77145-08-09 REFURB QXD8-V6b:EST Best Practice … · Sustainable refurbishment (2010 edition) 5 Introduction considered in SAP, as well as those from appliances and cooking which

Sustainable refurbishment

CE309

Towards an 80% reduction in CO2 emissions,water efficiency, waste reduction, andclimate change adaptation

2 Sustainable refurbishment (2010 edition)

Contents

1. Introduction 41.1 The task ahead 41.2 Minimum thermal standards for refurbishment 61.3 Trigger points - opportunities for including improvements 71.4 Carbon Emissions Reduction Target (CERT) 81.5 Refurbish or demolish/rebuild? 8

2. House type base cases 9

3. Energy efficiency measures - insulation 113.1 Walls 113.2 Roofs 173.3 Floors 203.4 Windows and doors 22

4. Energy efficiency measures - airtightness and ventilation 244.1 Reducing unwanted air leakage 244.2 Providing adequate controlled ventilation 25

5. Energy efficiency measures - heating systems/control and hot water systems 285.1 Fuel choice 285.2 Recommended upgrade package 285.3 Seasonal efficiency of boilers 295.4 Heating and hot water systems 295.5 Electric storage heating systems 305.6 Smart meters 30

6. Energy efficiency measures - lighting and appliances 316.1 Lighting 316.2 Appliances 32

7. Installation of renewable energy 337.1 Solar thermal hot water 337.2 Solar photovoltaic 347.3 Micro combined heat and power 347.4 Ground source heat pump 357.5 Air source heat pumps 357.6 Biomass 357.7 District heating and combined heat and power 367.8 Wind 367.9 The Low Carbon Buildings Programme 37

8. House types revisited 38

9. Water efficiency measures 409.1 Legislation 409.2 Trigger points for water efficiency measures 409.3 Water metering 419.4 Water efficiency fittings and appliances 419.5 Rainwater harvesting and grey water recycling 439.6 Water efficiency labelling 43

Sustainable refurbishment (2010 edition) 3

10. Recycling of waste and materials 4410.2 Construction waste from domestic refurbishment 4410.3 Domestic waste and provision of recycling facilities 45

11. Climate change adaptation 4611.1 Summer overheating 4611.2 Making use of existing thermal mass 4611.3 Flooding 4711.4 Storm 4711.5 Future proofing 4711.6 Trigger points for considering climate change adaptation measures 48

Appendix A – Glossary of technical terms 50

Appendix B – Relevant organisations and websites 52

Appendix C – Further information 53


The Climate Change Act (2008) requires that by2050, the UK’s annual carbon dioxide (CO2)emissions should be reduced by 80% compared to1990 levels. Home energy use is responsible forover a quarter of UK CO2 emissions whichcontribute to climate change. We must thereforeaim to reduce CO2 emissions from all dwellings byan average of 80% to help meet the UK’s longterm goal.

However this isn’t a straightforward target to meet,especially since the UK has a high percentage ofolder homes with poor energy performance. What’smore, because homes generally only have a majorrefurbishment every 50 years or so, the opportunityto improve energy performance before the 2050deadline will be lost unless energy efficiency measuresare incorporated next time an upgrade is done.

An 80% reduction in emissions from existinghousing is nonetheless very achievable. The key isto take a whole house approach. This means takinginto consideration the type of house, then lookingat all appropriate energy efficiency measures,examining renewable energy options and includingwater and waste reduction measures. Whetherroofing, central heating, re-plastering or a completerefurbishment, any upgrade work offers anopportunity to improve energy efficiency. The key isto do the maximum possible at each opportunity,and to consider each job in context within thewhole house.

This guide, developed by the Energy Saving TrustHousing programme, provides an integratedpackage of measures that will enable builders,developers and householders to hit the demanding80% target and make radical improvements toenergy performance that go beyond currentbuilding regulations.

We start by presenting a base case scenario of themost common housing types. Then we introducethe energy, water, waste and climate changeadaptation measures to be considered in a wholehouse approach to refurbishment. Finally, we revisitthe base case scenarios to show what is possible interms of energy performance.

Links to more in-depth reference materials are listedin Appendix C and provide more detailed technicalinformation when it is needed.

1.1 The task aheadIn 1990 the level of CO2 emissions from housingalone was in the region of 160 million tonnes peryear (see figure 1). It has reduced very little since 1990even though changes to the building regulations havemade newly built dwellings more energy efficient.However, these new houses still emit significantamounts of CO2 each year. Emissions from housingstock continues to increase as we attempt to meetthe ever-growing demand for housing in the UK.

The UK Government has signalled its intention thatfrom 2016 all newly built dwellings should be netzero carbon, and therefore these should not addfurther to CO2 emissions. This measure will stop thegrowth in CO2 emissions. However only bysignificantly improving the existing housing stockcan we achieve the required overall 80% cut in CO2

emissions across the entire housing stock. So by2050, CO2 emissions from most existing dwellingwill need to be no more than about 1.5 tonnes peryear1. Emissions from dwellings vary because oftheir size, build form, number of occupants andtheir lifestyle. Larger family dwellings will emit morethan 1.5 tonnes of CO2 per year, while single-occupied flats will emit less.

The Government’s approved methodology fordetermining emissions, Standard AssessmentProcedure (SAP), predicts these emissions in termsof kilograms of CO2 per square metre of floor areaper year. Using this measure, and using an averagedwelling size of between 75-100m2, a reasonableCO2 emissions target to aim for would be in theregion of 15-20kg/m2/yr for most existing dwellings.A note of caution though - these target figuresinclude both the emissions that are currently

1. Introduction

1. This is estimated from an 80% cut in emissions from 160 million tonnes per year to no more than 32 million tonnes per year, sharedby all the dwellings that will still be emitting CO2 in 2050.

2020

and where the effort needs to

come from

300

250

200

150

100

50

0

Mto

nn

es C

O2

equ

iv.

Figure 1: Built environment contribution to UK CO2

emissions (CLG 2008)


Introduction

considered in SAP, as well as those from appliancesand cooking which are not2.

Additionally, it has been estimated that about 24 million homes3, that either exist now or are builtbefore 2016, will still exist in 2050. This means thaton average, some 600,000 homes will need to berefurbished to a high degree of thermalperformance each year to reach the 80% target.Before embarking on a range of measures forimproving the thermal performance of a dwelling, itis important to know where you are starting from.

1.1.1 Finding out how an existing dwellingperformsThe Energy Performance Certificate (EPC) wasintroduced in August 2007 as a way of estimatingthe overall thermal performance of a dwelling (seefigure 2). The rating system is similar to that ofdomestic appliances/boilers etc., with band G beingthe lowest (i.e. worst performing dwelling), andband A the highest.

Figure 3 shows the average performance of thehousing stock is band E rated but there is a long tailof poorly performing housing that are only F or Grated, and it is here where significant CO2 savingscan be made.

Currently an up-to-date EPC is only required whena dwelling changes hands through a sale or a new

2. To estimate the CO2 emissions from appliances/cooking we have used the calculation method contained in the Code for SustainableHomes (CLG 2007).

3. This estimate is from the number of dwellings that exist now and emit CO2, some 26 million, plus an estimated one million newhomes that will be built between now and 2016, minus the potential number of existing dwellings that will be demolished before 2050,estimated to be up to three million (New Tricks with Old Bricks – Existing Homes Agency/Building and Social Housing Foundation 2008).

3737

8686

Figure 2: EPC ratings

5 or less

0%

5%

10%

6 to 10

11 to 15

16 to 20

21 to 25

26 to 30

31 to 35

36 to 40

41 to 45

46 to 50

51 to 55

56 to 60

61 to 65

66 to 70

71 to 75

76 to 80

81 to 85

86 to 90

91 to 96

96 to 100

SAP range

15%

20%

G F E D C B A

Perc

enta

ge

of

dw

ellin

gs

in t

he

stat

ed r

ang

e

Figure 3: Performance of UK’s housing stock

letting. However there is no reason why an EPCcannot be obtained from a Domestic Energy Assessor(DEA) as part of the planning of a refurbishmentproject. The certificate’s recommendations can beconsidered alongside the guidance in this publication.

Ultimately, if we are to reach our target of an overall80% cut in CO2 emissions across the housing stockby 2050, the majority of dwellings will need anenergy performance rating no worse than band B.


Introduction

1.1.2 Achieving best practical level ofrefurbishmentAlthough some of the guidance presented here maybe familiar, the levels of performance are significantlyhigher than has previously been recommended.

In most cases, national building regulations or localplanning policies will already require a minimumlevel of thermal performance when refurbishing.However the only additional cost to improvethermal performance further is the cost of the extrainsulation – in most cases, the installation andlabour costs will be the same.

For up-to-date information regarding the costs ofcarrying out the measures presented in this guide,please refer to www.energysavingtrust.org.uk/housing/existing/housetypes

1.2 Minimum thermal standards forrefurbishment

1.2.1 Building control

Anyone carrying out building work on a propertycontrolled by building regulations is required by lawto assess its performance with regards to theconservation of fuel and power.

The minimum standards set by building regulationsvary across the UK. The following guidance shouldbe consulted to determine the different technicalperformance requirements, definitions and procedures:

• Communities and Local Government (CLG)issues a series of 'Approved Documents'containing guidance on compliance in Englandand Wales. Approved Document L1B providesguidance as to the minimum level of thermalperformance needed when carrying outbuilding work on existing dwellings.

• The Scottish Building Standards Agencyprovides guidance on complying in Scotlandthrough a system of technical handbooks -section 6 deals with energy use.

• In Northern Ireland, The Building Regulations Unitof the Department of Finance and Personnelprovides guidance via a series of Technical Booklets- Technical Booklet F deals with energy use.

• In Wales, currently building regulations are thesame as in England so again, refer toApproved Document L1B.

Building regulations place minimum standards, i.e.they control thermal elements, fixtures and fittingswhich are being worked on, added to, or replaced.

Items controlled by building regulations

• Alterations and renovations to building fabric, i.e. walls, roofs, and floors.

• Home conversions to lofts or garages, etc.

• Home extensions.

• Replacing windows, doors, and rooflights.

• Replacing or upgrading heating and hot water systems, including controls.

• Other building services, i.e. lighting and ventilation.

You are advised to check with the local buildingcontrol team whether or not your proposal requiresapproval under the building regulations.

When working on, adding to, or replacing any ofthe above items, you must check what minimumbuilding regulation requirements apply. At the sametime, remember that building regulations are theminimum legal standard – so this is an idealopportunity to consider specifying the best practicallevel of performance. Once refurbished, a dwellingis unlikely to be significantly altered again withinthe foreseeable future.

It should also be noted that work to improve thethermal performance of the fabric and servicescould be required when carrying out either achange of use or a material alteration. These mayapply even if no work is actually proposed to bedone to the fabric.

For more detailed guidance on how buildingregulations may require thermal upgrading ofexisting fabric and improved building services,please see www.energysavingtrust.org.uk/housing/buildingregulations or contact your localbuilding control team.

In order to achieve an overall 80% reduction inCO2 emissions from dwellings, it will be necessaryto take every opportunity, where practical, toachieve the best possible level of thermalupgrading during a refurbishment.


Introduction

1.2.2 Planning permissionComplying with the building regulations is aseparate matter from obtaining planning permissionfor the work being undertaken. Planning permissionis mainly required when carrying externalalterations, such as adding external wall insulation,raising the roof line to accommodate over rafterinsulation, or building some types of extension, etc.Planning authorities may also require improvementsin the energy efficiency of an existing dwellingwhich is undergoing work that is subject toplanning permission.

Although it is generally the case that internal workwill not require planning permission, this may notbe the case if the property is listed or situated in aconservation area. Where the existing dwelling is ofhistoric or heritage value, it is essential to consultwith English Heritage, Historic Scotland, Cadw orNorthern Ireland Environment Agency, as to thebest way to incorporate energy efficiency measuresinto the dwelling in a sympathetic way which willnot cause long-term damage to its fabric andstructure.

It is therefore essential to discuss your proposalswith the local planning authority as early as possiblein the design stage to ensure all planning legislationis also adhered to.

1.3 Trigger points - opportunities forincluding improvementsHome improvements often provide the opportunityto improve levels of energy efficiency. For example,when installing a new kitchen, you could alsochoose to upgrade the internal wall insulation,install low energy lighting and appliances, low flowrate taps, floor insulation, efficient ventilation withheat recovery and recycling facilities.

This guide can be used to determine theopportunities for sustainable refurbishment. It usesan elemental approach to refurbishment byfollowing these trigger points and ensuring futureopportunities for improvements are not missed.Table 1 illustrates some of the opportunities.

Table 1: Trigger points for energy efficiency

Opportunity

Mo

vin

g in

or

ou

t

Exte

nd

ing

Loft

co

nve

rsio

n

Ad

din

g a

co

nse

rvat

ory

New

kit

chen

New

bat

hro

om

Re-

roo

fin

g

Re-

pla

ster

ing

Rep

laci

ng

win

do

ws

Re-

wir

ing

Re-

flo

ori

ng

New

hea

tin

g

Rep

lace

men

t b

oile

r

Rep

lace

men

t h

ot

wat

er c

ylin

der

Re-

ren

der

ing

Measures to consider

Wall insulation

Roof Insulation

Floor insulation

Heating controls

Cylinder/pipe insulation

Airtightness improvements

Efficient ventilation

Windows

Low energy lighting

Energy efficient appliances

KeyGood opportunity Possible opportunity


Introduction

1.4 Carbon Emissions Reduction Target(CERT)CERT requires certain gas and electricity suppliers tomeet a carbon reduction target in domesticproperties. It runs from 2008 until 2011 and isprojected to reduce emissions by 154MtCO2 overthe lifetime of the measures, the equivalent of ayear’s worth of UK household CO2 emissions.Funding of this scheme is estimated at about £3.3 billion over three years.

CERT is dominated by insulation measures withsmall contributions to high efficiency windowreplacements and microgeneration technologiesproducing electricity (e.g. solar photovoltaics (PV))and heat (in particular solar hot water and groundsource heat pumps). Cavity wall and loft insulationsare the main contributors though, and betweenthem they make up over 90% of the carbonsavings attributable to insulation, however CERTfunding is also available for solid wall insulation.

A further £350 million will also be contributed bythe energy suppliers to a new Community EnergySaving Programme (CESP). This will involve localcouncils, voluntary organisations and energysuppliers visiting householders street-by-street tooffer free and discounted central heating and otherenergy saving measures. The programme isdesigned to target those households most in needof energy efficiency improvements. It will operate in100 localities and the Government estimates thatsome 90,000 homes will benefit over the next three years.

1.5 Refurbish or demolish/rebuild?The UK has the oldest housing stock in thedeveloped world with 8.5 million properties over 60 years old. One of the problems that localauthorities, regional development agencies andprivate developers face when choosing whether torefurbish or rebuild is that the issues they need toconsider are broad-ranging and complex. This hasbeen explored and reported in recent majorpublications, such as ‘New tricks with old bricks’ byEmpty Homes Alliance with Building and SocialHousing Foundation, and ‘Knock it down or do itup’ (IHS BRE press). There are many factors whichshould be considered before a decision to demolishis made, such as the embodied energy of thereplacement dwelling, local housing needs, DecentHomes requirements and structural condition. Theseissues are fully explored in these publications.


This section focuses on how typical house typesperform, with sections 3, 4, 5 and 6 describing howto improve the energy efficiency.

Table 2 below summarises the performance of eight‘base case’ house types that we have used.

It is not possible to demonstrate every differenthouse type that exists, nor is it possible to show aselection of different scenarios for these housetypes. However, it is hoped that sufficientinformation is provided in order to understand thatthe upgrading of any type of existing dwelling interms of energy efficiency, even those built recently,is relatively straightforward.

To illustrate the additional detail available, we haveincluded the full performance information on oneof the cases, a typical 1950s semi-detached (seefigure 4) , built with a main wall of clear brick andbrick cavity.

In section 8, we show how energy efficiencymeasures can improve the performance of thishouse from band E to band A, through fabricimprovements and renewable technology.

Total CO2 emissions for this house are 72kg/m2/yr.This equates to about 6.5 tonnes of CO2 per year,putting the house in band E. As the dwelling is notwell insulated, about 3.5 tonnes of the CO2 emissionscome from energy used to heat the home.

2. House type base cases

Table 2: The performance of some typical existing dwellings

House type Floor area (m2) Existing EPC Band Existing total CO2 emissions

Tonnes/yr kg/m2/yr

Solid walled detached 104 F 13.7 132

Period end terrace 89 F 6.5 73

Period mid terrace 85 E 6.7 79

1950s semi-detached 90 E 6.5 72

1960s bungalow 64 E 6.2 98

1980s detached 111 E 7.7 69

1980s mid floor flat 61 E 4.2 68

Post 2002 mid terrace 79 C 3.4 43

The dwelling’s total emissions are about average forall UK housing. However because this house typeperforms so poorly, the fabric and servicesimprovements recommended in this guide offersignificant savings in CO2 emissions.

House type base cases


52 52

Typical existing features

Element Fabric U-value

Insulated roof, 100mm mineral wool. 0.41 W/m2K

Unfilled brick cavity walls.4 1.39 W/m2K

Uninsulated suspended timber floor. 0.57 W/m2K

Replacement UPVC double glazing. 3.10 W/m2K

Doors, half glazed solid timber. 3.70 W/m2K

Other features

• Natural ventilation.

• Typical envelope air leakage rate12m3/m2/h @ 50 Pa.

• Regular boiler 78% efficiency,programmer and room thermostat,electric fire secondary room heating.

• Water storage cylinder 150 litrecapacity, loose jacket on cylinder, nopipe insulation.

• No dedicated low energy lightfittings.

CO2 emissions (kg/m2/yr)Typical energy demand

Energy Total energy Energysource demand (kWh/yr) demand

per m2

(kWh/yr/m2)

Gas Main heating 21,970and hot water 258

Cooking 1,280

Electric Secondary heating, lights, 2,150 52fans and pumps

Appliances 2,510

1950

s se

mi-

det

ach

ed h

ou

se, f

loo

r ar

ea 9

0m2

Centralheating

Domestichot water

Lights/fans/pumps

Cooking &appliances

75

50

25

0

Table 3: CO2 emissions for 1950s semi-detached house, floor area 90m2 before improvements

Figure 4: The EPC rating for this house type incurrent state would typically be rated at band E

4. RDSAP default U-value for age.


Insulating the major elements of dwellings is one ofthe most effective ways to improve the energyperformance of the UK’s existing housing stock.

3.1 WallsThree types of wall construction dominate in the UK – solid wall, cavity wall and timber frame. Eachof these is described briefly below before we go onto explore the insulation options available for eachwall type.

Solid wall - approximately one in every five homesin the UK today has traditional 220mm solid brickwalls. This was the main form of construction untilthe 1930s. Other types of solid wall constructioncan be found, for example systems using no-finesconcrete or pre-cast concrete panels. Thesebuildings suffer high fabric heat loss, which leads tohigh fuel bills. Unfortunately, they are often occupiedby those least able to pay higher energy bills.

Solid walls can be thermally improved with eitherexternal or internal insulation.

Cavity wall - since the late 1920s, masonry cavitywalls have been used in house constructionthroughout most of the UK (see table 4) – thecavity was originally used to counteract damp.Cavity-walled houses are relatively easy to improvethermally as the cavity can be filled with insulation.Where this is not appropriate, they can be insulatedin a similar way to solid walls.

Even where cavity walls are insulated, theirperformance can be significantly enhanced withextra internal or external insulation.

‘Modern’ timber frame - for the past 30 years,timber-frame homes in the UK have been built withinsulation filling the studwork frames. Houses builtbetween 1920 – when ‘modern’ timber-frameconstruction was introduced in the UK, and themid-1970s, when the building regulations firstrequired a maximum wall U-value of 1.0 W/m2K –will have had little or no insulation.

The construction system used in a particularproperty should be identified before refurbishmentstarts. While it is easy to recognise early examplesof timber-frame housing, later designs such asthose built in the 1960s and 1970s look very similarto buildings of conventional masonry construction.

Where insulation has been built into the timberframe walls, it is likely to be very thin (25 – 50mm)and it may now be in poor condition. This cancause high heat loss and condensation, reducingcomfort for the occupants. Insulation can easily beadded to timber frame walls, but the process canbe very disruptive to householders and it is bestcarried out while the property is unoccupied.

3. Energy efficiency measures – insulation

Table 4: Evolution of cavity wall construction

Decade Development of cavity walls Cavity width

1920s Solid walls still dominate, but cavity walls Typically between 50mm and grow in popularity. 100mm

1930s Cavity walls become main form of Typically between 50mm and construction, but some solid walls still built. 100mm

1940s and 1950s Cavity width becomes standardised. 50mm

1960s Concrete blocks used to inner leaf. 50mm

1970s Lightweight blocks are introduced. 50mm

1980s Partial fill cavity wall insulation introduced, 60-70mmcavity widths increased.

1990s onwards Full fill cavity wall insulation becomes 50-100mmdominant.

Figure 5: Evolution of masonry construction based in information gathered by English Housing ConditionSurvey (2008)

0

500000

1000000

1500000

2000000

2500000

3000000

pre 1945 End terrace

pre 1945 Mid terrace

Solid

Uninsulated cavity

Insulated cavity

Nu

mb

er o

f d

wel

ling

s

pre 1945 Semi detached

pre 1945 Detached

pre 1945 Bungalow

pre 1945 Flat

Two points immediately jump out from figure 5 –the number of solid-walled houses that exist today,and the number of cavity walls that remain to befilled. Since houses with uninsulated solid wallsmake up the majority of the existing stock, thisseems a good place to start.

3.1.1 Solid wall insulationThe heat lost through an uninsulated solid wall istypically over 50% greater than through anuninsulated cavity wall. However refurbishing solidwall dwellings in an energy efficient way raisesparticular problems for specifiers. The first isdeciding whether to use internal or external wallinsulation. Both options offer advantages anddisadvantages and the final decision often dependsupon the scope of the work being planned. Forexample, if walls are to be re-rendered it clearlymakes sense to add external insulation while this isbeing done. And the work can be carried out whilethe dwellings are occupied, although it may causesome disruption. On the other hand, if major workis being carried out inside the dwelling (which hasto be vacant for this process) then internalinsulation may be the better choice.

(i) Internal insulation

Internal insulation typically consists of either a built-up system with insulation between and across astudwork frame, or dry lining in the form of alaminated insulating plasterboard (known as rigidinsulation board).

Insulated studworkThe insulation is held between a metal (orpreferably timber) framing system and finished witha vapour control layer and plasterboard or thermallaminate plasterboard. This approach allows for avariety of insulation thicknesses.

For small dwellings where internal space cannotreadily be sacrificed, a high-performance rigidinsulation board or an in-situ applied closed-cellPUR/PIR insulation may be preferable, either inaddition to internal studwork, or as a single-layerinstallation.

In-situ applied closed-cell insulation can be applieddirectly to the plaster, or if plaster is to be removed,directly onto the brickwork. This provides insulationand greatly reduced air leakage, in a singleapplication.

Energy efficiency measures – insulation



Thermal laminate plasterboardThermal laminate plasterboard consists ofplasterboard with a backing of insulation. The rigidinsulation backing can be specified in a variety oftypes and thicknesses. Thermal laminateplasterboard is usually fixed to the wall surfaceusing continuous ribbons of plaster or adhesive,plus additional mechanical fixings, or onto 25mmthick softwood battens. The joins between theboards should be taped and sealed to help preventair leakage and interstitial condensation.

Most types of thermal laminate plasterboardprovide better insulation than comparablethicknesses of fibre-based insulation (such asmineral wool). It is therefore possible to achieve the

same thermal performance using thinner insulation(which can be a major asset for small dwellings).

Before thermal laminate plasterboard is installed,the surface of the wall must be carefully prepared.Where existing plaster is removed and the brick isuneven, the wall must be levelled using a suitableparge coat to provide an even surface for fixing ofthe thermal laminate plasterboard, whether it is tobe fitted directly or on battens. The parge coat canalso greatly reduce air leakage. The balancebetween airtightness and ventilation is discussedlater in section 4 of this guide.

Table 5 shows how well a solid wall can be insulated.It also shows how thicker insulation (or insulationwith lower thermal conductivity5) can achieve


Figure 6: Insulation being inserted between studwork Figure 7: Thermal laminate plasterboard installation

Table 5: U-values of typical upgraded 220mm solid brick walls using thermal laminate plasterboard or in-situ applied closed cell insulation(W/m2K). N.B Uninsulated U-value of wall is 2.10W/m2K

Thermal conductivity of insulation (W/mK)

Internal 0.015 0.025 0.035insulation (advanced insulation) (high performance (typical insulation)thickness insulation)

U-values of insulated solid wall (W/m2K)

25mm 0.42 0.59 0.71

50mm 0.25 0.37 0.47

75mm 0.18 0.27 0.35

100mm 0.14 0.21 0.28

5. Thermal conductivities of various types of insulation can be found in the Energy Saving Trust publication ‘Insulation materials chart –thermal properties and environmental ratings (CE71)’. See www.energysavingtrust.org.uk/housing/publications

Vapourcontrollayer

Vertical timber studs at 600mmcentres to suit typical 1200mmwide plasterboard

Insulationinsertedbetweenstudwork

Electrical cables fixed beforeinsulation is installed

Batten for fixing skirting tofinished wall

Repairplasterfinishwhereskirting isremoved

AdditionalmechanicalfixingsRibbon of

adhesive

a really high level of thermal performance. The onlyextra cost of 100mm thickness compared to 25mmis the cost of the insulation. The labour andpreparation costs and the time involved are aboutthe same. But using 100mm of insulation instead of25mm reduces heat loss through the wall by abouttwo-thirds, and produces a finished wall with a U-value that is generally better than most currentnewbuild dwellings.

One disadvantage of internal insulation is that itcan introduce numerous thermal bridges, forexample at junctions where internal walls or floorsmeet the external wall. We are investigating theeffects of these heat loss paths in existing dwellings,and plan to publish specific guidance on how toreduce the effects of thermal bridging shortly.

(ii) External wall insulation

External wall insulation is generally a moreexpensive way to insulate solid-walled dwellings.However for existing external elevations that are inneed of periodic re-rendering, or where extensiveremedial action is needed, for example to preventrainwater penetration, then the only extra cost ofthe upgrade is the insulation itself. Re-roofing isanother point at which external insulation may becost effective.

Installing external wall insulation does have someadvantages over using internal insulation. Occupantscan remain in the dwelling during the work – thereis less thermal bridging because the insulation layeris continuous, and it can both improve thedwelling’s appearance and extend its lifespan.

External wall systems are made up of an insulationlayer fixed to the existing wall (using adhesives andmechanical fixings depending on the type ofinsulation to be used) and a protective render orcladding finish. The system chosen should beapproved by a suitable independent authority, andthe Insulated Render and Cladding Association (INCA)holds a register of proven systems and installers.(See Appendix B for relevant organisations.)

Wet render systemsMost external render systems consist of either athick sand/cement render applied over a wire mesh,or a thinner polymer based cement render appliedto a glass reinforced plastic scrim see figure 8.

Dry-cladding systemsThe use of dry-cladding systems allows for greaterflexibility of external appearance and could allowfor the design to meet local planning requirementsusing, for example:

• Timber panels.

• Stone or clay tiles.

• Brick slips (figure 9).

• Aluminium panels.



Figure 8: Wet render system

Figure 9: Brick slip cladding

The improvement in thermal performance mainlydepends upon the thickness of insulation provided.Table 5 can also be used as a guide as to what U-values can be achieved using external wallinsulation.


3.1.2 Cavity wall insulationUnfilled cavity walls can be filled at any time, withheat loss through the walls being reducedsignificantly, by up to 60% in most instances. Afterloft insulation, providing cavity wall insulation is themost cost-effective insulation measure.

If the internal surface is being replaced, a thermallaminate plasterboard can further improve thethermal performance.

(i) Description

Installing cavity wall insulation usually takes lessthan half a day and the occupants can remain inthe dwelling. The work should be carried out by aspecialist contractor who can provide a CavityInsulation Guarantee Agency (CIGA) guarantee, orin the case of injected polyurethane foam, amanufacturer’s guarantee authorised through theBritish Urethane Foam Contractors Association(BUFCA). The National Insulation Association (NIA)holds a register of proven systems and installers,and the British Board of Agrément (BBA) provides acertification scheme for installers and products. Aninspection is undertaken prior to installation toassess the wall’s suitability which covers factors such as the exposure of wall to driving rain, themasonry materials used and pointing of themasonry. It is recommended that cavities of lessthan 50mm should only be filled with in-situapplied closed cell insulation. Any defects ordampness problems should be put right beforework begins. If all is satisfactory, the installationprocess proceeds as follows:

• Injection holes are drilled through the mortarjoints according to the drilling patternspecified in the BBA certificate, which istypically at 1m intervals.

• Cavity barriers are installed to prevent the fillentering the cavities of adjacent properties.

• Air ventilators that cross the cavity are sleeved(or sealed, if obsolete).

• Air bricks and balanced flues should besleeved.

• The insulant is injected into the wall cavity.

• Quality checks are carried out on the fillmaterial prior to making good the injectionholes.

• Injection holes are filled with colour-matchedmortar or render.

N.B. Polystyrene cavity wall insulation should not beused if there are any unprotected PVC cables in thecavity, or if there are PVC cavity trays or damp proofcourses.


Figure 10: Insulation injected into the cavity

Figure 12: Insulation being injected into the wall

Figure 11: An injection hole prior to filling

Insulationinjectedthroughholes inouter leaf

Insulationis blowninto thecavity

(ii) Suitability

Most masonry cavity walls can be filled withinsulation, especially those under 12 metres inheight built after 1930. There are also systemsavailable for buildings up to or over 25 metres inheight and a few even taller buildings have beensuccessfully cavity-filled following suitableassessment.

Almost all of the systems on the market are approvedfor use in all parts of the UK. However, they assumethat the outer leaf is built for local exposureconditions so that rainwater penetration is minimal.

Where cavity walls are not suitable for cavityinsulation, for example when there is only a partialcavity, they can be treated in the same way as solidwalls and have internal insulation installed.

(iii) Benefits of cavity wall insulation

Cavity wall insulation can significantly reduce heatloss through the wall. Performance depends on theexisting construction as well as the properties of theinsulating material used. Table 6 shows theimproved thermal performance achieved withvarious insulation materials.



Table 6: U-values of typical upgraded existing cavity walls


Existing brick/ 0.025 0.035 0.045cavity/brick wall

Cavity width to be filled U-value of filled cavity wall (W/m2K)

50mm 0.46 0.58 0.67

75mm 0.35 0.44 0.52

100mm 0.22 0.29 0.36

Brick/50mm cavity/lightweight block wall 0.42 0.51 0.58

Table 7: Improved U-values of further upgrading of filled cavity walls (W/m2K)

Thermal conductivity of internal insulation (W/mK)

Existing cavity filled wall 0.015 0.025 0.035

Year built Existing U-value U-value of upgraded wall (W/m2K) - with additional20mm internal insulation

1986 - 1995 0.60 0.36 0.44 0.48

1995 - 2002 0.45 0.30 0.35 0.38

2002 + 0.35 0.26 0.29 0.31

with additional 40mm internal insulation

1986 - 1995 0.60 0.25 0.33 0.38

1995 - 2002 0.45 0.23 0.28 0.32

2002 + 0.35 0.20 0.24 0.27

with additional 60mm internal insulation

1986 - 1995 0.60 0.20 0.27 0.32

1995 - 2002 0.45 0.18 0.24 0.28

2002 + 0.35 0.16 0.21 0.24


(iv) Upgrading existing cavity filled walls

Houses with cavity wall insulation can be furtherimproved by internal or external insulation. Manyhouses have only ‘partial fill’ cavity insulation whichcannot be topped up, so internal insulation wouldmake a significant difference. Over the last decadeor so, internal wall lining has changed from wetplaster finish to mainly plasterboard on dabs. Thereare no technical reasons why the walls of evenrecently built dwellings cannot be improvedsignificantly. And it is likely that they will needrefurbishment at some point before 2050. Thepotential improvements from adding internalinsulation are detailed in table 7.

External wall insulation may not be suitable forcavity walls with a clear cavity, as convection of theair in the cavity may reduce the thermalperformance of the wall.

3.1.3 Timber frame and other wall typesOther common wall constructions can also benefitfrom extra insulation. However specialist adviceshould be sought and each dwelling type treatedon a case-by-case basis.

(i) Timber-framed dwellings

There are currently some 100,000 timber frameddwellings with little or no wall insulation. Evenmore recent timber framed dwellings, which willhave a full fill of insulation, could still benefit fromlaminated insulated plasterboard when it is time toreplace the existing wall lining (see figure 13below). Extra plasterboard may however berequired in this case to achieve the correct level offire resistance. For this and other technical reasons,

such as condensation control, professional guidanceis needed before considering how best to thermallyimprove the walls of any timber framed dwelling.

(ii) Other non-traditional methods of construction

There are many other non-traditional buildings thatcan benefit from wall insulation, such as:

• Wimpey no-fines (cast in-situ) concrete panels.

• Airey (pre-cast) concrete panels.

• BISF (steel framed).

For cast in-situ and pre-cast concrete walls (whichare in sound condition), external insulation is better,as the concrete construction is particularlysusceptible to thermal bridging.

Steel frame systems can be insulated internally orexternally. However specialist knowledge is neededto prevent problems with condensation on the non-galvanised frame members. The constructionconsists of a steel frame of rolled steel angles andchannels. For external insulation, the frame is cladwith rendered expanded metal lathing up to firstfloor level, and vertically profiled galvanised steelsheet above. Internally, the walls are lined with aglass fibre insulation blanket, and plasterboard on atimber frame (see figure 14).


Figure 13: Laminated plasterboard for timberframed dwellings

Figure 14: Steel frame system

3.2 RoofsLoft spaces are generally the easiest part of adwelling to insulate. Insulation can be placed atceiling or rafter level at any time, without muchdisruption to the occupants. Attic rooms and flatroofs can also be insulated, but this work shouldonly be done by professionals during a conversionor major renovation.

Existing timber weather boarding withventilation behind

Existing timber sheathing

Existing timber frame with plasterboardremoved to allow inspection andpreservative treatment of timber structure

If suitable, extra insulation should beadded to cavity

New plasterboard thermal laminate withintegral vapour control layer, nailed totimber studs

Note: an extra layer of plasterboard may be required forfireproofing. This should be fitted directly to the studs.

Plasterboard on timbersubstructure

Quilt insulation Profiled steelcladding

Steelcolumn

Externalfinish

Timber floor joist

Steel floorbeam

3.2.1 Insulation at ceiling levelLaying insulation at ceiling level is relativelystraightforward. The first layer is placed betweenthe ceiling joists and its thickness is determined bythe depth of the joists and the presence of anyexisting insulation. The top of this layer ofinsulation should be no more than 25mm eitherabove or below the top of the ceiling joists.Additional layers of insulation can then be placedon top, this time laid across the joists (see table 8).

There are three main technical issues to consider –condensation, storage and wiring.

Adequate ventilation in ‘wet’ rooms such askitchens, bathrooms and shower rooms will alsoreduce the risk of moist air entering the roof space.

It is also necessary to maintain or improve existingroof void ventilation. This is usually providedthrough gaps between the wall and soffit at eaveslevel, or through ventilator tiles positioned at a lowlevel on the roof slope. Roof insulation must notblock this ventilation. Some roofs may have noobvious means of ventilation (for example havingno sarking felt, or using a breathable felt). In thesecases, there is little risk of condensation. Here, it isrecommended that insulation is placed as far aspossible into the eaves to reduce thermal bridging.

StorageIf a small storage area is required in the roof void,then this should be located as close to the lofthatch as possible. A higher performance materialshould be used below the proposed storage areabecause the insulation will be thinner by necessity.The storage decking itself should be eitherlaminated with 100mm of rigid insulation, orsupported off 100mm deep cross timbers to spreadthe load between adjacent ceiling joists, again withinsulation placed between. Any boxing over existingrecessed lighting should also be insulated withhigher performance materials to make up for thereduced thickness of insulation in this spot.

WiringIt is most important that insulation is not laid overany existing cables, as this prevents them fromdissipating heat when in use. Continued heatingwill damage the cables, which could in turn lead toa fire risk. If the cables have sufficient slack, theymust be raised above the proposed insulation. Ifnot, they may need to be replaced before the roofcan be insulated.

When replacing the cables within the roof void, adedicated service void below the existing ceilingshould be considered. This could substantiallyimprove the airtightness of the ceiling structure andbecomes even more important if new recessed lightfittings are to be provided.



Figure 15: Insulation at ceiling level

CondensationThis is best avoided by preventing moist air fromentering the roof void from within the dwelling.Sealing any service penetrations through the ceiling(such as recessed light fittings depicted in figure15), draught-proofing loft hatches and pipes, andsealing and insulating water storage tanks (seefigure 16) will help avoid condensation. To stopwater tanks freezing, no insulation should beplaced below them.

Figure 16: Water tank insulation

Insulation between and above joists

Airtightenclosure forrecessed light

Eaves ventilatorensures correct

gap is maintainedin roof structure

Ceilinginsulationturned up

Insulatedexpansionpipework

Heat from below prevents water freezing


3.2.2 Insulation at rafter levelAlthough it is possible to insulate at rafter levelwhether the loft is a habitable space or not, it shouldonly be done where there is an existing room in theroof space, or when converting a loft into habitablespace. When the loft is not used as habitable space,it clearly makes sense to insulate at ceiling level inorder to minimise the heated volume of the dwelling.

If rafter level insulation accompanies re-roofing,consideration should be given to placing the insulationabove and between the rafters. This will raise theroof level slightly and may need planning permissionbut will improve the fixing of the insulation.

When using internal insulation, it is important tomaintain any existing cross ventilation. To achieve


Table 8: U-values of upgrading of ceiling insulation (W/m2K)


0.035 0.040 0.045

100mm insulation between joists U-values (W/m2K)

200mm 0.12 0.13 0.15

250mm 0.10 0.12 0.13

300mm 0.09 0.10 0.11

150mm insulation between joists

150mm 0.12 0.14 0.15

200mm 0.11 0.12 0.13

250mm 0.09 0.10 0.12

Thickness of insulation laid

over joists

Thickness of insulation laid

over joists

Table 9: U-values of upgrading of rafter insulation (W/m2K)


0.025 0.030 0.035

U-values (W/m2K)

50mm 0.26 0.30 0.34

75mm 0.20 0.24 0.28

100mm 0.17 0.20 0.23

25mm 0.23 0.27 0.30

50mm 0.19 0.22 0.25

75mm 0.16 0.18 0.21

Thickness of insulation fixedbelow rafters

Thickness of insulation fixedbelow rafters

50mm insulation between 100mmdeep rafters

100mm insulation between 150mmdeep rafters

this, insulation between the rafters must provide a50mm space between the insulation and the roofstructure (see figure 17). Where a breathablesarking membrane exists or is provided, this gapcan be reduced. The insulation must however notcome into contact with the membrane, as thiscould impair its ability to breathe.

Extra insulation will need to be placed below therafters to give a reasonable level of thermalresistance. Table 9 shows U-values that can beachieved using insulation placed between therafters and thermal laminate plasterboard belowthem (assuming a spacing of 600mm).

If there is a room in the roof space, its other areaswill also need insulating. The lower stud walls canbe insulated like the rafters, while any gable orparty wall should also be insulated if the adjacentproperties do not also have rooms in the roof voids.These can be considered in the same way as solidwalls. The ceiling above the room in the roof can betreated in the same way as either a normalinsulated ceiling, or if there is insufficient space,then insulation can be placed between and belowthe ceiling joists.

Again, it is crucial to stop moist air from within theroom from entering any of the new voids formedbeyond the insulation, as all of these will be colder,and condensation could easily form.

3.2.3 Insulation of flat roofsIf an existing flat roof is in need of re-roofing, thepreferred option is to put the insulation above thenew roof deck to avoid the risk of condensation. Itcan go below or above the weatherproofingmembrane; the latter option is known as aninverted warm deck (see figure 18) which has theadvantage of protecting the waterproofingmembrane and prolonging its life. However it is

possible for rainwater to penetrate the insulationlayer and reduce its thermal performance. So theinsulation should be of a type which is unaffectedby moisture – and it is possible to include a water-shedding layer that reduces this effect. Additionalinsulation is usually needed to achieve the samethermal performance as a warm deck construction.

It may not be necessary to remove any existinginsulation between the roof joists, as long as theentire existing roof deck is removed, any means ofcross-ventilation sealed, and perimeter walls builtup to the underside of the new roof structure.

Careful detailing is also required at abutment andparapet walls. Advice on preventing thermalbridging at these locations can be found in BR262Thermal insulation: avoiding risks (BRE), andAccredited Construction Details (CLG).

3.3 FloorsThe U-value for a ground floor is made up of thefloors thermal resistance and its geometry,specifically the ratio of floor perimeter (of externalwalls) to floor area. So the U-value for an end-terrace property will be higher than for the mid-terrace property next door, even if the samethickness and type of insulation is provided to both.For that reason it makes more sense to think interms of how much thermal resistance can beprovided to a floor. When deciding what can bedone to upgrade the thermal resistance of the floor,it is important to consider the type of existing floorand its condition.

3.3.1 Existing floor timbersSuspended timber ground floors offer little thermalresistance. And because the sub-floor void is usuallycross-ventilated, cold air readily leaks through thefloor into the dwelling. The air leakage paths canbe seen in figure 19.



Figure 17: Insulation between the rafters

Figure 18: Insulation options for flat roofs

Warm deck construction Inverted warm deck construction

Maintain 50mmventilation spacebetween insulationand underside ofroof covering

Insulation belowrafters only

Insulation below andbetween rafters

Weatherproofmembrane

Rigid insulation withR-value greater than3.7m2K/W


Timber orconcrete deck

Ballast layer to holddown insulation



Timber orconcrete deck


If the existing joists are in good condition, and notshowing any signs of wet or dry rot, then theeasiest way to upgrade a suspended timber floor isto lift the existing floorboards and lay insulationbetween the joists supported by netting, which isshown in figure 20.

In most circumstances, it is only possible to fill thefull depth of the joists with insulation. Extendinginsulation below the bottom of the joists couldrestrict the sub-floor ventilation which is needed toremove moisture and prevent wet or dry rot. It isalso important to ensure that any gap between the

wall and the first floor joist is also filled withinsulation, whether the wall is internal or external,as this reduces thermal bridging in this location.

When replacing the existing floorboards, it isessential to seal any gaps (such as servicepenetrations and between skirtings and the floorboards, etc.) to achieve a good level of draught-proofing and airtightness. If the existing floor joistsare not in a good condition, consideration shouldbe given to replacing the timber floor with aninsulated concrete floor.

There is more scope to insulate an existingsuspended timber floor if there is a basementbelow, and this could be less disruptive, asinsulation can be placed between and below thejoists. The basement ceiling should also haveplasterboard fixed directly to the underside of thejoists to provide fire resistance - and rigid insulationcould be fixed underneath the basement ceiling toimprove the floor’s thermal performance further.This also applies to suspended upper floors, such asthose with rooms above garages, walkways andrecesses, which are currently areas of large heat lossin many existing dwellings.

3.3.2 Replacement concrete floorReplacing a timber floor with concrete, or indeedreplacing an existing concrete floor presents anopportunity to install as much insulation as possible.It is most likely that replacing a floor with concretewill only be done once in the remaining lifetime ofthe dwelling, so it is important to achieve thehighest thermal resistance possible.

The insulation can either be placed above or belowthe concrete. Either way, consideration should begiven to how insulation continuity can bemaintained. Figure 21 below shows solid wall withinternal insulation together with floor insulationplaced over the concrete. A damp proof membraneis lapped up the wall behind the wall insulation.


Figure 19: Air leakage paths into a suspendedtimber floor

Figure 20: Insulating a suspended timber floor Figure 21: Solid wall with internal insulation

Seal gap between floor,wall and skirting with sealant or a compresseddraught seal

To eliminate draughts betweenfloorboards, nail hardboard over them oralternatively replace with chipboard

Insulationbetweenjoists

Supporting nettingdraped and stapledto joists to supportinsulation

Insulate gapbetweenlast joistand wall

Skirtingboardremoved

Existing floorboardslifted to offer access

Flooring gradechipboard or plywood


Damp-proof membrane

Minimum 10mm gap for expansion

If the insulation is placed below the concrete, it willbe necessary to provide an upstand of insulation tothe entire perimeter of the floor. This can either beused to maintain the continuity of the solid wallinsulation layer, or overlap any existing cavity wallinsulation. Figure 22 below also shows the use of adamp proof membrane which is laid below themain insulation and lapped up the walls.

performance whilst minimising the effect of raisingthe floor level. Figure 23 shows how to accommodateinsulation above an existing concrete floor.

Although the existing floor may be in goodcondition now, it may need to be replaced at somepoint in the future. This may influence the type ofinsulation that is chosen: it may make sense to usea type which can be re-used when the floor isreplaced. Raising the floor does of course raise issuesof accessibility, as well as requiring modifications:doors will need shortening; skirtings and low-levelelectrical sockets may need to be raised.

3.4 Windows and doors3.4.1 Replacement and secondary double glazingWindows and doors are a major source of heat lossfrom a dwelling. Energy efficient windows, whencorrectly selected and installed, will help to improvethermal comfort for the occupants as well asreducing fuel bills. Savings from high performanceglazing are significant. It is important to recognisethat windows are replaced very infrequently, sowindows of the highest thermal performanceshould be installed when the opportunity arises. Incases where the original character of the dwellingneeds to be maintained, as in listed buildings andconservation areas, then high performancesecondary glazing or indeed high performanceprimary single glazing may offer significantreductions in heat loss.



Figure 22: Damp proof membrane below theinsulation layer

3.3.3 Existing concrete floorsIf the existing concrete floor is in good condition,there is no real reason to replace it. In any case,suspended beam-and-block floors or raft slabscannot be replaced. However it is always possible toadd a layer of insulation on top of the existing floor.The use of a high performance material will allowfor a reasonable improvement in thermal

Figure 23: Insulating an existing concrete floor Figure 24: High performance glazing

Chipboardflooring

Polythenesheet toprovidevapourcontrollayer

Insulationaboveexistingfloor

Preservative treatedtimber batten, samethickness as insulationat the threshold

Metalnosing atchange infloor level

Bottom of dooradjusted toaccommodatethe newfinished floor level

New floorfinish


The performance of a window is not onlydetermined by U-value of the glazing, but also theU-value of the frame, the proportion of the framein the window, the solar transmittance of theglazing, i.e. its g-value, and also the airtightness ofthe unit as a whole. Together, these contribute to awindow’s energy rating as assessed under theBritish Fenestration Rating Council (BFRC) system(see figure 25).

More information on high performance windowscan be found on the British Fenestration RatingCouncil website www.bfrc.org

3.4.2 Secondary replacement glazingReplacement double glazing has been a majorsuccess story in terms of energy efficiency for manyyears and increases the market value of properties.Although the earliest examples of double glazingare much better than the single glazing theyreplaced, they are now well below even theminimum standard required by building regulations.Replacing glazing for a second time can thereforestill provide a significant reduction in heat loss andCO2 emissions.

3.4.3 Replacement doorsNew and replacement doors, whether un-glazed orpartially glazed, should have insulated cores, i.e.high performance insulation between the two outersurfaces. Insulated doors can currently achieve U-values as low as 0.8W/m2K, which is a significantimprovement over solid timber doors, which achievetypically 3.0W/m2K.


Figure 25: Window energy ratings

This system, set up in conjunction with Europeanpartners, compares the overall energy performanceof windows based on the total annual energy flowthrough the window (kWh/m2/yr). Most windowshave a negative rating, indicating a net loss ofenergy over the year, however a few have a positiverating, meaning that they create a net gain of energy.

Typical features of high performance glazing include(also see figure 26):

• The number of panes, i.e. two or three, withthe width of the gap between each paneinfluencing overall performance.

• Low-e coatings on the inside of the innerpane, applied during manufacture, help toreflect radiant heat back into the room.

• Filling the gap with a gas like argon, kryptonor xenon reduces the amount of heat lostthrough conduction.

• Low iron glass increases light and solartransmittance.

• Insulated window frames will also reduce theoverall heat loss through the window.

Figure 26: Typical features of high-performanceglazing

Argon/Xenongas-filled cavity

Low-e coating

Solarradiantheat

Outside Inside

A combined, consistent airtightness and ventilationstrategy should be part of any refurbishment work.The objective is to provide a balance by minimisingheat loss due to air leakage whilst maintainingindoor air quality.

Air leakage leads to heat loss as air warmed by theheating system leaks out through gaps and cracksin the fabric of the building. This warmed air isreplaced by cold air from outside, causing draughtsand discomfort. As this replacement air needs to beheated, it compromises the efficiency of the heatingsystem and wastes energy as outside air isunnecessarily heated.

At the same time, adequate ventilation is requiredto remove pollutants (such as water vapour fromcooking), provide fresh air for the occupants and toprovide a means of cooling in summer.

This is why both issues have to be tackled at thesame time. This can be summed up succinctly by‘build tight, but ventilate right’, i.e. making surethat the external envelope is sufficiently airtight butprovides adequate fresh air when and where it isneeded.

4.1 Reducing unwanted air leakageThe first stage of this strategy is therefore toimprove the airtightness of the fabric. The principleair leakage pathways are illustrated in figure 27.

With so many potential air leakage paths available,the location of the final gap in the building envelopemight be completely divorced from the originalsource. For example, a bath waste penetratesthrough the floorboards, the air then escapes intothe wall cavity through a gap between a joist andthe inner wall at the other end of the floor void.The air eventually leaks out through a gap betweena window frame and the outer wall on the groundfloor. All of these locations need to be sealed toprevent the unwanted air leakage.

It is therefore essential that as part of any majorrefurbishment works, air leakage paths should beidentified, possibly using a pressure test, andminimised.

The potential to improve a dwelling’s airtightnessdepends on the nature and construction of theexisting building and the type of works beingcarried out. It is generally more difficult to improvethe airtightness of existing dwellings than it is tobuild new, airtight ones, but low levels of airleakage are achievable in refurbishments.

The results of an airtightness test can be used to:

• Identify air leakage pathways and the overallair leakage rate.

• Assess the potential for reducing air leakage inthe dwelling.

• Measure improvements achieved byremediation.

• Help decide on what type of ventilation systemwill be most energy efficient.

Please note that care must be taken when dealingwith historic buildings.

4. Energy efficiency measures – airtightness andventilation


Figure 27: Air leakage pathways

1. Through air bricks which are required to ventilate sub-floor voids to prevent wet and dry rot.

2. Gaps between floor boards, at the floor edge, and around radiator pipes.

3. Leaking windows and doors.4. Pathways into floor voids and then through to the

cavity at poorly pointed in joist ends.5. Gaps between window and door frames and

external walls.6. Gaps at the edges of ceilings below a roof void.7. Open chimneys.8. Gaps around loft hatches.9. Service penetrations (light fitting and water pipes

etc.) through ceiling into floor or roof void.10.Vents passing through the roof void.11.Permanently open bathroom extract vents.12.Gaps around bathroom waste pipes.13.Permanently open kitchen extract vents.14.Gaps around kitchen waste pipes.15.Gaps between wall-to-floor joints, particularly

in timber framed construction.16.Gaps in and around electrical fittings in hollow walls.

1

2

3

4

5

6

7

8 9

10

11

12

13

14

15

16


4.2 Providing adequate controlledventilationHaving identified the dwelling’s air leakagepathways and carried out the necessaryremediation, the next stage is to provide adequatecontrolled ventilation which will remove pollutantsfrom the inside of the dwelling, whilst at the sametime providing the occupants with sufficient freshair. Provision of ventilation is covered by nationalbuilding regulations, so any system will need tocomply with these minimum legal standards.

The main types of ventilation systems that can beused in dwellings are:

• Natural ventilation and local extract fans.

• Whole house passive stack ventilation systems.

• Continuous mechanical extract ventilation.

• Positive input ventilation.

• Whole house balanced mechanical ventilationwith heat recovery.

Background ventilators, also know as trickle vents,are required to provide a minimum supply of freshair for occupants, and disperse residual water

vapour. Background ventilators provide continuousventilation throughout the dwelling. These are anessential part of most ventilation strategies, as theyprovide the minimum level of replacement fresh airneeded for the occupants.

Natural ventilation and local extract fansThis is probably the most widely used approach toachieving adequate ventilation for dwellings. Extractfans remove stale or polluted air from all wet roomssuch as kitchens, bathrooms, drying spaces, andutility rooms, while fresh air is drawn into thebuilding via background ventilators in these andother rooms.

Low power extract fans using DC motors are nowreadily available, typically saving up to 80% of theelectricity required by conventional units. Ideally, allextract fans should be fitted with a humidistatcontroller to keep the room humidity at anacceptable level, and the duct should not bepermanently open to the outside to reduce the levelof uncontrolled air leakage through the vent.

Energy efficiency measures – airtightness andventilation

Table 10: Basic information on how to reduce unwanted air leakage

Windows and doors Seal gaps around windows and doors to prevent air leakage via the reveals and thresholds.

Apply an external mastic seal to all window and door frames.

Seal any internal gaps where the wall reveals/window boards abut window units or external doors with a bead of mastic.

Repair any damage to window frames and ensure the casements, sashes and top-lights close firmly. It may be necessary to replace closing mechanisms.

Apply draught-stipping to gaps around window casements, sashes and top-lights.

Walls Air leakage behind dry-lining can be reduced by injecting continuous ribbons ofexpanding polyurethane foam between the plasterboard sheets and the inner leaf blockwork.

Make good damage to mortar joints and fill holes in external walls.

Floor Improve timber floors by laying hardboard sheeting over the top. Do not use plastic sheeting to cover timber floors as this may cause the timber to rot.

Seal around the edges of the room and make good gaps around service pipes.

Roof Ensure the loft hatch fits snugly into its aperture and apply draught-stripping between the hatch and the frame.

Services Seal gaps around any service pipes and cables passing through external walls, ceilings and ground floors.

For effective ventilation, extract fans should belocated:

• In accordance with manufacturersrecommendations.

• As high as possible in the room.

• As far as possible from the source of fresh air.

• Close to the source as possible, i.e. within acooker hood.

Passive infra-red detectors can be used to activatethis type of fan, or usage detection controls canturn on the extract system when a specificappliance (e.g. a shower) is used.

The single-room heat recovery ventilator is anextract fan which incorporates a heat exchanger. Itrecovers 60% or more of the heat from theoutgoing air, using it to preheat the incomingreplacement air (see figure 28).

unless the ducts are fitted with self-closing valveswhen ventilation is not required, they can allowsome warmed air to escape and slightly increase thedemand on the heating system.



Figure 28: Heat recovery ventilator

Background ventilation will still be required in allother rooms, and the design considerationsregarding location are similar to those for normalextract fans.

Whole house passive stack systemsThe layout of existing dwellings may make passiveducted ventilation systems difficult to incorporate.However, adequate levels of ventilation can beachieved by this method.

A passive stack system consists of vertical, or nearvertical, series of ducts that connect wet roomsdirectly with the outside, through the roof. Moistair is extracted by the stack effect – moist warm airis less dense than cold, dry air and so rises – as wellas by the effect of the wind blowing over the roof.Fresh air is replenished through backgroundventilators in the normal way (see figure 29).

Passive stack systems do not require electricity, sodo not directly cause any CO2 emissions. However

Figure 29: Passive stack system

Positive input ventilation systemsThis system (also known as mechanical inputventilation) consists of a fan, typically mounted inthe roof space, which supplies air into the dwellingvia the central hallway or stairwell, creating a slightpositive pressure in the dwelling. With these systems,excess water vapour is not directly removed fromwet rooms, but instead is allowed to escapethrough the required background ventilators. Fanstypically run continuously at low speeds with amanual or humidity controlled boost option.

Figure 30: Positive input ventilation

Stack ducts

Supplyfan

Extract(warmstale air)

Intake (coolfresh air)

Exhaust(cool staleair)

Supply (warmed fresh air)


If the fan draws air directly from the roof space (seefigure 30), it will depressurise the roof space relativeto the rest of the dwelling, and could causesignificant recirculation of the air from the dwellingto the roof space and back into the dwelling again.This needs to be minimised by ensuring theuppermost ceiling (including access hatches) is asairtight as reasonably practical. Additionally, as theroof void needs to be adequately ventilated fromoutside, it may be more practical to use air ducteddirectly from the outside (and not through the roofvoid) if the roof is sealed and has breathablesarking felt.

Continuous mechanical extract ventilationThis type of system is a combined form of theprevious two systems, and usually consists of asingle central continuously running ventilation unitpositioned in a cupboard or loft space, ductedthrough the dwelling to extract air from wet rooms.The replacement air can be from backgroundventilators (see figure 31).

Whole house balanced mechanical ventilation withheat recoveryThis system consists of extracting moist warm airfrom wet rooms and drawing in replacement airwhich is preheated by the outgoing air. As the rateof air intake matches the extract rate, there is noneed to provide background ventilation when usingthis system (see figure 32).

These systems deliver the required ventilation ratealmost independently of weather conditions.However, where the other systems discussed aboveprovide similar levels of energy efficiency, theimproved energy efficiency benefit of a wholehouse balanced mechanical ventilation system willonly be realised in really airtight properties.

Following a pressure test, and subsequent remedialworks, if the final air leakage rate is likely to bemuch less than 5m3/m2/h @ 50 Pa, then significantenergy efficiencies are possible with this type ofsystem if it has a specific fan power of 1.0 W/l/s orless and a heat recovery efficiency of 85% or more.Both should be tested in the appropriateconfiguration via SAP Appendix Q.


Figure 31: Continuous mechanical extract ventilation

The whole system should have a specific fan powerof 0.6W/l/s or less when tested in the appropriateconfiguration via SAP Appendix Q. Appendix Q ofthe SAP document explains a procedure allowingthe benefits of energy efficient technologies to berecognised in SAP. Further information on SAPAppendix Q, the test methodologies and test results of eligible systems can be found at www.sap-appendixq.org.uk

Figure 32: Whole house balanced mechanicalventilation with heat recovery

Extract system

Supply and extract system

Space heating provides thermal comfort where andwhen required. Heat gains from the sun, hot watersystem, lighting, cooking and electrical appliancessupplement the main heating source, while poorlevels of insulation and airtightness increase heating demand.

An energy efficient heating system is one that:

• Is correctly sized to warm up the dwellingfrom cold within a reasonable time.

• Uses fuel as efficiently as possible.

• Can be accurately and easily controlled by thedwellings occupants.

An efficient system will have lower running costsand CO2 emissions, and can also increase the valueof a property.

A complete system replacement provides the bestopportunity for improving energy efficiency. It alsoallows a reassessment of fuel choice, as thisinfluences running costs and CO2 emissions. Apartial upgrade can give many of the same benefits,particularly when controls and insulation areimproved, or the boiler replaced.

5.1 Fuel choiceThe choice of fuel depends on availability andaffects running costs and CO2 emissions. Solid fuelssuch as coal/coke, and electric heating systems havesignificantly higher emissions than mains gas or oil,whereas wood pellets or chips (biomass) potentiallyhave very low CO2 emissions. Unfortunately there isno current labelling scheme for wood pellets orchips, which means that without verification of thesource, levels of CO2 emissions (and other forms ofair pollution such as mono-nitrogen oxides (NOX)cannot always be guaranteed.

Electric resistance heating should only be usedwhen the heating demand is very low and allinsulation measures have been carried out to thebest achievable level.

5.2 Recommended upgrade packageThe recommended heating upgrade packages arethe best practice specification set out in CHeSS(2008) (table 11). Heating and hot water systemsneed to be correctly sized. A number of factorsshould be considered for new systems in dwellingswhere fabric insulation has been significantlyupgraded, and levels of air leakage have beenreduced:

• The size of the boiler will be increasinglydetermined by hot water demand fordwellings with lower heating demand.

• The system should be adequately controlled toavoid over-heating.

• The system needs to be easily controlled bythe occupants, and also be responsive toenvironmental conditions.

It is vital that occupants are advised on how best tooperate their new systems. For instance,thermostatic radiator valves (TRVs) are still relativelynew, and it is widely believed that by turning theseup to maximum will warm a room more quickly.This is not the case, as the speed of heating is solelydown to the boiler output and the size of theradiator. Thermostatic radiator valves only moderatethe room temperature by controlling the flow ofhot water through the radiator. Further advice onheating system controls specifically written fordwelling occupants can be found atwww.energysavingtrust.org.uk/Home-improvements/Heating-and-hot-water/Heating-controls

5. Energy efficiency resources – heatingsystems/controls and hot water systems


Table 11: CE51 – CHeSS specificationsRecommended best practice (2008)

Reference CHeSS – HR8 (2008)Description Domestic wet central heating system with regular boiler

(natural gas, LPG, or oil) and separate hot water store.

Boiler • A regular boiler (not a combi) which has a SEDBUK efficiency (see notes 5 and 6) of at least 90% (band A).

Hot water store EITHER

• High-performance hot water cylinder (see note 8).

OR

• High-performance thermal (primary) storage system (see note 9).In suitable buildings, consideration should be given to fitting a cylinder with an additional heat exchanger to allow for solar water heating.

Controls • Programmable room thermostat, with additional timing (see notes 10, 11 capability for hot waterand 12) • Cylinder thermostat

• Boiler interlock (see note 13)

• TRVs on all radiators, except in rooms with a room thermostat

• Automatic bypass valve (see note 14)

More advanced controls, such as weather compensation, may be considered, but at present cannot be confirmed as cost effective.

Installation See notes 1, 2, 3 and 4.

Recommended best practice (2008)

Reference CHeSS – HC8 (2008)Description Domestic wet central heating system with combi or CPSU boiler

(natural gas, LPG, or oil).

Boiler • A combi or CPSU boiler which has a SEDBUK efficiency of at (see notes least 90% (band A).5 and 6)

Hot water store None, unless included within boiler.

Controls • Programmable room thermostat(see notes • Boiler interlock (see note 13)10, 11 and 12) • TRVs on all radiators, except in rooms with a room

thermostat• Automatic bypass valve (see note 14)

More advanced controls, such as weather compensation, may be considered, but at present cannot be confirmed as cost effective.

Installation See notes 1, 2, 3 and 4


5.3 Seasonal efficiency of boilersAll gas and oil boilers, either newly provided orreplacement, must now be of a condensing typewith a SEDBUK efficiency of at least 90% unlessthere are exceptional circumstances as defined inthe building regulations. The SEDBUK efficiencyonly applies to the boiler acting in heating mode.The actual efficiency in supplying domestic hotwater can be significantly lower.

5.4 Heating and hot water systemsEfficient heating and hot water systems consist ofmany integrated components, all of which arerequired to maximise the efficiency of the system.These consist of a correctly sized boiler, the boilertype and its controls, the radiator size and itscontrol, the performance location and level ofinsulation of the hot water storage cylinder, and thecorrect use of insulation to the system’s pipework.

Type and size of boilerThe size of the boiler is determined by the overalldemand for both space heating and hot water. Forwell-insulated dwellings, the demand will mostlikely be dominated by the need to provide adequatehot water. The whole house boiler sizing tool canbe used to assist in determining the size of the boilerrequired to efficiently operate the system – seewww.energysavingtrust.org.uk/Housing/Tools

Two types of boiler are available, either regularsystem or combination (combi):

• Regular system boilers provide space heating,and hot water using a storage cylinder.

• Combi boilers provide space heating andinstant mains pressure hot water. They do notrequire a storage cylinder (or header tank).Some instantaneous combi boilers have a keephot facility which keeps water within the boilerpermanently hot to reduce response time atboiler start-up. This is particularly useful atreducing water usage.

It must be noted that combi boilers have minimumflow requirements to enable the heating of hotwater to be activated. This is particularly applicablewhen considering the installation of flow regulationto showers and taps as discussed in section 9.Whilst newer boilers can activate with flows as lowas three litres per minute, older combi boilers mayrequire at least eight litres per minute or more.

RadiatorsRadiators need to be adequately sized to providethe required level of heating to each room. It is veryimportant to ensure that each radiator (except theone in the room containing the main thermostat) isfitted with a thermostatic radiator valve, and thatthe occupants are fully conversant with how thevalves are to be used.

ControlsThe central heating boiler and pump must turn offautomatically when there is no demand for spaceheating or hot water. This is known as a boilerinterlock.

Larger houses should be divided into zones withtime and temperature controls for each zone.Generally the zones would be upstairs anddownstairs, but in a building with significant solargain and low overall heating demand, they may benorth and south facing.

Seven day programmable room thermostats arerecommended as they give the greatest choice oftemperature and timing. It is important to chooseone that is easy to operate or over-ride fordepartures from the normal occupancy hours (e.g.when going away for a few days). Someprogrammable thermostats incorporate hot watercontrols, but a separate hot water programmer isalso acceptable.

Time and temperature controls that users find easyto use and understand will allow for the mostefficient use of the heating system.

Other automatic heating system controls includeload or weather compensators, which adjust theboiler’s firing pattern to match the heating system’sreturn temperature, and a delayed start featurewhich determines the time that will be required forthe heating to reach the required temperature. Thismeans that when it is warmer outside, the boilerwill fire later as the heating system’s response timewill be reduced.

High performance hot water cylindersRapid-recovery coils in hot water cylinders increasethe rate of heat transfer into the water within thecylinder and reduce recovery times. The principleadvantages of high performance hot watercylinders are:

• Reduced operating time for the boiler.

• A thermostat prevents stored wateroverheating.

Energy efficiency resources – heating systems/controlsand hot water systems

• A smaller hot water cylinder can be used,reducing standing losses. (N.B. This needs tobe considered with regard to the potential useof a solar thermal hot water system toaugment the hot water provided by the boiler.)

• The most important feature is the insulation.High performance hot water cylinders aresupplied with factory-fitted insulationconsisting of high performance foam. This ismuch better than fitting a loose insulatingjacket to a standard hot water cylinder.

Pipework and system layoutAll primary pipework to the hot water cylinder mustbe insulated. In addition, any pipework outside ofthe heated envelope of the dwelling must be insulatedto save on heat loss and to prevent freezing, and itis also recommended that heating pipework in allfloor voids is insulated. Additionally, any cold watersupply pipes that are laid adjacent to hot waterpipes should also be insulated to avoid wastagewaiting for water to cool when it is drawn off.

The boiler should be positioned within the heatedliving space of the dwelling where possible, and thelength of the primary pipework runs to the hotwater cylinder minimised. Likewise, the hot watercylinder should be positioned close to the kitchenand bathroom in order to minimise pipe runs.

Passive flue gas heat recovery devicesThese can be fitted to some combi boilers betweenthe boiler and the flue outlet. They allow the fluegases to pass through a heat exchanger whichabsorbs the latent heat of the condensing fluegases. This additional heat is then used to preheatwater used to supply domestic hot water, reducingthe time needed for the boiler to run.

As the supply of domestic hot water is thedominant use of boilers in well insulated dwellings,this feature could offer savings not just in theenergy used in heating the water, but also byreducing water use.

The energy saved in operating such a system can bedetermined through the methodology of SAPAppendix Q in a similar way for ventilation systemsmentioned earlier. Further information on SAPAppendix Q, the test methodologies and test resultsof eligible systems can be found at www.sap-appendixq.org.uk

5.5 Electric storage heating systemsThe CO2 emissions and running costs of electricheating systems will be higher than those for gas.They should only be used in properties that havebeen insulated to a good standard, where theheating demand is very low, and where there areno other realistic fuel type options.

Recommended electric heating packages include:

• Fan-assisted off-peak storage heaters with top-up on-peak convectors in living rooms.

• Storage heaters in large bedrooms and largekitchens.

• On-peak fixed convector heaters with timeswitches and thermostats in small bedrooms.

• On-peak downflow heaters in bathrooms andsmall kitchens.

• Automatic charge control and thermostaticallycontrolled damper outlet on all storage heaters.

• Dual-immersion hot water cylinder withfactory applied insulation.

• Hot water controlled with one hour on-peakboost facility.

Hot water cylinders should be sized to allow mostwater heating to take place in off-peak hours, andcylinders with capacities of between 110 litres (forsmall dwellings) and 245 litres (for large dwellings)are recommended.

5.6 Smart metersSmart meters offer the dwelling’s occupants a real-time view of their energy usage, and so helpeliminate unnecessary use, and reduce runningcosts and CO2.

Installing smart meters while undergoingrefurbishment removes the need for any futuredisturbance to the dwellings occupants.

Energy efficiency resources – heating systems/controlsand hot water systems


Figure 33: Smart meter


Electricity for lights and appliances in our dwellingscan account for a significant proportion of totalenergy demand, and hence CO2 emissions. Thesecan be reduced by:

• Using energy efficient bulbs in both fixed andmovable lamps, for all light fittings internallyor externally.

• Using gas cookers and hobs whenever gas isavailable.

• Installing Energy Saving Recommended (ESR)domestic appliances.

• Ensuring that all of these are used in anenergy efficient manner.

6.1 LightingLow energy lighting can be installed at any time toany existing light fitting. When any major rewiringis being carried out, building regulations mayrequire that at least 25% of any fixed light fittingsshould be dedicated energy efficient light fittings,only capable of taking low energy light bulbs. Thereis now an extensive range of such dedicated fittingsto choose from, and therefore there is no reasonwhy 100% of all fixed lighting cannot be dedicatedenergy efficient light fittings.

Energy inefficient tungsten filament light bulbs areto be phased out by 2012 throughout the entireEuropean Union region.

Light-emitting diodes (LEDs) could becomesignificant in providing low energy lighting in thenear future. These extremely small semiconductorsemit coloured light when energised by a low-voltagedirect current. LEDs are usually too small to be usedsingly, and so are supplied in arrays or modules ofdiffering shapes and sizes. They have very long lifeand their efficacy is improving fast (newgenerations are about 60–70 lumens per watt).

Three main types of energy efficient lighting arecurrently available.

Compact fluorescent lampsThe life expectancy for these is around twelve timeslonger than conventional tungsten filament lightbulbs, and they use around a quarter of the energyto provide the same level of lighting. The efficacy of this type of lighting is generally in the range of50–75 lumens per watt. Good quality compactfluorescent lamps with ‘high-frequency ballasts’light up instantly, do not flicker, and produce fullbrightness quickly. Two or four pin lamps have light

fittings designed for them, and are also cheaper to buy. Four pin lamps can also be dimmable.

Fluorescent tubesThese contain high-frequency ballasts as standardwhich avoids flicker. Dimmable high-frequencyballasts are also available. Slimline 26mm diameterfluorescent tubes use about 10% less energycompared to older 38mm fluorescent tubes for thesame colour rendering, and are cheaper to buy. Theefficacy of this type of lighting is generally in therange of 50–100 lumens per watt.

6. Energy efficiency measure – lighting andappliances

Figure 34: Compact fluorescent lamps

Figure 35: Fluorescent tube

Tungsten halogenThese are only suitable for spotlighting or tasklighting, and should not be used for generalhousehold lighting. They are at least 50% moreefficient than tungsten filament light bulbs, and lastabout three times as long. The efficacy of this typeof lighting is generally in the range of 15–30lumens per watt, and thus cannot be used as lowenergy lighting in respect to current buildingregulations. They are often used for security lighting (which should also be fitted with daylightand movement sensors). Many tungsten halogenlights operate at 12 volts and hence require a small transformer.

Figure 36: Tungsten halogen

6.2 AppliancesDomestic appliances account for a large proportionof total energy demand. As energy efficientappliances use less electricity, they are lessexpensive to operate and are responsible for lowerCO2 emissions.

While appliances may be increasingly efficient, ourhomes contain more and more of them. There isoften very little different in purchase price, but a greatdifference in running costs since energy efficientappliances use less energy. Energy labelling schemesmake it easier to choose energy efficient appliances.

In 1995, the European Union introduced acompulsory energy labelling scheme for domestic

appliances, covering fridges, freezers and fridge-freezers. This scheme has since been extended toinclude washing machines, tumble dryers, washer-dryers, dishwashers and cookers. Energy labels aredisplayed on these products in shops andshowrooms in order to allow potential purchasersto make an educated judgement on the relativeenergy efficiency of different appliances. The energylabels (figure 37) show estimated fuel consumption(based on standard tests) and an energy gradingfrom A to G, although cold appliances can begraded up to A++.

However, the actual amount of electricity used willdepend on how the appliance is used, and in somecases (e.g. fridges) where they are located. If theyare positioned close to a cooker or a room heater,they will use more energy than if they were sited ina cooler location. Some energy labels now alsoprovide information on other aspects of theperformance of the appliance, such as water usagefor washing machines etc.

The Energy Saving Trust manages the Energy SavingRecommended labelling scheme for products ofproven energy efficiency. The scheme currently covers:

• Domestic appliances.

• Light bulbs and fittings.

• Gas and oil boilers.

• High performance hot water cylinders.

• Heating controls.

• Loft insulation.

• Cavity wall insulation.

• External wall and dry linings.

• Windows and doors.

These products carry the Energy SavingRecommended label, which marks the best 20% ofproducts. Currently endorsed products can befound at www.energysavingtrust.org.uk/compare

Energy efficiency measure – lighting and appliances


Figure 37: Energy labels for domestic appliances


Once energy efficiency measures have reduced theheat and electricity demand as far as is practicablein any given refurbishment project, low and zerocarbon technologies are then required to reduce thedwellings energy use further. Indeed it will be highlyunlikely that an 80% reduction in CO2 emissions fora dwelling can be achieved without the use of someform of renewable energy generation.

The technologies available are broadly divided intothe following low and zero carbon options, some ofwhich deliver heat and some electricity. Table 12clarifies how each technology is classified.

Some technologies are better suited to installationin refurbishment projects than others due to theinfrastructure required. The basic principles,constraints and opportunities for each technologyare discussed briefly below.

7.1 Solar thermal hot waterSolar thermal hot water systems capture heatenergy directly from the sun and are used toprovide domestic hot water rather than spaceheating. Flat plate or evacuated tube solar collectors(figure 38) absorb the incident solar radiation,which is transferred by a water or antifreeze loop tothe domestic hot water supply through a secondcoil in the storage cylinder.

Evacuated tube collectors are more efficient thanflat plate collectors, especially in overcastconditions, and are ideal in situations where theavailable unshaded south-facing roof is limited.Where suitable roof area or orientation is not aconstraint, the additional expense of evacuatedtubes puts both types of collectors roughly on a parin terms of cost effectiveness.

The yield depends on the collector size and type,angle of incidence, shading, size of tank and thegeographic location (see figure 39).

7. Installation and provision for renewable energy

Table 12: Low and zero carbon technologies

Heat output Electrical output

Zero carbon Solar Thermal Hot Water Solar PV(PV pump or thermosyphon) Wind

Low carbon Solar Thermal Hot WaterBiomassHeat PumpsDistrict Heating

Micro or Communal CHP

Figure 38: A solar thermal system

Figure 39: Solar radiation in the UK (PVGIS © European Communities, 2001-2008)

During the summer months, solar thermal systemswill typically provide over 80% of domestic hotwater demand, and on average the householdercan expect an annual reduction of about a third inthe energy required for hot water heating.

An auxiliary heat source will be required to ensurethat the water is heated to a sufficient temperaturein order to eliminate the risk of legionella (pleaserefer to Approved Code of Practice L8: Legionnaires’disease for further information). Therefore, solarthermal hot water systems need to be used incombination with a suitable heat producing appliance.

7.2 Solar photovoltaicSolar photovoltaic (PV) panels consist of semi-conductor cells which convert sunlight directly toDC electricity. This can then be used directly, storedin batteries or (more commonly) converted to AC,using an inverter, for household use or exporting tothe National Grid.

PV cells are commercially available in a range ofdifferent types – monocrystalline, polycrystalline,and hybrid amorphous mono. Hybrid is the mosteffective (and expensive) type. Monocrystalline is thesecond most expensive and efficient and works wellin bright conditions. The least expensive ispolycrystalline, and although not quite as efficientas monocrystalline, it is generally the most costeffective.

Solar PV should face close to due south, althoughany orientation between south west and south eastshould offer within 5% of the maximum output.Additionally, the output will depend upon thegeographical location (see figure 39). Locatingpanels to minimise shading is critical for PV systems,even more so than solar thermal.

The installed cost of PV is still relatively high,although it can be offset if the PV is designed to beintegral to the building, serving the same structuraland weather-protection properties as traditionalalternatives. As well as aluminium framed modules,which are fixed external to the existing roof, PV isavailable as roof tiles (figure 40) and semi-transparent atrium glass.

7.3 Micro combined heat and powerMicro combined heat and power (CHP) is anemerging technology which is expected to play asignificant role in future domestic energy provision.Micro-CHP units are about the same size as a smallfridge or floor-mounted boiler. They use a SterlingEngine to generate electricity as well as providingheating and hot water.

They are predominantly gas powered, deliveringbetween 4-8kW of heat, and 1-3kW of electricpower. They can therefore provide all of thedwelling’s heating and hot water needs with theadded benefit of providing some of its electricity.

In currently proposed systems, heat is delivered toradiators and hot water is supplied by aconventional storage cylinder. A micro-CHP unit canbe connected into an existing wet heating system,often as a replacement for the existing boiler.

Micro-CHP systems must be selected carefully inaccordance with a heating system design method.This will ensure the heat output is well matched tothe dwellings heating and hot water demand, andin that way they will be capable of out performinga conventional gas boiler.

Installation and provision for renewable energy


Figure 40: Solar PV roof tiles


7.4 Ground source heat pumpsThis technology makes use of the solar energywhich is stored as heat in the ground. Due to itshigh thermal mass, the ground under the firstmetre below the surface maintains a constanttemperature of about 11-12˚C all year round. Aground source heat pump uses this stored solarheat by using electricity to move it from the groundto a dwelling.

A ground source heat pump (GSHP) consists ofthree key elements:

Ground heat exchanger – a water/antifreezemixture circulating in a ground loop, which absorbslow-grade heat from the ground. The loop itself can be either vertical (figure 41), or horizontal(figure 42).

The heat pump – an electrically powered heatpump unit boosts the temperature by means of acompression and evaporation cycle in a similar wayto a domestic refrigerator.

Heat distribution system – this can be either bysome form of under floor heating system, or viaconventional radiators, or a combination of these.When using radiators to supply heat, or when usinga ground source heat pump to supply domestic hotwater, a secondary heating source will be requiredto ensure the water is heated sufficiently asdiscussed earlier.

The efficiency of a heatpump system is typicallybetween 300 and 400%(i.e. three to four timesmore heat energy is outputthan the electrical energyused to drive the system).However, efficiencies canbe up to 500% on morerecent units – theseefficiencies are incomparison to directelectric heating. Theimprovement compared to a highly efficient gasboiler will not be this high, because grid electricity ismore carbon-intensive than gas. If the heat pump’spower source is topped up by a low-carbon sourcelike solar PV, then a further reduction in CO2

emissions can be achieved. The difference intemperature between heat source and distributionsystem is key factor for efficiency. The smaller thedifference, the higher the efficiency – so under-floorheating is better suited, as its lower distributiontemperature maximises efficiency.

As for micro-CHP, its essential to ensure that heatpump systems are correctly designed/sized using asuitable method. In this way, they will be able toperform to their optimum potential.

7.5 Air source heat pumpsWhere the installation of a GSHP is not practical, airsource heat pumps (ASHP) – which concentrate theheat of the outside air, rather than the ground –offer an alternative. These can be air-to-air, or air-to-water and some units can also provide cooling insummer. Overall, ASHPs are not as efficient asground source systems, and they do not perform aswell as highly efficient gas boilers in terms of CO2

emissions. However, as for GSHPs, an air sourcesystem that is in part powered by solar PV willprovide a further overall reduction in CO2 emissions.

7.6 BiomassBurning biomass does release CO2, however this isbalanced by the CO2 that was absorbed during theplant or tree’s growth. So the process is close tobeing carbon neutral, with the only additional CO2

emissions involved associated with planting/harvesting, processing and transportation. Evenwith these, the resulting emissions represent abouta 90% reduction in emissions compared to theburning of fossil fuels.


Figure 41: Vertical GSHP

Figure 42: HorizontalGSHP installation

Heat pump

Compressor

Evaporator

Expansionvalve

CondenserHeat

distributionsystem

Ground heat exchanger

However, the combustion process can be veryinefficient if not properly controlled. Indeed theburning of logs in an open fire will result in around85% of the heat generated being lost to theatmosphere. Controlling the air supply, selectingproperly dried fuel and using an efficient applianceare the critical factors in achieving an efficient burn.Modern stoves and boilers have efficiencies in therange of 80–90%.

7.6.1 Fuel typesThere are three main types of biomass fuel used fordomestic heating – logs, woodchip and pellets.Disadvantages of biomass generally include thestorage space required for the fuel, theremoval/disposal of the ash residue, and the higheremissions of NOx compared to gas.

7.6.2 StovesThese can be log or pellet burning room heaters,and are ideal for smaller applications of between 2-12kW. They are most commonly used for spaceheating in conjunction with gas or oil centralheating, however for well insulated dwellings theycan provide the entire heating demand. They canalso be fitted with back boilers to supply oraugment the hot water supply. Many models havebeen approved for use in smokeless zones.

7.6.3 BoilersBiomass boilers may be suitable for larger singledwellings, where a greater heating capacity isrequired. They can be fed by any of the above fueltypes, and they work well in conjunction with athermal store, allowing the boiler to burn fuel at acontrolled and constant rate.

7.7 District heating and combined heatand powerDistrict heating uses a large-scale central heatsource along with a network of supply pipes inplace of individual household boilers. Advantagesinclude increased thermal efficiency, reducedinvestment in individual boilers and gasconnections, ease of maintenance and the optionof biomass as the fuel source in dwellings wheregas may otherwise be inappropriate.

From a householder’s point of view, district heatingprovides instant access to high pressure hot water,removing the need for their own hot water cylinderor any type of individual boiler and freeing upvaluable space within the dwelling.

A further option is combined heat and power(CHP). In this arrangement, natural gas, biomass orbio-gas (derived from the gasification of woodchips) drives an engine to generate electricity. Alarge proportion of the low-grade heat that wouldotherwise be wasted (at a power station, forexample) is captured for use in the district heatingnetwork. The combined efficiency of 75%compares with around 35% for grid electricity.

Systems range from a few kW electrical output (kWe)to several MWe, although they would typically besized to match heat rather than electrical demand.As a rule of thumb, in order to achieve economicalreturns, CHP plants need to run for at least 13-14hours per day on average, so are best suited tomixed-use developments where the demand profileis more consistent. For domestic only schemes,thermal storage is needed to match CHP heatoutput with the heat demand profile.

The scope of district heating and CHP systems inrefurbishment situations is likely to be limited by theworks required to install the distribution pipework.The most appropriate applications will be blocks offlats or high-density housing in urban areas.

7.8 WindA wind turbine converts power in a moving air mass(wind) into rotating shaft power and thus intoelectricity through a gearbox and generator. The UKis the windiest country in Europe, with 40% of theavailable resource. Wind speeds are typically greaterduring winter and during the day, matchingdemand patterns better than many of the otherrenewable options.



Figure 43: Biomass boiler


However, wind power on a domestic scale is limitedby the potential size and location of turbines in anurban setting. Since the power that can becaptured by a wind turbine increases by eight timesif the windspeed is doubled, the slower and moreturbulent wind resource in built-up areas greatlyaffects the potential output. Furthermore, the needfor smaller, quieter and more unobtrusive turbinesin urban areas also tends towards smaller rotordiameters.

As the hub height is raised further above the roofline, this turbulence is reduced and so the averagewindspeed and power output increases. Doublingthe rotor diameter increases the power output by four times.

For these reasons, the most cost effective option forwind generation is a community-scale turbine. Inrural areas, there may also be the opportunity tomount a 5-20kW turbine on a pole away from anysurrounding obstructions, and this also may provecost- and carbon-effective for detached homes with large gardens. A typical 5kW system cangenerate between 10,000-12,000 kWh per year,and reduce carbon emissions by 5-6 tonnes overthe same period.

7.9 The Low Carbon Buildings ProgrammeThe Low Carbon Buildings Programme (LCBP) wasdeveloped by the Department for Business,Enterprise and Regulatory Reform (BERR) andenables grant funding for microgenerationtechnologies. It is split into two phases – the firstwas restricted to householders, while the secondphase is for community groups, public and non-profit sector organisations.

All applicants are encouraged to have firstmaximised the energy efficiency of the dwelling toget maximum benefit from their microgenerationinstallations. To be eligible to receive a grant, youmust use an installer and a product certified underthe Microgeneration Certification Scheme (MSC) –www.microgenerationcertification.org

This grant scheme is due to be replaced by a cleanenergy cashback scheme for electricity in 2010 anda Renewable Heat Incentive in 2011. These willsubsidise the renewable generation, per unit, forthe above technologies.


Figure 44: Wind turbine in-situ

8. House types revisited


In section 2 we introduced the base case scenario.In this section we provide examples of howdwellings can be upgraded to achieve an EPC bandA rating, and significantly reduce their CO2

emissions. This is done by improving the thermalperformance of the fabric, improving services, andfinally using some form of renewable energygeneration. It is always possible to go further withfabric improvements than those demonstrated here.Table 15 indicates the improved performance andreductions in CO2 emissions which can be achievedby fabric and services improvements to the varioushouse types.

1950’s Semi-detached, floor area 90m2

In this section, using fabric and servicesimprovements, we show how this dwelling can beupgraded to an EPC band B, and then following theaddition of some renewable energy generation, thedwelling can achieve an EPC band A.

Typical improved (or upgraded)features

Element Fabric U-value

Insulated roof. 0.10W/m2K

Insulated cavity walls, 0.18W/m2K internal insulation.

Insulated replacement concrete floor. 0.12W/m2K

Windows, double glazed, 1.50W/m2K (BFRCtimber frames. g-value of glazing -

0.45W/m2K)

Doors, insulated panel. 1.00 W/m2K

Other improvements

• Mechanical ventilation with heat recovery85% efficiency, specific fan power 1W/l/s,air leakage rate 3m3/m2/h @ 50 Pa.

• Regular condensing boiler 91% efficiency,load compensation and delayed start,programmer, room thermostat andthermostatic radiator values (no secondaryroom heating needed).

• Water storage cylinder 110 litre capacity,80mm factory cylinder insulation, allpipework insulated.

• 100% dedicated low energy efficientfixed light fittings.

CO2 emissions (kg/m2/yr)

1950

s se

mi-

det

ach

ed h

ou

se

Centralheating

Domestichot water

Lights/fans/

pumps

Cooking&

appliances

Total

75

50

25

0

Table 13: CO2 emissions for a 1950s semi-detached house, floor area 90m2 following fabric and service improvements

Emissions prior to upgradingEmissions following upgrading

Typical energy demand

Energy Total energy Energysource demand (kWh/yr) demand

per m2

(kWh/yr/m2)

Gas Heating and 4,800hot water 68

Cooking 1,280

Electric Lights, fansand pumps 865 38

Appliances 2,510

Total CO2 emissionsfor this house havenow been reducedfrom around 72kg/m2/yr to about29 kg/m2/yr which is slightly below 2.6 tonnes of CO2

emitted each yearand is a 60%reduction. So with

only fabric and services improvements, thisupgraded dwelling now has an EPC band B rating andits CO2 emissions have reduced by 3.9 tonnes/yr.

The energy used for both gas (heating/hot waterand cooking) and electricity use (appliances, lightsetc.) for this upgraded dwelling are shown in table 13.

8787


However, this dwelling’s CO2 emissions are stillsubstantially above the suggested target emissionsof 15-20kg/m2/yr. Although various renewable energy generating strategies could be added to adwelling, depending upon location and orientation,the method selected here is to use 4m2 of solarthermal (including the use of a 200 litre twin coiledhot water vessel), and 2.2kWp of solar photovoltaicpanels (approx. 13m2). Additionally, if theappliances are replaced with Energy SavingRecommended models following the refurbishment,then the energy demand for these will be typicallyreduced by a further 10%.

With these additional improvements, the CO2

emissions from the heating and hot water reduceby nearly 3kg/m2/yr, while the solar photovoltaicpanels provide a CO2 emissions offset of about 11kg/m2/yr, which can be used to further offsetelectricity demand from the lights, pumps, fans andappliances. Overall the dwelling’s emissions havenow reduced to about 15kg/m2/yr, or about 1.4tonnes per year, and the dwelling now has an EPCrating of band A. The overall reduction in CO2

emissions is 80%.

Typical energy demand

Energy Total energy energysource demand (kWh/yr) demand

per m2 (kWh/yr/m2)

Gas 4,710 52

Electric 1,290 14

For further information and scenarios on improvingall eight house types from their existing EPC bandto an improved EPC, please seewww.energysavingtrust.org.uk/housing/housetypes

House types revisited

Table 15: Summary of dwelling types following fabric and services improvements

House type Floor Existing Existing total Upgraded Upgraded total Upgraded total area EPC CO2 emissions EPC CO2 emissions annual energy(m2) Band Band demand

(kWh/m2/yr)Tonnes/yr kg/m2/yr Tonnes/yr kg/m2/yr

Solid walled 104 F 13.7 132 B 3.0 29 109detached

Period end 89 F 6.5 73 B 2.8 32 110terrace

Period mid 85 E 6.7 79 B 2.6 30 108terrace

1950s semi- 90 E 6.5 72 B 2.6 29 106detached

1960s 64 E 6.2 98 B 2.1 33 127bungalow

1980s 111 E 7.7 69 B 3.3 30 78detached

1980s mid 61 E 4.2 68 B 2.1 35 83floor flat

Post 2002 79 C 3.4 43 B 2.4 30 99mid terrace

Table 14: Typical energy demand, including use ofrenewables

Currently, over half of all the water used in Englandand Wales is consumed in homes (7.7 billion litres aday) and each person uses about one tonne ofwater every week. The average consumption in theUK, as calculated from water company returns, isapproximately 150 litres per person per day. Figure45 shows the current uses of water in our homes,with toilets and showers using the majority ofhousehold water.

Over the past 30 years household waterconsumption has risen by 70%. Householdconsumption has remained relatively stable over thepast 10 years. Some appliances and fixtures havebeen broadly similar over this time period, howeverWC flush volumes have reduced, while personalbathing, predominantly showers, have increased.Lifestyle issues are beyond the scope of this guide,but when specifying appliances and fixtures, anyopportunity to reduce overall consumption,especially hot water, should be taken.

The benefits of reducing water usage do have aneffect on CO2 emissions. Approximately 23% ofdomestic CO2 emissions are from hot water usage6.This means that integrating water efficiency intorefurbishment projects will save water, money andcarbon.

Against this backdrop of water usage and increasedknowledge about climate change, carbon emissionreduction targets, water stress and increasinghousehold utility costs, our efforts to reducedomestic water consumption are more importantthan ever.

9.1 LegislationReducing future water usage in households from itscurrent level will be a challenge. The UKGovernment has issued a number of reports lookingat how attitudes and practices can be changed andhas put into place a number of policies to influencewater consumption. The sections below give detailson the main policies and their relevance torefurbishment.

9.1.1 Revision to Building Regulation Part G(newbuild and change of use)From October 2009, changes to Building RegulationsPart G include a maximum water consumption targetfor all new dwellings (either new build or thoseformed by a change of use) of 125 litres per personper day, which includes five litres per person perday for outside use. It is not proposed to requireany water efficiency measures when replacingkitchens and bathrooms, although this would be areasonable target to aim for while refurbishing adwelling. To achieve a target below 100 litres perperson per day with standard fittings are likely toneed some form of rainwater harvesting or greywaterrecycling. The proposed maximum of five litres perperson per day for outside water use is a substantialreduction from standard usage, and will need theuse of water butts to help achieve this reduction.

9.1.2 The Water Supply (Water Fittings)Regulations 1999 (currently under review)Water Fittings Regulations are applicable to allbuildings when any plumbing or water fitting-related work is carried out. Currently they includelimits on water use for certain fittings. For example,they were amended so any newly installed WC hasa maximum permissible flush volume of six litres.Water Fittings Regulations are being revised, andmay include extending the range of maximumwater use standards to a wider range of fittings andappliances.

9.2 Trigger points for water efficiencymeasuresFor existing buildings, the impacts of changingusers behaviour is similar to that for newbuild, butthe opportunities to install water efficient appliancescan be less due to the plumbing, structure of thebuilding, and the types of existing appliances

Table 16 provides an indication when thesemeasures may be appropriate.

9. Water efficiency measures


Shower/bathing and personal

washing 33%

WC flushing 30%

Clothes washing

13%

Washing up 8%

Outdoor use 7%

Other 5%

Kitchen 4%

Figure 45 : Water usage in UK homes

6. Quantifying the energy and carbon effects of water saving (July 2009) Energy Saving Trust and Environment Agency.


Water efficiency measures

Generally, the installation of a lower-flush WC andwater efficient shower heads are the easiest waysof reducing water consumption. Where a shower isprovided, a low-flow showerhead is a simple optionto improve water and energy efficiency.

If mains-pressure plumbing is available, reducedflow taps could be used, or flow regulators installedon existing models.

If provision can be made to accommodateadditional water storage, a form of water reusesystem can be considered. Whenever water-usingwhite goods are replaced, water and energyefficient models, with capacities appropriate to thehousehold, should be selected.

9.3 Water meteringAbout two-thirds of UK homes do not have watermeters. Installing them after construction tends tobe expensive, but many water companies will offerthis service free of charge, and are legally obligedto install meters if customers ask for them. Somemodern meters do not have to be read visually, sosubsequent access to the property is no longer anissue. Many meter installations are outside theproperty, as this is more cost-effective.

Many private house owners may not want watermeters because of the potential change in tariff.However, the majority of domestic customers nowaccept that metering is the fairest method of payingfor their water use. Current water charges arebased upon the rateable value of the home. Thisbenefits high-volume users like large families andthose with many inefficient water using appliances.However metered charging is likely to be cheaperafter improving the water efficiency of a dwelling.

Where water metering is not possible or practicableat the current time, a water audit could measurelikely consumption. Even if the property has a watermeter, a pre-refurbishment audit could identifyinefficient appliances or practices and help prioritiseactions to reduce consumption.

9.4 Water efficient fittings and appliancesReducing the amount of water used in fixtures andfittings can be achieved in a number of ways. Themost appropriate choices will vary from householdto household. The options are outlined briefly below.Reducing hot water consumption will also save thehouseholder energy. The water efficiency of manyproducts can be found on the Bathroom

Table 16: Trigger points to improve water usage efficiency

Opportunity

Mo

vin

g in

or

ou

t

Exte

nd

ing

Loft

co

nve

rsio

n

Ad

din

g a

co

nse

rvat

ory

New

kit

chen

New

bat

hro

om

Re-

roo

fin

g

Re-

pla

ster

ing

Rep

laci

ng

win

do

ws

Re-

wir

ing

Re-

flo

ori

ng

New

hea

tin

g

Rep

lace

men

t b

oile

r

Rep

lace

men

t h

ot

wat

er c

ylin

der

Re-

ren

der

ing


Water metering

Low flush WCs

Low flow taps

Low flow shower

Flow restrictors

Reduced capacity baths

Low water use appliances

Reducing water pipe lengthand/or insulating pipework

Rainwater harvesting

Greywater recycling


Manufacturers Association website (water-efficiency.org.uk) or additionally through theGreen Building Store (greenbuildingstore.co.uk/es4-about.php).

Low flush WCsAs mentioned above, about 30% of all potablewater used in dwellings is flushed down the toiletevery day. Low-flush WCs are specifically designedto reduce the volume of water used duringflushing. There are various systems that can bespecified to achieve a reduction in flush volume –low single-flush cisterns, delayed action water inletvalves (which prevent the cistern refilling until it hascompletely emptied), and dual-flush cisterns whichprovide a part flush and a full flush (figure 46). It is also possible to install aninterruptible flush device to an existing WC.

through the tap. Beyond the click point, the tapallows a full flow. The mains pressure should alsobe considered as it affects the water flow rate.

Low flow showersIt is possible to obtain showers with quite low flowrates. However, the perception of high pressure orflow showers are preferred. There is a possiblecompromise, as new technology showerheads cannow produce water flows that feel to be of a farhigher flow than they actually are. Water efficientshower heads have the greatest potential to saveboth water and energy with one simple device.

Flow regulatorsWhere wash hand basin and sink taps or showerunits are not being replaced, it is still possible toreduce water use by fitting a suitable flow regulatoreither to the inlet pipework of taps or showers, orto the outlets. Flow regulators contain precisionmade holes or filters to regulate flow.

Reduced capacity bathsA standard bath has a capacity to its overflow ofabout 225 litres. Even less than half full, it uses asubstantial amount of water. Baths with a muchlower capacity to overflow are now available.



Figure 46: Dual flush WC

Low flow tapsTaps with a low flow rate can be fitted to washhand basins and kitchen sinks. However, thesefittings are the most susceptible to differing usagepatterns, and therefore need to be considered on acase-by-case basis. For example a tap with a flowrate below five litres per minute might be acceptablefor a wash hand basin, but not filling the kitchensink or even a kettle. For kitchen sink taps, a clickpoint tap is better. These use a click point(sometimes known as a break point or dual action)which limits the opening action to reduce the flow

Figure 47: Reduced capacity bath in-situ

Waterwise was set up by the government topromote water efficiency, provide advice anddevelop the evidence base for large-scale waterefficiency. It also maintains a website that rankswashing machines and dishwashers in order ofwater efficiency. Seewww.waterwise.org.uk/reducing_water_wastage_in_the_uk/



9.5 Rainwater harvesting and greywaterrecyclingThere is a limit to how much water usage can bereduced with water efficient fixtures, fittings andwhite goods. However it is possible to reuse someof the waste water, capture rainfall, and to reducethe overall mains water usage of a householdfurther.

When considering alternative water supplies, it isimportant to assess the suitability of the technologyon a case by case basis. Factors to consider includelocal average rainfall, size of roof catchment areaand the likely increase to energy consumption andcarbon emissions if a pump is required. Areas ofvery low rainfall may not be suitable for somerainwater capture refurbishment options.

9.5.1 Rainwater harvesting (RWH)Rain from roofs and hard external surfaces can beused instead of mains water in WCs and washingmachines, and also for outdoor uses. Rainwater isusually collected in a tank placed into the groundthat needs electrical power to pump the water backinto the dwelling, requiring additional energy use.

If sufficient space is available on the upper floorlevel of the dwelling, in a cupboard or above thestairwell perhaps, then a header tank can beinstalled to store rainwater collected off the roof via the guttering and drain pipe. The tank will needan overflow at high level (which can be dischargedto an external rainwater butt for use in a garden)and a back-up mains feed to the top of the tankthat is activated when the water level is low (suchas a ball cock inlet valve at low level) to ensure aconstant water supply. As long as the header tankis situated above the level of the highest WCcistern, then gravity will ensure that the cistern isfilled when required. All systems must conform tothe recently published British Standard BS8515:2009 Rainwater harvesting systems – Code of practice and the Water Supply (Water Fittings)Regulations 1999.

9.5.2 Greywater recycling (GWR)Greywater (waste water from showers/baths andbathroom wash basins) can be collected, treatedand stored for re-use in place of mains water forWC flushing. Again this requires electricity to treatand pump the water to either a tank or direct to a cistern.

9.6 Water efficiency labellingTo assist refurbishment and retrofittingprogrammes, the Bathroom ManufacturersAssociation has recently released the WaterEfficiency Products Labelling Scheme (WEPS). Thislabel will help inform the purchase and installationof water efficient products within domestic andcommercial markets (figure 48).

Figure 48: Water Efficiency Labelling

Two aspects of managing waste in the context ofdomestic refurbishment are considered here –reducing the quantity of construction waste that isgenerated during refurbishment, and providingwaste collection facilities to increase recycling rates.

10.1 Construction waste from domesticrefurbishment

10.1.1 BackgroundConstruction waste is growing in importance as anissue, with rising costs and environmental impacts.In the UK it is estimated that over 120 milliontonnes of construction, demolition and excavationwaste is produced annually. It is estimated fivemillion cubic metres may be produced each yearfrom the domestic refurbishment sector, roughlyequivalent to over 350,000 tonnes of waste. Forcomparison, the amount of waste (excludingexcavation) from newbuild housing is thought to bearound ten million tonnes per year. About half ofthe inert waste is known to be recycled, the rest isused for covering and backfilling, or is disposed tolandfill as waste and spread on land, e.g. forlevelling, landscaping etc.

Government policy is starting to target constructionwaste as part of the wider sustainability agenda, witha recent joint government/industry target set tohalve the amount sent to landfill by 2012 based on2008 figures. Additionally, the construction industryhas recently seen the introduction of compulsorySite Waste Management Plan (SWMP) Regulationsfor projects costing over £300,000 in England.

10.1.2 Measuring and managing constructionwasteTypical waste from building projects includes bricks,soils, timber, packaging, metals, plasterboard andplastics. However, the type and amount of wastewill vary depending on the process creating it.

Waste from domestic refurbishment is likely to havea high percentage of timber, plastics, furniture,plasterboard and floor coverings, which is of lowrecovery value and is unlikely to be segregated atsource because of the low volumes generated andthe smaller scale of the projects undertaken. Thebuilder may prefer to pay a premium for a mixedwaste skip rather than using segregated skips. Mostof this waste will go to a transfer station wheresome of it will be sorted and sent for recovery.

The rate of recovery depends on the quality andquantity of that particular waste stream. Wastefrom domestic refurbishment can often be

contaminated (e.g. plasterboard covered with paint)which makes it difficult to recover. Re-use is morecommon for materials that have a salvage value,e.g. timber floorboards and slate tiles.

10.1.3 Policies and legislationMuch legislation covers waste management in theUK, the main aim of which is to protect theenvironment. Increasingly this legislation is makingthe waste producer responsible for bettermanagement of the waste they produce. The EULandfill Directive bans the co-disposal of certainwastes in landfill and requires the pre-treatment ofmost waste, including hazardous waste.

Fiscal drivers are important to encourage businessesto recycle waste rather than dispose of it in landfill.In the UK, the Landfill Tax is set at £32 per tonnefor active waste (i.e. waste that can biodegrade)and is increasing by £8 per tonne per year – inertwaste is set at £2.50 tonne. Additionally, a chargeof £2.00 is made on the use of a tonne of primaryaggregates (known as the Aggregates Levy) whichtherefore encourages the use of recycled andsecondary aggregates.

Site waste management plans (SWMPs)SWMPs aim to reduce waste crime – it is estimatedthat up to 31% of serious fly-tipping events involveconstruction related waste – and to encourageresource efficiency. Such plans must include anassessment of the type and amount of waste that islikely to be produced and how it will be managedand any decisions related to waste minimisation.This should then be recorded throughout theproject. The SWMP also requires that all legalobligations for waste management are compliedwith, particularly in relation to the Duty of Carelegislation and ensuring that waste managementcarriers and facilities are properly licensed. Thethreshold project value for a SWMP is set at£300,000 and the Government has indicated thatthe proportion of projects covered is 30% bynumber and 89% by value. However an increasingnumber of Local Authorities require a SWMP as partof the planning consent for a lower threshold. Thegovernment has committed to reviewing itsthreshold within three years.

Voluntary codes of practice and initiativesMore housing associations and local authorities arestarting to address the issue of refurbishment wasteand are working closely with their frameworkcontractors. Some technical guidance is given in Fitfor the Future (see Appendix C).

10. Recycling of materials and waste



Recycling of materials and waste

A key requirement is to develop partnerships with thewaste management industry and be able to predictthe amount and types of waste that are likely to beproduced through refurbishment activities. Largercontracts will now have to consider refurbishmentwaste as part of the SWMP requirements.

There has been much support for businesses in thearea of waste management in recent years whichhas resulted in a number of initiatives:

• Envirowise is a Government funded programmethat gives advice to businesses to help themreduce waste and save money. A number ofguides have been produced for the constructionindustry. See www.envirowise.gov.uk

• The Waste Resources Action Programme(WRAP) is a Government programme thatfocuses on promoting greater resourceefficiency. Guidance and advice onconstruction waste can be found on the WRAPwebsite. See www.wrap.org.uk

• Other organisations in this area include theNational Industrial Symbiosis Programme (NISP)which acts as broker for unwanted materials.

There are no financial incentives to encourage thehouseholder to manage the waste coming fromtheir refurbishment/DIY facilities more effectively,and there is a low level of awareness of the relevantissues. However, householders can take theirconstruction waste to local household wasterecycling centres, usually at no cost (though thismay vary depending upon the local authority).

10.1.4 Opportunities for reducing wasteWaste produced during the strip-out phase of therefurbishment can be reduced by considering someof the following issues:

• Carry out a pre-refurbishment audit of wastelikely to arise.

• Determine amounts and likely wastemanagement routes, which is in line withSWMP requirements for larger projects.

• Consider waste segregation on-site if possible.

• Liaise with local waste management contractorsto ensure waste is recycled as much as possible.

• Re-use, then recycle. Look for opportunities tore-use in the local community.

Waste produced during the installation phase canbe reduced by considering the following:

• Avoid the use of over-packaged products.

• Look for opportunities to return excessproducts/packaging to the supplier.

• Stockpile excess materials for later use.

• Avoid large off-cuts, look for opportunities atthe design stage.

• Avoid over-ordering.

10.2 Domestic waste and provision ofrecycling facilitiesDomestic waste has received much government andpolitical attention in recent years. It is estimatedthat 29.1 million tonnes of municipal waste (wastearising from households and other similar waste )was generated in 2006/07 in England, which is a1.4% increase from 2005/06. It is also estimatedthat only 31% of this waste was recycled in2006/07. Although this has increased by 4% from2005/06, the figure is still significantly lower than incomparable European countries.

One of the reasons for an increase in recyclinglevels is that it is now easier for people to recycle,with 94% of households receiving a doorstep orkerbside collection service from their local authority.The management of domestic waste is driven bynational and European targets which are largelyrelated to reducing the amount of biodegradablemunicipal waste that is landfilled. The EU WasteFramework Directive requires that at least 50% ofhousehold waste must be recycled by 2020.

A key issue is that biodegradable waste depositedin landfill can decompose to generate methane andother gases which contribute to climate change. It ispossible that such waste could be sorted and eitherallowed to decompose in a controlled manner toproduce green gas that could then be added to thegas supply, or the waste could be formed into asuitable fuel for use as biomass burning.

So when refurbishing dwellings, consideration shouldbe given to the storage (i.e. space, location andaccessibility) of both recyclable and non-recyclablehousehold waste and the provision (if appropriate)of facilities to compost green waste. Guidance isgiven in EcoHomes XB. An understanding of thecurrent local authority waste collection scheme willprovide an indication of storage requirements.Refurbishment of dwellings should seek to make iteasier for householders to recycle their householdwaste. When refurbishing a number of dwellings,opportunities exist to develop communal facilities(such as communal composting), and to bring incollection systems for recyclables that may not becollected by the local authority.

Given that the frequency of refurbishment istypically up to 50 years, such action should includeconsideration of future climate change impacts. Thehazards and associated remedial measures aredescribed below.

11.1 Summer overheatingHotter, drier summers will potentially lead to avariety of negative impacts, one of the worst will bethe risk of homes overheating during summer.Dwelling overheating takes place via severalmechanisms:

• Solar gain via glazed areas.

• Solar heating of the building fabric itself.

• Warm external air entering the internal livingspace.

• Heat gains from occupants, appliances andcooking.

To reduce the risk of overheating, heat gains fromeach of these areas must be controlled.

There are two strategies for cooling dwellings –passive and active. Passive cooling describesmeasures such as solar shades, which require littleor no energy to operate, and may even rely onoccupant intervention to operate effectively. Activecooling means processes such as air conditioning,which use mechanical systems to deliver cooled airto the interior of the dwelling. Whilst airconditioning is a simple ‘fit and forget’ solution, itcauses other knock-on effects such as waste heat,increased CO2 emissions and noise. For thesereasons, passive techniques are preferable,providing they can achieve a suitable level ofprotection. The following techniques are sometypical options that can be used in the existinghousing stock:

Insulating walls and lofts - as well as reducingheat loss in cold periods, insulating walls and loftswill help to prevent heat ingress during hot weather.Painting external walls with reflective paint alsoreduces the warming effect on the building fabric.

Solar shading or shutters - solar gain via glazedareas can be beneficial during cold periods, butduring warmer weather this can lead touncomfortable and potentially dangerous internaltemperatures. External awnings, shades or windowshutters can be effective in maintaining coolinternal temperatures.

Cross ventilation - providing that external air iscooler than internal air, this can be a good way of

purging heat from the dwelling. Cross ventilation isoften difficult to achieve due to internal partitionsand doors. A solution to this problem is to uselouvers above internal doors, to permit the passageof air whilst maintaining privacy.

Night ventilation - this is a very effectivetechnique for purging heat from the internalenvironment, as the external temperature is typicallymuch lower during the night. This technique isparticularly useful for houses with high thermalmass, as heat absorbed during the day can bereleased to the external environment. Any potentialsecurity issues should be considered carefully beforechoosing this approach.

Pre-cooling air - where the ventilation is via eithercontinuous mechanical extract ventilation, orbalanced mechanical ventilation with heat recovery,it becomes possible to make use of the ground’salmost constant temperature. If the inlet ducting formechanical systems can be switched in summer,then a duct laid below ground level, either aroundthe building or below an insulated floor will pre-cool incoming replacement air to the sametemperature as the ground, i.e. about 11-12˚C.

11.2 Making use of existing thermal massThermal mass can be defined as the ability of partsof a dwelling with a high specific heat capacity tostore excess heat within a building and release it ata later time. Air has a very low specific heatcapacity so even a small heat gain can lead to alarge temperature increase. However, if the surplusheat can be absorbed by parts of the building’sfabric and then released again when airtemperature falls, it will increase comfort foroccupants.

In the preceding section we looked at ways oflimiting heat gains during summer to preventoverheating. However, during winter periods wecan use the existing thermal mass of dwellings tosupplement the space heating needs. For this to bepossible, dwellings need to have a significantproportion of glazing that faces the sun at somepoint during the short winter day.

Therefore when it comes to refurbishment andimproving the overall levels of insulation,consideration should also be given to allowingmaterials with high specific heat capacity to remainin contact with the air inside the dwelling.

11. Climate change adaptation



Climate change adaptation

Although this becomes more difficult where internalinsulation is to be provided to solid or cavityexternal walls, it should still be possible to retainsolid plastered internal walls, and if possible provideconcrete replacement floors which are not isolatedfrom the internal air by insulating layers such ascarpets, but instead finished with stone or clay tiles.Additionally, allowing for the movement of airbetween rooms, such as cross ventilation, can alsobe beneficial. This will allow air warmed by the sunduring winter in a south-facing room to flow tocooler, north-facing rooms.

Although it is inherently more difficult to providethermal mass to existing dwellings, opportunities tomake use of existing thermal mass should beconsidered whenever these are possible.

11.3 FloodingMore intense rainfall is expected, particularly inwinter, with an increased risk of surface waterflooding. And with more and more paving in urbanareas, drainage systems built in Victorian times caneasily become overwhelmed, leading to waterbacking up and causing flooding from withindwellings.

To guard against water damage, the following twobroad strategies may be used:

Resistance – resistance strategy involves limiting orpreventing water ingress into the dwelling byphysical barriers, e.g. door covers, waterproofrender or membranes.

• A resistance strategy may not be suitable fordwellings at risk of deep flooding (0.9m ormore), due to the pressure of the externalhydrostatic head on the structure of the dwelling.

• A resistance strategy requires a large one-offinvestment, and will only be effective if allpotential points of water ingress have beenmade safe.

• Post-flood costs are likely to be low, as thedwelling is essentially sealed off and remains dry.

Resilience – this involves choosing materials whichare not damaged by immersion in water, andconfiguring the dwelling to minimise damage toareas likely to become immersed in the event of aflood. For example, having solid ground floors insteadof suspended timber, replacing carpets with tiling,installing closed cell rigid polyurethane (PUR)/polyisocyanurate (PIR) insulation in cavities, andrelocating meters and wiring above the expectedwater level.

• Resilience measures are cumulative, and canbe added gradually rather than requiring alarge single investment.

• Even when a resilience strategy is in place,post-flood costs are still likely to occur;however a well-designed strategy can beexpected to reduce costs by between 50%and 80%.

In general, external measures such as green roofs,porous paving and drainage pathways away fromthe dwelling are also essential parts of a robustflooding strategy.

Materials used in refurbishment should be carefullyconsidered and only those with demonstrablyrobust performance selected. Materials which sufferirreversible damage from water should not beincorporated into a refurbishment if flooding is apossibility. For further information seewww.floodprotectionassoc.co.uk

11.4 StormClimate change is expected to bring an increase inwinter rainfall and wind speeds, leading to potentialnegative impacts on existing dwellings. Roofs are atrisk from higher suction forces created by strongwinds. Low-level damage, for example tile loss, canbe minimised by using more robust roof tile fixings,e.g. holding straps.

Due to greater understanding of the risks that windloading can pose, new design codes have in somecases been tripled in stringency. Protecting againstmore serious damage may require strengthening ofthe roof structure itself.

Gable walls can also be at risk, and again mayrequire structural bolstering to minimise any risk ofcollapse.

Driving rain will potentially have a major impact onthe suitability of cavity fill in affected areas and givea higher risk of damp problems in dwellings.Cladding or waterproof render may be required tominimise risks.

11.5 Future proofingWhilst the decision to install microgenerationtechnologies may not be taken at the time adwelling is refurbished, consideration should begiven to the potential of future inclusion and,wherever possible, the infrastructure required canbe installed where there is little additional cost. Thismay well save costs in the long term and acceleratethe future integration of such technologies. Possibleactions include:

Twin-coil hot water cylinder - these cylinders arerequired for solar thermal systems and do not costmuch more than standard cylinders. Suitablecylinders are often slightly larger capacity thannormal to allow more of the sun’s energy to beusefully captured in summer months. Further,depending on the location of the hot watercylinder, pipework connecting the additional coil tothe roof space may facilitate future connection ofsolar thermal systems.

Thermal store - these are beneficial for biomassboilers and solar thermal systems. They allow boilersto work for longer periods at full capacity (higherefficiency). And during summer months, thermalstores mean water can be heated to a greatertemperature (e.g. 80°C) than would be acceptablefor a domestic hot water supply due to scalding.

Reasonable sized loft hatch - this will provide accessto the roof space for installation of any roof-basedmicrogeneration technologies, e.g. solar thermal,solar PV, and to upgrade roof insulation at a laterdate.

Over-sized fuse board - this should have sufficientspace for inverters, etc.

Underfloor heating system - where centralheating is being installed or renewed, an underfloorheat delivery system would in most cases bepreferable to radiators, since the heating circuitmust be at a greater temperature for radiators. Theefficiency of a GSHP unit increases significantly asthe delivery temperature drops.

Boiler position in house - this should be close toappropriate external wall to allow space for biomassstorage hopper, or to facilitate easy connection ofground loops.

Suitability of roof - issues to consider are:

• Maximise south-facing roof space andminimise shading (e.g. from dormer windowsand disused chimneys).

• If older existing dwellings are to be re-roofed,strengthening of the roof structure may beappropriate to ensure that the additionalweight and aerodynamic stresses of any solarthermal hot water or solar PV panels could beaccommodated in future. In the UK, optimumroof pitch for solar PV collectors isapproximately 37°; low pitch roofs are lesssuitable. Installing an electrical inverter in theroof void would also be appropriate.

• Consideration may also be given to selectingtiles that will be of appropriate dimensions tobe compatible with currently available solartiles, so these could be easily retrofitted intothe building fabric.

11.6 Trigger points for considering climatechange adaptation measuresTable 17 indicates when it may be possible toconsider and incorporate measures that canmitigate the effects of climate change.

Further information can be found in Your home in achanging climate - Retrofitting existing homes forClimate Change Impacts (2008) - Three RegionsClimate Change Group (see Appendix C).





Table 17: Trigger points for considering climate change adaptation measures

Opportunity

Mo

vin

g in

or

ou

t

Exte

nd

ing

Loft

co

nve

rsio

n

Ad

din

g a

co

nse

rvat

ory

New

kit

chen

New

bat

hro

om

Re-

roo

fin

g

Re-

pla

ster

ing

Rep

laci

ng

win

do

ws

Re-

wir

ing

Re-

flo

ori

ng

New

hea

tin

g

Rep

lace

men

t b

oile

r

Rep

lace

men

t h

ot

wat

er c

ylin

der

Re-

ren

der

ing



Summer overheating

Using existing thermal mass

Flooding

Storm

Future proofing:

Twin coil water cylinder

Thermal store

Access to roof void

Use of roof structure

Underfloor heating

Appendix A – Glossary of technical terms


Technical Descriptionterm

Air barrier The layer in the building fabric whose primary function is to restrict air flow through the construction. Examples of this include a plaster finish to a wall or a vapour control layer to a ceiling.

Air leakage rate This is a measure of how much air leaks through the building fabric, and excludes air movement through intended ventilation measures. This is uncontrolled ventilation, which leads to additional energy use as heated air is lost, while the replacement air also needs to be heated. It can be measured during a pressurisation test and is expressed as the volume of air that leaks through every square metre of the fabric each hour when the dwelling is subject to an internal/external pressure difference of 50 Pascals (N.B. Atmospheric pressure is approximately 100,000 Pascals)

Low-e coatings Low emissivity coatings are applied to one or more of the internal glass surfaces of double/triple glazing units. The coating reduces the heat flow from the inside of the dwelling through the glazing.

NOx There a variety of oxides of nitrogen which are formed during combustion process, and these are collectively known as NOX. These are also a more powerful greenhouse gas than CO2 although they exist in significantly lower concentrations.

Reduced Data Also known as RD SAP, this is the version of SAP that is used to determine the cost SAP efficiency rating on an EPC for existing dwellings. Although the data inputs are

either estimated or defaults, it still provides a reasonably accurate SAP rating for a dwelling that has not undergone thermal upgrading.

SAP SAP is the Standard Assessment Procedure which is favoured by the UK Government to determine the cost efficiency of the energy use in a dwelling for space heating, domestic hot water and lighting, and the amount of CO2 this energy use produces.

SAP Appendix Q A procedure within SAP that allows for the calculation of reduced CO2 emissions from a dwelling through the use of suitably tested energy efficient services and low and zero carbon technologies.

SEDBUK The Seasonal Efficiency Database for Boilers in the UK, allows for manufacturers data for boiler efficiencies and controls to be entered directly into SAP.

Solar This is the proportion of the incident solar radiation reaching the external glazed transmittance surface of a window that penetrates through to the inside of the dwelling. The of the glazing higher the solar transmittance (known as the g-value) the more sunlight penetration

is allowed and the greater the solar gains which can be used to offset the need to heat the dwelling with the central heating system.

Specific heat A building material with a high specific heat capacity can be used to store excess capacity heat within a building and release it at a later time. Air has very low specific heat

capacity so a small energy input will result in a large temperature increase. If the surplus heat in the air can be temporarily stored in the structure and then released when air temperatures fall, occupant comfort will be increased.

Thermal bridges A region within the building fabric where the transfer of heat is higher than in other adjacent parts of the structure. A severe thermal bridge could lead to mould growth or condensation. A thermal bridge can also refer to a junction between two building elements where the transfer of heat is higher than in neighbouring elements.


Appendix A – Glossary of technical terms

Technical Descriptionterm

Thermal This is the ability of a material to allow heat energy to be transferred through conductivity conduction. The lower the value, the higher the thermal resistance per unit

thickness, and consequently the lower the amount of heat transfer through the fabric.

U-value The rate of heat transfer through the fabric of the building. It is expressed in W/m2K. A lower U-value represents a reduction in heat transfer and an improved thermal performance.

Vapour control A layer in the building fabric which reduces the ability of water vapour to layer penetrate it.

Water audit A water audit would typically involve checking all existing fittings to establish that any form of excessive water use is eliminated. This means, for example, checking taps are not leaking, ensuring well fitting plugs are provided, or the WC cistern is not overflowing.

Appendix B – Relevant organisations and websites


Accredited Construction Details (CLG)www.planningportal.gov.uk/england/professionals/en/1115314255826.html

Bathroom Manufacturers Association water-efficiency.org.uk

British Board of Agrément (BBA) www.bbacerts.co.uk

British Fenestration Rating Council websitewww.bfrc.org

British Urethane Foam Contractors Association(BUFCA) www.bufca.co.uk

Cavity Insulation Guarantee Agency (CIGA) www.ciga.co.uk

Envirowise www.envirowise.gov.uk

Federation of Environmental Trades Association www.feta.co.uk

Heat Pump Associationwww.heatpumps.org.uk

Insulated Render and Cladding Association (INCA) www.inca-ltd.org.uk

Microgeneration Certification Scheme www.microgenerationcertification.org

National Insulation Association (NIA) www.nationalinsulationassociation.org.uk

Renewable Energy Association www.r-e-a.net

SAP Appendix Q www.sap-appendixq.org.uk

The UK Rainwater Harvesting Association www.ukrha.org

Waterwise www.waterwise.org.uk

Waste and Resources Action Programme www.wrap.org.uk


Appendix C – Further information

The Energy Saving Trust provides free technicalguidance and solutions to help UK housingprofessionals design, build and refurbish to highlevels of energy efficiency. These cover all aspects ofenergy efficiency in domestic new build andrenovation. They are made available throughtraining seminars, downloadable guides, onlinetools and a dedicated helpline.

A complete list of guidance categorised by subjectarea can be found in ‘Energy Efficiency is bestpractice’ (CE279). To download this, and to browse all available Energy Saving Trustpublications, please visitwww.energysavingtrust.org.uk/housing/publications

The following publications may also be of interest:

General

• Energy efficient refurbishment of non-traditional houses – case studies (CE193)

• The effect of Building Regulations Part L1 (2006)on existing dwellings – Information for installersand builders in England and Wales (CE53)

Airtightness and efficient ventilation

• Energy efficient historic homes – case studies(CE138)

• Energy efficient ventilation in housing(CE124/GPG268)

• Improving airtightness in dwellings(CE137/GPG224)

Heating systems

• Central Heating System Specification (CHeSS)Year 2008 (CE51/GIL59)

• Domestic heating by gas boiler systems (CE30)

• Domestic heating by oil boiler systems (CE29)

• Whole house boiler sizing method (CE54)

Insulation

• Cavity wall insulation in existing housing (CE16)

• Cavity wall insulation: unlocking the potentialin existing dwellings (GIL23)

• External wall insulation for dwellings (CE118)

• Insulation materials chart – thermal propertiesand environmental ratings (CE71)

• Internal wall insulation in existing housing – aguide for specifiers and contractors (CE17)

Lighting

• Energy efficient lighting (CE61)

• Low-energy domestic lighting (GIL20)

Renewables

• Domestic low and zero carbon technologiesguide (CE310) - in development, to bepublished mid-2010.

Windows

• Windows for new and existing housing (CE66)

Other publications listed in this guidance

The Climate Change Act (2008) www.opsi.gov.uk/acts/acts2008/ukpga_20080027_en_1

Code for Sustainable Homeswww.planningportal.gov.uk/england/professionals/en/1115316369681.html

New Tricks with Old Brickswww.emptyhomes.com/documents/publications/reports/New%20Tricks%20With%20Old%20Bricks%20-%20final%2012-03-081.pdf

Knock it down or do it up www.bre.co.uk/newsdetails.jsp?id=522

English Housing Condition Surveywww.statistics.gov.uk/ssd/surveys/english_house_condition_survey.asp

BR 262 Thermal insulation: avoiding risks www.brebookshop.com/details.jsp?id=556

Approved Code of Practice L8: Legionella’ Diseasewww.accepta.com/industry_water_treatment/hse-acop-l8-part1.asp

Fit for the Futurewww.housingcorp.gov.uk/server/show/ConWebDoc.14312/changeNav/440

Your home in a changing climate - Retrofittingexisting homes for Climate Change Impacts(2008) – Three Regions Climate Change Group.www.london.gov.uk/trccg

Energy Saving Trust, 21 Dartmouth Street, London SW1H 9BP Tel 0845 120 7799 Fax 0845 120 7789 [email protected] www.energysavingtrust.org.uk/housing

CE309 © Energy Saving Trust February 2010. E&OEThe Energy Saving Trust Housing programme is grant aided by the Department of Energy and Climate Change.

This publication (including any drawings forming part of it) is intended for general guidance only and not as a substitute for the application of professional expertise. Any figures used are indicativeonly. The Energy Saving Trust gives no guarantee as to reduction of carbon emissions, energy savings or otherwise. Anyone using this publication (including any drawings forming part of it) must

make their own assessment of the suitability of its content (whether for their own purposes or those of any client or customer), and the Energy Saving Trust cannot accept responsibility for any loss,damage or other liability resulting from such use.

So far as the Energy Saving Trust is aware, the information presented in this publication was correct and current at the time of the last revision. To ensure you have the most up to date version,please visit our website: www.energysavingtrust.org.uk/housing The contents of this publication may be superseded by statutory requirements or technical advances which arise after the date of

publication. It is your responsibility to check latest developments.

CE309