insulation, if any, less than 100 and over joists as required appropriate provision in accordance with
mm, mineral fibre (or equivalent to achieve the target the requirements of Part C. Also see
resistance) or in poor condition U-value – Warm structure BS 6229:2003 for design guidance
and likely to be significantly
disturbed or removed as part
of the planned work

Renewal of the ceiling to flat roof 0.18 Insulation placed between Assess condensation risk and make
area. Existing insulation removed and to underside of joists appropriate provision in accordance with
as part of the works to achieve target U-value the requirements of Part C. Also see
BS 6229:2003 for design guidance.
Where ceiling height would be adversely
affected, a lower performance target may
be appropriate

Solid wall constructions

Renewal of internal finish to 0.30 Dry-lining to inner face of Assess the impact on internal floor area. In
external wall or applying a finish for wall – insulation between general it would be reasonable to accept a
the first time studs fixed to wall to reduction of no more than 5% in the area
achieve target U-value – of a room. However, the use of the room
thickness dependent and the space requirements for movement
on insulation and stud and arrangements of fixtures, fittings and
material used furniture should be assessed
Insulated wall board fixed In situations where acoustic attenuation
to internal wall surface issues are particularly important (e.g.
to achieve the required where insulation is returned at party walls)
U-value – thickness a less demanding U-value may be more
dependent on material appropriate. In such cases, the U-value
used target may have to be increased to 0.35 or
above depending on the circumstances
Assess condensation and other moisture
risks and make appropriate provision in
accordance with the requirements of Part
C. This will usually require the provision of
a vapour control and damp protection to
components. Guidance on the risks involved
is provided in BR 262 and, on the technical
options, in Energy Saving Trust publications

Renewal of finish or cladding to 0.30 External insulation system Assess technical risk and impact of
external wall area or elevation with rendered finish or increased wall thickness on adjoining
(render or other cladding) or cladding to give required buildings
applying a finish or cladding for the U-value
first time

Ground floor constructions

Renovation of a solid or suspended See comment Solid floor – replace screed The cost-effectiveness of floor insulation is
floor involving the replacement of with an insulated floor deck complicated by the impact of the size and
screed or a timber floor deck to maintain existing floor shape of the floor (perimeter/area ratio).
level In many cases existing un-insulated floor
U-values are already relatively low when
Suspended timber floor – compared with wall and roof U-values.
fit insulation between floor Where the existing floor U-value is greater
joists prior to replacement than 0.70 W/(m2.K), then the addition of
of floor deck insulation is likely to be cost-effective.
Analysis shows that the cost–benefit curve
for the thickness of added insulation is very
flat, and so a target U-value of 0.25 W/(m2.K)
is appropriate subject to other technical
constraints (adjoining floor levels, etc.)

12
Specification of thickness of insulation is based on lambda values (conductivity) of 0.04 W/(m.K).

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L1B ONLINE VERSION
Appendix B: Documents referred to
BRE Health and Safety Executive (HSE)
www.bre.co.uk www.hse.gov.uk
BR 262 Thermal insulation: avoiding risks (2002 L24 Workplace Health, Safety and Welfare:
Edition) printed in 2006. ISBN 978 186081 515 4 Workplace (Health, Safety and Welfare)
Regulations1992, Approved Code of Practice
BRE Report BR 443 Conventions for U-value
and Guidance, The Health and Safety
calculations, 2006. (Available at www.bre.co.uk/
Commission 1992. ISBN 978 0 71760 413 5
uvalues)

Department for Business, National Association of Rooflight

Innovation and Skills Manufacturers (NARM)
www.narm.org.uk
www.bis.gov.uk
NARM Technical Document NTD 2, 2010.
Technical Standards and Regulations Directive
98/34/EC. (Available at www.bis.gov.uk/policies/
innovation/infrastructure/Standardisation/tech- NBS (on behalf of the Department
standards-directive) for Communities and Local
Department of Energy and Climate Government)
Change (DECC) www.thebuildingregs.com

www.decc.gov.uk Domestic Building Services Compliance Guide,

DCLG, 2013 incorporating 2018 amendments.
The Government’s Standard Assessment
Procedure for energy rating of dwellings, SAP Domestic Ventilation Compliance Guide,
2012. (Available at www.bre.co.uk/sap2012) DCLG, 2010.

Current Energy Prices (www.gov.uk/government/ (Both available to download from

organisations/department-of-energy-climate- www.gov.uk)
change/about/statistics#energy-price-statistics)
Legislation
Department for Communities and Ancient Monuments and Archaeological Areas
Act 1979
Local Government (DCLG)
Listed Buildings and Conservation Areas) Act 1990
www.gov.uk
SI 2010/2214 The Building Regulations 2010
Accredited Construction Details for Part L
(Available to download from SI 2010/2215 The Building (Approved Inspectors
www.planningportal.gov.uk/england/ etc.) Regulations 2010
professionals/en/1115314255826.html)

Energy Saving Trust (EST)

www.est.org.uk
Energy Efficient Glazing – guidance
(Available at www.energysavingtrust.org.uk/
Home-improvements-and-products/
Home-insulation-glazing/Glazing)

English Heritage
www.english-heritage.org.uk
Energy Efficiency and Historic Buildings,
English Heritage, 2011.

Glass and Glazing Federation (GGF)

www.ggf.org.uk
Guide to the Calculation of Energy Ratings for
Windows, Roof Windows and Doors, GGF, 2013.

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 ONLINE VERSION L1B
Appendix C: Standards referred to
BS EN ISO 13370 Thermal performance of
buildings – Heat transfer via the ground –
Calculation methods [2007 incorporating
corrigendum March 2009].
BS EN 14351-1 Windows and doors – Product
standard, performance characteristics.
Windows and external pedestrian doorsets
without resistance to fire and/or smoke leakage
characteristics [2006 (+AMD 1:2010)].
BS 5250:2002 Code of practice for control
of condensation in buildings.
BS EN ISO 13788:2002 Hygrothermal
performance of building components and
building elements.
BS 6229:2003 Flat roofs with continuously
supported coverings. Code of practice.

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L1B ONLINE VERSION
Index
A D I
Accredited construction details DER Information provision 7.1–7.3
schemes 5.6 See Dwelling CO2 Emission Rate Insulation
Airtightness 5.5 (DER) See Thermal insulation
Ancient monuments 3.6, 3.7 Design flexibility 4.4–4.7, 4.16 Internal lighting 4.3
Approved Document L1B Doors Table 1, 4.2, 4.8, 4.15, 4.19
Conventions 1.9 Dormer windows Table A1
Purpose 1.1–1.6 Dry lining 5.7 L
Types of work covered 3.2–3.4 Dwelling Legislation Appendix B
Architectural interest 3.8 Definition 3.1 See also Building Regulations
Area-weighted U-value 4.5 Dwelling CO2 Emission Rate (DER) Lighting 4.3
4.6–4.7 Limitation on requirements 2.2–2.4
B Listed buildings 3.6, 3.7

BCB
E Low and zero carbon (LZC)
technologies 4.27, 4.29
See Building Control Body (BCB) Emergency repairs 3.18
British Standards Appendix C Energy efficiency requirements 2.1
BR 262: 2002 Appendix A Compliance with 1.2–1.3, 1.11 M
BS EN 14351: 2006 4.20 Definition 3.1 Maintenance instructions 7.2–7.3
BS EN ISO 13370 4.10 Exemptions 3.6 Major renovation 5.6A
Building Control Body (BCB) Fixed building services 4.25–4.26 Definition 3.1
Definition 3.1 Energy performance Material change of use 4.11, 4.15
Notice of completion of Consequential improvements 3.1, Materials and workmanship 3.26–3.28
commissioning 4.35–4.37 6.1–6.5 Minor works 3.23–3.25
Notification of work 3.17–3.18 See also Dwelling CO2 Emission Rate Mixed-use buildings 3.4
Building envelope (DER) Multiple dwellings 4.11
Definition 3.1 Energy Performance Certificate
Building fabric 2.1–2.4
Standards 4.1 Definition 3.1 N
See also Thermal elements Energy status change 4.12–4.15
National parks 3.8
Building log book 7.2–7.3 Exemptions 3.6
Non-notifiable work 3.23–3.25
Building Regulations 2.1–2.4, Extensions 3.5, 4.1–4.10
Notice of completion of
Appendix B Consequential improvements 6.2
commissioning 4.35–4.37
Building services Historic or traditional dwelling 3.11
Notification of work 3.17–3.18
See. Fixed building services
F O
C Fabric
Operating and maintenance
Cavity walls Table 3 See Building fabric
instructions 7.2–7.3
Certification Fixed building services 4.24–4.27
Competent person self-certification Commissioning 4.30–4.37
schemes 3.19–3.22 Consequential improvements 6.2 P
Change of energy status 4.12–4.15 Definition 3.1
Change of use 4.11, 4.15 Replacement 4.26 Payback period 5.9, 5.12
Cladding 5.7 System efficiencies 4.25–4.26 Porches 3.15–3.16
Commissioning See also Controlled services; Heating Product certification schemes
Definition 3.1 and hot water systems; Lighting 3.29–3.31
Fixed building services 4.30–4.37 Flat roofs 5.7, 5.8, Table A1 Publications (excluding BSI and
Common areas 3.29 Floors European Standards) Appendix B
Competent person self-certification Upgrades Table 3 Conventions for U-value calculations
schemes 3.19–3.22 U-values Table 2, Table A1 (BR 443, 2006) 4.20
Compliance with requirements Domestic Building Services
1.2–1.3, 1.11 Compliance Guide (DCLG, 2010)
Materials and workmanship 3.26 G 4.24
Self-certification 3.21 Domestic Ventilation Compliance
Glazing
Consequential improvements 2.1, 3.1, Guide (DCLG, 2010) 4.33
See Windows
6.1–6.5
Conservation areas 3.6, 3.7
Conservatories 3.15–3.16, 4.8–4.9 H
Controlled fittings 4.17–4.23, Table 1
Health and safety 3.29
Definition 3.1
Heating and hot water systems
Controlled services 4.22, 4.24–4.29
Commissioning 4.30–4.37
Definition 3.1
Controls 4.8
Extensions 4.3
Non-notifiable work 3.24
See also Fixed building services
Historic buildings 3.6–3.13

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INDEX ONLINE VERSION L1B
R W
Rendering 5.7, 5.8 Walls
Renewable energy systems 4.27 Upgrades Table 3
Renovation 3.3, 4.7 U-values Table 2, Table A1
Definition 3.1 Whole dwelling calculation method
Historic and traditional buildings 3.12 4.6–4.7
Thermal elements 5.1, 5.7–5.10, Window Energy Rating (WER) 4.22
Appendix A, Table A1 Windows
Replacement Area of glazing 4.2
Appliances 4.26–4.28 Conservatories and porches 4.8
Thermal elements 5.1, 5.8 Replacement 4.15
Windows 4.19, 4.23 U-values 4.19–4.23, Table 1
Replacement windows 4.15 Workmanship 3.26
Replastering 5.8 Workplace (Health, Safety and
Rooflights Table 1, 4.21 Welfare) Regulations 1992 3.29–3.30
Roofs
Renovation 5.7, 5.8
Upgrades Table 3
U-values Table 2, Table A1
Roof windows 4.2, 4.8, 4.15, 4.19, 4.21,
Table 1
Room for residential purposes
Definition 3.1

S
SAP 2009 4.6
Self-certification schemes 3.19–3.22
Simple payback 5.9, 5.12
Definition 3.1
Standard Assessment Procedure
(SAP 2009) 4.6
Standards 3.27–3.28
See also British Standards
Swimming pools Table 2, 4.10

T
Technical specifications 3.27
Thermal bridges 5.5–5.6
Thermal elements 5.1–5.13
Definition 3.1
Renovation 5.7–5.10, Appendix A,
Table A1
Replacement 5.1, 5.8–5.8A
Retained 5.11–5.13
Upgrades 5.9, 5.12–5.13, Table 3
U-values 5.2–5.4
Thermal insulation 3.24, 5.5–5.6,
Appendix A
Thermal separation 4.8, 4.9
Traditional construction 3.8

U
Upgrades 4.7
Thermal elements 5.9, 5.12–5.13,
Table 3
U-values 4.15, 5.1, Table 2
Area-weighted 4.5
Controlled fittings 4.19–4.23, Table 1
Renovation targets Table A1

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L1B ONLINE VERSION

Conservation of fuel and power Approved Document L1B

28
ONLINE VERSION
 ONLINE VERSION
LIST OF APPROVED DOCUMENTS
The following documents have been published
to give guidance on how to meet the Building
Regulations. You can find the date of the edition
approved by the Secretary of State at
www.gov.uk.
Approved Document A
Structure
Approved Document B
Fire safety
Volume 1: Dwellinghouses
Volume 2: Buildings other than dwellinghouses
Approved Document C
Site preparation and resistance to contaminants
and moisture
Approved Document D
Toxic substances
Approved Document E
Resistance to the passage of sound
Approved Document F
Ventilation
Approved Document G
Sanitation, hot water safety and water efficiency
Approved Document H
Drainage and waste disposal
Approved Document J
Combustion appliances and fuel storage systems
Approved Document K
Protection from falling, collision and impact
Approved Document L1A
Conservation of fuel and power in new dwellings
Approved Document L1B
Conservation of fuel and power in existing dwellings
Approved Document L2A
Conservation of fuel and power in new buildings
other than dwellings
Approved Document L2B
Conservation of fuel and power in existing buildings
other than dwellings
Approved Document M
Access to and use of buildings
Volume 1: Dwellings
Volume 2: Buildings other than dwellings
Approved Document P
Electrical Safety – Dwellings
Approved Document Q
Security – Dwellings
Approved Document R
Physical infrastructure for high speed
electronic communication networks
Approved Document 7
Materials and workmanship

ONLINE VERSION
 ONLINE VERSION

The Building Regulations 2010, Approved Documents are available from:

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