Designing with rooflights...Designing with rooflights: supporting Part L Building Regulation...

Designing

with rooflights Supporting Part L Building Regulation guidance in England;Approved Documents L1A, L1B, L2A and L2B (2013 editions)

Designing with rooflights: supporting Part L Building Regulation guidance in England; L1A, L1B, L2A and L2B (2013)

PAGE

Scope 1

Introduction 2

Designing with Rooflights to save energy 3

Artificial Lighting Control 4

AD L2A 2013 New Buildings other than dwellings 5

5 Criteria 5

Criterion 1. Achieving the TER (mandatory regulation) 6

SBEM/Notional Building Results 8

Criterion 2. Limiting Design Flexibility (statutory guidance) 11

Criterion 3. Limiting the effect of solar gain in summer (guidance only) 12

Criterion 4. Building performance consistent with BER 13

Summary of the requirements of AD L2A on rooflights 14

AD L2B Work on Existing Buildings that are not dwellings 15

Definitions within AD L2B 15

Repairs to Rooflights 16

Refurbishment of Rooflights 17

New Extensions 18

Consequential Improvement 19

Summary to AD L2B 20

Frequently Asked Questions on rooflight refurbishment 21

Supporting the guidance in ADLIA and ADLIB (2013) 22

AD L1A New Dwellings 22

AD L1B Extension, repair and refurbishment of existing dwellings 27

Appendix 1. How to enter rooflight data into SBEM 29

Appendix 2. The De Montfort University Research 35

CONTENTS

Designing with rooflights: supporting Part L Building Regulation guidance in England; L1A, L1B, L2A and L2B (2013) 1

• This document gives guidance on the use ofnatural daylight via rooflights to providecompliance with Building Regulations L1 and L22010 - Conservation of Fuel and Power forDwellings and Buildings other than Dwellings -asamended in 2013

• This document only applies to England.Technical Document F in Northern Ireland has asimilar basis to England. Scotland have theirown Regulations under section 6 - they require a43% reduction in emissions for non-domesticbuildings from October 2015, but thedocuments are not available until November2014. Wales, for the first time has moved awayfrom the England Regulations, for non-domesticaiming for a greater reduction in CO2 emissionsc.f. Part L 2010. Extensions will requireimprovements to walls and roofs, but windowsremain unchanged. The Welsh Regulationscome into effect in July 2014.

• This document covers both ApprovedDocument L2A (ADL2A) which applies to NewWork for non-domestic buildings, ApprovedDocument L2B (ADL2B) - Repairs,Refurbishment and Extensions to non-domesticbuildings, and for the first time NARM haveincluded comment on Part L1A & B forDomestic Buildings.

• Note that large extensions to existing buildings,where the total floor area of the extension isgreater than 100m2 and greater than 25% of thetotal floor area of the existing building, aretreated in the same way as new build and fallunder the control of AD L2A.

• Note that Dwellings relate to self contained unitsonly. However, buildings exclusively containingRooms for Residential Purposes such as nursinghomes, and student accommodation or similar,are not considered as dwellings and thereforesuch buildings come under the control of ADL2

• Buildings that fall outside the requirements ofPart L, e.g. unheated agricultural buildings, arenot covered by this document. Industrial sites,workshops and agricultural buildings with lowenergy demand for heating or cooling areexempt from the Part L Regulations. Note thatwarehouses (for example) with a low energydemand are not exempt since they are notbuildings in the exempt category.

• Note that such buildings, with low energydemand that are not exempt, may be built withless demanding requirements. However, beaware that a subsequent change of use for thebuilding may require the building to be upgradedto fully meet AD L2A requirements and such a fitout could be far more expensive than complyingwith AD L2A at the new build stage – (refer to ADL2A para 2.24 to 2.27)

• This document does not give guidance on theuse of vertical windows

• It does not give guidance on matters that haveno bearing on the use, effect and control onnatural daylighting into buildings

• Reference will be made to the SimplifiedBuilding Energy Model (SBEM) software which isa free-of-charge approved calculation toolreferenced by AD L2A Section 2.3a to determinebuilding compliance, including guidance on howvarious rooflight systems should be entered intoSBEM. All results shown have been calculatedusing SBEM v5.2.b. For AD L1A, the approvedcomplaint software is Standard AssessmentProcedure (SAP) which is referred to in thisdocument for dwellings. This document doesnot cover other approved software tools.

• Reference will also be made to the NationalCalculation Methodology modelling guide(NCM) which provides the data that isembedded within SBEM.

• This document provides background informationon the research carried out by De MontfortUniversity (DMU) into the impact of rooflights onthe overall energy demand and the associatedcarbon dioxide (CO2) emissions. It shows thatas rooflight area is increased up to 20% of thefloor area, CO2 emissions will generally decreaseas the contribution of natural daylight throughrooflights replaces the need for artificial lighting.

• Via examples using SBEM, this document willdemonstrate the need to consider the totallighting demand for a building and to use lightsaving devices for all installed artificial lighting.

• It does not make any recommendation on thetypes of artificial lighting or lighting control thatmay be used to supplement the natural daylightprovided by rooflighting.

SCOPE


All reference to the changes to ADL1A & B willbe found on pages 21-26 of this document. Thefollowing refers to the changes relating to Non-Domestic Buildings.

The Building Regulations Part L 2013, designed tosave energy and power consumption in buildings,is the latest phase of an ongoing legislativeprogramme by Government with further updatesplanned over the next 6 years to create a long termbuilding stock that will generate an ever decreasingrelease of CO2 into the atmosphere. TheRegulations came into effect on 1st April 2014.

The Key Changes to Part L2A 2013 c.f. Part L2A 2010.

1. For non-domestic buildings there is a need todeliver an aggregate uplift of 9% saving incarbon emissions with elemental back stops.

2. In the 2010 Regulations, Criterion 2recommended a limit on design flexibility withworst case “U” values for the fabric elementsof the building. Criterion 2 2013 now makes ita Statutory requirement to comply with theselimiting Fabric Parameters, as shown in ADL2A Table 3 (see note 1.4 of ADL2A). Forrooflights this is a U value of 2.2W/m2K.

3. The Notional Building used to determine CO2

targets remains the same size and shape asthe actual building, and is still separatelydefined for top-lit, side-lit and side-lit (airconditioned) buildings). The Notional Buildingair permeability has been further sub dividedby size.

4. A summary of the Part L2A 2013 NotionalBuildings is now published in Table 5 of theADL2A , with full details defined in theNational Calculation Modelling (NCM) Guide.If the actual building is constructed entirely tothe notional building specification, it will meetthe CO2 targets and the limiting fabric andservice parameters.

It is clear that the statutory minimum requirementsfor the fabric of the building as stated in Table 3are fall back values. In practice to achieve theTarget Emission Rate (TER) for the building, someor all of the fabric limits will need to be improved.Designers and builders will need to look at everyelement of the design and services of theirbuilding and seek to achieve performanceimprovements over the fall back requirements andbe guided by the figures used in the NotionalBuilding in Table 5 ADL2A.

INTRODUCTION


Independent research carried out in 2005 by DeMontfort University proved conclusively thatrooflights save energy. A well designed buildingwith a good spread of natural light will benefitfrom passive solar gain and a reducedrequirement for artificial light. The combination ofthese factors means that including rooflights canoffer a dramatic reduction in a building’s totalenergy consumption and the emissions of CO2

associated with this energy use. Theseconclusions are reflected in SBEM. A naturally litinterior will save money, provide a more pleasantenvironment people want to spend time in andcontribute to the government’s target to reduceemissions of CO2.

The primary reason for including rooflights is toprovide a bright, naturally lit interior and reducethe requirement for artificial lighting. Daylight hasmany advantages over artificial light - not least thefact that it is a completely free, unlimited naturalresource. Whilst artificial light is essential, it’sprovision uses a lot of energy, so reducing therequirement will dramatically cut energy use, andthe CO2 emissions which result from this.

There has previously been a widely held view thatwhilst rooflights are an excellent way of bringingthe many benefits of natural light into a building,their poorer insulation value allowed more heat toescape than the rest of the roof structure,increasing the running costs of the building.Research over a number of years has confirmedthis view is wrong.

Increased rooflight area can dramatically reducethe energy requirements of lighting systems whilstresulting in a much smaller increase in energyrequirements of the heating system, but therelative effects depend on a number of otherparameters for the building, such as temperatureset point, hours of occupancy, and internal gains,as well as the details of the building construction.The savings in total energy costs and carbonfootprint therefore vary from building to building,but are usually found to be positive as rooflightarea increases often up to 20% of the roof area forlarge buildings with internal work height greaterthan 6m and up to 15% rooflight area for buildingsof lower than 6m work height.

The Institute of Energy & SustainableDevelopment at Leicester’s De Montfort University(DMU) have investigated the effect that rooflightshave on the total energy needed to operate abuilding, and the annual CO2 emissions whichresult from this. The research proved that installingan appropriate level of rooflighting (typically 15% -20% of the roof area) will usually reduce overallenergy consumption, and the associated CO2

emissions, in addition to providing the widelyrecognised benefits of natural daylight within abuilding environment. Their work is summarisedin Appendix 2 of this publication.

The Simplified Building Energy Method (SBEM),the free-of-charge computer modelling packageused to demonstrate compliance with Part L2ABuilding Regulations, uses the same principles asthe DMU research, and so also recognises thecontribution to energy saving and reduction in CO2

emissions which are offered by the inclusion ofhigh levels of rooflights.

Many factors affect the contribution whichrooflights can make, and hence the optimum areaof rooflights will vary from building to building.However, in general, the conclusions of the DMUwork (reflected in results from SBEM) show thatrooflights always make a positive contribution:omission of rooflights or reduction of rooflightarea gives a very significant increase in CO2

emissions, and that savings offered by rooflightsare dramatic:

• Typically the total CO2 emissions associatedwith all aspects of operating a buildingwithout rooflights can be over 50% higherthan for a building with 12% rooflights

• in almost all relevant buildings, savingscontinue to be achieved as rooflight area isincreased up to and beyond 15% of floor area

• in some buildings (typically with higherillumination requirements, and usedpredominantly during the daytime) there are significant further savings as rooflight area increases up to 20% at higherillumination levels

DESIGNING WITH ROOFLIGHTS TO SAVE ENERGY


Designers need to recognise that artificial lightingwill be essential during parts of the working day andparticularly in the winter months, and specifically inworking areas where light levels need to remainconstant. In order to minimise the use of artificiallighting, thereby maximising the energy savings fromnatural daylight, artificial lighting should be, whereever possible controlled by automatic means thatoperate on “need” requirements.

Designers need to bear in mind these key points :-

• The electric light is carbon inefficient in thatpower from the National Grid is largelygenerated from burning fossil fuel at modestgeneration efficiencies.

• Where natural daylight levels are low, withoutlighting control, the lights in the work place getturned on in the morning and stay on all day,regardless of the need for them.

• Natural daylight through rooflights iscompletely free, provides some useful solargain and makes the work place a morepleasant environment.

There are specific changes/requirements relatingto artificial lighting that are now built into theNotional Building used by SBEM:

1. General lighting will have efficacy of 60luminaire lumens/circuit watt.

2. All zones which receive natural daylight willincorporate photo-electric dimming.

3. All zones will incorporate “manual on – autooff” occupancy sensing systems.

This document does not detail all the options thatare available, however a Joint Document fromNARM and the Lighting Industry Federation (LIF)called “Designing with Rooflights andControlled Artificial Lighting to reduce CO2

emissions – supporting the requirements of theBuilding Regs Part L2A & L2B” is available onthe NARM web site www.narm.org.uk

ARTIFICIAL LIGHTING CONTROLS

• in other buildings (typically with lowerillumination requirements, and used 24 hoursa day) the savings as rooflight area isincreased from 12% to 15% are relativelyminor, with very slight increases in CO2

emissions as area increases further, to 20%

• Rooflight area of 15% or more of floor areamay therefore be a useful approximation ofthe optimum rooflight area.

• Care should be taken to avoid risk of solaroverheating (see guidance on ADL2A Criterion3, page 11): typically, rooflight area should belimited to 18-20% of floor area in buildingsover 6 metres tall, and 12-13% of floor area inbuildings less than 6 metres tall.


General CommentThe 2013 Regulations require a delivery of a further9% aggregated saving across the mix of non-domestic buildings c.f. AD L2A 2010. The buildingtype savings are given below:

Distribution Warehouse 4%

Deep Plan Office with Air Conditioning 12%

Retail Warehouse 8%

Shallow Plan Office 13%

Hotel 12%

School 9%

Small Warehouse 3%

Aggregate value 9%

These savings will be built into the NationalCalculation Model for the building type which isused in SBEM.

The concept is that designers and builders are freeto design and build, provided the CO2 emissions ofthe actual building as calculated by SBEM (theBER) are no more than the emissions of a notionalbuilding of the same size and type (the TER):

Building Emission Rate (BER) ≤ TER

It should be noted that unless high standards ofspecification and build are maintained throughout,compliance will be difficult to achieve. The limitingFabric Standards in Criterion 2 are now a Statutoryrequirement, but to achieve the TER, it is likely thatthere will be a need to improve the performance ofthe Limiting Standards.

AD L2A NEW BUILDINGS OTHER THAN DWELLINGS

AD L2A defines 5 Criteria to achieve Compliance:

Criterion 1 : Achieving the TER

Criterion 2 : Limits on Design Flexibility

Criterion 3 : Limiting the effect of heat gains insummer

Criterion 4 : Building performance consistent withthe BER

Criterion 5 : Provisions for energy efficientoperations of the building (this is notcovered in this document)

5 CRITERIA

Note that:

- Criterion 1 is a regulation and thereforemandatory

- Criterion 2 is Statutory Guidance

- Criteria 3, 4 and 5 are for guidance.

Target (CO2) Emission Rate (TER)The TER is the maximum CO2 emission rate that isallowable for any new building. It is expressed interms of the mass of CO2 emitted per year per sq.metre of the total useful floor area of the building(kg/m2/year).

The TER is calculated for a Notional Building ofthe same size, shape, location, orientation, andusage as the actual building, but with performanceof fabric, services and controls all as defined in ADL2A and the NCM Modelling Guide.

Building Emission Rate (BER)The BER is the CO2 emission rate for the actualbuilding, calculated in exactly the same way as theTER but based on the properties (fabric, servies andcontrols) of the actual rather than Notional Building.

All the data for the actual building (geometry andfull details of the building fabric and buildingservices) are entered into SBEM which calculatesand compares the BER and the TER. If the BER ≤TER then the building is compliant.

It is mandatory that the BER is less than or equalto the TER. How rooflights can be best used tohelp achieve this is explained in this documentand demonstrated in Appendix 1.

Notional Building SpecificationSBEM uses one of 3 different Notional Building types:

a. Side lit or unlit (with heating only)

b. Side lit or unlit (with heating and cooling)

c. Top lit

The specification of each Notional Building isdetailed within the NCM Modelling Guide, andsummarised in AD L2A Table 5 (see ADL2A page27), an extract of which is shown below. For all

rooflit areas, the specification includes:

• 12% rooflight area

• Rooflight U-value 1.8 W/m2K

• Rooflights with 60% light transmission, 55%G-value and 15% frame factor

• Proportional (dimming) control of all artificiallighting systems, with parasitic power that isthe lesser of either 3% of the installed lightingload, or 0.3W/m2

If the actual building has a rooflight area of 12%,and all other values match those in Table 5 (assummarised below), then the SBEM calculation forthe actual building will exactly match that for thenotional building, BER=TER, and the building willachieve compliance.

Note that the illumination provided by rooflights isdefined by the product of:

Area x light transmission x glazed area (i.e. 1 –frame factor)

which for the notional building is:

12% x 60% x (1-15%) = 12% x 60% x 85% = 0.0612.

Designers can amend individual values andbuildings will remain compliant, provided thisoverall value is not reduced: for example, if actualrooflight transmission is 54%, frame factor is 12%and rooflight area is 13%, then this value is notreduced:

13% x 54% x (1-12%) = 13% x 54% x 88% = 0.0618 ie ≥0.0612

and the building will therefore remain compliant.

CRITERION 1 ACHIEVING THE TER

6Designing with rooflights: supporting Part L Building Regulation guidance in England; L1A, L1B, L2A and L2B (2013)


Table 5 Extract from ADL2A Table 5 Summary of concurrent notional building specification

Element Side lit or unlit Side lit or unlit Top lit(where HVAC (where HVAC

specification is specificationheating only) includes cooling)

Roof U-value (W/m2K) 0.18 0.18 0.18

Wall U-value (W/m2K) 0.26 0.26 0.26

Floor U-value (W/m2K) 0.22 0.22 0.22

Window U-value (W/m2K) 1.6 (10%FF) 1.6 (10%FF) N/A

G-value(%) 40 40 N/A

Light transmission (%) 71 71 N/A

Roof-light U-value (W/m2K) N/A N/A 1.8 (15%FF)

G-value (%) N/A N/A 55

Light transmission (%) N/A N/A 60

Lighting luminaire (lm/circuit watt) 60 60 60

Occupancy control (Yes/No) Yes Yes Yes

Day-light control (Yes/No) Yes Yes Yes


SBEM ResultsIf an actual building is modelled within SBEMwith all parameters defined exactly in accordancewith the Notional Building (including 12%rooflights with 60% light transmission andproportional control of the electric lighting

system), then the SBEM results show the sameCO2. If all other parameters are then leftunchanged, but rooflight area is altered, thefollowing graph (showing results calculated bySBEM v5.2.b) demonstrates the effect on CO2 emissions:

20

60

180

0

100

140

2 4 6 8 10 12 14 16 18 20

40

80

120

160

% o

f no

tio

nal b

uild

ing

(TE

R)

Rooflight area (%)

Heating (dimming)

Lighting (dimming)

Total (dimming)

Notional building

Graph 1: SBEM results - CO2 emissions for the Notional Building at varying rooflight area

It can be seen from this graph that:

• at 12% rooflight area the actual building hasexactly the same CO2 emissions as thenotional building i.e. the BER exactly matchesthe TER (100% of TER) so is a marginal pass

• as rooflight area is reduced there are dramaticincreases in CO2 emissions due to use of thelighting system whilst there are smallerreductions in CO2 emissions due to use of theheating system. This gives a dramatic increasein total CO2 emissions.

• if rooflights are omitted entirely, then

o total CO2 emissions from all aspects ofoperation of the building are 42% higherthan they are with 12% rooflights

o CO2 emissions from the lighting system are220% higher than they are with 12% rooflights

o CO2 emissions from the lighting systemalone are higher than the total permissibleCO2 emissions from all aspects ofoperation

• this does not mean that rooflights cannot beomitted, but it does mean that the efficiency ofthe lighting system would have to bedramatically improved compared to thespecification in the notional building, whichalready reflects current good practice

• as rooflight area is increased from 12% to 20%there is a small reduction in CO2 emissions dueto use of the lighting system, almost balancedby a small increase in CO2 emissions due touse of the heating system, so there is littlechange in total CO2 emissions


The following graph shows the same data, whenless sophisticated light control systems are used –both a simple auto switched on-off system rather

than the proportional (dimming) system which isdefined in the notional building, and also whenthere is no automatic control of the lighting system.

Graph 2: SBEM results – effects of lighting control system at varying rooflight area

20

60

0

100

140

2 4 6 8 10 12 14 16 18 20

40

80

120

160

% o

f no

tio

nal b

uild

ing

(TE

R)

Rooflight area (%)

Total (auto switched)

Total (manual control)

Lighting (auto switched)

Lighting (manual control)

Heating (auto switched)

Heating (manual control)

Notional building

This graph shows that:

• with a simpler auto switched (on-off) system,total CO2 emissions are slightly increased, andthe building does not achieve compliance. Otherimprovements to the building will be required tocompensate for the increased energy use of thelighting system

• without any automatic control of the lightingsystem SBEM assumes the lights stay on all thetime (which is probably an accurate reflection ofmany applications), so the CO2 emissions due touse of the lighting system are constant, at thesame level as if there were no rooflights

• without automatic control, CO2 emissions fromthe lighting system alone are higher than thetotal permissible CO2 emissions from allaspects of operation, regardless of rooflightarea. This does not mean that lighting systemsmust be automatically controlled, but it doesmean that if they are not, the efficiency of thelighting system would have to be dramaticallyimproved compared to the specification in thenotional building, which already reflects currentgood practice


Graphs 1 and 2 assume that all properties of theactual rooflights are identical to those specified inthe Notional Building: U-value 1.8 W/m2K, lighttransmission 60% and frame factor 15%. Inpractice, rooflight properties may be different – forexample they may have slightly lower lighttransmission, and slightly better insulation. As anexample, the following graph shows the

performance of an actual building specified exactlyin accordance with the Notional Building, but with:

• Light transmission 50%

• U-value 1.3W/m2K

• Frame Factor 10%

Graph 3: SBEM results – effect of varying rooflight area on CO2 emissions for an actual building with realisticrooflight properties and dimming light controls

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60

180

0

100

140

2 4 6 8 10 12 14 16 18 20

40

80

120

160

% o

f no

tio

nal b

uild

ing

(TE

R)

Rooflight area (%)

Heating

Lighting

Total

Notional building

It can be seen from this graph that the overalltrends are the same as with the notionalspecification rooflights: as rooflight area isreduced there are dramatic increases in CO2

emissions due to use of the lighting system, whilstthere are smaller reductions in the CO2 emissionsdue to use of the heating system giving dramaticincreases in total CO2 emissions.

The graph also shows that in this case, the actualrooflights perform slightly better than the notionalrooflights, so that:

• the total CO2 emissions of the actual buildingwith 12% rooflights are slightly better than thenotional building (offering approx. 2%reduction in total CO2 emissions)

• if rooflights are omitted entirely, then:

o CO2 emissions from the lighting systemare 230% higher than they are with 12% rooflights

o total CO2 emissions from all aspects ofoperation of the building are 44% higherthan they are with 12% rooflights

• as rooflight area is increased from 12% to20%, then:

o the reduction in CO2 emissions due to useof the lighting system is greater than theincrease in CO2 emissions due to use ofthe heating system

o total CO2 emissions are reduced, giving a saving of 5% compared to the notional building


In addition to limits on overall CO2 emissions,Criterion 2 also sets limits on the worstacceptable standards for both elements of thebuilding fabric, and services. Limits on the

insulation values for the Building fabric are givenin ADL2A Table 3 (note that these figures are nowstatutory guidance as stated in ADL2A para 1.4 Note):

CRITERION 2 LIMITING DESIGN FLEXIBILITY (STATUTORY GUIDANCE)

AD L2A Table 3 Limiting fabric parameters

Roof 0.25 W/m2.K

Wall 0.35 W/m2.K

Floor 0.25 W/m2.K

Windows, roof windows, rooflights, curtain walling and pedestrian doors 2.2 W/m2.K

Note that the limit of 2.2W/m2K for rooflights is:

• the limiting U-value for windows and rooflightsassumes the glazing has been assessed in thevertical position, even though rooflights areusually used horizontally. If a rooflight isassessed horizontally the limit should beincreased by 0.3 W/m2K (see AD L2A para 4.32and BR443 section 11.1) so the limiting value is2.5 W/m2K when manufacturers quote rooflightperformance horizontally, as they are used.

• based on the developed area of the rooflight,not the area of the roof aperture, which isdefined in NARM Guidance Note NTD2 (2010)

The above table defines the worst acceptableperformance for each element of the building; itshould be noted that the Notional Building asdetailed under Criterion 1 above are significantlyhigher performance, and if an actual building onlycomplies with the worst acceptable values forbuilding fabric and services, then it will beconsiderably poorer performance than theNotional Building and will fail Criterion 1.

Specifiers may therefore opt to specify rooflightswith an improved U-value to match or exceed theU-values used in the Notional Building as one wayof meeting Criterion 1. See ADL2A Table 5, assummarised on page 7.

Note that “plastic” rooflights will need to be atleast triple skin in order to achieve the worst caseU-value of 2.2W/m2K.

To achieve higher levels of performance, rooflightmanufacturers will modify the internal air gap andthe internal design of the middle skin. Since this isdesign variable but could be critical to achieving theTER, builders and contractors need to be fully awarethat changing the specification or the nominatedsupplier to buy cheaper options, may well failbuilding compliance, thus incurring far greateradditional cost to reinstate the correct specification.

For buildings that produce high internal heat gainsdue to the process within the building, a lessdemanding weighted average U-value for rooflightsmay be an appropriate way to reduce overall CO2

emissions and hence the BER. In such a case, therooflight U-value may be higher than 2.2 but itshould never be higher than 2.7 W/m2K, which willstill necessitate triple skin rooflights.


The Regulations define measures to avoidoverheating in the summer period – one of whichis to limit glazed areas (windows and rooflights)to limit the solar load to limit the requirement forair conditioning.

It should be borne in mind that solar gain throughwindows and rooflights is just one aspect ofinternal gains within the building. People(including their density and activity), artificiallighting, display lighting, process equipment,computers and other equipment all contribute to

internal heat gains, and along with ventilationstrategy have an effect on the potential for excessheat build up.

The Regulations place limits on both window androoflight area to limit the solar loads; theyrecognise the effect of solar gain is influenced bythe height of the building due to the effects ofstratification and the height of the rooflights abovethe work zone and the limits on rooflight area inAD L2A Criterion 3 para 2.53 b/c, vary dependingon the building height, as follows:

CRITERION 3 LIMITING THE EFFECT OF SOLAR GAIN IN SUMMER

Note that the solar load through the rooflights isdefined by the product of:

Area x g-value x frame factor

and the glazing area limit will consequently be metprovided this product remains the same, even ifeach individual parameter is different.

For example, for a taller building, if the g-value is0.51 rather than 0.46, then the limit on rooflightarea in will be reduced from 20% to 18%,because:

18% x 0.51 x 85% = 20% x 0.46 x 85% (= 0.0782)

and similarly for a lower building, if the g-value is0.51 rather than 0.68, then the limit on rooflightarea in will be increased from 10% to 13.3%,because:

13.3% x 0.51 x 75% = 10% x 0.68 x 75% (= 0.051)

SBEM considers the glazed areas (including bothwindows and rooflights) for each individual zone ofthe building on the above basis, taking intoaccount the glazed area and frame factor in thezone, the height of the zone, and the glazinggvalue, and output shows whether the glazed arealimits have been met (and how close to the limitseach zone is).

In general, these limits are not usually exceededfor rooflight areas up to 17-20% in buildings over6m tall, or for rooflight areas up to 10-15% inlower buildings, although care should be taken ifthere are also large areas of window in the samezone, as this could cause total glazed area to be exceeded.

Solar gain should only be considered for workzones where a person will be working for asubstantial part of the day. It should not beconsidered for circulation spaces, transientoccupancy such as toilets and spaces notintended to be occupied.

Zone Height Max Rooflight Area Frame Factor g value*

< 6m 10% 25% 0.68

> 6m 20% 15% 0.46

* The g value is a measure of the total transmitted solar energy: it is the direct transmission in the total solar spectrum plusthe proportion of absorbed energy which is retransmitted internally.


The Regulations require that most buildings thatare not dwellings must be tested for air tightnesson completion of the building structure, and theworst case acceptable value (under Criterion 2) is10m3/hr/m2 at 50 Pa, as shown in AD L2A Table 3.

In addition to meeting the worst case value, themeasured air permeability must be entered intoSBEM and the BER calculated accordingly, andmust still meet the TER. The value used in theNotional building to calculate the TER is moredemanding than the limiting values and will be basedon building size/type as shown in ADL2A Table 5.

CRITERION 4 BUILDING PERFORMANCE CONSISTENT WITH BER

Buildings of less than 500m2 do not have to besubject to the air pressure test, but if not, the BERcalculation will use a value of 15m3/hr/m2 at 50Pa.This will require compensating improvements inother elements of the fabric and services to ensurethe BER is no worse than the TER.

This performance is very demanding, particularlyon smaller buildings and attention to fine detail inthe construction of the building will be critical.

For rooflights, attention to the detail of the fixingprocess is critical. In particular, the correct type, sizeand positioning of sealants, and correct compressionof sealants by the use of the correct number,position, size and type of fasteners is vital. It must benoted that “in plane” rooflights to match the opaquesheeting of the roof have a different performance andfixing specification than the opaque sheeting and thismust be observed by the fixer to ensure both waterand air tightness. The consequences of failing the airpressure test will mean that remedial work will needto be carried out and likely to prove very expensivefor those concerned.

Table 5 Extract from ADL2A Table 5 Summary of concurrent notional building specification

Element Side lit or unlit Side lit or unlit Top lit(where HVAC (where HVAC

specification is specificationheating only) includes cooling)

Air permeability (m3/(m2.hour)) 5 5 7Gross internal area less than or equal to 250 m2

Air permeability (m3/(m2.hour)) 3 3 7Gross internal area greater than 250 m2 and less than 3,500 m2

Air permeability (m3/(m2.hour)) 3 3 5Gross internal area greater than 3,500 m2 and less than 10,000 m2

Air permeability (m3/(m2.hour)) 3 3 3Gross internal area greater than or equal to 10,000 m2


• Criterion 1 of Approved Document L2A of the2013 Regulations requires an actual buildingto match the performance of a NotionalBuilding which will give an overall 9% savingin energy use and associated CO2 emissionscompared to 2010 regulations.

• The major savings will need to come from thebuilding services. Some improvement willcome from improving the U-value of thebuilding fabric but the impact of more andmore insulation is a law of diminishing returns.

• Rooflights offer opportunity for dramaticsavings in the overall CO2 emissions byreducing the use of electric lighting systems,often the biggest source of CO2 emissionswhen operating a building.

• Rooflights are also a very positive means ofsaving energy. Natural daylight is free andprovides the essential feel good factor at theplace of work and as a result people workmore efficiently. Rooflights are an ideal way toreduce the building energy demand whendesigners are struggling to find that additionalenergy saving that will achieve compliance.

• The Notional Building has 12% rooflights.Rooflight area in the actual building is criticalto matching the TER and achievingcompliance: omission of rooflights canincrease the total CO2 emissions by 50%making compliance very difficult.

• Specification of as high a rooflight area aspractical, with rooflights as well insulated aspossible, should be considered to help meetthe TER and achieve compliance.

• Automatic control of artificial lights is criticalto harness the benefits offered by rooflightsand achieve compliance; manual lightswitching in a work zone is unlikely to providea compliant building. Proportional (dimming)control is better than switching (on/off)automatic control.

• Criterion 2 is now statutory guidance thatrequires that rooflights should have a U-valueof 2.2W/m2K or better, which means theyshould be at least triple skin. Use of rooflightswith a U-value of 1.8 W/m2K (to match theNotional Building) or significantly better U-values can be considered by the specifier as auseful way to help meet the TER, but this isnot a requirement.

• Criterion 3 sets limits on glazed areas to avoidexcessive solar load and care should be takennot to exceed these areas – typically 17-20%for buildings over 6metres tall, and 10-15% forlower buildings.

• Attention to detail on the fixing of rooflights tothe manufacturers recommendations will becritical to achieve a compliant Air Permeabilitytest and achieve Criterion 4.

• Designers/builders will require full technicaldetails from the NARM manufacturer whichwill include - U-value, frame factor, lighttransmission and g value. These will varydependant on the product, design andmanufacturer. The data input into SBEM maybe very critical to achieving Compliance.Contractors need to be aware that changingthe designer’s specification to save money onproduct price may lead to a Non-Compliantbuilding and resulting extra costs to rectify thenon-compliance.

• The Notional Building is the same size andshape of the actual building. A wider set ofNotional Buildings has been defined and thedata embedded within the NotionalBuilding/SBEM has now been released inTable 5. Design and build in accordance withparameters in Table 5 will provide complianceto the TER.

In summary:

o for work zones < 6m high, rooflight areasshould be 10-15% of the floor area.

o for work zones > 6m high, rooflight areasshould be 12-20% of the floor area.

For a smaller carbon footprint just addrooflights

SUMMARY OF THE REQUIREMENTS OF AD L2A ON ROOFLIGHTS


IntroductionThe Government have announced that the ADL2B2010 Regulation –“Work on existing buildings thatare not dwellings” will remain in force at2013/2014. It was suggested that there would bechanges to the Regulations in respect of“Consequential Improvements”, but this will nothappen in the foreseeable future. Thus ADL2B hasnot been issued for 2013, the 2010 Regulationsstill being in force. However there are a number ofApproved Amendments to the 2010 edition thathave been issued. These are generally of minordetail and will not be identified in this documentexcept for changes to ADL2B 2010 Table 3 and toADL2B 2010 Annex A –Document Referenceswhich are identified in the text below.

For convenience all the NARM references toADL2B 2010 in the “Designing for Rooflights2010” document, will be reissued in this 2013/14edition and will also include for the amendmentsas indicated above.

This NARM guidance document is designed toassist the reader to understand the Guidance inADL2B in respect of the use and application of rooflights.

There are four areas of work to consider :-

• Repairs

• Refurbishments

• New Extensions

• Consequential Improvements

Buildings exempt from AD L2B

• Section 1 Listed Buildings and some buildingsin Conservation Areas

• Buildings primarily used for worship

• Stand alone buildings of less than 50m2 usefulfloor area

• Certain porches and conservatories of lessthan 30m2 where the heating system is notextended into the porch or conservatory

• Certain historic buildings where there is arequirement to match the original building

• Buildings with low energy demand

Large BuildingsWhere the extension is greater than 100m2 andgreater than 25% of the useful floor area of theexisting building, then the work is regarded as aNew Building and must comply to therequirements of AD L2A. In addition, therequirement for consequential improvements to theoriginal building will also apply, as explained below.

Definitions within ADL2B 2010The following terms are used within AD L2BRegulations and are referred to in this document.

• Thermal ElementThis is defined as the fabric of the building toinclude floor, walls and roof but does notinclude windows, rooflights and doors.

• Controlled FittingsRooflights, along with windows and doors, arenot considered as part of the “fabric” of thebuilding but are regarded as ControlledFittings and considered separately from thebuilding fabric

• Fixed Building ServicesThis includes fixed internal artificial lightingsystems and fixed systems for heating, airconditioning and medical ventilation

AD L2B WORK ON EXISTING BUILDINGS THAT ARE NOT DWELLINGS


Where the glazing of all rooflights on a building isbeing replaced, even if the frames are not, it islikely to be regarded as refurbishment rather thanrepair and the requirements of AD L2B will apply;see below.

Where a whole rooflight including the frame ie aControlled Fitting, is being replaced, then therequirements of AD L2B as detailed below apply.

Windows, rooflights and doors are defined asControlled Fittings; this definition includes anyframes. If the glazing of a rooflight is beingreplaced without replacing the frame, then a newControlled Fitting is not being fitted and AD L2Bdoes not apply (see AD L2B para 4.23).

Consequently, if replacing the glazing of anindividual rooflight without replacing the frame(e.g. the upstand or the surrounding opaquesheeting), replacing like with like will beacceptable even if the original rooflight is singleskin – although where practical, it would besensible to upgrade to Part L standards.

1. RepAiRs to Rooflights


ADL2B 2010 Table 3 has been amended in the2013 Amendments. The revised Table 3 is givenbelow as it relates to rooflights/roof windows.

2. RefuRbishment to Rooflights

AD L2B Table 3 Standards for Controlled Fittings

Fitting Standard

Windows in buildings that are essentially domestic A window Energy Rating3 of Band C in character2 or U-value 1.6 W/m2.K

All other windows and roofwindows and rooflights1,4 U-value 1.8 W/m2K for the whole unit

Comments to Table 3

• These limits on U-values assume the windowor rooflight has been assessed in the verticalposition, even though rooflights are usuallyused horizontally. If a rooflight is assessedhorizontally, these limits should be increasedby 0.3 W/m2K (see AD L2B para 4.26), so2.1W/m2K is the limiting value whenmanufacturers quote rooflight performancehorizontally, as they are used.

• For plastic rooflights this will always require atriple skin rooflight.

• Plastic rooflights are normally supplied, in theUK, in Glass Reinforced Polyester (GRP) orPolycarbonate. Other materials are availablefrom abroad but such materials will generallyfail the UK requirements for non-fragilityand/or the fire resistance Regulations.

In buildings with high internal heat gains from amanufacturing process, a less demanding U-valuefor rooflights may be appropriate. In such casesthe requirements to AD L2B Table 3 may berelaxed but the value should not be worse than 2.7W/m2K, which will still require a triple skin rooflight.

Notes to Table 3

1 Display windows are not required to meet thestandard in this Table

2 For example Student Accomodation whereoccupancy levels are essentially domestic incharacter.

3 See Guide to Energy Rating for Roof WindowsGGF 2013 at www.ggf.org.uk

4 For the purpose of checking compliance withthis Table 3, the true U-value based onaperture area can be converted to the U-valuebased on the developed area of the rooflight –see NARM technical Document NTD2 (2010)


Work on extensions which are less than 100m2, orare less than 25% of the existing floor area, fallunder AD L2B and as a general rule will bemeasured by the Elemental Method i.e productsachieving a minimum specified performance.

However, the use of SBEM to calculate thebuildings performance and compare CO2

emissions from the actual building to a NotionalBuilding (as Criterion 1 under AD L2A) can beused as an alternative means to show Compliance(see AD L2B paras 4.9-4.11).

When designing an Extension, Controlled Fittings(including rooflights) should meet the standardsshown in Table 3 (see above) - U-values shouldbe 1.8 W/m2K (when measured in the verticalplane, or 2.1W/m2K when measured in thehorizontal plane).

The areas of windows and rooflights should notexceed the values shown in Table 2.

3. new extensions

AD L2B Table 2 Opening Areas in the Extension

Building type Windows and personnel Rooflights as %doors as % of exposed wall of area of roof

Residential buildings where people 30 20temporarily or permanently reside

Places of assembly, offices and shops 40 20

Industrial and storage buildings 15 20

Vehicle access doors and display As required N/Awindows and similar glazing

Comments to Table 2If the original building had a rooflight area greaterthan 20% of the roof area, rooflight area in theextension can match the area in the originalbuilding, rather than the areas in Table 2 (see ADL2B para 4.4)

It is also permitted to vary the U-values shown inTable 3 and the opening areas shown in Table 2provided that the area weighted U-value of all theelements of the extension is no greater than thatof an extension of the same size and shape thatcomplies with Tables 2 and 3 (see AD L2B para4.7-4.8).

The norm for a new extension will be to fit rooflightsup to 20% of the roof area with a U-value of 1.8W/m2K (measured in the vertical plane).

Note that since it will be unlikely that a SBEMcalculation will be carried out which will verify thepoint, designers need to recognise that, whereappropriate, it is essential to incorporate rooflightsinto the design to reduce the carbon footprint ofthe building.

Conservatory ExtensionsWhere the extension is a Conservatory or a Porchand is not exempt, then reasonable provision willbe :-

• Effective thermal separation between theexisting building and the extension

• Independent temperature and on/off controlswithin the extension

• Glazed area should meet the Standards toTable 3 above. However the limitation to totalglazed area in Table 2 will not apply


Where an existing building has a floor area over1000m2, and work is to be carried out on thebuilding by way of an extension, or the initialprovision or a capacity increase of any fixed buildingservices, then a requirement for consequentialimprovement to the building is triggered.

These are to improve the energy performance ofthe original building, in addition to the proposedbuilding work (the “principal works”), and shouldbe to a value of at least 10% of the principalworks. The principal works must still comply withPart L in the normal way.

Consequential improvement is only required ifboth technically and economically feasible, thelatter defined by a simple payback of 15 years(see AD L2B Key Terms 3.1)

AD L2B provides a list of 9 possible measures toupgrade the original building in Table 6“Improvements that in ordinary circumstances arepractical and economically feasible”

Item 7 in AD L2B Table 6 identifies “Replacingexisting windows, roof windows or rooflights ordoors which have a U-value worse than 3.3W/m2K” as one such measure, and this example isused in the text (see AD L2B para 6.4).

If, as well as extending a building, old rooflightsthat have U-values greater than 3.3 are replacedwith new rooflights that have U-value of 1.8

W/m2K (when measured in the vertical plane) thiswould satisfy the requirement for consequentialimprovements, provided the cost of the rooflightreplacement was at least 10% of the cost of the extension.

Since there will be a basic requirement for thislevel of financial commitment to upgrade theoriginal building there will be considerableadvantage to selecting this option as the methodof providing consequential improvement, since:

• There will be considerable thermal efficiencysavings by replacing old rooflights at a U-value in excess of 3.3 W/m2K with newrooflights at a U-value of 1.8W/m2K

• The old rooflights may have lost a large part oftheir light transmitting qualities – newrooflights will put daylight back into thebuilding to make it a more pleasant place to work

• The additional daylight will mean the electriclights can be switched off creating furtherconsiderable energy savings and reduction inCO2 emissions

• The new rooflights will be non-fragile makingthe roof a safer place should maintenancestaff need to access the roof (but note that the opaque roof areas may also be fragile and remain so after the rooflights have been replaced)

4. CONSEQUENTIAL IMPROVEMENTS


4. Repairs to individual rooflights, wheretheglazing is replaced within the existingframe, do not fall under the requirements ofPart L. Thus the repair can be like for like.

5. Where Consequential Improvements arerequired for the original building, replacing allthe original single skin rooflights with newtriple skin rooflights will be a very carbon andcost efficient solution with the added bonusthat the people inside the building will greatlyappreciate the better working conditions.

1. The requirement for any rooflight which isrefurbished or replaced, and for new rooflightsin extensions, is a U-value of 1.8W/m2K whenmeasured in the vertical plane. This meansthat rooflights will be triple skin as shown inAD L2B 2010 Table 3 as amended in 2013.

2. The norm for rooflight area in extensions willbe up to 20% of the roof area as shown in ADL2B Table 2.

3. It would be sensible for the designer toconsider rooflight area carefully, to maximisethe benefits of daylight on both energy useand the internal environment whilst avoidingsolar overheating as outlined under AD L2A,although these considerations are notrequirements of AD L2B.

SUMMARY TO AD L2B


1. What am I required to do if replacing orrepairing an individual broken rooflight?

Replacement of the glazing without replacingthe frame of a rooflight is not regarded asreplacement of the Controlled Fitting so doesnot come under the scope of Part L, and likefor like replacement is permissible (see ADL2B para 4.23).

This is also likely to be the situation ifreplacing a damaged outer sheet on anindividual in-plane rooflight.

Replacement of a whole rooflight including theframe is defined as replacement of aControlled Fitting and the replacementrooflight would need to achieve an overallUvalue of 1.8 W/m2K in compliance withADL2B Table 3, so the replacement rooflightwould have to be triple skin.

2. What am I required to do if replacingdegraded outer sheets of all the existing in-plane rooflights in a roof?

This is likely to be regarded as refurbishmentrather than repair, and the upgraded rooflightswould then need to achieve an overall U-valueof 1.8 W/m2K in compliance with ADL2B Table3, so the replacement rooflights would have tobe triple skin.

3. What should I do if I want to add additionalrooflights to the existing building?

For an existing building the maximum area ofrooflighting is 20% of the floor area as shownin AD L2B Table 2, and new rooflights may beadded up to this maximum. Any new rooflightswould need to achieve an overall U-value of1.8 W/m2K in compliance with ADL2B Table 3,so the new rooflights would have to be tripleskin. There is no requirement for the insulationlevel of the existing lights to be improved,unless they were replaced with new rooflights.

4. I am extending the building. What control isthere on any rooflights?

The extension may have up to 20% rooflightswith a U-value of 1.8 W/m2K in compliancewith ADL2B Table 3, so the rooflights in theextension would have to be triple skin. If theoriginal building had rooflights to a greaterarea than 20%, then the extension may bedesigned to the same level of rooflights as theoriginal building. Options with more designflexibility are shown in AD L2B paras 4.7-4.8.

Note that an extension may trigger a need for a“Consequential Improvement” on the originalbuilding, as detailed in the previous section ofthis document. If this is the case, upgrading theexisting rooflights can be a very carbon andcost efficient solution with the added bonusthat the people inside the building will greatlyappreciate the better working conditions.

FREQUENTLY ASKED QUESTIONS ON ROOFLIGHT REFURBISHMENT


General CommentADL1A gives guidance for compliance with theBuilding Regulations for building work carried outin England on new Dwellings.

SUPPORTING THE GUIDANCE IN ADL1A AND ADL1B (2013)

ADL1A defines 5 Criteria to achieve compliancefor new dwellings (in the same way as AD L2Adoes for non-domestic buildings):

Criterion 1 : Achieving the TER and TFEE

Criterion 2 : Limits on Design Flexibility

Criterion 3 : Limiting the effect of heat gains inthe summer

Criterion 4 : Dwelling actual performance isconsistent with the DER and DFEE

Criterion 5 : Provision for energy efficientoperation of the dwelling (this is notcovered in this document)

5 CRITERIA

Note that:

- Criterion 1 is a regulation and thereforemandatory

- Criterion 2 is Statutory Guidance

- Criteria 3, 4 and 5 are for guidance

ADL1A NEW DWELLINGS

Criterion 1 sets a maximum carbon dioxideemission target (in the same way as TER is set fornon-domestic buildings), but in addition also setsa separate requirement for fabric energy efficiencyfor dwellings. The target and actual values of boththe CO2 Emission and fabric efficiency are allcalculated by approved software implementing theStandard Assessment Procedure 2012 (SAP)

Target CO2 Emission Rate (TER) The TER is the maximum CO2 emission rate that isallowable for any new dwelling. It is expressed interms of the mass of CO2 emitted per year per sq.metre of the total useful floor area of the building(kg/m2/year).

CRITERION 1 ACHIEVING THE TER AND THE TFEE


The TER is calculated for a Notional Dwelling ofthe same size, shape, location and orientation asthe actual dwelling, but with performance offabric, services and controls all as defined inAppendix R of the Standard AssessmentProcedure 2012, (using the formulae in AD L1Apara 2.4 and the fuel factors shown in para 2.5and Table 1). The Standard Assessment Procedure(SAP 2012) document can be downloaded fromthe BRE website at www.bre.co.uk/sap2012

Target Fabric Efficiency rate (TFEE) The TFEE is the maximum energy consumptionthat is allowable for any new dwelling. It isexpressed in terms of the energy consumed peryear per sq. metre of the total useful floor area ofthe building (kWh/m2/year).

The TFEE is also calculated for a Notional Dwellingof the same size, shape, location and orientationas the actual dwelling, but with performance offabric, services and controls all as defined inAppendix R of the Standard AssessmentProcedure 2012, (using the formula in AD L1A para2.6)

Dwelling Emission Rate (DER) The DER is the CO2 emission rate for the actualdwelling, calculated in exactly the same way asthe TER but using the actual properties of thematerials and services used to construct thedwelling instead of the reference values.

Dwelling Fabric Energy Efficiency (DFEE) RateThe DFEE is the energy consumption of the actualdwelling, calculated by SAP in exactly the sameway as the TFEE but using the actual properties ofthe materials and services used to construct the

dwelling instead of the reference values.

ComplianceAll the data for the actual dwelling (geometry andfull details of the building fabric and services) isentered into approved software implementing SAP,which will calculate both the target values (TERand TFEE) and the values for the actual building(DER and DFEE)

If both the DER ≤TER, and the DFEE ≤TFEE thenthe dwelling is compliant.

Designers and builders are free to use flexibility inthe design and build provided the finished buildingachieves both these target values.

Notional Dwelling SpecificationThe reference specification for the notionaldwelling is given in the SAP 2012 documentAppendix R and is summarised in AD L1A section5 Table 4. For rooflights the specification includes:

• Rooflight U-value =1.4 W/m2K (assessedvertically, with an adjustment of +0.3 W/m2Kwhen installed horizontally, giving a resultantU-value of 1.7 W/m2K)

• G-value = 0.63

• Light transmission = 80%

• Frame factor = 0.7

• Overshading factor = 1.0


CRITERION 2 LIMITS ON DESIGN FLEXIBILTY

Table 2 Limiting fabric parameters

Roof 0.20 (W/m2K)

Wall 0.30 (W/m2K)

Floor 0.25 (W/m2K)

Party wall 0.20 (W/m2K)

Swimming pool basin 0.25 (W/m2K)

Windows, roof windows, glazed roof-lights, curtain walling and pedestrian doors 2.00 (W/m2K)

Air permeability 10.0m3(h-m2) at 50 Pa

In addition to limits on overall CO2 emissions, andoverall fabric efficiency set under Criterion 1,Criterion 2 sets limits on the worst acceptablestandards for both elements of the building fabric,

Note that the limit of 2.00 W/m2K for rooflights is:

• the area weighted average for all elements ofthat type. For example, if one opening and twofixed rooflights were fitted to a dwelling, theopening one could be permitted to have a worseU-value than in the above table, provided thatthe two fixed ones have a better U-value so thatthe average U-value (based on area) is as goodor better than the limiting figure in Table 2

• based on rooflight U-value having beenassessed in the vertical position, even thoughrooflights are used horizontally or on a pitchedroof. If a rooflight has been assessedhorizontally and installed at a pitch of less than20 degrees then the limits should be increasedby 0.5 W/m2K for double glazed units (or 0.3W/m2K for triple glazed units), so the limitingvalue becomes 2.5 or 2.3 W/m2K for double, ortriple, glazed rooflights respectively (see BR443section 11.1 for adjustments at pitches above20 degrees)

• based on the developed area of the rooflight, asdefined in NARM Guidance Note NTD02, ratherthan the area of the aperture

The above table defines the worst acceptableperformance of each element of the building; itshould be noted that in common with most

elements, rooflights in the Notional Dwelling (asdetailed under Criterion 1) have a much higherperformance, and that if the fabric and/or servicesare all specified to the minimum standards definedby Criterion 2, the dwelling will not achieve theoverall level of performance required by Criterion 1

Specifiers may therefore opt to specify rooflightswith an improved U-value to match or exceed the U-values used in the Notional Dwelling.

Note that rooflights fitted with double glazed glasswith a hard coat low emissivity coating and argonfilled cavity will have a centre pane U-value of 1.4W/m2K which is likely to meet the minimum fabricparameters defined in Criterion 2. However,rooflights will need to be fitted with double glazedglass with a soft coat low emissivity coating andargon filled cavity to give a centre pane U-value of1.1 W/m2K, to match the performance of therooflights defined in the Notional Dwelling to meetCriterion 1. In both cases performance of therooflight frame is critical, as the values defined inboth Criteria 1 and 2 should apply to the wholerooflight value rather than centre pane U-value.

To achieve higher levels of performance triple glazingshould be considered. Triple glazing options arereadily available and can help make a majorcontribution to achieving the TER.

and services. Limits on the insulation values forthe Building fabric are given in ADL1A Table 2(note that these figures are now statutory guidanceas stated in ADL1A para 1.4 Note):


The regulations define measures to avoidoverheating in summer – one of which is to limitglazed areas (windows and rooflights) to limit thesolar load, to limit the requirement for airconditioning.

It should be borne in mind that solar gain throughglazing is just one aspect of internal gains withinthe building. People, artificial lighting and electricalappliances all contribute to internal gains.

Solar gains can be beneficial in the winter to offsetdemand for heating but can contribute tooverheating in the summer. Specialist solar controlglasses can be used to control solar gain butthese will also reduce daylight levels and reducewinter solar gains. SAP 2012 assumes glass with alight transmission of 80% and a g-value of 0.63.Common soft coat low emissivity glasses willtypically have a light transmission of 78% with ag-value of 0.61 for double glazing with two panesof 6mm glass. Some high performance glassescan provide a g-value of 0.41 but thecorresponding light transmission drops to 68%.

To maintain good light levels the BuildingRegulations recommend that glazing is providedequating to a minimum of 20% of the floor area toavoid parts of the dwelling experiencing poorlevels of daylight, resulting in increased use ofelectric lighting, and hence increasing CO2

emissions (see Note to AD L1A para 2.41).

Effective ventilation can contribute to controllingheat gains in dwellings; opening rooflights can bean effective method of providing naturalventilation. If electrically operated they can beautomatically controlled to provide daytimeventilation when required, and/or night timepurging.

CRITERION 3 LIMITING THE EFFECTS OF HEAT GAINS IN SUMMER


The regulations require that dwellings should beconstructed and equipped so that actualperformance is consistent with the calculated DERand DFEE rate.

When calculating the DER and DFEE rates careshould be taken to ensure that the correct data isentered into the software. For a rooflight,the U-value entered should be the true U-value for thewhole rooflight, correctly adjusted for the actualinstallation angle and based on the area of theaperture in the roof (the developed area U-value,Ud, is only used to check for compliance withCriterion 2).

In addition to the actual U-value, the measured airpermeability must be entered into SAP to allow itto calculate the DER and DFEE rates. The dwelling(or on larger developments a representativesample of each dwelling type) must be pressuretested to obtain this data. Where only arepresentative sample of a dwelling type has been

tested, the average of the results is used and thefigure increased by +2.0m3/hr/m2 at 50 Pa. Forsmall developments the builder can opt not totest, in which case a value of 15.0m3/hr/m2 at50Pa must be entered into SAP, which issignificantly poorer than the value in the NotionalBuilding, so would require other compensatingimprovements to be made in order for the DER tomatch the TER.

For rooflights, particular attention should be paidto the quality of the builder’s kerb (or the roofsurface where the rooflight is supplied with anupstand) and correct application of any sealantsbetween the two to ensure an airtight seal isachieved. It is vital to follow the manufacturer’sinstructions carefully to ensure the declaredperformance is achieved. For opening rooflightsthe design of the seal between the fixed andopening sections and continuity of the seals atcorners are critical to the air leakage performance.

CRITERION 4 BUILDING PERFORMANCE CONSISTENT WITH DER AND DFEE RATE


Table 1 Standards for controlled fitting

Fitting Standard

Window, roof window or roof-light WER Band C or better (see paragraph 4.22), or U-value 1.6 W/m2K

Doors with >60% of internal face glazed Door Set Energy Rating (DSER) Band E or better (seeparagraph 4.22), or U-value 1.8 W/m2K

Other doors DSER Band E or better (see paragraph 4.22), or U-value 1.8 W/m2K

ADL1B EXTENSION, REPAIR & REFURBISHMENT OF EXISTING DWELLINGS

Repairs To RooflightsWindows, rooflights and doors, including theframes, are defined as Controlled Fittings. If onlythe glazing of a rooflight is being replaced withinthe existing frame, then a new Controlled Fitting isnot being installed and ADL1B does not apply.

Where a whole rooflight or roof window, includingthe frame, is being replaced then the requirementsof ADL1B as detailed below will apply.

Rooflights in listed buildings, buildings inconservation areas or scheduled monumentswhere compliance with energy efficiencyrequirements of ADL1B would unacceptably alterthe character or appearance of the dwelling areexempted from these requirements.

Replacement RooflightsWhere the whole rooflight is being replaced thenthe replacement rooflight must comply with thestandards specified in ADL1B Table 1.

Notes to Table 1

• The WER referred to above is the WindowEnergy Rating; the WER scheme does not includerooflights. Therefore rooflights must achieve awhole-unit U-value of 1.6 W/m2K .

• This limiting value is based on rooflight U-valuehaving been assessed in the vertical position, eventhough rooflights are used horizontally or on apitched roof. If a rooflight has been assessedhorizontally and installed at a pitch of less than 20degrees then the limits should be increased by 0.5W/m2K for double glazed units (or 0.3 W/m2K fortriple glazed units), so the limiting value becomes2.1 or 1.9 W/m2K for double, or triple, glazedrooflights respectively (see BR443 section 11.1 foradjustments at pitches above 20 degrees)

• The relevant rooflight U-value for checkingagainst these limits is based on the developedarea of the rooflight, not the area of the roofaperture. See NARM guidance note NTD2 forfurther detail.

• If a rooflight is enlarged or a new rooflight isfitted then the total area of windows, roofwindows, rooflights and doors should not exceed25% of the total floor area of the dwelling unlesscompensating measures are taken elsewhere inthe work.

Note that a Building Control Body should normallybe notified that the work is to take place at least 5days before work starts. The competent personschemes (such as FENSA) which avoid the needfor this are limited to doors and windows and doesnot include rooflights.


New Extensions

For new extensions on existing dwellingsreasonable provision of glazing area would bedemonstrated by limiting the total area ofwindows, doors, roof windows and rooflights inthe extension so that it does not exceed 25% ofthe floor area of the extension plus the total areaof all doors and windows which as a result of theextension works, no longer exist or are no longerexposed.

Alternatively more flexible approaches are alsopermitted based either on an area weighted U-value method or a whole dwelling calculationmethod. The area weighted method is based ondemonstrating that the area weighted U-value forall the elements in the extension is no greater thanthat of an extension of the same size and shapethat complies with the fabric standards referred toabove.

The calculation method is based on using SAP2012 and demonstrating that the CO2 emissionsfor the whole building with the new extension willbe no greater than the dwelling plus a notionalextension built to the fabric standards above.

In order to achieve this it may be necessary toupgrade elements to the existing dwelling; a goodway to contribute to this may be to replace any oldrooflights or roof windows in the existing dwellingwith new units that meet the minimum fabricstandards set out in ADL1B.

Consequential Improvements

When an existing dwelling has a total useful floorarea in excess of 1,000m2 and work is to becarried out on either an extension, provision ofnew services or an increase in the capacity ofexisting services then consequentialimprovements may be triggered, if they aretechnically, functionally and economically feasible.

Technical guidance of consequentialimprovements is not provided in ADL1B but isavailable in ADL2B, as outlined on page 19 of thisdocument. Replacing existing windows, roofwindows, rooflights or doors which have a U-valueworse than 3.3W/m2K is one likely measure.


All users of SBEM should be familiar with theSBEM User Manual and help facilities; thisdocument does not attempt to explain how to useSBEM, but is intended to highlight how dataspecific to rooflights should be entered intoSBEM, and key points to be aware of.

(a) rooflight data

For each type of rooflight which are going to beused on any particular building, the main thermal,light and solar transmission properties should beentered into SBEM in the “Project database” form,under the “Glazing” tab. It is recommended thatthe user uses the “Introduce my own values”option, and enters data available from rooflightmanufacturers, as shown below:

APPENDIX 1 HOW TO ENTER ROOFLIGHT DATA INTO ISBEM

Properties which should be entered for the actualrooflights are:

• U-value (in W/m2K) as measured in the vertical plane

• T-solar

• L-solar

U-value This value should include allowance for any heatloss through glazing bars and frame, not just acentre pane value and should be based on the

developed area i.e. the Ud-value as defined inNARM Technical Guidance NTD2.

This value should be less than the limiting valuesin AD L2A and L2B - for new build it should beless than 2.2, and for refurbishment or extensionsit should be less than 1.8

Note that out-of-plane rooflights are generallymounted on a kerb or upstand, which may bemanufactured on site, or supplied as part of therooflight.


Where kerbs are supplied with the rooflight, theyshould be regarded as part of the rooflight, and theUd-value for both the rooflight alone, and therooflight-and-kerb assembly should be calculated inaccordance with NARM Guidance Note NTD2. Bothvalues must achieve the relevant limiting value (2.2or 1.8 W/m2K), and the value for the the rooflight-and-kerb assembly should be entered into SBEM.

Where kerbs are existing or manufactured on site,they can either be regarded as part of the rooflightand analysed as above, or regarded as part of theroof in which case they should meet therequirements for the roof, or where less wellinsulated treated as a thermal bridge.

T-solarT-solar is the total solar transmittance, or the G-value of the actual rooflight. This is used only forsolar overheating calculations (not for CO2

emission calculations)

L-solar L-solar is the light transmission of the actualrooflight. This is used only for CO2 emissioncalculations to determine whether the actualbuilding achieves the TER (not for solaroverheating calculations)

(b) rooflight geometry

Once all the rooflight properties have been enteredin the “Project Database” form, the geometry ofeach rooflight should be entered in the

“Geometry” form, under the “Windows andRooflights” tab:

Surface area ratio –1 for in-plane rooflights

Rooflight type

Rooflight area

Transmission factor - foroverhangs above windows

- 1 for rooflights

Area ratio – forauto zoning

Aspect ratio – for auto zoning

Frame factor


Properties which should be entered for eachactual rooflights are:

• In Envelope

• Glazing Type

• Area (projected)

• Shading System

• Transmission factor

• Surface Area ratio

• Frame factor

• Area ratio covered

• Aspect ratio

In EnvelopeThis simply defines the specific element of thebuilding that the rooflight is positioned in

Glazing TypeThis refers to the description of the relevant rooflighttype as already entered into the Project databaseform, and ensures the correct thermal, light andsolar transmission properties are used

Area (projected)This is the projected area of the actual rooflight (notthe developed area as defined in NARM NTD2which is used for U-value calculations), and is thearea used for illumination and solar gain calculations

Shading SystemThis relates to shading systems such as blindswhich rarely applies to rooflights, so this shouldusually be set “All other cases”

Transmission factorThis is related to loss of transmission due toshading eg from overhangs above windows, whichrarely applies to rooflights so this should usuallybe set to 1

Surface Area ratioThis is the ratio of the developed (ie surface) area ofthe rooflight (as defined in NARM Guidance NoteNTD2, and used to calculate the Ud-value) to theprojected area. By definition, this is also the ratio ofthe true U-value to the Ud-value.

If the surface area ratio for a particular rooflight isnot available, an acceptable alternative is to enterthe true U-value (based on projected area) intothe Project Database form then enter a value of 1as surface area ratio, as this will give the correctheat loss.

However, if the U-value entered into the ProjectDatabase form is a Ud-value based on adeveloped area that is greater than the projectedarea (giving a Ud-value which is lower than the U-value), then the surface area ratio must beentered correctly.

Note that for in-plane rooflights, because theeffect of profile can affect developed areadramatically, the U-value quoted is usually thetrue U-value rather than a Ud-value, and a surfacearea ratio of 1 should therefore be used.

For out-of-plane rooflights, it is more common toquote the Ud-value (for comparison to thelimiting values in AD L2A and L2B) and thecorresponding surface area ratio must be entered.

Frame factorThis is the percentage of the rooflight area whichis not glazed.

For in-plane rooflights, this is the proportion ofthe area covered by opaque sheet at laps (sideand end) and purlins.

For out-of-plane rooflights, this includes anyglazing bars, or effective reduction in area due tosplayed kerbs.

Area ratio coveredThis is a factor used when automatic daylightzoning is selected, but SBEM does not nowsubdivide rooflit zones, so this parameter is nolonger relevant for rooflights. It referred to theratio of the floor area illuminated by rooflightsdivided by the rooflight area.

Aspect ratio This is also a factor only used when automaticdaylight zoning is used, but SBEM does not nowsubdivide rooflit zones, so this parameter is nolonger relevant for rooflights. It defined the ratioof the length: width of the rooflight which SBEM assumes.


(c) Lighting system

Details of the lighting system are entered in theGenerally, details for a full lighting design have to

“Building Services” form, under the “zones” tab,be entered for each zone:

The wattage of the lights in each zone and thedesign illuminance they are designed to achievehave to be entered into SBEM: the latter is theilluminance which the lighting system is expectedto achieve not the design illuminance for the zone,which is fixed in the SBEM database, dependingon the activity in the zone. Entering a higher figuredoes not imply a brighter internal environment, itjust means a more efficient lighting system hasbeen defined.

Note that details of the efficiency of lightingsystems assumed in the Notional Building areshown on pages 20-21 of the National Calculationmethodology modelling guide 2013. It assumeslighting with an efficacy of 60 luminaire lumens percircuit-watt, and Equation 7 defines the actualpower density (ie the watts per 100lux), whichdepends on the zone geometry.


Properties which should be entered for the lightingcontrol system in every zone are:

• Light Controls

• Automatic daylight zoning for light controls

• Photoelectric options

• Occupancy sensing

• Parasitic power

Light ControlsThe “photoelectric” box should always be ticked ifthe actual building has automatic control of thelighting system – and for many buildings this willbe critical in order to achieve compliance.

Note that the Notional Building includesphotoelectric contol of the lighting system forrooflit zones.

Automatic daylight zoning for light controlsSBEM does not now subdivide zones for rooflitareas, but assumes rooflights illuminate a zone evenly.

Photoelectric switching

Proportion ofzone lit byrooflights

(d) Lighting control system

It is essential that correct control of the artificiallighting system is defined (as detailed in Graph 2of this report): without automatic control of thelighting system SBEM assumes the lights stay onall the time regardless of available daylight, so thatin the example building, CO2 emissions from thelighting system alone are higher than the total

permissible CO2 emissions from all aspects ofoperation, having a dramatic negative impact onoverall performance of the building and makingcompliance extremely difficult.

Details of the lighting control system are entered inthe “Building Services” form, under the “zones”tab, and the “lighting (Controls)” subtab.


For clarity, it is recommended to select “No,percentage controlled is” and enter 100% - this isthe percentage of the area of a zone that isilluminated by the rooflights. If the rooflights arenot distributed evenly but only illuminate part of azone, an appropriately lower figure should beentered here.

Photoelectric optionsThe “switching” (ie on-off control) or “dimming” (ieproportional) option can be selected here,depending on the type of lighting control systembeing specified for the actual building.

Graphs 1 and 2 of this document show the effect ofthis change – dimming controls give greater savingin energy consumption of the lighting sytem.

Note that the Notional Building includes dimmingcontol of the lighting system for rooflit zones.

Parasitic powerThis is the energy used by the lighting sensors andcontrol system even when the lights themselvesare turned off, and will depend on the specificationof the lighting control system to be used in theactual building

Note that the Notional Building assumes parasiticpower to be the lesser of 3% of the installedlighting load, or 0.3 W/m2.


Assessing the overall impact of rooflights andglazing on the energy efficiency of a building is acomplex task, and detailed research has beencarried out by The Institute of Energy andSustainable Development at De Montfort University.

Consideration was given to the difference ininsulation value between rooflights and thesurrounding cladding, balanced against thepassive solar gain through the glazing and theamount of energy needed to artificially light thebuilding whenever there is insufficient natural light.The amount of energy required to provide artificiallight is much greater than the energy needed tocompensate for loss of heat through the rooflight.

Thermal and lighting analysis was undertakenusing state of the art software to process actualweather data for a test reference year at a numberof locations around the country, assessed on anhour-by-hour basis for a whole year. It analysed theheat flow and illuminance through an entire roofincluding rooflights covering between 0 and 20%of the roof area.

Thermal analysis used ‘EnergyPlus’ software,widely recognised as the most accurate availablefor this type of work, and significantly moreaccurate than the SBEM software used for Part Lcompliance. This took account of the different

insulation values of the roof and rooflights, differinginternal and external temperatures, radiant heat onthe roof, and included the beneficial effect ofpassive solar gain through the rooflights. Resultsshow the effect of rooflight area on heat flowthrough the whole roof, which is the only heatingload affected by rooflight area: it did not assessheat loss through the rest of the building wherethere are many more variables.

Illumination levels inside a building for differentrooflight areas and types were also calculated. Thedesign illumination level, and efficiency of thelighting and lighting control systems define theenergy needed to provide artificial lighting. Theresults show the effect of rooflight area on annuallighting system energy use and allow the effects ofdifferent patterns of building use (eg designillumination levels and hours of use) to be assessed.

Data for the energy used by heating and lightingsystems was combined and converted intoequivalent CO2 emissions to show the overall effectthat rooflight area has on total CO2 emissions.

The findings prove conclusively that rooflightsprovide an overall energy benefit - with the level ofthat benefit depending on many factors,particularly the area of rooflights installed, design

APPENDIX 2 THE DE MONTFORT RESEARCH

10

30

50

70

90

0

20

40

60

80

2 4 6 8 10 12 14 16 18 20

Figure 1: Effect of rooflight area on CO2 emissions due to artificial lighting system

Ann

ual C

O2

emis

sio

ns d

ue t

o a

rtic

ial l

ight

ing

(kg

CO

2/m

2 )

Rooflight area (% of floor area)

9am-5pm 300lux

9am-5pm 600lux

24 hour 300lux

24 hour 600lux


illumination level, type of artificial lighting controlused and the pattern (hours) of building use.

Lighting level is measured in lux. The level oflighting required within a building will depend uponthe building’s use. The model created by theresearch allows lux levels to vary. The illustrationsbelow use 300 and 600 lux. A light level of 300 luxis moderate giving adequate lighting for generalactivities and circulation spaces such aspackaging areas. A light level of 600 lux would berequired where a degree of colour judgement wasrequired or more detailed visual tasks were takingplace such as in many retail and officeenvironments, or product assembly areas.

Figure 1 clearly shows that the greater the rooflightarea, the less artificial light is required - and hencethe lower the total power consumption. The higher

the illumination level, the greater the lightingsystem’s power consumption will be - and thegreater the saving which can be offered byincreasing rooflight area.

Figure 2 shows the overall effect of rooflight areaon CO2 emissions for a building used 9am-5pm.The red line shows the effect on emissions due tothe energy use of the heating system for heat lossthrough the roof (only), the blue lines show the

effects on emissions due to the energy use of thelighting system for both 300 and 600 lux (asshown in Figure 1), and the black line shows thesum total of heating and lighting.

For example, with 300 lux illumination and 9am-5pm use, there is a reduction in lighting system’sCO2 emissions from 14 to 1 kgCO2/m2 as rooflightarea increases from 0 to 20%. As hours of use

5

10

25

30

0

15

20

2 4 6 8 10 12 14 16 18 20

Figure 2: Effect of rooflight area on CO2 emissions - 9am-5pm

Tota

l CO

2 em

issi

ons

(kg

CO

2/m

2 )


Heating CO2

Lighting - 300lux

Total - 300lux

Lighting - 600lux

Total - 600lux

increase, the overall energy use increases and sodoes the saving: a saving of 18 kgCO2/m2 perannum is made for 24 hour use. At an illuminationlevel of 600 lux, an increase in rooflight area from 0to 20% results in a saving of 25 kgCO2/m2 for 9am-5pm use and up to 33 kgCO2/m2 for 24 hour use.

Increasing the rooflight area reduces the need forartificial light, cuts the energy requirement of thebuilding and reduces CO2 emissions.


Note that an increase in rooflight area (at leastwithin the range 0 to 20%) will result in a dramaticreduction in total CO2 emissions. Based ontraditional considerations of insulation value alone,it may have been expected that the heating energyrequirement would increase as rooflight areaincreased, but the research proves that for abuilding occupied primarily during the day this isnot the case. Passive solar gain through therooflights actually balances the insulation value, so

heating requirements are barely affected and by farthe dominant effect is the decreasing requirementfor artificial light as rooflight area is increased.

The worst case scenario for rooflights is a buildingthat is occupied 24 hours a day because duringthe night there are no benefits either from naturallight or passive solar gain – but even in thissituation rooflights still provide a very significantenergy benefit.

Figure 3 shows the overall effect of rooflight areaon CO2 emissions for a building used 24 hours aday. The red line again represents the heatingrequirement - and in this case it can be seen thatthe total heat loss through the whole roofapproximately doubles as rooflight area increasesfrom 0 to 20% since at night there is increasedheat loss through the rooflights which is notbalanced by any solar gain. However, in mostcases, the savings in lighting energy requirementstill far more than outweigh this.

With a lighting requirement of 600 lux the totalenergy use continues to drop as the rooflight areaincreases, up to 20%. Where the lightingrequirement is a relatively low 300 lux, at rooflightareas up to approximately 14%, the savings inlighting energy are the dominant effect and totalCO2 emissions fall as rooflight area increases; athigher rooflight areas the increase in heatingrequirement and decrease in lighting requirementare approximately equal, so the overall CO2

emissions then remain constant up to a rooflightarea of 20%.

10

30

90

100

0

50

70

2 4 6 8 10 12 14 16 18 20

20

40

60

80

Figure 3: Effect of rooflight area on CO2 emissions - 24 hour

Tota

l CO

2 em

issi

ons

(kgC

O2/

m2


Heating CO2

Lighting - 300lux

Total - 300lux

Lighting - 600lux

Total - 600lux


o at higher illumination levels, there aresavings as rooflight area is increased upto 20%, but the further savings asrooflight area is increased above 15% arerelatively minor

In summary, these results show that rooflight areaequal to 15% - 20% of floor area may be a usefulapproximation of the optimum rooflight area. Insome buildings there may be benefit from slightlyhigher rooflight areas, and occasionally theoptimum may be slightly lower, so there maysometimes be small further gains available fromadjustments in rooflight area - but in almost allcases a rooflight area of 15% - 20% will achievealmost all of the available savings in overall energyuse and CO2 emissions.

Conclusions of the De Montfort UniversityResearchThese examples look at 2 illumination levels (300and 600lux) and 2 patterns of use (9am-5pm and24 hour), clearly demonstrating that where use ofrooflights is appropriate:

• rooflights always make a positive contribution:omission of rooflights gives a very significantincrease in CO2 emissions

• in most buildings, savings continue to beachieved as rooflight area is increased up to 20%

• in buildings used 24 hours a day:

o there are savings as rooflight areaincreases up to 15% in all cases

o where illumination levels are relatively low,the savings as rooflight area is increasedfrom 10% to 15% are relatively minor, withvery slight increases in CO2 emissions asarea increases further, to 20%


FULL MEMBERS

Brett Martin Daylight Systems LtdSandford CloseAlderman’s Green Industrial EstateCoventry CV2 2QUTel: 024 7660 2022 Fax: 024 7660 2745Web: www.brettmartin.com

Filon Products LtdUnit 3 Ring Road Zone 2 Burntwood Industrial ParkBurntwoodStaffordshire WS7 3LQTel: 01543 687300 Fax: 01543 687303Web: www.filon.co.uk

Glazing VisionSaw Mills RoadDiss, Norfolk IP22 4RGTel: 0333 8000 881 Fax: 0333 8000 882Web: www.glazingvision.co.uk

Hambleside Danelaw LtdLong MarchDaventryNorthamptonshire NN11 4NRTel: 01327 701900 Fax: 01327 701909Web: www.hambleside-danelaw.co.uk

Lareine Engineering LtdUnit 1, Armadale Industrial EstateLower BathvilleArmadale, West Lothian EH48 2NDTel: 01501 731600 Fax: 01501 733828Web: www.lareineengineering.com

Lonsdale Metal Company LtdUnit 40 Millmead Industrial CentreMill Mead Road, London N17 9QUTel: 020 8801 4221 Fax: 020 8801 1287Web: www.roofglazing.co.uk

Surespan LtdLeamore CloseLeamore Enterprise ParkWalsall, West Midlands, WS2 7NLTel: +44 (0) 1922 711185 Fax: +44 (0) 1922 714099Web: www.surespancovers.com

Twinfix201 Cavendish PlaceBirchwood Park, BirchwoodWarrington WA3 6WUTel: 01925 811311 Fax: 01925 852955Web: www.twinfix.co.uk

Velux Company LtdWoodside WayGlenrothesFife KY7 4NDTel: 01592 778225Web: www.velux.co.uk

Xtralite (Rooflights) LtdSpencer RoadBlyth Riverside Business ParkBlyth, Northumberland NE24 5TGTel: 01670 354157 Fax: 01670 364875Web: www.xtralite.co.uk

ASSOCIATE MEMBERS

Jet Cox LtdCRH HouseUnits 1-3Prothero Industrial EstateBilport LaneWednesbury, West Midlands WS10 0NTTel: 0121 530 4230 Fax: 0121 530 4231Web: www.coxbp.com

Keylite Roof Windows (NI)Derry Loran Industrial EstateSandholes RoadCookstown, Co. Tyrone BT80 9LUTel: 028 86 758921 Fax: 028 86 758923Web: www.keyliteroofwindows.com

Kingspan LtdGreenfield Business Park 2Holywell, FlintshireNorth Wales CH8 7GJTel: 0800 587 0090 Fax: (0) 1352 716111Web: www.kingspanpanels.com

Roofglaze LtdUnit 4 Little End RoadEaton SoconSt NeotsCambridgeshire PE19 8JH Tel: 01480 474797 Fax: 01480 474774Web: www.roofglaze.co.uk


SPONSORS

Reichhold UK Ltd54 Willow LaneMitchamSurrey CR4 4NA Tel: 020 8648 4684 Fax: 020 8640 6432Web: www.reichhold.com

The Rooflight CompanyWychwood Business CentreShipton-under-Wychwood OX7 6XUTel: 01933 833108 Fax: 01993 831066Web: www.therooflightcompany.co.uk

Büfa Composite Systems GmbH & Co.KGHone Looge 2-8. 26180 Rastede.GermanyTel: 07876 030296

SECRETARIAT

Lorraine Cookham43, Clare CroftMiddletonMilton KeynesMK10 9HDTel: 01908 692325 Fax: 01908 674122Mobile: 07989 872 149Email: [email protected]: www.narm.org.uk

(November 2014)

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