building regulations part l1a_2010

8/11/2019 Building Regulations Part L1A_2010

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Conservation of fuel and power

The Building Regulations 2000

L1AL1A Conservation of fuel and power

in new dwellings

APPROVEDDOCUMENT

2010

ed

ition

Coming into effect 1 October 2010


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Approved Document G Sanitation, hot water safety and water efficiency

All references to the Building Regulations 2000(as amended) should be read as references tothe Building Regulations 2010.

All references to the Building (ApprovedInspectors etc.) Regulations 2000 should beread as references to the Building (ApprovedInspectors etc.) Regulations 2010.

There have been no substantive requirementsamendments to either set of regulations, butplease note the simplification of the definition ofroom for residential purposes in regulation 2 ofthe Building Regulations 2010. Please also notethat L1(c) has now become regulation 40.

The following tables will help you to find the newregulation number for regulations which havebeen re-numbered in the 2010 Regulations. For

any regulation number not included in the tablesbelow, the number of the regulation has not changed.

Amendments to Approved Documents andCompliance Guides 2010


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Building RegulationsRegulationnumberin BuildingRegulations2000

Regulationnumberin BuildingRegulations2010





2(2A) 2(3) 12(7) 12(8) 20AA 42

2(2B) 2(4) 13(2)(c)(iii) 13(2)(ii) 20B 43

2(2C) 2(5) 13(3) deleted 20C(A1) 44(1)

2(3) deleted 13(5) 13(3) 20C(1) 44(2)

3(1)(g) 3(1)(h) 13(6) 13(4) 20C(2) 44(3)

3(1)(h) 3(1)(g) 13(7) 13(5) 20C(3) 44(4)

4(1A) 4(2) 14(3)(aa) 14(3)(b) 20D 27

4(2) 4(3) 14(3)(b) 14(3)(c) 20E 37

4A 23 14A 15 21(1) 18(1)

4B(1) 22 15 16 21(2) 18(8)

4B(2) deleted 16A 20 21(3) 18(2)

6(1)(cc) 6(1)(d) 16B 38 21(4) 18(3)

6(1)(d) 6(1)(e) 16C 39 21(5) 18(4)

6(1)(e) 6(1)(f) 17A 24 21(6) 18(5)

6(1)(f) 6(1)(g) 17B 25 21(7) 18(6)

6(1)(ff) 6(1)(h) 17C 26 21(8) 18(7)

6(1)(g) 6(1)(i) 17D 28 22 47

9(1A) 9(2) 17E(4) 29(5) 22B(1)(a) 48(1)(a)

9(2) 9(3) 17E(5) 29(4) 22B(1)(b) 48(1)(b)

9(3) 21(1) 17F 30 22B(1)(c) 48(1)(c)

9(4) 21(2) 17G 31 22B(1)(d) 48(1)(g)

9(5) 21(3) 17H 32 22B(1)(e) 48(1)(d)

9(5A) 21(4) 17I 33 22B(1)(f) 48(1)(i)

9(6) 21(5) 17J 35 22B(1)(g) 48(1)(j)

12(2) 12(1) 17K 36 22B(1)(h) 48(1)(l)

12(2A) 12(2) 18 45 22B(1)(ha) 48(1)(m)

12(4A) 12(5) 19 46 22B(1)(i) 48(1)(n)

12(5) 12(6) 20 19 22B(1)(j) 48(1)(o)

12(6) 12(7) 20A 41 22B(1)(k) 48(1)(h)

22B(1)(ka) 48(1)(k) J2A J3 J6 J7

22B(1)(l) 48(1)(e) J3 J4 L1(c) Regulation 40

22B(1)(m) 48(1)(f) J4 J5 Schedule 2A Schedule 3

22B(2) 48(2) J5 J6 Schedule 2B Schedule 4


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Building (Approved Inspectors etc.) Regulations

Regulationnumberin Building(ApprovedInspectors etc.)Regulations2000






1 1 and 38 13(1)(d) 12(6)(c) 25(2) 25(3)

3 4 13(2) 12(1) 25(3) 25(4)

4 3 13(3) 12(2) 31A(a) 32(c)

8 10 13(4) 12(3) 31A(b) 32(c)

9 11 13(5) 12(4) 31A(c) 32(e)

10(1) 9(5) 13(6) 12(5) 31A(d) 32(f)

10(2) 9(1) 13A 13 31A(e) 32(h)

10(3) 9(2) 14 14(1) 31A(ea) 32(i)

10(4) 9(3) 15(1) 14(2) 31A(f) 32(j)

10(5) 9(4) 15(2) 14(3) 31A(g) 32(k)

11(1)(a) 8(1)(a) 15(3) 14(4) 31A(h) 32(d)

11(1)(c) 8(1)(b) 16 15 31A(ha) 32(g)11(2) 8(2) 17 16 31A(i) 32(a)

11A 20(1) 18(1) 17(1) 31A(j) 32(b)

12 20(1) and (3) 18(2) 17(2) and (3) *Sch 3 7A Sch 2 8

12A 20(1) and (5) 18(3) 17(4) Sch 3 8 Sch 2 9

12AA 20(1) 18(4) 17(5) Sch 3 9 Sch 2 10

12B 20(1) 18(5) 17(6) Sch 4 7A Sch 3 8

12C 20(1) and (6) 18(6) 17(7) Sch 4 8 Sch 3 9

12D 20(1) and (2) 19 18 Sch 6 5A Sch 5 6

12E 20(1) and (4) 20 19 Sch 6 6 Sch 6 7

13(1) 12(6) 23A 24

13(1)(b) 12(6)(a) 24 25(1)13(1)(c) 12(6)(b) 25(1) 25(2)

Please note that some of the numbering and cross referencing in the forms in Schedule 1 has changed slightly.

*Sch =Schedule


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MAIN CHANGES IN THE

2010 EDITION

1. This Approved Document L1A comes into forceon 1 October 2010 in support of the Buildingand Approved Inspectors (Amendment)Regulations 2010, SI 2010 No. 719. The mainchanges to the legal requirements and the

supporting guidance since the issue of theprevious Approved Document L1A areas follows:

Changes in the legal requirements

2. The exemption from the energy efficiencyprovisions for extensions consisting of aconservatory or porch is amended to grantthe exemption only where the existing walls,windows or doors are retained, or replaced ifremoved, and where the heating system ofthe building is not extended into theconservatory or porch.

3. A new requirement is introduced, whereregulation 17C applies, for CO2 emission ratecalculations to be carried out and given tothe Building Control Body, along with a list ofspecifications used in the calculations beforethe start of building work on the erection of anew building. This is in addition to the CO2emission rate calculation required to besubmitted after completion of the work.

Changes in the technical guidance

4. The annual CO2 emission rate of the completeddwelling is now calculated using SAP2009

and must not exceed the target set byreference to a notional dwelling with anadditional overall improvement of 25%relative to 2006 standards.

5. The notional dwelling now includes a partywall heat loss of zero, meaning that thetargeted improvement of 25% is in additionto treating party walls between connecteddwellings against heat loss.

6. Secondary heating is counted as part of theannual CO2 emission rate of the completeddwelling only when actually provided for andcredit is allowed wherever low-energy lighting

is installed.

7. Some of the reasonable limits for buildingfabric and services performance specificationsare strengthened.

8. Revised guidance is provided for avoidingthermal bridging at construction jointsincluding the option of adopting a quality-assured accredited construction detailsscheme approach.

Details of approval of such schemes to beconfirmed at www.communities.gov.uk

9. New provisions and guidance are introducedto limit heat loss from a swimming poolbasin where this is constructed as part ofa new dwelling.

10. Appendix A contains guidance for presenting

the evidence that demonstrates compliancewith the energy efficiency requirements andhighlighting key features that are critical inachieving the annual CO2 emission rate target.


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Approved Document L1A Conservation of fuel and power

PAGE

Section 1: Introduction 2

What is an Approved Document? 2

Consideration of technical risk 2

How to use this Approved Document 2

Where you can get further help 3

Responsibility for compliance 3

Section 2: The Requirements 4

LIMITATION ON REQUIREMENTS 6

Section 3: General guidance 7

Key terms 7

Types of work covered by this

Approved Document 8Buildings that are exempt from theenergy efficiency requirements 8

Notification of work covered by theenergy efficiency requirements 8

Materials and workmanship 9

The Workplace (Health, Safety andWelfare) Regulations 1992 9

Demonstrating compliance 10

Section 4: Design standards 11

REGULATIONS 17A AND 17B 11

Target CO2emission rate (TER) 11

Buildings containing multiple dwellings 12

CRITERION 1 ACHIEVING THE TER 12

Calculation the CO2emissions from the

actual dwelling 12

CO2emission rate calculations 13

Secondary heating 13

Internal lighting 14

Buildings containing multiple dwellings 14Achieving the target 14

CRITERION 2 LIMITS ON DESIGNFLEXIBILITY 14

Fabric standards 15

System efficiencies 15

CRITERION 3 LIMITING THE EFFECTSOF SOLAR GAINS IN SUMMER 16

PAGE

Section 5: Quality of construction andcommissioning 17

CRITERION 4 BUILDING PERFORMANCE

CONSISTENT WITH DER 17Party walls and other thermal bypasses 17

Thermal bridges 18

Air permeability and pressure testing 19

Alternative to pressure testing onsmall developments 20

COMMISSIONING OF HEATING ANDHOT WATER SYSTEMS 20

Section 6: Providing information 21

CRITERION 5 PROVISIONS FORENERGY-EFFICIENT OPERATIONOF THE DWELLING 21

Section 7: Model designs 22

Appendix A: Reporting evidenceof compliance 23

Appendix B: Documents referred to 24

Appendix C: Standards referred to 25

Contents L1A


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Section 1: Introduction

What is an Approved Document?

1.1 This Approved Document, which takeseffect on 1 October 2010, has been approvedand issued by the Secretary of State to providepractical guidance on ways of complying with the

energy efficiency requirements(see Section 2)and regulation 7 of the Building Regulations 2000(SI 2000/2531) for England and Wales, as amended.Regulation 2(1) of the Building Regulations definesthe energy efficiency requirementsas therequirements of regulations 4A, 17C, 17D and 17Eand Part L of Schedule 1. The Building Regulations2000 are referred to throughout the remainder ofthis document as the Building Regulations.

1.2 The intention of issuing Approved Documentsis to provide guidance about compliance withspecific aspects of building regulations in someof the more common building situations. They

set out what, in ordinary circumstances, may beaccepted as reasonable provision for compliancewith the relevant requirement(s) of buildingregulations to which they refer.

1.3 If guidance in an Approved Document isfollowed there will be a presumption of compliancewith the requirement(s) covered by the guidance.However, this presumption can be overturned,so simply following guidance does not guaranteecompliance; for example, if the particular caseis unusual in some way, then normal guidancemay not be applicable. It is also important to notethat there may well be other ways of achieving

compliance with the requirements. There istherefore no obligation to adopt any particularsolution contained in this Approved Documentif you would prefer to meet the relevantrequirement in some other way. Personsintending to carry out building work shouldalways check with their building control body,either the local authority or an approvedinspector, that their proposals comply withbuilding regulations.

1.4 It is important to note that this ApprovedDocument, as well as containing guidance, alsocontains extracts from the Regulations. Such

regulatory text must be complied with as stated.For example, the requirement that the targetcarbon dioxide (CO

2) emission rate for the

building shall not be exceeded (regulation 17C)is a regulatory requirement. There is therefore noflexibility to ignore this requirement; neither cancompliance with this particular regulation bedemonstrated via any route other than that setout in regulations 17A and 17B.

1.5 The guidance contained in this ApprovedDocument relates only to the particular requirementsof the Building Regulations that the documentaddresses (set out in Section 2). However, building

work may be subject to more than one requirementof building regulations. In such cases the workwill also have to comply with any other applicablerequirements of building regulations.

1.6 There are Approved Documents that giveguidance on each of the parts of Schedule 1 andon regulation 7. A full list of these is provided atthe back of this document.

Consideration of technical risk1.7 In relation to the construction of newdwellings, building work must satisfy all thetechnical requirements set out in regulation 17Cof, and Schedule 1 to, the Building Regulations.When considering the incorporation of energyefficiency measures in dwellings, attention shouldalso be paid in particular to the need to complywith Part B (fire safety), Part C (site preparationand resistance to contaminants and moisture),Part E (resistance to the passage of sound), PartF (ventilation), paragraph G3 (hot water supplyand systems), Part J (combustion appliancesand fuel storage systems) and Part P (electricalsafety) of Schedule 1 to the Building Regulations,as well as Part L. The adoption of any particularenergy efficiency measure should not involveunacceptable technical risk of, for instance,excessive condensation. Designers and buildersshould refer to the relevant Approved Documentsand to other generally available good practiceguidance to help minimise these risks.

How to use this Approved Document

1.8 This Approved Document is subdividedinto seven sections as detailed below. Thesemain sections are followed by supportingappendices.

This introductorysection sets out the generalcontext in which the guidance in the ApprovedDocument must be considered.

Section 2sets out the relevant legal requirementscontained in the Building Regulations.

Section 3contains general guidance, includingthe definition of key terms, the types of buildingwork covered by this Approved Document, thetypes of building work that are exempt, proceduresfor notifying work, materials and workmanshipand health and safety issues, an overview of theroutes to compliance and how to deal with specialareas of buildings that contain dwellings.

Section 4details the considerations that applyto demonstrating that the design of the dwellingwill meet the energy efficiency requirements.This section begins the detailed technical guidancerelating to showing compliance with the energyefficiency requirements.

Section 5details the considerations that applywhen demonstrating that the design has beenappropriately translated into actual constructionperformance.

Section 6describes the information that shouldbe provided to occupiers to help them achievereasonable standards of energy efficiency inpractice.

L1A

2

Conservation of fuel and power Approved Document L1A


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INTRODUCTION L1ASection 7provides a pointer to some usefulinformation on different design approaches tomeeting the energy efficiency requirements.

1.9 In this document the following conventionshave been adopted to assist understanding andinterpretation:

a. Texts shown against a green background areextracts from the Building Regulations or

Building (Approved Inspectors etc.) Regulations2000 (SI 2000/2532) (the Approved InspectorsRegulations), both as amended, and set outthe legal requirements that relate to compliancewith the energy efficiency requirementsofbuilding regulations. As stated previously,there is no flexibility in respect of such text;it defines a legal requirement, not guidancefor typical situations. It should also beremembered that, as noted above, buildingworks must comply with all the other applicableprovisions of building regulations.

b. Key terms are defined in paragraph 3.1 and

are printed inbold italic text.

c. Details of technical publications referred toin the text of this Approved Document will begiven in footnotes and repeated as referencesat the end of the document. A reference to apublication is likely to be made for one of twomain reasons. The publication may containadditional or more comprehensive technicaldetail, which it would be impractical to includein full in the Approved Document but which isneeded to fully explain ways of meeting therequirements; or it is a source of more generalinformation. The reason for the reference will

be indicated in each case. The reference will beto a specified edition of the document. TheApproved Document may be amended from timeto time to include new references or to refer torevised editions where this aids compliance.

d. Additional commentary in italic textappearsafter some numbered paragraphs. Thiscommentary is intended to assist understandingof the immediately preceding paragraphor sub-paragraph, or to direct readers tosources of additional information, but isnot part of the technical guidance itself.

Where you can get further help1.10 If you do not understand the technicalguidance or other information set out in thisApproved Document and the additional detailedtechnical references to which it directs you, thereare a number of routes through which you canseek further assistance:

the CLG website: www.communities.gov.uk;

the Planning Portal website:www.planningportal.gov.uk;

if you are the person undertaking the building

work you can seek assistance either fromyour local authority building control service orfrom your approved inspector (depending onwhich building control service you are using;

persons registered with a competent personself-certification scheme may be able to gettechnical advice from their scheme operator;

if your query is of a highly technical nature youmay wish to seek the advice of a specialist, orindustry technical body, for the relevant subject.

Responsibility for compliance

1.11 It is important to remember that if you arethe person (e.g. designer, builder, installer) carryingout building work to which any requirement ofbuilding regulations applies you have aresponsibility to ensure that the work complieswith any such requirement. The building ownermay also have a responsibility for ensuringcompliance with building regulation requirementsand could be served with an enforcement noticein cases of non-compliance.


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2.1 This Approved Document, which takeseffect on 1 October 2010, deals with the energyefficiency requirementsin the BuildingRegulations 2000 (as amended). Regulation 2(1)of the Building Regulations defines the energyefficiency requirementsas the requirements ofregulations 4A, 17C, 17D and 17E and Part L ofSchedule 1. The energy efficiency requirementsrelevant to this Approved Document, which dealswith new dwellings, are those in regulations 17Cand 17E and Part L of Schedule 1, and are setout below.

New buildings Regulation 17C

Where a building is erected, it shall not exceed the target CO2

emission rate for the building that has been approved pursuant

to regulation 17B.

Energy performance certificates Regulation 17E

(1) This regulation applies where

(a) a building is erected; or

(b) a building is modified so that it has a greater or fewer

number of parts designed or altered for separate use than it

previously had, where the modif ication includes the provision

or extension of any of the fixed services for heating, hot water,

air conditioning or mechanical ventilation.

(2) The person carrying out the work shall

(a) give an energy performance certificate for the buildingto the owner of the building; and

(b) give to the local authority notice to that effect,

including the reference number under which the energy

performance certificate has been registered in accordance with

regulation 17F(4).

(3) The energy performance certificate and notice shall be

given not later than f ive days after the work has been completed.

(4) The energy performance certificate must be accompanied

by a recommendation report containing recommendations for

the improvement of the energy performance of the building,

issued by the energy assessor who issued the energy

performance certificate.

(5) An energy performance certificate must

(a) express the asset rating of the building in a way

approved by the Secretary of State under regulation 17A;

(b) include a reference value such as a current legal

standard or benchmark;

(c) be issued by an energy assessor who is accredited to

produce energy performance certificates for that category of

building; and

L1A

Section 2: The Requirements


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THE REQUIREMENTS L1A

Energy performance certificates Regulation 17E (continued)

(d) include the following information

(i) the reference number under which the certificate

has been registered in accordance with regulation 17F(4);

(ii) the address of the building;

(iii) an estimate of the total useful floor area of thebuilding;

(iv) the name of the energy assessor who issued it;

(v) the name and address of the energy assessors

employer, or, if he is self-employed, the name under which he

trades and his address;

(vi) the date on which it was issued; and

(vii) the name of the approved accreditation scheme of

which the energy assessor is a member.

(6) Certification for apartments or units designed or altered

for separate use in blocks may be based

(a) except in the case of a dwelling, on a common

certification of the whole building for blocks with a commonheating system; or

(b) on the assessment of another representative apartment

or unit in the same block.

(7) Where

(a) a block with a common heating system is divided into

parts designed or altered for separate use; and

(b) one or more, but not all, of the parts are dwellings,

certification for those parts which are not dwellings may be

based on a common certification of all the parts which are not

dwellings.

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

(c) 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.


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LIMITATION ON REQUIREMENTS

2.2 In accordance with regulation 8 of theBuilding Regulations, the requirements in Parts Ato D, F to K and N and P (except for paragraphsG2, H2 and J6) of Schedule 1 to the BuildingRegulations do not require anything to be doneexcept for the purpose of securing reasonable

standards of health and safety for persons inor about buildings (and any others who maybe affected by buildings or matters connectedwith buildings).

2.3 Paragraph G2 is excluded as it deals withwater efficiency and paragraphs H2 and J6 areexcluded from regulation 8 because they dealdirectly with prevention of the contamination ofwater. Parts E and M (which deal, respectively,with resistance to the passage of sound andaccess to and use of buildings) are excluded fromregulation 8 because they address the welfareand convenience of building users. Part L is

excluded from regulation 8 because it addressesthe conservation of fuel and power.

L1A THE REQUIREMENTS


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L1A

Key terms

3.1 The following are key terms used in thisdocument:

Air permeabilityis the physical property used

to measure airtightness of the building fabric.It is defined as air leakage rate per hour persquare metre of envelope area at a test referencepressure differential across the building envelopeof 50 Pascal (50 N/m2). The envelope area of thebuilding, or measured part of the building, is thetotal area of all floors, walls and ceilings borderingthe internal volume subject to the test. Thisincludes walls and floors below external groundlevel. Overall internal dimensions are used tocalculate this area and no subtractions are madefor the area of the junctions of internal walls,floors and ceilings with exterior walls, floors andceilings. Thelimiting air permeabilityis the

worst allowableair permeability. The design airpermeabilityis the target value set at the designstage, and must always be no worse than thelimiting value. Theassessed air permeabilityisthe value used in establishing theDER, and isbased on a specific measurement of the dwellingconcerned, or on measurements of otherdwellingsof the same dwelling type.

The envelope area of a terraced house includesthe party wall(s). The envelope area of a flat in amultiple storey building includes the floors, wallsand ceilings which are shared with adjacent flats.

BCBmeans Building Control Body: a localauthority or an approved inspector.

Commissioningmeans the advancement ofa fixed building servicefollowing installation,replacement or alteration of the whole or partof the system, from the state of static completionto working order by testing and adjusting asnecessary to ensure that the system as a wholeuses no more fuel and power than is reasonable inthe circumstances, without prejudice to the needto comply with health and safety requirements.For each system commissioningincludessetting-to-work, regulation (that is testing and

adjusting repetitively) to achieve the specifiedperformance, the calibration, setting up andtesting of the associated automatic controlsystems, and recording of the system settingsand the performance test results that have beenaccepted as satisfactory.

Controlled service or fittingmeans a service orfitting in relation to which Part G (sanitation, hotwater safety and water efficiency), H (drainageand waste disposal), J (combustion appliancesand fuel storage systems), L (conservation of fueland power) or P (electrical safety) of Schedule 1to the Building Regulations imposes a requirement.

DERis theDwellingCO2Emission Rate expressedas kgCO

2/(m2.year).

Dwellingmeans a self-contained unit designedto accommodate a single household. Buildingsexclusively containing rooms for residentialpurposessuch as nursing homes, studentaccommodation and similar are not dwellings,and in such cases, Approved Document L2Aapplies.

Dwelling typeis a means of allocating eachdwellingon a development to a particular groupto provide the basis for assessing the pressuretesting regime. The allocation of each dwellingto a dwelling typeshould be the responsibility ofthe person carrying out the pressure testing. To beclassed as of the same type dwellingshave to:

i. be of the same generic form (i.e. detached,semi-detached, end terrace, mid-terrace,ground-floor flat (inc. ground-floor maisonette),mid-floor flat, top-floor flat (inc. top-floor

maisonette);ii. be of the same number of storeys;

iii. be of the same design air permeability;

iv. have similar adjacency to unheated spacessuch as stairwells, integral garages, etc.

iii. have the same principal construction details(as identified by the Accredited ConstructionDetails (ACD) or bespoke detail reference codes);

iv. have a similar (i.e. 1) number of significantpenetrations, i.e. for windows, doors, flues/chimneys, supply/exhaust terminals, waste

water pipes);vii. have envelope areas that do not differ by more

than 10 per cent (seeair permeabilityfor adefinition of envelope area).

Energy efficiency requirementsmeans therequirements of regulations 4A, 17C, 17D and17E of, and Part L of Schedule 1 to, the BuildingRegulations.

Fixed building servicesmeans any part of, orany controls associated with:

a. fixed internal or external lighting systems, butdoes not include emergency escape lightingor specialist process lighting; or

b. fixed systems for heating, hot water, air-conditioning or mechanical ventilation.

Room for residential purposesmeans a room,or a suite of rooms, which is not a dwelling-house or a flat and which is used by one ormore persons to live and sleep and includes aroom in a hostel, a hotel, a boarding house, ahall of residence or a residential home, whetheror not the room is separated from or arrangedin a cluster group with other rooms, but doesnot include a room in a hospital, or other similar

establishment, used for patient accommodationand, for the purposes of this definition, a clusteris a group of rooms for residential purposeswhich is:

Section 3: General guidance


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a. separated from the rest of the building inwhich it is situated by a door which isdesigned to be locked; and

b. not designed to be occupied by a singlehousehold.

TERis the Target CO2Emission Rate expressed

as kgCO2/(m2.year) (see paragraphs 4.2 to 4.6).

Types of work covered by this

Approved Document

3.2 This Approved Document is intended togive guidance on what, in ordinary circumstances,may be considered reasonable provision forcompliance with the requirements of regulation17C of, and Part L of Schedule 1 to, the BuildingRegulations for those creating new dwellings. Inaddition it gives guidance on compliance withregulations 20B, 20C and 20D of the BuildingRegulations and 12B, 12C and 12D of theApproved Inspectors Regulations.

Live-work units

3.3 If a unit contains both living accommodationand space to be used for commercial purposes(e.g. workshop or office), the whole unit should betreated as a dwellingas long as the commercialpart could revert to domestic use. This could bethe case if, for example:

a. there is direct access between the commercialspace and the living accommodation; and

b. both are contained within the same thermalenvelope; and

c. the living accommodation occupies a substantialproportion of the total area of the unit.

Sub-paragraph c means that the presence of (e.g.)a small managers flat in a large non-domesticbuilding would not result in the whole buildingbeing treated as a dwelling. Similarly, theexistence of a room used as an office or utilityspace within a dwellingwould not mean that thebuilding should not be treated as a dwelling.

Mixed-use developments

3.4 When constructing a dwellingas part

of a larger building that contains other types ofaccommodation, sometimes called a mixed-usedevelopment, this Approved Document L1Ashould be used for guidance in relation to eachindividual dwelling. Approved Document L2Agives guidance relating to the non-dwelling partsof such buildings such as heated common areas,and in the case of mixed-use developments, thecommercial or retail space.

Material changes of use

3.5 The erection of a new dwellingis not amaterial change of use. Approved Document L1B

applies where a dwellingis being created in anexisting building as the result of a materialchange of use of all or part of the building.

Buildings that are exempt from

the Energy Efficiency requirements

3.6 No new dwellingsare exempt from theenergy efficiency requirementsof the BuildingRegulations.

Notification of work covered by

the Energy Efficiency requirements

3.7 In all cases where it is proposed to erecta new dwellingbuilding regulations require theperson proposing to carry out the work to notifyaBCBin advance of any work starting. Thisnotification would usually be by way of full plans(or possibly a building notice) given to a localauthority, or an initial notice given jointly withthe approved inspector. However, some elementsof the work may not need to be notified to aBCBin advance, as set out in paragraphs 3.8to 3.11 below.

Competent person self-certification schemes

3.8 It is not necessary to notify aBCBinadvance of work which is to be carried out by aperson registered with a relevant competent personself-certification scheme listed in Schedule 2A tothe Building Regulations. In order to join such ascheme a person must demonstrate competenceto carry out the type of work the scheme covers,and also the ability to comply with all relevantrequirements in the Building Regulations.

3.9 Where work is carried out by a personregistered with a competent person scheme,

regulation 16A of the Building Regulations 2000and regulation 11A of the Building (ApprovedInspectors etc) Regulations 2000 require that theoccupier of the building be given, within 30 daysof the completion of the work, a certificateconfirming that the work complies fully with allapplicable building regulation requirements.There is also a requirement to give theBCBanotice of the work carried out, again within 30 daysof the completion of the work. These certificatesand notices are usually made available throughthe scheme operator.

3.10 BCBsare authorised to accept these

certificates and notices as evidence of compliancewith the requirements of the Building Regulations.Local authority inspection and enforcementpowers remain unaffected, although they arenormally used only in response to a complaintthat work does not comply.

3.11 There are no competent person schemeswhich cover all aspects of the construction of anew dwelling. There are, however, schemes whichcover the electrical and plumbing installationwork and the installation of certain fixed buildingservices(heating, hot water, air-conditioning,mechanical ventilation).

3.12 A list of competent person self-certification schemes and the types of workfor which they are authorised can be found atwww.communities.gov.uk

L1A GENERAL GUIDANCE


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GENERAL GUIDANCE L1A

Materials and workmanship

3.13 Any building work which is subject tothe requirements imposed by Schedule 1 to theBuilding Regulations should, in accordance withregulation 7, be carried out with proper materialsand in a workmanlike manner.

3.14 You may show that you have complied

with regulation 7 in a number of ways. Theseinclude demonstrating the appropriate use of:

a product bearing CE marking in accordancewith the Construction Products Directive(89/106/EEC)1, as amended by the CEMarking Directive (93/68/EC)2, the LowVoltage Directive (2006/95/EC)3and theEMC Directive (2004/108/EC)4;

a product complying with an appropriatetechnical specification (as defined in thoseDirectives mentioned above), a BritishStandard, or an alternative national technical

specification of a Member State of theEuropean Union or Turkey5, or of anotherState signatory to the Agreement on theEuropean Economic Area (EEA) that providesan equivalent level of safety and protection;

a product covered by a national or Europeancertificate issued by a European TechnicalApproval Issuing body, provided the conditionsof use are in accordance with the terms ofthe certificate.

3.15 You will find further guidance in theApproved Document which specifically supportsregulation 7 on materials and workmanship.

Independent certification schemes

3.16 There are many UK product certificationschemes. Such schemes certify compliance withthe requirements of a recognised standard that isappropriate to the purpose for which the materialis to be used. Materials which are not so certifiedmay still conform to a relevant standard.

3.17 Many certification bodies that approveproducts under such schemes are accredited bythe United Kingdom Accreditation Service (UKAS).Such bodies can issue certificates only for thecategories of product covered under the termsof their accreditation.

3.18 BCBsmay take into account the certificationof products, components, materials or structuresunder such schemes as evidence of compliancewith the relevant standard. Similarly,BCBsmayaccept the certification of the installation ormaintenance of products, components, materialsor structures under such schemes as evidence of

1 As implemented by the Construction Products Regulations 1991

(SI 1991/1620).2 As implemented by the Construction Products (Amendment) Regulations

1994 (SI 1994/3051).3 As implemented by the Electrical Equipment (Safety) Regulations 1994

(SI 1994/3260).4 As implemented by the Electromagnetic Compatibility Regulations 2006

(SI 2006/3418).5 Decision No 1/95 of the EC-Turkey Association Council of 22 December 1995.

compliance with the relevant standard. Nonetheless,before accepting that certification constitutescompliance with building regulations, aBCBshould establish in advance that the relevantscheme is adequate for that purpose.

Standards and technical specifications

3.19 Building regulations are made for specific

purposes, including securing the health, safety,welfare and convenience of people in or aboutbuildings; furthering the conservation of fuel andpower; furthering the protection or enhancementof the environment; and facilitating sustainabledevelopment. Guidance contained in standardsand technical approvals referred to in ApprovedDocuments may be relevant to compliance withbuilding regulations to the extent that it relates tothose purposes. However, it should be noted thatguidance in standards and technical approvalsmay also address other aspects of performancesuch as serviceability, or aspects which, although

they relate to health and safety, are not coveredby building regulations.

3.20 When an Approved Document makesreference to a named standard or document,the relevant version of the standard or documentis the one listed at the end of the ApprovedDocument. Until the reference in the ApprovedDocument is revised, the standard or documentlisted remains the approved source, but if theissuing body has published a revised or updatedversion, any content that addresses the relevantrequirements of the Building Regulations may beused as a source of guidance.

3.21 The appropriate use of a product incompliance with a European Technical Approvalas defined in the Construction Products Directivewill meet the relevant requirements.

3.22 Communities and Local Government intendsto issue periodic amendments to its ApprovedDocuments to reflect emerging harmonisedEuropean standards. Where a national standardis to be replaced by a European harmonisedstandard, there will be a coexistence periodduring which either standard may be referred to.At the end of the coexistence period the nationalstandard will be withdrawn.

The Workplace (Health, Safety and

Welfare) Regulations 1992

3.23 The Workplace (Health, Safety andWelfare) Regulations 1992, as amended, apply tothe common parts of flats and similar buildings ifpeople such as cleaners, wardens and caretakersare employed to work in these common parts.These Regulations contain some requirementswhich affect building design. The main requirementsare now covered by the Building Regulations,but for further information see Workplace health,

safety and welfare, Workplace (Health, Safety andWelfare) Regulations 1992, Approved Code ofPractice and guidance, HSE publication L24,HMSO, 1996.


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Demonstrating compliance

3.24 In the Secretary of States view, compliancewith the energy efficiency requirementscouldbe demonstrated by meeting all five criteria setout in the following paragraphs. It is expectedthat software implementations of SAP 2009 willproduce an output report that will assistBCBs

to check that compliance has been achieved.The output report can benefit both developersandBCBsduring the design and constructionstages as well as at completion.

3.25 Criterion 1: in accordance with regulation17C, the calculated rate of CO

2emissions from

the dwelling(the Dwelling Emission Rate,DER)must not be greater than the Target EmissionRate (TER), which is determined by following theprocedure set out in paragraphs 4.7 to 4.17.

Criterion 1 is a regulation and is therefore mandatory,whereas Criteria 2 to 5 are only guidance. The

calculations required as part of the procedureused to show compliance with this criterion canalso provide information needed to prepare theEnergy Performance Certificate required byregulation 17E of the Building Regulations and bythe Energy Performance of Buildings (Certificatesand Inspections) (England and Wales) Regulations2007 (SI 2007/991) as amended.

3.26 Criterion 2: the performance of thebuilding fabric and the fixed building servicesshould achieve reasonable overall standards ofenergy efficiency following the procedure set outin paragraphs 4.18 to 4.24.

This is intended to place limits on design flexibilityto discourage excessive and inappropriatetrade-offs e.g. buildings with poor insulationstandards offset by renewable energy systemswith uncertain service lives. This emphasises thepurpose of Criterion 2.

3.27 Criterion 3: the dwellingshould haveappropriate passive control measures to limitthe effect of solar gains on indoor temperaturesin summer, irrespective of whether or not thedwellinghas mechanical cooling. The guidancegiven in paragraphs 4.25 to 4.27 of this ApprovedDocument provides a way of demonstrating that

reasonable provision has been made.

The aim is to counter excessive internal temperaturerise in summer to reduce or eliminate the needfor air conditioners. Criterion 3 should be satisfiedeven if the dwellingis air conditioned.

3.28 Criterion 4: the performance of thedwelling, as built, should be consistent with theDER. The guidance in Section 5 should be usedto demonstrate that this criterion has been met.Extra credits will be given in the TER/DERcalculation where builders provide robustevidence of quality-assured procedures in the

design and construction phases.

3.29 Criterion 5: the necessary provisions forenergy efficient operation of the dwellingshouldbe put in place. One way to achieve this wouldbe by following the guidance in Section 6.

Special areas related to dwellings

3.30 The following paragraphs describe somespecial areas that fall outside the normal five

criteria, and give guidance on how reasonableprovision for the conservation of fuel and powercan be demonstrated.

Common areas in buildings with multipledwellings

3.31 The common areas of buildings containingmore than one dwellingare not classified asdwellings, and therefore fall outside the scopeof the five criteria outlined above. For such areas,reasonable provision would be:

a. if they are heated, to follow the guidance inApproved Document L2A; or

b. if they are unheated, to provide fabricelements that meet the fabric standards setout in paragraphs 4.20 to 4.22.

Conservatories and porches

3.32 Where conservatories and porches areinstalled at the same time as the construction ofa new dwelling, the guidance in this documentapplies. For conservatories and porches addedas extensions to a dwelling, see guidance inApproved Document L1B.

Swimming pool basins

3.33 Where a swimming pool is constructed aspart of a new dwelling, reasonable provision shouldbe made to limit heat loss from the pool basin byachieving a U-value no worse than 0.25 W/m2.Kas calculated according to BS EN ISO 133706.

3.34 In terms of Criterion 1, the dwellingshould be assessed as if the pool basin were notthere, although the pool hall should be included.The area covered by the pool should be replacedwith the equivalent area of floor with the sameU-value as the pool surround.

6 BS EN ISO 13370 Thermal performance of buildings. Heat transfer via

the ground. Calculation methods.

L1A GENERAL GUIDANCE


16/3411


L1A

Section 4: Design standards

REGULATIONS 17A AND 17B

4.1 Regulations 17A, 17B and 17C of theBuilding Regulations implement Articles 3, 4and 5 of the Energy Performance of BuildingsDirective. Regulations 17A and 17B state that:

Methodology of calculation of the

energy performance of buildings

17A. (1) The Secretary of State shall approve

a. a methodology of calculation of the energyperformance of buildings, including methodsfor calculating asset ratings and operationalratings of buildings; and

b. ways in which the energy performance ofbuildings, as calculated in accordance withthe methodology, shall be expressed.

(2) In this regulation

asset rating means a numerical indicator of theamount of energy estimated to meet the differentneeds associated with a standardised use of thebuilding; and

operational rating means a numerical indicatorof the amount of energy consumed during theoccupation of the building over a period of time.

Minimum energy performance

requirements for buildings

17B.The Secretary of State shall approveminimum energy performance requirements fornew buildings, in the form of target CO

2emission

rates, which shall be based upon the methodologyapproved pursuant to regulation 17A.

Target CO2Emission Rate (TER)

4.2 The Target CO2Emission Rate (TER) is the

minimum energy performance requirement for anew dwellingapproved by the Secretary of Statein accordance with regulation 17B. It isexpressed in terms of the mass of CO

2, in units of

kg per m2of floor area per year, emitted as a

result of the provision of the specified fixedbuilding servicesfor a standardised householdwhen assessed using approved calculation tools.

4.3 In accordance with the methodologyapproved by the Secretary of State in the Noticeof Approval7, the TERfor individual dwellingsmust be calculated using SAP 2009.

4.4 The TERis calculated in two stages:

a. First calculate the CO2emissions from a 2002

notional dwellingof the same size and shapeas the actual dwellingand which is constructedaccording to the reference values set out in

Appendix R of SAP 2009. No values may be

7 Notice of Approval of the methodology of calculation of the energy

performance of buildings in England and Wales.

varied from these reference values whenestablishing the TER. The calculation tool willreport the CO

2emissions (based on SAP2005

CO2emission factors) arising from:

i. The provision of space heating and hot

water (which includes the energy used bypumps and fans), C

H

ii. The use of internal lighting, CL

b. Secondly, calculate the 2010 TERusing thefollowing formula:

TER2010

(CHFF EFA

HC

LEFA

L)

(1 0.2) (1 0.25)

Where FF is the fuel factor8taken from Table 1 inaccordance with the guidance in paragraph 4.5.

Where EFA is the Emission Factor Adjustmentwith separate values for heating and lighting. EFA

is the ratio of the CO2emission factor for therelevant fuel at 2010 divided by the value used inthe 2006 edition of Part L (see table 12 of SAP2009 and table 12 of SAP 2005 for the relevantvalues). For those fuels with a fuel factor of 1.0,the EFA should always be based upon mains gas.

Note that the notional dwellingused to determineC

Hhas a party wall heat loss of zero. This means

that the targeted improvement of 25 per cent is inaddition to treating the party wall loss (seeparagraphs 5.3 to 5.8).

4.5 The fuel to be used for determining thefuel factor from Table 1 is one of those used toprovide heating and hot water to the actualdwellingas follows:

a. Where all the space heating and domestic hotwater heating appliances are served by thesame fuel, the fuel used in those appliances.

b. Where the dwellinghas more than oneappliance for space heating and/or domestichot water and these are served by different fuels,

i. mains gas if any of the appliances arefired by mains gas,

ii. otherwise the fuel used for the main

space heating system.c. Where the dwellingis served by a community

heating scheme,

i. mains gas if the community scheme usedmains gas for any purpose,

ii. otherwise the fuel that provides the mostheat for the community scheme.

8 The fuel factor is the greater of 1.0 and the square root of the ratio of

the CO2emission factor for the fuel to the emission factor for mains gas

(both taken from table 12 of SAP 2005) rounded to two decimal places.


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L1A DESIGN STANDARDS

Table 1 Fuel factor

Heating fuel Fuel factor1

Mains gas 1.00

LPG 1.10

Oil 1.17

B30K 1.00

Grid electricity for direct acting and storage systems 1.47

Grid electricity for heat pumps2 1.47

Solid mineral fuel3 1.28

Any fuel with a CO2emission factor less than that of mains gas 1.00

Solid multi-fuel3 1.00

Notes:

1. The fuel factors in Table 1 will be kept under review as progress is made towards the zero carbon target.

2. The fuel factor for electric heat pumps will be reviewed after the renewable heat incentive is introduced.

3. The specific fuel factor should be used for those appliances that can only burn the particular fuel. Where an appliance is classed as multi-fuel, themulti-fuel factor should be used except where the dwelling is in a Smoke Control Area. In such cases the solid mineral fuel figure should be used,unless the specific appliance type has been approved for use within Smoke Control Areas.

Buildings containingmultiple dwellings

4.6 Where a building contains more than onedwelling(such as in a terrace of houses or in ablock of flats), an average TERcan be calculatedfor all the dwellingsin the building. In suchcases, the average TERis the floor-area-weighted average of all the individual TERs, andis calculated according to the following formula:

{(TER1Floor area

1) (TER

2Floor area

2)

(TER3Floor area

3) )}

{(Floor area1

Floor area2

Floor area3)

}Block averaging is only permitted for multipledwellingsin the same building. It is not permittedacross multiple buildings on the samedevelopment site.

CRITERION 1

ACHIEVING THE TER

4.7 Regulation 17C states that:

New buildings Regulation 17C

Where a building is erected, it shall not exceed

the target CO2emission rate for the building thathas been approved pursuant to regulation 17B.

Calculating the CO2emissions

from the actual dwelling

4.8 To comply with regulation 17C, theDERmust be no worse than the TERcalculated asset out in paragraphs 4.2 to 4.6. The finalDERcalculation produced in accordance with regulation20D (see paragraph 4.11 below) must be basedon the building as constructed, incorporating:

a. any changes to the list of specifications thathave been made during construction; and

b. theassessedair permeability.Theassessed air permeabilityshall bedetermined as follows:

i. where the dwellinghas been pressuretested, theassessed air permeabilityisthe measuredair permeability;

ii. where the dwellinghas not been tested,theassessed air permeabilityis theaverage test result obtained from other

dwellingsof the same dwelling typeonthe development increased by a marginof +2.0 m3/(h.m2) at 50 Pa;

iii. on small developments (see paragraph5.23), where the builder has opted to avoidtesting, theassessed air permeabilityisthe value of 15 m3/(h.m2) at 50 Pa.

Note that builders can test a greater proportion oftheir dwellingsand take credit for the increasedrobustness of the data, compared to option ii),where theassessed air permeabilityis taken as theaverage of other test results plus a safety margin.This margin has been taken as approximately onestandard deviation as derived from the analysis ofa large sample of data from post-2006 dwellings.The outcome of this change is that the design airpermeabilityshould be at most 8.0 m3/(h.m2) at50 Pa, so that untested dwellingsshould achieveanassessed air permeabilityless than the limitingvalue of 10 m3/(h.m2) at 50 Pa. If the design isaiming to achieve a low design air permeability,then the margin added under paragraph ii willhave a significant impact on the calculatedDER.In such cases, the builder should consider testingthe dwellingso that the measured permeabilitycan be included in the calculation.


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DESIGN STANDARDS L1A

CO2emission rate calculations

4.9 Regulation 20D9states:

20D.(1)This regulation applies where a buildingis erected and regulation 17C applies.

(2)Not later than the day before the work starts,the person carrying out the work shall give the

local authority a notice which specifiesa. the target CO

2emission rate for the building,

b. the calculated CO2emission rate for the

building as designed, and

c. a list of specifications to which the building isto be constructed.

(3)Not later than five days after the work hasbeen completed, the person carrying out thework shall give the local authority

a. a notice which specifies

i. the target CO2emission rate for the building,

ii. the calculated CO2emission rate for the

building as constructed, and

iii. whether the building has beenconstructed in accordance with the list ofspecifications referred to in paragraph (2)(c), and if not a list of any changes tothose specifications; or

b. a certificate of the sort referred to inparagraph (4) accompanied by theinformation referred to in sub-paragraph (a).

(4)A local authority is authorised to accept, as

evidence that the requirements of regulation 17Chave been satisfied, a certificate to that effect byan energy assessor who is accredited to producesuch certificates for that category of building.

(5)In this regulation

energy assessor means an individual who is amember of an accreditation scheme approved bythe Secretary of State in accordance withregulation 17F; and

specifications means specifications used for thecalculation of the CO

2emission rate.

CO2

emission rate calculationbeforecommencement of work

4.10 As required by regulations 17C and 20D,before the work starts, the builder shall carry outa calculation that demonstrates that theDERofthe dwellingas-designed is not greater than theTER. This design-based calculation shall beprovided to theBCB, along with a list ofspecifications used in calculating theDER.

9 There is a similar regulation (Regulation 12D) in the Building (Approved

Inspectors etc.) Regulations 2000 (SI 2000/2532) which applies when

an approved inspector is the BCB.

This design stage calculation and provision of alist of specifications will assist theBCBto confirmthat what is being built aligns with the claimedperformance. As set out at Appendix A, it isexpected that software implementations ofSAP2009 will be used to produce the list ofspecifications and highlight those features of thedesign that are critical to achieving compliance.

These key features can be used to prioritise therisk-based inspection of the dwellingas part ofconfirming compliance with Regulation 17C. If aprovisional energy rating is calculated at thisstage and an interim recommendations report istherefore available, the recommendations shouldbe reviewed by the developer to see if furthercarbon mitigation measures might beincorporated in a cost effective manner.

CO2emission rate calculationafter completion

4.11 After work has been completed, thebuilder must notify theBCBof the TERandDER

and whether the building has been constructed inaccordance with the list of specificationssubmitted to theBCBbefore work started. Ifnot, a list of any changes to the design-stagelist of specifications must be given to theBCB.BCBs are authorised to accept, as evidence ofcompliance, a certificate to this effect signed offby a suitably accredited energy assessor.

It would be useful to provide additionalinformation to support the values used in theDERcalculation and the list of specifications.For example, U-values might be determined froma specific calculation, in which case the details

should be provided, or from an accreditedsource, in which case a reference to that sourcewould be sufficient. For example, for a boiler,the model reference and fuel type is sufficientevidence to allow the claimed performance tobe checked against the SEDBUK (SeasonalEfficiencies of Domestic Boilers in the UK)database. It would also be useful if evidence wasprovided that demonstrates that the dwellingasdesigned satisfies the requirements of Criteria 2and 3.

Secondary heating

4.12 A secondary heating appliance may meetpart of the space heat demand. When calculatingtheDER, the fraction provided by the secondaryheating system must be as defined by SAP 2009for the particular combination of main heatingsystem and secondary heating appliance. Thefollowing secondary heating appliance must beused when calculating theDER:

a. Where a secondary heating appliance isfitted, the efficiency of the actual appliancewith its appropriate fuel must be used in thecalculation of theDER;


19/3414



b. Where a chimney or flue is provided butno appliance is actually installed, then thepresence of the following appliances shallbe assumed when calculating theDER:

i. if a gas point is located adjacent to thehearth, a decorative fuel effect gas fireopen to the chimney or flue with anefficiency of 20 per cent;

ii. if there is no gas point, an open fire ingrate for burning multi-fuel with anefficiency of 37 per cent, unless thedwelling is in a smoke control area whenthe fuel should be taken as smokelesssolid mineral fuel;

c. Otherwise it shall be assumed that thesecondary heating system has the sameefficiency as the main heating system and isserved by the same fuel, i.e. the equivalentof having no secondary heating system.

Internal lighting4.13 In all cases theDERshall be calculatedassuming the proportion of low-energy lamps asactually installed in the fixed lighting locations.

This means that low-energy lighting provision istradable. The minimum amount that would bereasonable provision in the actual building isgiven in the Domestic Building ServicesCompliance Guide.

Buildings containing

multiple dwellings

4.14 Where a building contains more than onedwelling(such as in a terrace of houses or in ablock of flats), compliance with regulation 17C isachieved if:

a. EITHER every individual dwellinghas aDERthat is no greater than its corresponding TER;

b. OR the averageDERis no greater than theaverage TER. The averageDERis the floor-area-weighted average of all the individualDERs, and is calculated in the same way asthe average TER. Block averaging is permittedonly across multiple dwellingsin a single

building, NOT across multiple buildings ona development site (see paragraph 4.6).

When adopting the averageDERapproach, it willstill be necessary to provide information for eachindividual dwelling, as required by regulation 20D.

Achieving the target

4.15 Provided the dwellingsatisfies the limitson design flexibility as set out in Criterion 2, thecompliance procedure allows the designer fullflexibility to achieve the TERutilising fabric andsystem measures and the integration of low andzero carbon (LZC) technologies in whatever mixis appropriate to the scheme. The approvedcompliance tools include appropriate algorithmsthat enable the designer to assess the role

LZC technologies (including local renewableand low-carbon schemes driven by planningrequirements10) can play in achieving the TER.

4.16 Where a dwellingis connected to acommunity energy system, the same percentagereduction in emissions should be attributed toeach connected dwelling, and the submissionshould demonstrate that the capacity of thecommunity scheme is sufficient to provide thepercentage that is assumed.

4.17 In order to facilitate incorporation ofimprovements in system efficiencies and theintegration with low and zero carbontechnologies, the designer should:

a. consider adopting heating system designsthat use low distribution temperatures; and

b. where multiple systems serve the same enduse, organise the control strategies such thatpriority is given to the least carbon-intensiveoption; and

For example, where a solar hot water system isavailable, the controls should be arranged so thatthe best use is made of the available solar energy.

c. consider making the dwellingeasily adaptableby facilitating the integration of additional lowand zero carbon technologies at a later date.Providing appropriate facilities at the constructionstage can make subsequent enhancementsmuch easier and cheaper, e.g. providingcapped off connections that can link intoa planned community heating scheme.

CRITERION 2 LIMITS ONDESIGN FLEXIBILITY

4.18 While the approach to complying withCriterion 1 allows considerable design flexibility,paragraph L1(a)(i) of Schedule 1 to the BuildingRegulations requires that reasonable provisionshould be made to limit heat gains and lossesthrough the fabric of the building, andparagraphs L1(b)(i) and (ii) require that energy-efficient fixed building serviceswith effectivecontrols should be provided.

4.19 One way of showing that the requirementhas been satisfied would be to demonstrate thatthe fabric elements and the fixed building servicesall satisfy the minimum energy efficiency standardsspecified in the following paragraphs.

Note that in order to satisfy the TER, the buildingspecification will need to be considerably better thanthe stated values in many aspects of the design.

10 See the Planning Policy Statement Planning and climate change

and its supporting practice guidance at: www.communities.gov.uk/

planningandbuilding/planning/planningpolicyguidance/

planningpolicystatements/planningpolicystatements/ppsclimatechange/


20/3415


DESIGN STANDARDS L1A

Fabric standards

4.20 Table 2 sets out the worst acceptablestandards for fabric properties. The stated valuerepresents the area-weighted average value for allelements of that type. In general, the achievementof the TERis likely to require significantly betterfabric performance than is set out in Table 2.

4.21 U-values shall be calculated using themethods and conventions set out in BR 44311,and should be based on the whole element orunit (e.g. in the case of a window, the combinedperformance of the glazing and the frame).

In the case of windows, the U-value can be takenas that for:

a. the smaller of the two standard windowsdefined in BS EN 14351-112; or

b. the standard configuration set out in BR 443; or

c. the specific size and configuration of the

actual window.For domestic-type construction, SAP 2009 Table6e gives values for different window configurationsthat can be used in the absence of test data orcalculated values.

4.22 The U-values for roof windows androoflights given in this Approved Document arebased on the U-value having been assessed withthe roof window or rooflight in the vertical position.If a particular unit has been assessed in a planeother than the vertical, the standards given inthis Approved Document should be modifiedby making an adjustment that is dependent on

the slope of the unit following the guidance givenin BR 443.

Table 2 Limiting fabric parameters

Roof 0.20 W/m2.K

Wall 0.30 W/m2.K

Floor 0.25 W/m2.K

Party wall 0.20 W/m2.K

Windows, roof windows, glazed rooflights, curtain walling and pedestrian doors 2.00 W/m2.K

Air permeability 10.00 m3/h.m2at 50 Pa

Approved Document C gives limiting values forindividual elements to minimise condensation risk.

11 BR 443 Conventions for U-value calculat ions, BRE, 2006.12 EN 14351-1, Windows and doors Product standard, performance

characteristics, 2006.

System efficiencies

4.23 Each fixed building serviceshould be atleast as efficient as the worst acceptable valuefor the particular type of appliance as set outin the Domestic Building Services ComplianceGuide13. If the type of appliance is not coveredby the Guide, then reasonable provision would

be to demonstrate that the proposed system isnot less efficient than a comparable system thatis covered by the Guide.

To not inhibit innovation.

4.24 The efficiency claimed for the fixed buildingserviceshould be based on the appropriate teststandard as set out in the Guide and the test datashould be certified by a notified body. It would bereasonable forBCBsto accept such data at facevalue. In the absence of such quality assureddata, theBCBshould satisfy itself that theclaimed performance is justified.

13 Domestic Building Services Compliance Guide, CLG, 2010 Edition.


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CRITERION 3 LIMITING

THE EFFECTS OF SOLAR

GAINS IN SUMMER

4.25 As required by paragraph L1(a)(i) ofSchedule 1 to the Building Regulations,reasonable provision should be made to limit

solar gains. Solar gains are beneficial in winter asa means of offsetting heating demand, but cancontribute to overheating in the summer months.Limiting the effects of solar gain in summer canbe achieved by an appropriate combination ofwindow size and orientation, solar protectionthrough shading and other solar control measures,ventilation (day and night) and high thermalcapacity. If ventilation is provided using a balancedmechanical system, consideration should be givento providing a summer bypass function duringwarm weather (or allow the dwellingto operatevia natural ventilation) so that the ventilation ismore effective in reducing overheating.

4.26 SAP 2009 Appendix P contains a procedureenabling designers to check whether solar gainsare excessive. Reasonable provision would beachieved if the SAP assessment indicates that thedwellingwill not have a high risk of high internaltemperatures. This assessment should be doneregardless of whether or not the dwellinghasmechanical cooling. If the dwellinghas mechanicalcooling, the assessment should be based on thedesign without the cooling system operating, butwith an appropriate assumption about effectiveair change rate through openable windows.

Designers may wish to go beyond the requirementsin the current Building Regulations to considerthe impacts of future global warming on the risksof higher internal temperatures occurring moreoften. CIBSE TM 36 Climate change and the indoorenvironment14gives guidance on this issue.

4.27 When seeking to limit solar gains,consideration should be given to the provision ofadequate levels of daylight. BS 8206 2 Code ofpractice for daylighting15gives guidance onmaintaining adequate levels of daylight.

The Building Regulations do not specify minimumdaylight requirements. However, reducing

window area produces conflicting impacts on thepredicted CO

2emissions: reduced solar gain but

increased use of electric lighting. As a general guide,if the area of glazing is much less than 20 percent of the total floor area, some parts of thedwellingmay experience poor levels of daylight,resulting in increased use of electric lighting.

14 TM36 Climate change and the indoor environment: impacts and

adaptation, CIBSE, 2005.15 BS 82062:2008 Lighting for buildings. Code of practice for daylighting.


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L1A

CRITERION 4 BUILDING

PERFORMANCE CONSISTENT

WITHDER5.1 Dwellingsshould be constructed andequipped so that performance is consistent withthe calculatedDER. As indicated in paragraph 4.8,a final calculation of theDERis required to takeaccount of any changes in performance betweendesign and construction and to demonstrate thatthe building as constructed meets the TERasrequired by regulation 17C. The followingparagraphs in this section set out what in normalcircumstances would be reasonable provisionto ensure that the actual performance of thebuilding is consistent with theDER.

The provision of information referred to inparagraph 4.10 will assistBCBsin checking thatthe key features of the design are included duringthe construction process.

5.2 In accordance with Part L and regulation7, the building fabric should be constructed to areasonable standard so that:

a. the insulation is reasonably continuous overthe whole building envelope; and

b. theair permeabilityis within reasonable limits.

Party walls and other thermal

bypasses

5.3 Contrary to previous assumptions, partycavity-walls may not be zero heat loss wallsbecause air flow in the cavity provides a heat lossmechanism.

Where outside air is able to flow into the partywall cavity a cold zone is created which results inheat flux through the wall sections on either side.The extent of air flow and heat flux will depend onexternal conditions such as wind and temperaturesand also on the setting up of a ventilation stackeffect caused by the warmed air rising in thecavity to be replaced by cooler air drawn in fromoutside. The air movements involved can besignificant and, if no steps are taken to restrictflows, the resulting heat losses can be large.

5.4 The heat loss can be reduced by measuresthat restrict air movement through the cavity,either by means of fully filling the cavity and/or byproviding effective sealing around the perimeter.Generic solutions to minimising party wall heatloss are available at www.planningportal.gov.uk.The extent to which heat loss can be reducedwill be dependent on the detailed design andthe quality of construction. In the absence of anyspecific, independent scientific field evidence,reasonable provision would be to adopt theguidance on U-values in paragraph 5.5.

Fully filling the cavity may have implications forsound transmission through party walls. Developerswho follow this route must satisfy theBCBthat

the requirements of Part E will be satisfied, eitherby adopting a full fill detail accredited underthe Robust Details scheme, or through specificsite testing.

5.5 In calculating theDERfor a dwelling, theparty wall U-value to be assumed for the type ofconstruction adopted is set out in Table 3.

5.6 In applying the U-values in Table 3 it isimportant that where edge sealing is adopted,either on its own or in conjunction with a fullyfilled cavity, the sealing is effective in restrictingair flow and is aligned with the thermal envelope.Although effective sealing may be part of a cavity

barrier which is provided in order to comply withPartB (Fire), a cavity barrier on its own may notbe effective in restricting air flow. In order to claima reduced U-value (0.2 or 0.0) it will be necessaryto demonstrate that the design adopted is likelyto be robust under normal site conditions. Inaddition, it is important that the sealing systembe applied in such away as to be in line with thethermal envelope. Any solution to reducing partywall heat loss must take into account all therequirements in Schedule 1, but particular attentionshould be given to the requirements of Part E.

For example, in a room-in-roof design, the

insulation layer may follow the sloping roofsections to a horizontal ceiling then continue atceiling level. In such a case it is important thatthe party wall cavity seal follows the line of theinsulation in the slope and horizontal ceilingsections (though for the purposes of Part B (Fire)it may be necessary to ensure that the fire cavitybarrier follows the slope to the ridge). In the caseof flats, the sealing system should follow the lineof party floors and other party structures as wellas the main thermal envelope.

5.7 In considering heat losses via party wallsit is important to remember that wherever the

wall penetrates an insulation layer, such as whenthe blockwork of a masonry party wall penetratesinsulation at ceiling level, a thermal bridge islikely to exist. This will be the case even wherethe party wall U-value is zero. The evaluation ofthermal bridges should ensure that any bridgingat the party wall is taken into account along withother thermal bridges. It is important also to besatisfied that any solution to the party wallbypass does not contravene other parts of theRegulations, in particular Part E (Sound).

Section 5: Quality of constructionand commissioning


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5.8 The party wall is a particular case of themore general thermal bypass problem that occurswhere the air barrier and the insulation layer arenot contiguous and the cavity between them issubject to air movement. To avoid the consequentreduction in thermal performance, either theinsulation layer should be contiguous with the airbarrier at all points in the building envelope, orthe space between them should be filled withsolid material such as in a masonry wall.

Thermal bridges

5.9 The building fabric should be constructedso that there are no reasonably avoidable thermalbridges in the insulation layers caused by gapswithin the various elements, at the joints betweenelements, and at the edges of elements such asthose around window and door openings.

5.10 Where calculated in support of theapproaches set out in paragraphs 5.12a and5.12b, linear thermal transmittances andtemperature factors should be calculated

following the guidance set out in BR 49716

.Reasonable provision would be to demonstratethat the specified details achieve a temperaturefactor that is no worse than the performance setout in BRE IP 1/0617.

5.11 Similarly, in support of the approaches setout in paragraphs 5.12a and 5.12b, the builderwould have to demonstrate that an appropriatesystem of site inspection is in place to giveconfidence that the construction proceduresachieve the required standards of consistency.

5.12 Ways of demonstrating that reasonableprovision has been made are:

a. To adopt a quality-assured accreditedconstruction details approach in accordancewith a scheme approved by the Secretary ofState. If such a scheme is utilised then thecalculated linear thermal transmittance canbe used directly in theDERcalculation;

16 BR 497 Conventions for calculating linear thermal transmittance and

temperature factors, BRE 2007.17 IP 1/06 Assessing the effects of thermal bridging at junctions and around

openings in the external elements of buildings, BRE 2006.

For new buildings, such scheme(s) accredit andquality assure the calculation of thelinear thermaltransmittance, accredit details in terms ofbuildability and have an associated qualityassurance regime that inspects a sample of sitesto confirm that the details are being implementedcorrectly. The use of such schemes may alsoallow a reduction in the Building Control charges.

b. To use details that have not been subject to

independent assessment of the constructionmethod. However, in this case, the linearthermal transmittance should still have beencalculated by a person with suitable expertiseand experience following the guidance setout in BR 497, and a process flow sequenceshould be provided to theBCBindicating theway in which the detail should be constructed.The calculated value increased by 0.02 W/mKor 25 per cent whichever is greater can thenbe used in theDERcalculation;

Evidence of suitable expertise and experience forcalculating linear thermal transmittance would be

to demonstrate that the person has been trainedin the software used to carry out the calculation,has applied that model to the example calculationsset out in BR 497 and has achieved results thatare within the stated tolerances. Builders followingthis route will inevitably add to the burden ofchecking required of theBCBand adopting thisroute may attract higher building control feesthan the alternative approaches.

c. To use unaccredited details, with no specificquantification of the thermal bridge values. Insuch cases a conservative default y-value of0.15 must be used in theDERcalculation.

5.13 The alternative approaches a and babove are not mutually exclusive. For example,a builder could use the accredited constructiondetails scheme approach for the majority of thejunctions, but use a bespoke detail for thewindow head. In this case, the 0.02 W/mKor25 per cent, whichever is greater margin, wouldapply only to the thermal transmittance of thewindow head detail.

L1A QUALITY OF CONSTRUCTION AND COMMISSIONING

Table 3 U-values for party walls

Party wall construction U-value (W/m2K)

Solid 0.0

Unfilled cavity with no effective edge sealing 0.5

Unfilled cavity with effective sealing around all exposed edges and in line withinsulation layers in abutting elements

0.2

A fully filled cavity with effective sealing at all exposed edges and in line withinsulation layers in abutting elements

0.0


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QUALITY OF CONSTRUCTION AND COMMISSIONING L1A

Air permeability and pressure testing

5.14 In order to demonstrate that an acceptableair permeabilityhas been achieved, Regulation20B states:

Pressure testing

20B.(1) This regulation applies to the erection of

a building in relation to which paragraph L1(a)(i)of Schedule 1 imposes a requirement.

(2) Where this regulation applies, the personcarrying out the work shall, for the purpose ofensuring compliance with regulation 17C andparagraph L1(a)(i) of Schedule 1:

a. ensure that:

i. pressure testing is carried out in suchcircumstances as are approved by theSecretary of State; and

ii. the testing is carried out in accordancewith a procedure approved by the

Secretary of State; and

b. subject to paragraph (5), give notice of theresults of the testing to the local authority.

(3) The notice referred to in paragraph (2)(b) shall:

a. record the results and the data upon whichthey are based in a manner approved by theSecretary of State; and

b. be given to the local authority not later thanseven days after the final test is carried out.

(4) A local authority is authorised to accept, asevidence that the requirements of paragraph

(2)(a)(ii) have been satisfied, a certificate to thateffect by a person who is registered by the BritishInstitute of Non-destructive Testing in respect ofpressure testing for the air tightness of buildings.

(5) Where such a certificate contains the informationrequired by paragraph (3)(a), paragraph (2)(b)does not apply.

5.15 The approved procedure for pressuretesting is given in the ATTMA publication Measuringair permeability of building envelopes18, and,specifically, the method that tests the buildingenvelope. The preferred test method is that

trickle ventilators should be temporarily sealedrather than just closed.BCBsshould be providedwith evidence that test equipment has beencalibrated within the previous 12months using aUKAS-accredited facility. The manner approvedfor recording the results and the data on whichthey are based is given in section 4 of thatdocument.

5.16 BCBsare authorised to accept, as evidenceof compliance, a certificate offered under regulation20B(4). It should be confirmed to theBCBthatthe person has received appropriate trainingand is registered to test the specific class of

building concerned.

18 Measuring air permeability in the envelopes of dwellings, Technical

Standard L1, ATTMA, 2010

5.17 The approved circumstances under whichthe Secretary of State requires pressure testingto be carried out are set out in paragraphs 5.18to 5.23.

5.18 On each development, an air pressuretest should be carried out on three units of eachdwelling typeor 50 per cent of all instances ofthat dwelling type, whichever is the less. For thepurposes of this Approved Document, a block offlats should be treated as a separate developmentirrespective of the number of blocks on the site.The dwelling(s)to be tested should be takenfrom the first completed batch of units of eachdwelling type.

Most larger developments will include manydwelling types and multiple units of each typeshould be tested to confirm the robustness of thedesigns and the construction procedures.

5.19 The specific dwellingsmaking up thetest sample should be selected by theBCBin

consultation with the pressure tester. They shouldbe selected so that about half of the scheduledtests for each dwelling typeare carried outduring construction of the first 25 per cent ofeach dwelling type. All tests on dwellingsin thesample shall be reported to theBCB, includingany test failure (see paragraphs 5.20 to 5.22).

The aim is to enable lessons to be learned andadjustments to design and/or site proceduresto be made before the majority of the dwellingsare built.

Showing compliance with regulation 20B and

the consequences of failing a pressure test5.20 Compliance with the requirements wouldbe demonstrated if:

a. the measuredair permeabilityis not worsethan the limit value of 10 m3/(h.m2) at 50 Pa; and

b. theDERcalculated using the measuredairpermeabilityis not worse than the TER.

This means that if a design adopted a low (i.e.better) design air permeabilityin order to achievea performance better than the TER, it would notfail to comply with Part L if the pressure testachieved the limit value and the TERwas achieved.

5.21 If satisfactory performance is not achieved,then remedial measures should be carried out onthe dwellingand a new test carried out until thedwellingachieves the criteria set out in paragraph5.20. In addition, a further dwellingof the samedwelling typeshould be tested, therebyincreasing the overall sample size.

5.22 In addition to the remedial work on adwellingthat failed the initial test, other dwellingsof the same dwelling typethat have not beentested should be examined and, where appropriate,similar remedial measures applied.


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L1A QUALITY OF CONSTRUCTION AND COMMISSIONING

Alternative to pressure testing on

small developments

5.23 As an alternative approach to specificpressure testing on development sites where nomore than two dwellingsare to be erected,reasonable provision would be:

a. to demonstrate that during the preceding12 month period, a dwellingof the samedwelling typeconstructed by the samebuilder had been pressure tested accordingto the procedures given in paragraphs 5.14to 5.19 and had achieved the design airpermeability; or

b. avoid the need for any pressure testing byusing a value of 15 m3/(h.m2) at 50 Pa for theair permeabilitywhen calculating theDER.

The effect of using this cautious value wouldthen have to be compensated for by improvedstandards elsewhere in the dwellingdesign.

COMMISIONING OF HEATING

AND HOT WATER SYSTEMS

5.24 Paragraph L1(b)(iii) of Schedule 1 to theBuilding Regulations requires fixed buildingservicesto be commissioned by testing andadjustment as necessary to ensure that they useno more fuel and power than is reasonable inthe circumstances. In order to demonstrate thatthe heating and hot water systems have beenadequately commissioned, regulation 20C states:

20C Commissioning(A1) This regulation applies to building work inrelation to which paragraph F1(2) of Schedule 1imposes a requirement, but does not apply tothe provision or extension of any fixed system formechanical ventilation or any associated controlswhere testing and adjustment is not possible.

(1) This regulation applies to building work inrelation to which paragraph L1(b) of Schedule 1imposes a requirement, but does not apply tothe provision or extension of any fixed buildingservice where testing and adjustment is notpossible or would not affect the energy efficiency

of that fixed building service.

(2) Where this regulation applies the personcarrying out the work shall, for the purpose ofensuring compliance with paragraph F1(2) orL1(b) of Schedule 1, give to the local authority anotice confirming that the fixed building serviceshave been commissioned in accordance with aprocedure approved by the Secretary of State.

(3) The notice shall be given to the local authority

a. not later than the date on which the noticerequired by regulation 15(4) is required to begiven; or

b. where that regulation does not apply, not morethan 30 days after completion of the work.

5.25 It would be useful to prepare a commissioningplan, identifying the systems that need to be testedand the tests that will be carried out and providethis with the design stage TER/DERcalculationso that theBCBcan check the commissioningis being done as the work proceeds.

The use of the templates in the ModelCommissioning Plan (BSRIA BG 8/2009) is a wayof documenting the process in an appropriate way.

5.26 Not allfixed building services will need tobe commissioned. With some systems adjustmentis not possible as the only controls are on andoff switches. Examples of this would be somemechanical extraction systems or single fixedelectrical heaters. In other cases commissioningwould be possible but in the specific circumstanceswould have no effect on energy use.Fixed buildingserviceswhich do not require commissioningshould be identified in the commissioning plan,along with the reason for not requiringcommissioning.

5.27 Where commissioningis carried out it mustbe done in accordance with a procedure approvedby the Secretary of State. For heating and hotwater systems the approved procedures are setout in the Domestic building services complianceguide. For ventilation systems, the approvedprocedure is set out in the Domestic Ventilation:Installation and Commissioning Compliance Guide19.

5.28 Commissioningis often carried out by theperson who installs the system. In other cases itmay be carried out by a subcontractor or by aspecialist firm. It is important that whoever

carries it out follows the relevant approvedprocedure in doing so.

5.29 Where a building notice or full plans havebeen given to a local authorityBCBthe notice ofcompletion of commissioningshould be given tothatBCBwithin five days of the completion ofthe commissioningwork. In other cases, forexample where work is carried out by a personregistered with a competent person scheme (seeparagraph 3.9), it must be given within 30 days.

5.30 Where an approved inspector is theBCBthe notice of completion of co