Retrofitting Historic Buildings - Westminster City Council

Retrofitting Historic Buildingsfor SustainabilityRetrofitting GuideJanuary 2013

AcknowledgementsThis guide is partly based on work previously undertaken for the City Council by Eight Associates, with inputfrom Sturgis Carbon Profiling. Thanks to the following who have assisted in the development of this guide:Cathedral Area Residents Group; Centre for Sustainable Energy; CityWest Homes; Eight Associates; EnglishHeritage; Grosvenor Plc; HOK; Lucy Drake; Marylebone Association; Peabody; Pitman Tozer Architects;Royal Borough Kensington and Chelsea; Sturgis Carbon Profiling; Thames Water Utilities Ltd; Tony LloydJones, University of Westminster; Westminster Property Association.Front cover images in running order left to right were supplied by Royal Borough of Kensington and Chelsea,Westminster City Council and Grosvenor plc.Costs are intended as a guide only. All references to legislation included permitted development rights accurate attime of printing, although these are updated frequently.Document title: Retrofitting Historic Buildings for SustainabilityDate: January 2013Produced by:Westminster City Council, Built EnvironmentCity Planning Delivery UnitWestminster City Hall64 Victoria StreetLondon SW1E 6QPContact: Nina MilesEmail:nmiles@westminster.gov.ukTelephone: 020 7641 10812

ContentsIntroduction 4Limitations of this guidance 6Leasehold/Freehold Issues 6Permitted Development 6Conservation areas 6Article 4 Directions 8Listed Buildings 10Approach to retrofittinghistoric buildings 10Grants and Sources of Funding 13Measures 14Loft and roof insulation 15Floor insulation(suspended timber floors) 18Internal solid wall insulation 21External solid wall insulation 25Draughtproofing 29Secondary glazing 31Double (or triple) glazing 33Boiler upgrade 36Heating controls 38Micro Combined Heat andPower (CHP) 40Ground source heat pumps 42Air source heat pumps 44Solar photovoltaic system(PV electric panels) 47Solar thermal panels 50Living roof 52Case Study:15 Passmore Street SW1 54Case Study:The Flagship Home 56Summary 58Westminster’s Planning Policy 60Unitary Development Plan 60The Local DevelopmentFramework 61Supplementary PlanningGuidance 61Notes and References 623

IntroductionAccording to the English Housing Condition Survey 2007, England has the oldest housing stock inEurope with 21% constructed prior to 1919. Westminster is particularly rich in historic buildings;three quarters of Westminster housing was constructed prior to 1915, with half prior to 1870. 1 It hasover 11,000 listed building, in 56 Conservation Areas, which together cover 76% of the City. Theseolder properties are often sought after for their character, which has a cultural as well as economicvalue. In Westminster such buildings are well protected and valued. But with rising fuel pricespushing more people into fuel poverty and new obligations on landlords coming into force whichmean that from 2018 the most inefficient properties cannot be rented out, 2 there is a drive toensure that historic properties do not slip into this category.Nationally buildings are responsible for around 40% of carbon dioxide (CO 2 ) emissions, but inWestminster buildings account for around 90% of CO 2 emissions 3 . With stretching UKcommitments to an 80% reduction in CO 2 emissions by 2050, a London Mayoral target to reduceCO 2 emissions by 60% by 2025 4 , and estimates that around 75% of buildings expected to be inuse in 2050 have already been built, we cannot rely on improved performance of new buildingsalone to offset rising CO 2 emissions. More needs to be done to retrofit existing buildings, includinghistoric buildings, to ensure they are fit for the future.This guidance is consistent with the National Planning Policy Framework. This sets out a series ofcore principles for land-use planning which include encouraging the reuse of existing resourcesand conversion of existing buildings as part of a transition to a low carbon future and conservingheritage assets so they can be enjoyed by future generations. It requires local authorities to adoptboth proactive strategies to mitigate and adapt to climate change, helping to secure ‘radicalreductions in greenhouse gas emissions’, and strategies for the conservation and enjoyment of thehistoric environment. It states that in drawing up such strategies local authorities should recognisethat heritage assets are an irreplaceable resource and conserve them in a manner appropriate totheir significance. It builds on London Plan policies and the Council’s own Core Strategy policyCS24 Heritage which says: ‘...Historic and other important buildings should be upgradedsensitively, to improve their environmental performance…’ See the section on planning policiesfrom page 60 for further information.The City Council is working with developers, businesses and residents to help shape a sustainablecity where buildings of high environmental performance are commonplace. The sensitive andappropriate refurbishment of historic buildings, incorporating features of sustainable design, is keyto delivering this vision in Westminster. This document aims to encourage retrofitting of historicbuildings wherever possible by setting out guidance on likely permissions and consents that willbe necessary for individual measures in the following three cases:• Unlisted properties in a conservation area• Listed properties• Unlisted properties outside a conservation area.4

This guidance will be of most use to owner occupiers in pre-1919 properties of a solid wallconstruction, but many measures are equally applicable to later buildings. It covers energyefficiency measures, domestic microgeneration equipment, which will contribute to a reduction inenergy bills, and green roofs which increase biodiversity and reduce flood risk. It will be of use tocouncil officers, architects, engineers, developers and residents who would like to improve theperformance of their building.While most cost-effective to undertake a comprehensive programme of retrofit measures to anempty building, this will not often be possible, so the guidance highlights opportunities where it isparticularly practical or cost-effective to undertake certain measures together. It also identifies risksinherent in particular measures, and requirements arising from Part L1B of the BuildingRegulations. Importantly, while this can require energy efficient upgrades when certain definedworks are undertaken, historic buildings are exempted from the full requirements. They arehowever required to be made as energy efficient as possible to the extent that this does notprejudice the character of the building or increase the risk of long-term deterioration.Conservation of historic buildings is part of sustainable development – it minimises the use of newnatural resources; prevents the wastage of existing resources; provides economic value throughtourism revenue; and contributes a range of social values important to our health, well-being andeducation 5 . Appropriate refurbishment of historic buildings is a crucial part of their conservation toensure they have a sustainable future. Improving the environmental performance of buildings andprotection of the historic built environment are therefore complementary objectives. Planningpolicies for both heritage conservation and sustainable design have a crucial role to play. So toodoes guidance to illustrate how this balance can be achieved through the developmentmanagement process.5

Limitations of this guidanceMeasures contained in this guidance are not necessarily recommended as appropriate for allproperties. The notes in the permissions and consents and risks sections should be carefullyconsidered, and advice sought where there is any doubt. All costs are approximate and will varydepending on many factors including location, condition of property, cost of labour and whetherthe measures are being undertaken in isolation or as part of a larger programme of works. Detailsof permitted development rights and all costs were accurate at time of writing. It is intended toupdate the online version of this document periodically.Leasehold/Freehold IssuesIt is recognised that leaseholders will be constrained by the terms of their lease which often limitstheir ability to make alterations to a property without the consent of the freeholder 6 .This means inpractice that they have a reduced scope to make changes, often only being able to changeinternal fittings and boilers, rather that alter the building fabric. Tenants will have little ability tomake changes, although from 2016 the Energy Act will give tenants the right to request consent forreasonable improvements to the energy efficiency of their property, and this consent cannot beunreasonably withheld where financial support is available (such as the Green Deal or EnergyCompany Obligation).Landlords and freeholders, who have sold the leasehold are also at present unlikely to considerinvesting in substantial energy efficiency measures as currently they cannot recharge the costs toleaseholders, who are the beneficiaries of any energy efficiency improvements, although theEnergy Act contains provisions which will require buildings to achieve a minimum EPC rating of ‘E’from 2018 if they are to be rented out. At present a landlord who wishes to install such measuresmust first obtain agreement as to apportioning of costs and ongoing maintenance.Permitted DevelopmentSome types of development are considered to be ‘permitted development’, for which planningpermission is not required. This guidance seeks to give some advice relating to this, although itshould also be noted that permitted development rights are amended regularly. The PlanningPortal website (www.planningportal.gov.uk) is a good source of information. Also areas covered byan ‘Article 4 direction’ (see below) which are listed on the Council’s website may have had theirpermitted development rights altered. These may also have been removed by a condition on aplanning application. Where there is any doubt over whether an application is required, you mayseek an optional “Certificate of Lawful Development”, which may be applied for ahead of works, orretrospectively. This gives peace of mind that works are lawful, and may be of use when a propertyis sold in the future.Conservation areasThese are areas of special historical or architectural interest where the distinctive townscape,buildings, spaces and other features of special interest are protected. There are 56 conservationareas covering 76% of Westminster. These can be seen on the map at figure 1.6

Article 4 DirectionsFor some buildings there may be further controls on development, including minor changes suchas to external doors or windows. These are referred to as Article 4 Directions and relate to worksthat would otherwise be ‘permitted development’. A list of the areas subject to an Article 4Direction together with detailed information on properties covered, and the exact works for whichplanning permission is required can be found on the Council’s website. The Article 4 Directionareas are: Abbey Gardens, NW8; Bridstow Place, W2; Bristol Gardens, W9; Moncorvo Close, SW7;Queen’s Park, W10, Relton Mews, SW7; Sussex Gardens, W2. For further detail on the exactwording and properties in these areas subject to the order please seehttp://www.westminster.gov.uk/services/environment/planning/permission/permitted-developmentrights/.The map at figure 2, below shows the location of the Article 4 Direction Areas inWestminster.8

2. Consider the type of heritage protection that appliesIs your property a listed building? The Council website includes a feature to search forlisted buildings by map or by searching the database of listed buildings:http://www.westminster.gov.uk/services/environment/planning/conservationlistedbuildings/listedbuildings/ This is a guide only, the only definitive list is in the ‘Greenback’ book heldby English Heritage and the local authority.Is it within a conservation area? Seehttp://www.westminster.gov.uk/services/environment/planning/conservationlistedbuildings/areaprofilesConsider developing a strategy for your building refurbishment measures that adopts the‘Energy Hierarchy’ approach of being ‘lean, clean and green’, focusing firstly on measuresto improve energy efficiency which will reduce the amount of energy that is required in thebuilding, (making it more ‘lean’). Typically this will include no/low cost measures referred toabove and those which conserve energy such as insulation. Then consider whether it ispossible for the supply of energy to be as efficient and ‘clean’ as possible; lower carbonsources of energy such as connection to a combined heat and power plant or districtheating will be the most efficient energy source for buildings with appropriate heating/hotwater demand to make it economic. Finally consider installing renewables such aselectricity generating solar panels. Such a strategy should take into account whichmeasures are most suitable for your property and whether they will complement oneanother, and which are most cost effective or practical when undertaken together, what therisks are as well as heritage and conservation considerations. Seek professional advicewhere necessary.3. What scope do you have to make changes?Freeholders will have the most scope, while leaseholders and tenants will be constrainedby the terms of their lease and will require permission/consent of the freeholder/landlord.Landlords wishing to make energy efficiency upgrades to their property will need to agreethis with leaseholders, including any cost apportionment and ongoing maintenance costsand note that leaseholders cannot be compelled to agree to this.4. What is the budget?Each building is unique and costs will vary depending on the requirements. Consider thecost effectiveness, and the likely payback period of measures that will have a medium tohigh cost. Check eligibility for any grants or loans to assist with costs, or for any feed-intarifffor renewables as these will improve the payback period.5. What permissions/consents do you need to obtain?Some measures will be ‘permitted development’ for which planning permission is notrequired, as long as the property is not subject to an Article 4 direction or planningcondition amending the permitted development rights. This will often depend on whetherthe property is a house or flat, although for some types of measure, permitted developmentdoes apply to flats. This guide will give you an idea of the likely permissions and consentsthat might be needed in Westminster, in terms of planning and listed building consent, butyou may also need sign off under Building Regulations for certain works, and where no ‘11

competent person’ scheme exists. Where you are uncertain about whether a particularmeasure is ‘permitted development’, you can always apply for a ‘certificate of lawfulness’.This may be important if the property is sold in the future.6. Undertake workEnsuring that any new systems work effectively, and that occupants (and future occupants)understand how to use them. There may also be changes necessary to the way in which aproperty is occupied, which must be clearly understood. For example, with many types ofinternal solid wall insulation it is vital not to pierce the waterproof membrane behind theinsulation which might happen easily when putting up shelves or hanging a picture.7. Monitor and undertake necessary maintenance12

Grants and Sources of FundingGrants and assistance are available from Government to those in receipt of certain means testedbenefits under its Warm Front scheme in England. This will typically fund replacement insulationand heating costs. Qualifying households can get improvements worth up to £3,500 (£6,000 whereoil central heating and other alternative technologies are recommended). Contact Warm Front on0800 316 2805Energy companies with a certain number of customers are obliged by the Carbon EmissionsReduction Target (CERT) to provide financial assistance towards installation of energy efficiencymeasures. Contact the London Energy Saving Trust Advice Centre on freephone 0800 512 012 forup to date information about grants and discounts.The Council has a legal responsibility to assist in achieving national and European targets for theimprovement of the energy efficiency of the housing stock. The City Council also wishes to assistin reducing the numbers of persons living in fuel poverty. This is where a household has to spendmore than 10% of their disposable income on fuel costs. As such the Council offers the followingassistance:• Owner occupiers and private tenants in Queen’s Park and Harrow Road wards can obtainfree loft insulation and draught proofing regardless of their circumstances through the Loftand Draught Proofing Insulation grant. To qualify buildings should have:o less than an average of 150mm of loft insulation in the main or sole pitched roofspace and/oroHave inadequate draught-proofing to window and external door openings.For information on how to apply contact Westminster Home Improvement Agency on020 7641 8959.• Decent Homes grants are available until the end of 2012/13 to owner-occupiers on meanstested benefits who live in a home that fails the decent homes standard. It can provide upto £5000 for gas central heating; repairs to existing heating systems; draught-proofing; loftinsulation; hot water tank jackets; cavity wall insulation and home repairs. To find out moreand apply contact Westminster Home Improvement Agency on 020 7641 8959.It is expected that there will be significant changes to the current national programme of grantswhich may impact on Westminster policies, for up to date information see the Energy Saving Trust.13

MeasuresThis section outlines measures which might be appropriate to retrofit in Westminster. It excludesmeasures which might be appropriate in other locations but which are not considered generally tobe suitable in Westminster such as biomass heating, which has considerable negative air qualityimpacts and is not generally considered to be sustainable unless you have a nearby source of fuel.For each measure a table summarises the different consents that might be needed in terms of thethree alternative heritage building scenarios.These have been colour coded as below, with the lightest colour reflecting those measures whichmay be permitted development, or for which permission is unlikely to be needed, and the darkestcolour indicating that permission would need to be sought and the measure is unlikely to beacceptable.123Measure unlikely to require permission or consent; may be permitted development insome cases.Measure likely to require planning permission or consent and may be acceptable subjectto detailed design.Measure unlikely to be considered acceptable in most cases.Dotted outline indicates a different approach depending on whether the building is a flator a house, see summary chart at pages 58-59.14

Loft and roof insulationDoesBuildingRegs applyNot forsimpleinstallationof loftinsulation inan existingloft, butwhererenovatinga thermalelement,e.g.replacing aroof, loftinsulationwill berequired.Does Part L1B require this?http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADL1B_2010.pdfPart L1B requires improvementsto the whole of thermal elements,such as roofs where renovationwork is taking place on morethan 50% of the surface of thatelement.Note: buildings which are:1. listed2. in conservation areas3. of architectural andhistorical interest, referredto in a local authoritydevelopment plan4. of traditional construction.will not be required to undertakeworks which would ‘prejudice theappearance and character of thebuilding’. It is not likely to be thecase here. English Heritagehave produced guidance onapplying part L to historicbuildings 11Permissions and consents...Disruption Risks Unlisted within a Listed buildingconservation areaLowLow risks if installingbetween existingjoists, but ensure anair gap aroundedges of loft toavoid damp andallow air to circulate.Installation ofinsulation at rafterlevel has more risksassociated.Permission notrequired as longas it doesn’t alterexternalappearance ofroofPermission/consent notnormallyrequired as longas it doesn’t alterexternalappearance ofroof or involvemodification ofroof structure.Unlisted outside aconservation areaPermission notrequired as long asit doesn’t alterexternal appearanceof roof15

Installing insulation in existing roof voids can have a significantpositive impact on energy efficiency. Historic buildings with atimber roof structure lend themselves to insulation betweenjoists and rafters without any visual impact or harm to thehistoric building. Natural insulation materials such as wool areparticularly beneficial as these allow a building to breathe,reducing the possibility of moisture and damp problems. Whenfitting, an air gap must be left around the margins of the buildingto allow air to circulate. Care should be taken around electricalcables (lay these over the insulation), and allow a gap aroundany lights that may heat up (e.g. downlighters installed for therooms below). It is also advised to insulate loft hatches.Whilst insulation of a loft (betweenjoists) is straightforward (sometimesreferred to as ‘cold roof’), insulationat rafter level (where a loft space hasalready been converted to provideadditional space, referred to as‘warm roof’) is more complicated.There are various options includinginsulation between the rafters, on topof the rafters and below the rafters.Some options will result in the roofheight changing. Additionalconsiderations in heritage buildingsmay include whether there is ahistorically significant lining or ceilingfixed to the underside of the rafters. If this cannot be removed,and the only way to attach insulation is by removing the roof tilesand inserting from above then this may not be economic, unlessother works to the roof are being undertaken at the same time.Generally in Westminster this will beacceptable as long as it doesn’t alterthe roof height as seen from theexterior. If proposals are moreextensive, involving alterations toroof height then this is likely torequire planning permission, and if alisted building, listed buildingconsent.Risks: There are risks associatedwith reducing air flow and ventilationand consideration should be givento the most appropriate materialsand technique, particularly for rooflevel insulation. Ensure an air gap is retained around margins ofloft.Costs and grants: Capital costs of loft insulation will varydepending on the size of loft, depth of existing insulation andwhether the work is professionally installed or DIY. There areadditional costs associated with the time to empty and refill aloft, and possibly extending joists if the householder requires theloft to be boarded (otherwise significant depths of insulationmaterial may reduce utility of the loft). Costs quoted bycontractors to fit loft insulation in a listed building will besignificantly higher reflecting the range of additional possibleissues that can complicate the job.16

Loft androofinsulationUnitCost(lower)Cost(Upper)Cost(average)Subsidies(refer toESTwebsitefor latestinfo 12Listed 80m 2 £1000 £1400 £1200 50-100%building 13Unlistedbuilding 14 80m 2 £193 £352 £272.50 50-100%Costs of rafter level insulation will be higher, depending on thecomplexity of the technique and the material selected.When to do this: Loft insulation can be undertaken at any time,either in isolation or as part of a whole house refurbishment. It issensible to insulate any water tanks and lag pipework at thesame time, and don’t forget an insulated loft trapdoor. If youhave downlighters that you are planning to change, do thisbefore installing insulation (and remember to leave a clearspace around them to minimise risk of overheating). Whenconverting loft spaces or replacing a roof, insulation will berequired.For further information see:• Factsheet produced by English Heritage:http://www.climatechangeandyourhome.org.uk/live/insulating_roofs_generic.aspx• http://www.helm.org.uk/upload/pdf/eehb-warmroofs.pdf?1308028610• ‘An Introduction to Low Carbon Domestic Refurbishment’Construction Products Association (2010)http://www.constructionproducts.org.uk/publications/dbfiles/Domestic%20Refurbishment%20Revised11010%20(low%20res).pdf• Roofs – A guide to Alterations and Extensions onDomestic Buildings, Westminster City Council SPG(2004)http://www3.westminster.gov.uk/spgs/publications/Roof%20guide.pdf17

Floor insulation (suspended timber floors)Does BuildingRegs applyYes whereinsulation isexposed to theground or airbuildingregulationsapplies.Does Part L1B require this?http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADL1B_2010.pdfPart L1B requires improvementsto the whole of thermal elements,such as floors where renovationwork is taking place on morethan 50% of the surface of thatelement.Note: buildings which are:1. listed2. in conservation areas3. of architectural andhistorical interest, referredto in a local authoritydevelopment plan,4. of traditional construction.will not be required to undertakeworks which would prejudice theappearance and character of thebuilding. This would depend onthe existing floor. EnglishHeritage have producedguidance on applying part L tohistoric buildings xvPermissions and consents...Disruption Risks Unlisted within a Listed buildingconservation areaHigh – it makessense to dothis when floorboards arebeing lifted orreplaced dueto the cost anddisruption.Low risk, but careneeded when liftingfloorboards. Ensureair bricks are notcovered byinsulation ascirculating air isneeded to preventdamp and rot.Internalalterations of anunlisted propertyin a conservationarea don’t requireplanningpermission.May requirelisted buildingconsentdepending onexisting floor.Unlisted outside aconservation areaPermission notrequired.18

Heat loss through the floor amounts to around 15% for theaverage house. Simple draught-proofing of gaps between floorand skirting and between floorboards with sealant can beundertaken relatively easily and at low cost (around £20).Suspended timber floors on the ground floor, typical for manyolder properties can be insulated to improve thermal comfort.This will be quite straightforward if there is a cellar or crawlspacebelow, but without this, floorboards can be lifted and insulationinserted underneath, supported by netting. This should be to thedepth of the joist only and should not block air bricks. Careneeds to be taken when lifting boards to minimise damage.Avoid blocking airbricks when draughtproofing or wheninsulating, and take care to maintain cross ventilation beneathsuspended timber floors to avoid rotting floor timbers. Considerthe potential loss of historic fabric (floorboards/skirting/doorsurrounds/doors) that may occur if insulation increases floorheight.Advantages: Underfloor insulation can save around £50 per yearon energy bills and improve thermal comfort, with draughtproofing saving around £15 per year.Disadvantages: This will be fairly disruptive as it will requirerooms to be emptied, and floorboards to be lifted, which risksdamaging the floor. For this reason it is sensible to takeadvantage of any opportunity to insulate, for example if existingrotten floorboards are being replaced.Risks: Incorrectly installed insulation which blocks air bricks andreduces air circulation beneath a floor may result in damp andcondensation problems. The risks inherent in lifting floorboardsmay be too great in a listed building where one of the featuresfor which it is listed is a particularly attractive floor. Some historicbuildings may also contain historic pugging, which is a coarsemortar between joists and beneath floor boards to deadensound.Costs: Generally although the capital cost of insulation is nothigh, there is significant disruption and cost in having floorslifted. The cost of lifting floorboards properly can be around£25/m 2 while the cost of the insulation itself is only around £5/m 2Floorinsulation(suspendedtimber)UnitCost(lower)Cost(Upper)Cost(average)Subsidies(refer toESTwebsite forlatest info 16Unlisted 80m 2 £875 £917 £896 50-100%building 17When to do this: Floor insulation is disruptive therefore it is bestdone as part of a whole house refurbishment, or whenfloorboards are being lifted or replaced, for example to install oraccess heating pipes below. When it is carried out ensure thatgaps are sealed such as under skirting boards and where waterand gas pipes are located to minimise draughts.19

For further information see:• Factsheet produced by English Heritage:http://www.climatechangeandyourhome.org.uk/live/insulating_timber_ground%20floors.aspx• ‘An Introduction to Low Carbon Domestic Refurbishment’Construction Products Association(2010)http://www.constructionproducts.org.uk/publications/dbfiles/Domestic%20Refurbishment%20Revised11010%20(low%20res).pdf• Information from the Energy Saving Trusthttp://www.energysavingtrust.org.uk/In-your-home/Roofsfloors-walls-and-windows/Floor-insulation20

Internal solid wall insulationDoesBuildingRegs apply?YesDoes Part L1B require this?http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADL1B_2010.pdfPart L1B requiresimprovements to thermalelements, such as walls whererenovation work is taking placeon more than 50% of thesurface of that element (or 25%of the whole building envelope)Note: exemptions for buildingswhich are:1. listed2. in conservation areas3. of architectural andhistorical interest,4. of traditional construction.These buildings should‘improve energy efficiency asfar as is reasonably practicable.The work should not prejudicethe character of the hostbuilding or increase the risk ofdeterioration of the buildingfabric or fittings’.English Heritage haveproduced guidance onapplying part L to historicbuildings 18Permissions and consents...Disruption Risks Unlisted within a Listed buildingconservation areaHigh - this willprobably bebest donewith a vacantproperty orwhen a wholehouse isbeingrefurbishedas the kitchenandbathroommay needrefitting.Very high-Specialistadvice andinstallationrequired dueto possiblemoisture andventilationproblems.Internal alterationsof an unlistedproperty in aconservation areadon’t requireplanningpermission.Would require listedbuilding consent forchanges affectingthe building’scharacter as one ofspecial architecturalor historic interest,such as materials,details and finishes.This may begranted in limitedcircumstances,such as whereoriginal finisheshave already beenlost.Unlisted outside aconservation areaInternal alterationsof an unlistedproperty don’trequire planningpermission.21

Solid wall insulation can be a way of improving the thermalefficiency of a building, and could save energy and reduceheating bills. Most of the historic buildings in Westminster havesolid masonry walls, either of brick or stone. Masonry walls arenot good insulators and they often feel cold to the touchbecause they conduct heat. The only way to insulate them is byadding a layer of insulation either internally or externally. Around35% of heat loss from a typical home is through its walls.Advantages: This can improve the thermal comfort of a propertyand reduce energy bills substantially. It raises no planningissues for unlisted buildings in conservation areas and may incertain circumstances be acceptable for listed buildings forexample where internal finishes have already been lost. It is alsolikely to be cheaper than external wall insulation although thereare likely to be additional costs associated with the need toreapply decorative finishes, and possibly refit kitchens andbathrooms, so for this reason is best considered for wholehouse refurbishment projects.fabric this may be acceptable, but will require listed buildingconsent.Risks: Older properties were designed to breathe, i.e. allow acertain amount of moisture in and out. Typically, they would onlyhave heating in some rooms, and would be cooler than we keepthem today. Modern materials including insulation and evenemulsion paints are more moisture resistant and can restrict theability of walls to breathe. The risk of water vapour passing into awall, but not being able to escape, is that it can condense insidethe fabric of the wall. This is known as ‘interstitial condensation’,and it may cause damage to a wall structure and finish. Thermalbridging, where water vapour condenses on relatively cooleruninsulated surfaces can also be a problem around roofs, floorjoists, windows and partition walls. Any damp problems,whether through water penetration, rising damp, or any othersources must be dealt with first before deciding on the mostappropriate strategy for internal insulation. Once this has beendealt with there are generally two strategies.Disadvantages: It is disruptive and will typically require aproperty to be empty, and probably kitchens and bathrooms tobe completely refitted. It will take up internal floorspace and alterthe relationship of the door and window reveals, and will requireskirting boards, cornicing and decorative plasterwork to berelocated. Again there are inherent risks in creating thermalbridges for moisture which can result in damp and rot problemsin localised areas, so an air gap is recommended. It is alsomore expensive than external insulation, and the additionalcosts associated with having to vacate a property andcompletely refit kitchens and bathrooms adds significantly to theoverall cost, unless such works are programmed when a wholehouse refurbishment is planned. In some situations, such aslisted buildings where there is little remaining internal historic22

Breathable solution: The first and less risky, and probably themost appropriate option for historic buildings, and certainlywhere there have been any previous damp problems, is toensure that materials with similar breathable qualities are usedfor the internal insulation (though this also applies to roof andfloor insulation, in order to avoid moisture condensing onvulnerable areas). In this case no vapour barrier is needed, andthere is no risk of it failing in future. In addition care must betaken not to introduce any impermeable finishes such as vinylwallpaper or emulsion paint (internally or externally).Watertight solution: The second approach is to ensure the wallsare made completely watertight, either through the use of acarefully installed vapour barrier (which might be plasticsheeting) or insulation with integral vapour membrane. In eithercase it should be taped across all joints and penetrations (e.g.sockets) and great care will be needed to ensure that futureoccupants do not break the vapour membrane when hangingpictures or putting up shelves for example, as there are veryserious risks of interstitial condensation resulting in damage towalls with even the smallest penetration to the vapour barrier.Thermal Bridges: Very careful detailing will also be needed toensure that there are no thermal bridges in places whereinsulation coverage is incomplete or reduced which might resultin more water condensation at these points due to them beingrelatively colder than insulated surfaces. Particular care isneeded around windows and doors and at the ends of floorjoists embedded in masonry walls, particularly intermediatefloors, and specialist advice should be sought on what is mostsuitable. A ventilated cavity between a new internally insulatedstud wall and the existing external wall can be created, whichcan overcome many of the moisture and damp related risks,although the cavity must be ventilated to the outside of thebuilding. Internal insulation should be returned a short distancealong the party walls in terrace properties. Often it is hidden inthe alcove alongside the chimney breast.Costs: The costs of solid wall insulation vary very significantlyand are also related to property type, wall area, finish, number ofinstallations (economies of scale may apply for example tosocial housing projects where a bulk number of units can beinsulated). However there are additional costs associated withthe disruption, the need to vacate a property and possibly theneed to refit the kitchen or bathroom, and reapply details suchas skirting boards or coving where appropriate. For this reason itis probably most cost-effective to consider this as part of awhole house refurbishment.InternalSold WallInsulationUnitCost(lower)Cost(Upper)Cost(average)Subsidies(refer to ESTwebsite forlatest info 19Listed 80m 2 £6400 £8000 £7200 0-50%building 20Unlistedbuilding 21 80m 2 £5600 £8500 £7050 0-50%When to do this: Owing to the disruption and likelihood thatkitchens and bathrooms would need to be refitted this is bestdone as part of a whole house refurbishment with a vacantproperty although it can be undertaken room by room.23

For further information see:• Factsheet produced by English Heritage:http://www.climatechangeandyourhome.org.uk/live/insulating_solid_walls.aspx• ‘An Introduction to Low Carbon Domestic Refurbishment’Construction Products Association (2010):http://www.constructionproducts.org.uk/publications/dbfiles/Domestic%20Refurbishment%20Revised11010%20(low%20res).pdf• Information from the Energy Saving Trusthttp://www.energysavingtrust.org.uk/In-your-home/Roofsfloors-walls-and-windows/Solid-wall-insulationCase Study: 88 Lothrop Street, Queens Park,Westminster (Retrofit for the Future)Consultant: Eco Alchemists LtdClient: CityWest HomesGoal: 80% reduction in carbon emissions.Due to its location in a conservation area, externalwall insulation was not a possibility, so to achieve ahigh level of insulation (minimum 0.15W/m2K) theSpacetherm range of aerogel thermal dry lininginsulation was applied on the walls. This wasreturned along party walls and combined with floorand loft insulation, with Mechanical Ventilation withHeat Recovery (MVHR) system installed to providepre-warmed, filtered, fresh air, secondary glazing, amicro CHP (combined heat and power unit) andupgraded lighting and appliances, as well as lowVOC paints and natural flooring.The house achieved a 79% reduction in carbonemissions.24

External solid wall insulationDoesBuildingRegsapply?YesDoes Part L1B require this?http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADL1B_2010.pdfPart L1B requires improvements tothermal elements, such as wallswhere renovation work is taking placeon more than 50% of the surface ofthat element (or 25% of the wholebuilding envelope)Note: exemptions for buildings whichare:1. listed2. in conservation areas3. of architectural and historicalinterest,4. of traditional construction.These buildings should ‘improveenergy efficiency as far as isreasonably practicable. The workshould not prejudice the character ofthe host building or increase the riskof deterioration of the building fabricor fittings’.English Heritage have producedguidance on applying part L tohistoric buildings 22Permissions and consents...Disruption Risks Unlisted within aconservation areaMediumHigh-Specialistadvice andinstallationrequired due topossiblemoisture andventilationproblems.Planning permissionwill be needed in allcases for external wallinsulation comprising orincluding the following:stone, artificial stone,pebble dash, render,timber, plastic or tiles 23 .This is likely to becontentious, but maybe allowed in certaincircumstances such ason the rear elevation, inan enclosed situation(not part of a unifiedterrace) where thematerials used are of asimilar appearance tothe existing building orextension.Listed buildingPlanningpermission andlisted buildingconsent would beneeded and thisis generally notconsideredappropriate forlisted buildings.Unlisted outside aconservation areaCentralGovernmentguidance suggeststhis is permitteddevelopment onthe principalelevation (or otherelevations) of adwelling house(not flats) subjectto the materialbeing of a similarappearance to theexisting building orextension.Dashed line indicates different approach for flats and house25

Solid wall insulation can be a way of improving the thermalefficiency of a building, and could save energy and heating bills.Most of the historic buildings in Westminster have solid masonrywalls, either of brick or stone. Masonry walls are not goodinsulators and they often feel cold to the touch because theyconduct heat. The only way to insulate them is by adding a layerof insulation either internally or externally. Most external systemsconsist of a layer of insulating material fixed to the wall andcovered by a render, which provides a degree of protection fromweather and impact damage.The major issue to consider is that external wall insulation willhave an impact visually on the relationship between the buildingenvelope and its openings, altering the detailing aroundwindows and doors, and also eaves and roof verges. It ispossible to extend roof eaves to deal with this.For this reason it would need to be very carefully designed, andin conservation areas planning permission is likely to be neededin most cases and it is likely to be contentious but it may beallowed in certain circumstances such as on the rear elevation,and only in an enclosed situation, not for part-only of a unifiedterrace, although applications to apply to the whole of a terracewould be considered. In all cases, where acceptable, thecladding would be expected to match the original facingmaterial. In addition careful detailing is required around windowsto minimise the impact of altered window reveals. Outside aconservation area, external wall insulation is likely to bepermitted development as long as it uses materials of a similarappearance to the existing buildingAdvantages: This can improve the thermal comfort of a propertyand reduce energy bills substantially, as typically 35% of heat islost through a building’s walls. This does not require theproperty to be vacated, is simpler and easier to achieve thaninternal wall insulation (although note that it may require worksuch as extending the eaves of a house in order to make itpossible). External wall insulation works better with the thermalmass of existing walls, meaning that walls which absorb heat willbe able to release it back into the interior of the building when itbegins to cool. It is also generally considered a safer solution interms of the risk of damp and moisture in a building than internalsolid wall insulation. It will not reduce floorspace internally.Disadvantages: This will probably require work to ensure thedetailing around the roof and window reveals is dealt withappropriately, which may include extending the eaves of ahouse where there is insufficient overhang. There are inherentrisks in creating thermal bridges for moisture which can result indamp and rot problems in localised areas, so professionaladvice is necessary. It is only likely to be acceptable in limitedcircumstances (see table above), and is not consideredacceptable for listed buildings.Risks: Older properties were designed to breathe, i.e. allow acertain amount of moisture in and out. Typically, they would onlyhave heating in some rooms, and would be cooler than wetypically keep them today. Modern materials including insulationand even emulsion paints are more moisture resistant and canrestrict the ability of walls to breathe. The risk of water vapourpassing into a wall, but not being able to escape, is that it cancondense inside the fabric of the wall. This is known as‘interstitial condensation’, and it may cause damage to a wallstructure and finish.Thermal bridging, where water vapour condenses on relativelycooler uninsulated surfaces can also be a problem aroundroofs, floor joists, windows and partition walls, although withexternal insulation this is less likely to be an issue.26

Walls with structural problems which cannot be repaired shouldnot be externally insulated. Any damp problems, whetherthrough water penetration, rising damp, or any other sourcesmust be dealt with first before considering whether external wallinsulation is appropriate.Breathability: It is vital to ensure that materials used in externalinsulation and weatherproofing are breathable (preventing waterpenetration from outside while allowing moisture inside or risingfrom the ground to pass out), and have similar properties toexisting walls. English Heritage recommends that progressivelayers of an insulated wall should become more permeable frominterior to exterior enabling moisture to escape. Materials toavoid include acrylic or cement based renders or pointing, nonbreathableinsulation materials and vapour barriers. In additioncare must be taken not to introduce any impermeable finishessuch as vinyl wallpaper or emulsion paint (internally orexternally), which can compromise the ability of the wall toabsorb and release moisture.Thermal Bridges: This will also need very careful detailing toensure that there are no thermal bridges, in places whereinsulation coverage is incomplete or reduced which might resultin water condensation at these relatively colder surfaces.However, if it requires work to extend roof eaves, or alterdetailing around window and door reveals, or deal with servicesthese will add substantially to the cost. It should be noted thatavailable data on typical costs for solid wall insulation tends tobe based on a typical 3 bedroom semi detached property, andin Westminster this is not typical therefore costs for Westminsterproperties including the finish and scaffolding are likely to besignificantly higher.ExternalSolid WallInsulationUnitCost(lower)Cost(Upper)Cost(average)Subsidies(refer toESTwebsite forlatest info 24Listed 80m 2 £7600 £13200 £10400 0-50%building 25Unlistedbuilding 26 80m 2 £10500 £14500 £12500 0-50%When to do this: External wall insulation is not very disruptive tooccupants, but owing to the high cost (as well as cost ofscaffolding) it is something to consider when you are thinking ofupgrading or replacing existing render.Particular care is needed around windows and doors. Specialistadvice should be sought on what is most suitable.Costs: The costs of solid wall insulation will vary significantly andare also related to property type, wall area, finish, number ofinstallations (economies of scale may apply for example tosocial housing projects where a bulk number of units can beinsulated). Although external solid wall insulation has a highercapital cost, and will require scaffolding, it may have lessassociated costs as it can be applied with residents in situ.27

Advantages: This can improve the thermal performance ofexisting windows and comfort at a relatively lower cost without asignificant aesthetic impact, provided the system is installedwithin the window fabric.Disadvantages: Lower cost DIY options may not be as effective,and will need to be replaced frequently.Costs: Costs vary depending on whether it is done as a DIY job,although generally better performing results will be obtained witha professionally fitted system, which might cost £200-250 for atypical sash window for example.DraughtproofingwindowsListedbuilding 27Unlistedbuilding 28UnitCost(lower)Cost(Upper)Cost(average)Subsidies(refer to ESTwebsite forlatest info 26Perwindow1.36m 2 £200 £400 £300 0-50%Per £200 £250 £225 0-50%1.36m 2windowWhen to do this: It is a good idea to undertake this either as astandalone measure, or combined with secondary glazing.Draughtproofing around skirting boards and gaps in floorboardsis also advisable, as well as where pipes and cables enter thehome.For further information see:• English Heritage research on sash windows:http://www.climatechangeandyourhome.org.uk/live/research_generic.aspx• English Heritage Factsheet on draughtproofing:http://www.climatechangeandyourhome.org.uk/live/content_pdfs/892.pdf• Centre for Sustainable Energy publication “Warmer Bath”which includes useful detail on draughtproofing windowsamongst other topics:http://www.cse.org.uk/downloads/file/warmer_bath_june2011.pdf30

Secondary glazingDoesBuildingRegsapply?YesIs this work a requirement triggered by PartL1B?http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADL1B_2010.pdfNo, although in certain cases wherereplacement windows are unable to meetrequired U-values due to heritagerequirements for example then secondaryglazing may be a solution. English Heritagehave produced guidance on applying part Lto historic buildings 29 Medium Medium – Advicemay be needed onventilation andcondensation. Takecare not to damageexisting windowsand shutters(if present)Permissions and consents...Disruption Risks Unlisted within a Listed buildingconservation areaInternal alterationsof an unlistedproperty in aconservation areadon’t requireplanningpermission.Listed Buildingconsent will berequired, althoughthis will generallybe acceptable,subject todetailed design.Unlisted outside aconservation areaInternal alterationsof an unlistedproperty do notrequire planningpermission.A significant amount of heat is lost through windows, both theglass and the gaps in and around the frames. As an alternativeto double or triple glazing, secondary glazing is available in avariety of systems to suit different window styles. This also hasbenefits in terms of noise reduction. There are a variety ofsystems – those that are openable – hinged or sliding, fixed,and lightweight removable. In all cases careful thought shouldbe given to how to access original windows for cleaning andmaintenance.Advantages: It can have a positive impact on reducingdraughts and improving comfort, especially when combinedwith repairs to existing windows. It will generally be acceptableon most buildings. It can have better noise insulatingproperties than double glazing (due to the larger cavity), somay be suitable for windows fronting onto busy roads. It will beless expensive than replacing with double or triple glazing.The heritage conservation value of a building will influence theoptions that are available, as alterations to windows can havea significant impact on the historic value of the building.Secondary glazing will generally be possible for all types ofhistoric property, subject to obtaining listed building consent(where relevant). For best results it should be combined with arefurbishment of existing single glazed windows.31

Disadvantages: It can be more expensive than simplerefurbishment measures, and care must be taken wheninstalling not to damage existing window frames, or existingshutters. Removable secondary glazing which is taken down insummer will require careful storage, and care taken to select asystem which enables access to the original windows forcleaning and maintenance.Risks: As with other measures that reduce air flow, specialistadvice will be needed to deal with ventilation and condensation.Measures which reduce ventilation may not be appropriate inkitchens and bathrooms. Although the secondary glazing unitmay be well sealed, the original windows should not be sealed,ensuring that there is still ventilation, of the cavity to the outside,preventing moisture and condensation build up within the cavitybetween the original window and the secondary glazed unit.When to do this: This works as a standalone measure, but forthe best results consider doing this at the same time asrefurbishing existing timber windows.Costs: Costs will vary greatly depending on the type of system,whether it is ‘seasonal’ (i.e. a lightweight system, removable insummer) or fixed and double glazed, the degree to which it canbe opened, and ‘matches’ existing windowSecondaryGlazingListedbuilding 31UnitCost(lower)Cost(Upper)Cost(average)Per £100 £250 £175 -1.36m 2windowSubsidies(refer toESTwebsite forlatest info 30For further information see:• Factsheet produced by English Heritage on secondaryglazing:http://www.climatechangeandyourhome.org.uk/live/content_pdfs/891.pdf• ‘An Introduction to Low Carbon Domestic Refurbishment’CPA (2010)http://www.constructionproducts.org.uk/publications/dbfiles/Domestic%20Refurbishment%20Revised11010%20(low%20res).pdfCase Study88 Lothrup Street has includedsecondary glazing in itsstrategy for whole houserefurbishment under theRetrofit for the FutureProgramme, funded by theTechnology Strategy Board.The house is located in aConservation Area, and thewindows to the front wererefurbished with double glazedsecondary glazing installedbehind. The window also hadthermal blinds installed.32

Double (or triple) glazingDoesBuildingRegs. apply?Yes -No need tonotify ifinstaller ispart of acompetentpersonscheme, e.g.FENSAapprovedIs this work a requirementtriggered by Part L1B?http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADL1B_2010.pdfPart L1B requires improvements to‘controlled elements’ whichincludes windows (where the wholeof the window unit including theframe is being replaced) to meetspecified U-values.Note: exemptions for buildingswhich are:1. listed2. in conservation areas3. of architectural and historicalinterest,4. of traditional construction.These buildings should ‘improveenergy efficiency as far as isreasonably practicable. The workshould not prejudice the characterof the host building or increase therisk of deterioration of the buildingfabric or fittings’. English Heritagehave produced guidance onapplying part L to historicMedium Medium–Advicemay be neededon ventilationandcondensationPermissions and consents...Disruption Risks Unlisted within a Listed buildingconservation areaPlanningpermission will berequired for flatswhere newwindows materiallyaffect the externalappearance of thebuilding, e.g.where the framesize changes;openingmechanismschange ormaterials for thewindow change.For adwellinghouse(not flats) this ispermitteddevelopment butis subject tocertainconditions. 33Listed Buildingconsent will berequired, and thiswill generally notbe consideredacceptable,although there aresome instanceswhere it will beconsideredpossible, such aswhere installed toa modernextension or laterpart of thebuilding.Unlisted outside aconservation areaPlanningpermission will berequired for flatswhere newwindows materiallyaffect the externalappearance of thebuilding, e.g. wherethe frame sizechanges; openingmechanismschange ormaterials for thewindow changes.For adwellinghouse (notflats) this ispermitteddevelopmentsubject to certainconditions. 34Dashed line indicates difference of approach for flats and houses33

A significant amount of heat is lost through windows, both theglass and the gaps in and around the frames. The heritageconservation value of a building will influence the options thatare available, as alterations to windows can have a significantimpact on the historic value of the building.Modern double glazed sash windows can now achieveimproved thermal performance as well as security and acousticbenefits. There are slim profile options as well as those with lowemissivity coatings which improve performance and may beappropriate in some situations.The PassivHaus standard, which aims to achieve very highlevels of air tightness, common in Germany has been applied ina small number of retrofitting projects, experimentally in the UK.To meet the high levels of air tightness required a building wouldtypically fit triple glazing rather than double glazing. Such anapproach would require a whole building approach, outside thescope of this guidance. It is worth noting that at present it isdifficult to achieve the necessary U values and levels of airtightness with sash windows due to the heavier weight of tripleglazed units, although manufacturers and designers are workingto develop a solution to this.Advantages: Double or triple glazing will have the best thermalperformance. It can have a positive impact on reducingdraughts and improving comfort and will improve the U value(rate of heat loss through a material). Appropriately detailedtimber double glazing may add to the value of a property.Risks: As with other measures that reduce air flow, specialistadvice will be needed to deal with ventilation and condensation.Trickle vents (which are common on most modern windows)may sometimes be necessary to provide adequate ventilation ofinternal condensation and pollutants, especially in propertieswhere there is only a single window and the space is otherwisewell sealed. Care should be taken to ensure that such vents areused appropriately as when used wrongly they can becomeblocked and ineffective. Measures which reduce ventilation maynot be appropriate in kitchens and bathrooms.Costs: The cost of replacement double or triple glazing is asignificant investment, but particularly when it returns a windowto its original style material, it may add to the value of a property.DoubleGlazingListedbuilding 36UnitCost(lower)Cost(Upper)Cost(average)Per £465 £525 £495 -1.36m 2windowSubsidies(refer to ESTwebsite forlatest info 35When to do this: This can be done as a standalone measure,but would also be beneficial to consider alongside internal wallinsulation, as part of a strategy to minimise condensation andthermal bridging.Disadvantages: It can be more expensive than simplerefurbishment measures and secondary glazing. Triple glazedoptions exist, but create bigger sections and heavier units, andthese are more expensive than double glazing.34

For further information see:• ‘An Introduction to Low Carbon Domestic Refurbishment’Construction Products Association (2010)http://www.constructionproducts.org.uk/publications/dbfiles/Domestic%20Refurbishment%20Revised11010%20(low%20res).pdf• Comparison of performance of double glazing in historicbuildings in Edinburgh trial:http://www.changeworks.org.uk/uploads/Double_Glazing_In_Listed_Building_-_Project_Report_(Changeworks_2010).pdf• Replacing Windows in Conservation Areas guidance fromWood Window Alliance.http://www.woodwindowalliance.com/fileadmin/docs/guides/WWA_conservation_brochure_2011_web2.pdf35

Boiler upgradeDoesBuildingRegsapply?Is this work arequirement triggeredby Part L1B?http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADL1B_2010.pdfPermissions and consents...Disruption Risks Unlisted within aconservation areaListed buildingUnlisted outside a conservationareaYes -Workmustcarriedout byaninstallerwho ison theGas SafeRegisterHeating systems are a‘controlled service’under Part L1B. Workshould comply with the“Domestic HeatingCompliance Guide”.http://www.planningportal.gov.uk/uploads/br/BR_PDF_PTL_DOMHEAT.pdfLow-Medium Low A flue is permitteddevelopment on adwellinghouse (notincluding flats) subject tothe height of it notexceeding the roof bymore than 1m, and in aconservation area notfronting a highway orbeing on principal or sideelevation. 37Will generally beacceptable on the rear ofa property. If an existingflue is lawful andproposed new one is ofthe same dimensions itprobably won’t requireplanning permission toreplace.Listed buildingconsent would berequired for the flueand for any internalalterations.The flue should bepositioned in avisually discreetlocation on the rearelevation. If anexisting flue islawful andproposed new oneis of the samedimensions itprobably won’trequire planningpermission toreplace.A flue is not permitteddevelopment for flats. 38 Planningpermission would be required forany flue that would materiallyaffect the external appearance ofthe building.Would be permitted developmentfor a dwellinghouse subject to itnot exceeding the highest part ofthe roof by 1m or more.If an existing flue is lawful andproposed new one is of the samedimensions it probably won’trequire planning permission toreplace.Dashed line indicates difference of approach for flats and houses36

When existing boilers break down or are older than 10-15 yearsthey should be replaced with an A-rated condensing boiler(although there are some exceptions). A condensing boiler ismore efficient than a traditional combination boiler as it extractsadditional latent heat from water vapour, improving its efficiency.In general all new boilers should be condensing boilers unless inexceptional circumstances an exemption is necessary due tothe difficulty and cost of installation, for example where it islocated far from a drain. This exemption would be determined bya points based assessment. Heating controls should beprogrammable on a timer, with individual room TRV(Thermostatic Radiator Valves) which switch off the heating in aroom when it reaches the required temperature.At the same time as upgrading a boiler the opportunity shouldbe taken to install advanced heating controls (which increasethe options in terms of temperatures and timing), as well asupgrading the hot water system.As part of a refurbishment consideration could be given to thepossibility of installing low carbon alternatives such as heatpumps (best suited to relatively air tight properties with goodlevels of insulation, and to buildings with underfloor heatingsystems) or micro CHP (Combined Heat and Power), whichmakes electricity at point of use and makes use of the heatproduced as a by-product (best suited to properties with a highand fairly consistent demand for heat) together with improvedtemperature/time zoning controls.CostsBoilerUpgradeAssumedDomestic 40UnitPerinstallationCost(lower)Cost(Upper)Cost(average)£2,200 £2,550 £2,375 -Subsidies(refer toESTwebsite forlatest info 39For further information see:• http://www.planningportal.gov.uk/permission/commonprojects/boilersheating/• ‘An Introduction to Low Carbon Domestic Refurbishment’Construction Products Association (2010)http://www.constructionproducts.org.uk/publications/dbfiles/Domestic%20Refurbishment%20Revised11010%20(low%20res).pdf37

Heating controlsDoesBuildingRegs apply?Is this work a requirement triggeredby Part L1B?http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADL1B_2010.pdfPermissions and consents...Disruption Risks Unlisted within a Listed buildingconservation areaUnlisted outside aconservation areaNo, althoughin practiceusuallyinstalledtogether witha new boilerwhich issubject tobuildingregulationsapproval.Heating systems are a ‘controlledservice’ under Part L1B. Workshould comply with the “DomesticHeating Compliance Guide”.http://www.planningportal.gov.uk/uploads/br/BR_PDF_PTL_DOMHEAT.pdfLow-Medium Low Internal alterations donot require planningpermission.Does not requireplanningpermission orlisted buildingconsent.Internal alterations donot require planningpermission.Without proper programmable heating controls, the benefits of amore efficient condensing boiler will not be realised. Thereforethermostats should be programmable ‘Chrono-proportional’thermostats on a timer, enabling a number of differentprogrammable room temperature levels each day. These shouldbe combined with TRV (Thermostatic Radiator Valves) in eachroom (except the room where the thermostat is located, and thebathroom) which switch off the heating in a room when itreaches the required temperature. Such systems can bewireless, which mean that no wiring or making good is required.When to do this: It makes sense to upgrade heating controlswhenever a new boiler is installed, but also when new sources oflow and zero carbon heating are installed, such as heat pumps,and perhaps also if you are considering installing underfloorheating.38

CostsHeatingcontrolsProgrammableheatingcontrollerThermostaticRadiatorValves 42Hot watercylinder jacket 43UnitPertypicalcontrollerPer TRVinstalledPercylinderjacketselfinstalledCost(lower)Cost(Upper)Cost(average)£50 £100 £75 -£35 £75 £55 -Subsidies(refer to ESTwebsite forlatest info 41- - £30 0-100%Case StudyThe Retrofit for the Future property at LothropStreet is trialling an intelligent fully automaticheating controller which senses when the house isoccupied, and learns heating preferences meaningthat occupants do not need to programme thetimer. The Wattbox is being deployed in a numberof the Technology Strategy Boards Retrofit for theFuture projects. It also has the capability to monitora range of other inputs such as humidity and CO 2levels and functions with other smart meters.For further information see:• http://www.planningportal.gov.uk/permission/commonprojects/boilersheating/• ‘An Introduction to Low Carbon Domestic Refurbishment’Construction Products Association (2010)http://www.constructionproducts.org.uk/publications/dbfiles/Domestic%20Refurbishment%20Revised11010%20(low%20res).pdf• http://www.beama.org.uk/en/news/index.cfm/tacma%20publicationThe Wattbox in Lothrop Street39

Micro Combined Heat and Power (CHP)DoesBuildingRegs apply?Is this work a requirementtriggered by Part L1B?http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADL1B_2010.pdfPermissions and consentsDisruption Risks Unlisted within a Listed buildingconservation areaUnlisted outside aconservation areaYes -Installer mustbe on theGas SafeRegister.Heating systems are a ‘controlledservice’ under Part L1B.Work should comply with the“Domestic Building ServicesCompliance Guide”.http://www.planningportal.gov.uk/uploads/br/domestic_building_compliance_guide_2010.pdfMedium-High Low In a conservation area,a flue for CHP on adwellinghouse (hereincluding flats) wouldbe permitteddevelopment exceptwhere it is more than1m above highest partof roof or a wall or roofslope which fronts ahighway. xlivListed buildingconsent wouldbe required forthe flue and forany internalalterations.The flue shouldbe positioned ina visuallydiscreet locationon the rearelevation.Planning permissionfor a flue for CHP ona dwellinghouse(here including flats)not normallyrequired, and theflue will be permitteddevelopment up to amaximum of 1mabove highest partof the roof. xlv40

Micro Combined Heat and Power (CHP) isa relatively new technology which is stillbeing trialled,but has good potential to replacedomestic gas boilers. A Micro CHPsystem produces electricity at point ofuse, and makes use of the heat producedas a by-product, which would ordinarily bewasted. Because it doesn’t requiredistribution it is highly efficient. Generally itis best suited to properties with a highheat demand, such as hotels or guesthouses to make it most economic, and itcould be considered as part of a majorrefurbishment.Costs: Although initial costs will be higher than purchase of acondensing boiler the Micro CHP can reduce fuel bills if you optto utilise electricity when heating is on. It does also attract Feed-In Tariff payments and enables sale back to the grid of excessenergy generated.MicroCHPMicroCHP 47UnitPeraveragedomesticsystemCost(lower)Cost(Upper)Cost(average)Subsidies(refer to ESTwebsite forlatest info 46£4000 £5000 £4500 EnhancedCapitalAllowancesWhen to do this: It is advisable to install this generally inproperties that have a high demand for heat and hot water, asthis will make it most economic.Case StudyMicro CHP is being trialled in the Lothrop Streetproperty to determine whether this is viable wheresolar thermal panels are not a possibility. It isanticipated that this will produce around 300w ofelectricity per hour when the unit is producing heator hot water, which is enough to run the TV,washing machine, low energy lighting and MVHR(Mechanical Ventilation with Heat Recovery).For further information see:• Combined Heat and Power Association:http://www.chpa.co.uk• ‘An Introduction to Low Carbon Domestic Refurbishment’Construction Products Association (2010)http://www.constructionproducts.org.uk/publications/dbfiles/Domestic%20Refurbishment%20Revised11010%20(low%20res).pdf41

Ground source heat pumpsDoesBuildingRegsapply?Is this work a requirement triggeredby Part L1B?http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADL1B_2010.pdfPermissions and consentsDisruption Risks Unlisted within a Listed buildingconservation areaUnlisted outside aconservation areaYes.Acompetentpersonschemeapplies.Heating systems are a ‘controlledservice’ under Part L1B.Work should comply with the“Domestic Building ServicesCompliance Guide”.http://www.planningportal.gov.uk/uploads/br/domestic_building_compliance_guide_2010.pdfMedium-High Low Permitteddevelopment fordwellinghouses 48(including buildingswholly consisting offlats)Listed buildingconsent wouldbe required.Permitted development fordwellinghouses 49 (includingbuildings wholly consisting offlats)Ground source heat pumps consist of pipes underneath theground which extract warmth to supply heating or hot water to abuilding. It consists of a loop of pipes filled with water andantifreeze, laid horizontally, in a trench or vertically (up to 100mdeep). The fluid in the pipes warms up and passes through aheat exchanger in the heat pump converting it to high gradeheat.Heat pumps require electricity to run, so are not strictly speakingrenewable, but are a low carbon source of energy. These arebest suited to buildings that are fairly air-tight, with goodinsulation levels, and not on the gas-grid 50 , as they produce lessheat than a conventional boiler. Therefore it works better withunderfloor heating than with radiators (which would becomewarm rather than hot). Alternatively radiators would need to beoversized. When used to heat water a backup system may berequired to provide top up heat.Ground source heat pumps are ‘permitted development’ fordwellinghouses, although for listed buildings, listed buildingconsent would be required, where the works affect the building’scharacter as one of special architectural or historical interest.42

Advantages: They can achieve reductions in fuel bills,particularly for customers previously on electricity, oil fired orLPG systems. They are low maintenance once installed.Disadvantages: They work best in well insulated properties withunderfloor heating – if this is not the case additional costs will beincurred.Carbon savings may not be significant. They also require acertain amount of space externally.Costs: Running costs vary depending on different factorsincluding the level of insulation and size of property. TheGovernment’s renewable heat incentive (RHI) may benefit theseinstallations in the future although it is specifically excluded fromthe start of the RHI.When to do this: This should be installed where there isappropriate heat demand, in a well insulated property preferablywith underfloor heating.For further information see:• ‘An Introduction to Low Carbon Domestic Refurbishment’Construction Products Association (2010)http://www.constructionproducts.org.uk/publications/dbfiles/Domestic%20Refurbishment%20Revised11010%20(low%20res).pdf• http://www.energysavingtrust.org.uk/Media/node_1422/Getting-warmer-a-field-trial-of-heat-pumps-PDFGroundSourceHeatPumpGroundSourceHeatPump 52UnitPeraveragedomesticsystemCost(lower)Cost(Upper)Cost(average)Subsidies(refer to ESTwebsite forlatest info 51£9000 £17000 £13000 RenewableHeat Incentive43

Air source heat pumpsDoesBuildingRegsapply?Is this work arequirementtriggered by PartL1B?http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADL1B_2010.pdfPermissions and consentsDisruption Risks Unlisted within a conservationareaListed buildingUnlisted outside a conservationareaYes.Acompetentpersonschemeapplies.Heating systemsare a ‘controlledservice’ under PartL1B.Work shouldcomply with the“Domestic BuildingServicesComplianceGuide”.http://www.planningportal.gov.uk/uploads/br/domestic_building_compliance_guide_2010.pdfMedium Low Permitted development from1/12/2011 for dwellinghousesor a block of flats, subject tocertain restrictions 53 includingtheir use only for heating, andlimited to 1 per building.Air Source Heat Pumpswhich are not permitteddevelopment must conform toUDP Policy ENV7 ControllingNoise From Plant andMachinery and InternalActivity. Those which arepermitted developmentshould minimise effect onamenity of the area. One wayof doing this is by complyingwith the noise standards inENV7. Seek advice fromacoustics team inEnvironmental Health forlarger/noisier systems.Listed building consent wouldbe required.The external unit should bepositioned in a visually discreetlocation on the rear elevation.Noise may be an issue whereplanning permission isrequired.Air Source Heat Pumps whichare not permitted developmentmust conform to UDP PolicyENV7 Controlling Noise FromPlant and Machinery andInternal Activity. Those whichare permitted developmentshould minimise effect onamenity of the area. One wayof doing this is by complyingwith the noise standards inENV7. Seek advice fromacoustics team inEnvironmental Health forlarger/noisier systems.Permitted development from1/12/2011 for dwellinghouses ora block of flats subject to certainrestrictions including their useonly for heating 54 and limited to1 per building.Air Source Heat Pumps whichare not permitted developmentmust conform to UDP PolicyENV7 Controlling Noise FromPlant and Machinery and InternalActivity. Those which arepermitted development shouldminimise effect on amenity ofthe area. One way of doing thisis by complying with the noisestandards in ENV7. Seek advicefrom acoustics team inEnvironmental Health forlager/noisier systems.44

Air source heat pumps take warmth from the air and use anevaporator coil to supply heating or hot water to a building. Asystem consists of an external unit, usually near a wall, though itcan be located away from the building (requiring a clear amountof space either side for air circulation), and an internal unit with ahot water cylinder.Air source heat pumps require electricity to run, so are notstrictly speaking renewable, but are a low carbon source ofenergy, providing typically up to 4 units of heat for every unit ofelectricity. A conventional boiler produces around 0.8-0.9 unitsof heat from a unit of electricity. Performance varies by modelbut some models can work even at temperatures as low as -15˚, (although below about 7˚, a defrost cycle, which wouldeffectively reverse the heat pump, using warmth from the houseto defrost ice build up would impair performance).These are best suited to buildings that are fairly air-tight, withgood insulation levels, and not on the gas-grid 55 , as theyproduce less heat than a conventional boiler. Therefore it worksbetter with underfloor heating than with radiators (which wouldbecome warm rather than hot). Alternatively radiators wouldneed to be oversized. They may also be used to heat water, inwhich case a backup system may be required to provide top upheat. Air source heat pumps can be noisy which means they arenot suitable in all instances. Air Source Heat Pumps mustcomply with the requirements of MCS Planning Standards inorder to be permitted development.Advantages: They can achieve reductions in fuel bills,particularly for customers previously on electricity, oil fired orLPG systems.Disadvantages: They work best in well insulated properties withunderfloor heating (which is designed for low temperaturesystem) – if this is not the case additional costs will be incurred.Carbon savings may not be significant.Costs: Running costs vary depending on different factorsincluding the level of insulation and size of property.The Government’s renewable heat incentive (RHI) may benefitthese installations in the future although it is specificallyexcluded from the start of the RHI.AirSourceHeatPumpAirSourceHeatPump 57UnitPeraveragedomesticsystemCost(lower)Cost(Upper)Cost(average)Subsidies(refer to ESTwebsite forlatest info 56£6000 £10000 £8000 RenewableHeatIncentiveWhen to do this: This should be installed where there isappropriate heat demand, in a well insulated property preferablywith underfloor heating.45

For further information see:• ‘An Introduction to Low Carbon Domestic Refurbishment’Construction Products Association (2010)http://www.constructionproducts.org.uk/publications/dbfiles/Domestic%20Refurbishment%20Revised11010%20(low%20res).pdf• http://www.energysavingtrust.org.uk/Media/node_1422/Getting-warmer-a-field-trial-of-heat-pumps-PDF46

Solar photovoltaic system (PV electric panels)Does BuildingRegs apply?Yes. Althoughthere is acompetentpersons scheme,ensure installer isqualified to adviseon roof structuralandweatherproofingaspects too orcontact BuildingControl foradvice.Is this work arequirementtriggered byPart L1B?No, it iscoveredunder Part Pas anelectricalinstallation.Permissions and consentsDisruption Risks Unlisted within a conservationareaMedium Medium –Specialistinstallationadvice neededand possibly afeasibility studyor structuralsurvey to ensurethe roofstructure willbear the weightof the panels.Have a supply ofreplacementroof tiles in casethese are brokenduringinstallation.This is permitted development lviii ,even on the roofs of principalelevations of dwellinghouses andflats in conservation areas,subject to it being ‘sited so as tominimise its effect on the externalappearance of the building andthe amenity of the area’, i.e.where there are alternativeoptions for installation, thelocation which minimises thevisual and amenity impacts mustbe selected.Would not be permitteddevelopment:• If it protrudes more than20cm from the roof slope;• If it is higher than the highestpart of the roof (excludingchimney).• In a conservation area, on awall which fronts a highwayListed buildingListed buildingconsent will berequired and thiswill generally beacceptable in adiscreetlocation, wherenot visible fromsurroundingproperties (e.g.internal valleyroof or flat wallbehind aparapet).Unlisted outside aconservation areaThis will not generallyrequire planningpermission as it ispermitteddevelopment lix , on anyroof or wall slope ofdwellinghouses andflats, subject to it being‘sited so as to minimiseits effect on the externalappearance of thebuilding and theamenity of the area’, i.e.where there arealternative options forinstallation, the locationwhich minimises thevisual and amenityimpacts must beselected.Not permitteddevelopment if itprotrudes more than20cm from roof slopeor is higher than thehighest part of the roof(excluding chimney).47

Solar PV panels convertenergy from the sun intoelectricity. The installation ofPV panels can significantlyreduce CO 2 emissions, andhelp to reduce energy bills.The orientation of the roof isthe critical factor indetermining maximumoperational efficiency of solarPanels on a roof at New CavendishStreetPV panels. They should be as close to south facing as possible,and work best at an angle of 30˚ to the horizontal. They shouldnot be shaded by trees or neighbouring buildings.An alternative to conventional solar PV panels are solar roof tiles,which are designed to look similar to normal slate roofing tiles.These may be appropriate where the roof is not original – asthey would replace existing roof fabric. Where historic fabric isretained solar panels would involve less loss of original roof tiles.For many properties, even flats in a conservation area this willbe permitted development and will not require planningpermission, although if you live in a listed building, this is not thecase.Costs: The original Feed in Tariff rates introduced in April 2010,offered a payback period of around 10-15 years for solar PVpanels and the chance to generate income through sellingexcess electricity back to the national grid. Under this schemeenergy suppliers make regular payments to householders andcommunities who generate their own electricity from renewableor low carbon sources such as solar PV panels. The schemeguarantees a minimum payment for all electricity exported to thegrid, which is in addition to the bill savings made by using theelectricity generated on site.The Government has announced a significant reduction in Feedin Tariff rates, which cuts payments by around 50%. For moreinformation see:http://www.energysavingtrust.org.uk/Generate-your-ownenergy/Financial-incentives/Feed-In-Tariffs-scheme-FITsandfurther information available at Department of Energy andClimate Change website:http://www.decc.gov.uk/en/content/cms/meeting_energy/Renewable_ener/feedin_tariff/feedin_tariff.aspxSolarcentury.co.uk48

Photovoltaic(PV)electricpanelsPhotovoltaic(PV)electricpanels 61UnitCost(lower)Cost(Upper)Cost(average)Subsidies(refer to ESTwebsite forlatest info 60£13000 £15000 £14000 Feed in tariffCase Study: 15 Passmore StreetClient: GrosvenorSolar panels were installed at 15 Passmore Street, aproperty owned by Grosvenor. The solar panels cost£11.342 for a system size of 1.88KWp inclusive ofinstallation, fees, VAT and warranty, which under the Feed-In-Tariff rate in force at the time of £0.41 would be expectedto generate around £780/annum, based on an assumptionthat around 50% of electricity generated would power thesite, with the remainder sold back to the grid. This gives apayback period of 14.5 years.When to do this: For buildings which have an appropriate southfacing roof slope the current feed in tariffs, which are open until31 March 2012 offer payments for the next 25 years based onunits generated of power generated although in November 2011the Government announced consultation on reducing thesetariffs.Case Study: Clarence HouseClient: Royal Household Property SectionArchitect: BLB Architects LimitedAn application was approved to install 32 solar panels on the roofof grade 1 listed Clarence House. These cannot be seen from theground due to the roof slope and parapet walls. The purposewas both to reduce emissions of CO 2 and to raise the profile ofthis technology. The application notes that “Given that manyother households do not have suitable roof space for a similarsized array, they are dependent on others, such as the HRH’sHousehold, to contribute where they can towards a moresustainable, low carbon energy supply.”See page 54 for full case study overviewFor further information see:• ‘An Introduction to Low Carbon Domestic Refurbishment’Construction Products Association (2010)http://www.constructionproducts.org.uk/publications/dbfiles/Domestic%20Refurbishment%20Revised11010%20(low%20res).pdf• http://www.climatechangeandyourhome.org.uk/live/content_pdfs/482.pdf49

Solar thermal panelsDoes BuildingRegs apply?Yes. Althoughthere is acompetentpersons schemeensure installeris qualified toadvise on roofstructural andweatherproofingaspects too orcontact BuildingControl foradvice.Is this work a requirementtriggered by Part L1B?Heating systems are a‘controlled service’ underPart L1B.Solar thermal water heating(consisting of indirectsystems with a collector areaof up to 20m 2 and a thermalstore of no more than 440litres ) is covered by the“Domestic Building ServicesCompliance Guide”, covershttp://www.planningportal.gov.uk/uploads/br/domestic_building_compliance_guide_2010.pdfPermissions and consentsDisruption Risks Unlisted within aconservation areaMedium Medium –Specialistinstallationadviceneeded andpossibly afeasibilitystudy orstructuralsurvey toensure theroofstructure willbear theweight of thepanels.Have asupply ofreplacementroof tiles incase theseare brokenduringinstallation.This is permitteddevelopment 62 , even on theroofs of principal elevationsof dwellinghouses and flatsin conservation areas,subject to it being ‘sited soas to minimise its effect onthe external appearance ofthe building and the amenityof the area’, i.e. where thereare alternative options forinstallation, the locationwhich minimises the visualand amenity impacts mustbe selected.Would not be permitteddevelopment:• If it protrudes more than20cm from the roof slope;• If it is higher than thehighest part of the roof(excluding chimney).• In a conservation area,on a wall which fronts ahighwayListed buildingListed buildingconsent will berequired and thiswill generally beacceptable in adiscreet location,where not visiblefrom surroundingproperties (e.g.internal valley roofor flat wall behinda parapet).Unlisted outside aconservation areaThis will notgenerally requireplanning permissionas it is permitteddevelopment 63 , onany roof or wallslope ofdwellinghouses andflats, subject to itbeing ‘sited so as tominimise its effect onthe externalappearance of thebuilding and theamenity of the area’,i.e. where there arealternative optionsfor installation, thelocation whichminimises the visualand amenity impactsmust be selected.Not permitteddevelopment if itprotrudes more than20cm from roofslope or is higherthan the highest partof the roof (excludingchimney).50

Solar thermal panels use the radiant heat of the sun to warmwater in solar collectors which is pumped to a thermal store.It is most likely to be used to top up or supplement a mainsystem, rather than meet all of a building’s water heatingdemand. It is well suited to domestic buildings which have ademand for hot water. The minimum amount of space needed tobe effective is around 2-4m 2 , ideally between south east andsouth west facing, at an angle of 30˚ and should not be shadedby trees or neighbouring buildings. In addition to the collectorpanels, space is typically needed to house a large hot-watercylinder with a storage capacity of at least 120 litres, and up to200-300 litres for larger buildings. Additional pipework will alsobe necessary.There are different types of system, direct and indirect. Directsystems heat potable water in the collector panel, and pump it toa tank for use. Indirect systems are filled with fluid (oftenantifreeze) which passes through the collector panel and a heatexchanger transfers heat to potable water which is separate fromthe fluid circulating in the panels. This slightly more complexsystem provides freeze and overheating protection.For many properties this will be permitted development and willnot require planning permission, although if you live in a listedbuilding, this is not the case.CostsSolarThermalPanelsPhotovoltaic(PV)electricpanels 65UnitPeraveragedomesticsystemCost(lower)Cost(Upper)Cost(average)Subsidies (refer toEST website forlatest info 64£4500 £5500 £5000 Renewable HeatIncentiveWhen to do this: For buildings which have an appropriate southfacing roof slope the renewable heat incentive, will offer asubsidy making this more financially attractive and reducing thepayback period.For further information see:• ‘An Introduction to Low Carbon Domestic Refurbishment’Construction Products Association (2010)http://www.constructionproducts.org.uk/publications/dbfiles/Domestic%20Refurbishment%20Revised11010%20(low%20res).pdf51

Living roofDoesBuildingRegsapply?Is this work arequirementtriggered by PartL1B?Permissions and consentsDisruption Risks Unlisted within aconservation areaNo No Medium-High Medium – Specialistinstallation adviceneeded and possiblya feasibility study orstructural survey toensure the roofstructure will bear theweight of thesubstrate;permeability of roofmembrane by plantroots, and that anyheight of balustrade issufficient, andstructure has sufficientcapacity to bear theload, where it is usedas amenity space,although this wouldbe less likely to beviewed favourably.Planning permission requiredwhere depth of build up isgreater than 150mm, whichis fairly likely with a welldesigned living roof.However for dwellinghouseswhere the build up is lessthan 150mm and doesn’texceed highest part of theexisting roof this is likely tobe permitted development, 66but this would be for flatroofs in a discreet location(not pitched roofs 67 ) but noteproposals for ‘intensive’ livingroofs which can be used asan amenity space would beless likely to receivepermission.For flats planningpermissions would berequired.Listed buildingListed BuildingConsent andPlanningPermission willbe required. Maybe acceptableon an existingflat roof in adiscreet locationsuch as behinda parapet wall.Unlisted outside aconservation areaPlanning permissionrequired where depth ofbuild up is greater than150mm, which is fairlylikely with a welldesigned living roof.However fordwellinghouses wherethe build up is less than150mm and doesn’texceed highest part ofthe existing roof this islikely to be permitteddevelopment, 68 but thiswould be for flat roofsin a discreet location,(not pitched roofs 69 ) butnote proposals for‘intensive’ living roofswhich can be used asan amenity spacewould be less likely toreceive permission.For flats planningpermissions would berequired.Dashed line indicates difference of approach for flats and houses52

Technologies have evolved to enable planted roofs – both ‘brown’and ‘green’, ensuring they have an appropriate medium to grow inand the necessary support system. A well designed living roof willmake a significant contribution to conserve and enhancebiodiversity, creating green corridors. They also are beneficial inmanaging flood risk, as they attenuate rainwater, reducing thelikelihood of flooding from surface water runoff. There is also someevidence that they act to reduce overheating (and reduce the urbanheat island effect), reduce CO 2 emissions, absorb noise and trapair pollutants.An intensive roof, which can bear the weight of people walking onit, will require a greater load bearing capacity, and this will be lessachievable on historic buildings.Costs: The cost of a living roof will vary depending on the type ofroof and specification. The issue is considered in detail in the GLAtechnical report ‘Living Roofs and Walls: Technical Reportsupporting London Plan Policy’ 70When to do this: A living roof is worth considering even when thereare competing demands for roofspace, such as for solar panels.Solar PV can work very well with a living roof with the panels on aframe above a living roof. This has benefits of microclimate – theliving roof helps to cool the PV panels, which can have problems ifthey overheat, and the shade that the panels provide on the livingroof, create areas more hospitable to a wider range of biodiversity.For further information see:• www.livingroofs.org• Environment Agency Green Roof Toolkit:http://www.environmentagency.gov.uk/business/sectors/91967.aspxLivingRoofListedBuilding 71UnitCost(lower)Cost(Upper)Cost(average)SubsidiesFor £2400 £6000 £4200 -20m 253

Case Study: 15 Passmore Street, SW1Client: GrosvenorArchitect: GRAContractor: GrangewoodEnvironmental Consultant: Eight AssociatesGoal: BREEAM Ecohomes ‘Excellent’The property, originally a one bedroom cottage, was extended tobecome a two bedroom terrace house and the whole house wasretrofitted to improve its sustainability. Although situated justoutside a conservation area, the boundary of which runs down themiddle of Passmore Street, the property was treated as if it were ina conservation area consistent with Council draft proposal in 2008.On completion it was awarded a BREEAM Ecohomes score of 78.The retrofit strategy included:• A solar PV array sized to supply 1.88KWp on the roof• New insulated roof, and insulation to floor• Internal insulation to walls• Secondary glazing to front, double glazing to the rear• Bath replaced with single shower room• Low water use fittings (9L shower and low flow sanitaryware)• Low energy lighting in 75% of the house.• Soft landscaping and rainwater collectionDetail of solar array with secondary glazing visible, Grosvenor Plc54

The completed property achieved a BREEAM Ecohomesscore of 78.94%. The investment represented an extraover cost of 5-6% compared to a Grosvenor standardrefurbishment, with the additional costs coming from PVpanels, insulation elements and increased low energylighting.Secondary glazing at 15 Passmore Street, Grosvenor Plc55

Case Study: The Flagship HomeArchitect: ECD Architects; Rickaby ThompsonContractor: Beechwood Property RenovationsClient: SE Land and Estates with Royal Borough Kensington andChelsea and City of WestminsterThis 5 storey Victorian house, split into 23 bedsits, was in very poorcondition with mould growth and damp problems. It wasrefurbished to improve its energy efficiency and meet spacestandards. The objectives included:• To demonstrate and promote practical, cost effectiveenergy efficiency improvements to private landlords.• To demonstrate the potential for improving older, solidwalledproperties in conservation areas.• To encourage a closer working relationship betweenstatutory bodies and building preservation organisations.• To show how issues such as fuel poverty may be alleviatedthrough improvements in energy efficiency.• To provide an opportunity for the Royal Borough ofKensington and Chelsea and Westminster City Council toexplore innovative measures, identify new ways of workingand promote sustainable housing.• To create a showcase for innovative energy efficiencysolutions.Improved interior finishesBefore and after refurbishmentThe strategy included:• Installation of 35 mm internal wall insulation toachieve a U value of 0.6W/m 2 K.• Replacing rear windows with timber framed argonfilled double glazing including low emissivitycoatings and draught stripping and secondaryglazing where possible at the front (not to the threearched windows).• A new top floor incorporating a highly insulated roofenabling 3 further bedsits.• Insulation to basement floor slab.• Solar thermal panels to supply up to 60% of hotwater.• New condensing boilers with individuallyprogrammable room thermostats.• Mechanical ventilation and heat recovery installedon each floor.• Energy efficient lighting.56

Installed Solar Thermal Panels on the roofPerformanceSolid wall insulation and secondary glazing being installed at the propertyFurther information on the specification is available from EnergySaving Trust 72 . Monitoring undertaken by Rickaby Thompson for aperiod of 19 months post completion suggests that assumptionsmade in the initial feasibility study about occupants’ heatingpreferences were inaccurate. The actual consumption of electricitywas 7% less than predicted, but gas consumption was 57% higher.A revised simulation model, taking into account more accurate detailsregarding occupancy, heating demand and internal temperaturepreferences demonstrated that to maintain the actual measuredinternal temperatures in the original unimproved building would havecost an additional £7450 and result in an additional 16.62 tonnes ofCO 2 . The user satisfaction ratings were also high with users feeling73comfortable, with some scope for further temperature reduction.57

SummaryMeasureUnlisted, within aconservationAreaListed BuildingFor a dwellinghouse (not flats)Unlisted, NoconservationareaSee pageLoft insulation1 11151 2Floor insulation118Internal solid wall insulation1212123 1External solid wall insulation (on rear) 25Draughtproofing11129Secondary glazing12131Double glazing13133Boiler12136Heating controls11138121Micro CHP 40Ground Source Heat pumps1 2142Air Source Heat pumps2 2 244Solar PV12147Solar Thermal12150Living Roof12152For flatsLoft insulation1 11151 21Floor insulation 18Internal solid wall insulation1 21212 3 2External solid wall insulation (on rear) 25Draught Proofing1 11291 21Secondary glazing 3158

Double glazing2 3233Boiler2 2236Heating controls 1 11 38Micro CHP 1 21 40Ground Source Heat pumps1 2 142Air Source Heat pumps2 2244Solar PV1 2147Solar Thermal1 2150Living Roof2 2252123Measure unlikely to require permission or consent; may be permitted development in somecases.Measure likely to require planning permissions or consent and may be acceptable subjectto detailed design.Measure unlikely to be considered acceptable in most cases.59

Westminster’s Planning PolicyThis guidance gives general advice on when planning permission is likely to be required, in orderto assist homeowners in a bolder approach to retrofitting their historic buildings. Whetherpermission will be required in any individual case will usually depend on a number of factors, thekey one being whether the building is listed.This guide also sets out a number of permitted development rights that apply to unlisted buildingsand which will enable a degree of freedom and flexibility in changes that you may make to yourproperty. These are defined by the Town and Country Planning (General Permitted Development)Order 1995 and subsequent amendments. Remember that although these rights generally permita householder to make changes to their property, these rights can be amended either by aplanning condition or by an Article 4 direction.Pre-application advice on the application process, likely options open to you and necessarysupporting documentation can be given although there is a fee charged for this service. Contactthe relevant area team for pre-application advice through the Council’s website athttp://www.westminster.gov.uk/services/environment/planning/permission/Unitary Development PlanThe Council’s UDP is being replaced by the Local Development Framework, but a number of itspolicies still apply. A full list of the policies which still apply may be downloaded from the Council’swebsite:http://www.westminster.gov.uk/services/environment/planning/unitarydevelopmentplan/Those that may be of relevance to retrofitting projects include:STRA 34 Pollution: air, water and landENV4 Planning around and on buildingsENV5 Air pollutionENV6 Noise pollutionENV7 Controlling noise from plant, machinery and internal activityENV12 Waste and recycling storageENV13 Protecting amenities, daylight, sunlight and environmental qualityENV17 Nature conservation and biodiversityDES1 Principles of urban design and conservationDES5 Alterations and ExtensionsDES6 Roof level alterations and extensionsDES9 Conservation areasDES10 Listed buildings60

The Local Development FrameworkWestminster is producing its Local Development Framework to replace its Unitary DevelopmentPlan. The Local Development Framework, a ‘portfolio’ of documents which together provide acomprehensive local policy framework for the city. The Core Strategy is the key document in thatportfolio, setting overarching policies. Further detailed policies will be set out in the CityManagement Plan, currently being prepared.There are a number of key policies which are of relevance to applicants seeking to improve theenergy efficiency of their property, including:CS24 Heritage‘Recognising Westminster’s wider historic environment, its extensive heritage assets will beconserved, including its listed buildings, conservation areas, Westminster’s World Heritage Site, itshistoric parks including five Royal Parks, squares, gardens and other open spaces, their settings,and its archaeological heritage. Historic and other important buildings should be upgradedsensitively, to improve their environmental performance and make them easily accessible.’CS27 Design‘Development must incorporate exemplary standards of sustainable and inclusive urban designand architecture. In the correct context, imaginative modern architecture is encouraged providedthat it respects Westminster’s heritage and local distinctiveness and enriches its world-class cityenvironment.Development should:• Reduce energy use and emissions that contribute to climate change during the life-cycle ofthe development in line with national and regional standards as a minimum; and• Ensure the reduction, reuse or recycling or resources and materials, including water, wasteand aggregates.This will include providing for an extended life-time of the building itself through excellence indesign quality, high quality durable materials, efficient operation, and the provision of high qualityfloorspace that can adapt to changing circumstances over time.’Other relevant policies include:CS28 Health, Safety and Well-BeingCS29 Flood RiskCS30 Air QualityCS31 NoiseCS37 Biodiversity and Green InfrastructureCS38 Decentralised Energy NetworksCS39 Renewable EnergySupplementary Planning GuidanceRepairs and Alterations to Listed Buildings, (1996), Westminster City CouncilDevelopment and Demolition in Conservation Areas (1996), Westminster City CouncilRoofs – A guide to Alterations and Extensions on Domestic Buildings (2004), Westminster CityCouncilSustainable Buildings (2003), Westminster City Council61

Notes and References1 Westminster Housing Condition Survey 20012 http://www.decc.gov.uk/en/content/cms/legislation/energy_act2011/energy_act2011.aspx.From 2018 landlords must bring all private rented housing and business premises up to anenergy efficiency rating of ‘E’. It will be unlawful to rent out premises which do not meet thisstandard.3 Statistical release Carbon Dioxide emissions and local authority and regional level, 15 thSeptember 2011,http://www.decc.gov.uk/en/content/cms/statistics/climate_stats/gg_emissions/uk_emissions/2009_laco2/2009_laco2.aspx4 London Mayors ‘Delivering London’s Energy Future’, Climate Change Mitigation and EnergyStrategy http://www.london.gov.uk/who-runs-london/mayor/publication/climate-changemitigation-energy-strategy5 English Heritage, ‘Conservation Principles Policies and Guidance’ (2008) is available todownload at http://www.english-heritage.org.uk/publications/conservation-principlessustainable-management-historic-environment/6 ‘Energy Efficiency in Private Sector Flatted Buildings’ 2010, ECD Architects on behalf ofWestminster City Council and Dolphin Square Foundation. ECD Architects were commissioned toconsider barriers to improving energy efficiency in private residential flatted buildings. Thisidentified the difficulties for both lessees who may not make alterations without landlords consent,and also landlords, who cannot require lessees to make changes to their properties, or to pay forsuch changes. The report highlights the split incentive issue, in terms of the benefit of energyefficiency measures going to the occupant while costs are difficult to recharge to theoccupant/leaseholder.7 See the Energy Saving Trust website for ideas which will save energy and money at no cost:www.energysavingtrust.org.uk8 Energy Saving Trust9 Energy Saving Trust10 English Heritage, Climate Change and Your Home11 English Heritage, ‘Energy Efficiency and Historic Buildings, Application of Part L of the BuildingRegulations to historic and traditionally constructed buildings’, see www.englishheritage.org.uk/partL12 http://www.energysavingtrust.org.uk/Easy-ways-to-stop-wasting-energy/Energy-saving-grantsand-offers.13 Costs Estimates from Sturgis Carbon Profiling and Samson Associates14 Cost estimates prepared for the Committee on Climate Change by Element Energy: ‘Uptake ofEnergy Efficiency in buildings’ (2009) include capital and time costs of loft insulation installed in an80m 2 property at the lower estimate represent installation on a DIY basis with upper end estimatebeing for installed cost.15 English Heritage, ‘Energy Efficiency and Historic Buildings, Application of Part L of the BuildingRegulations to historic and traditionally constructed buildings’, see www.englishheritage.org.uk/partL16 http://www.energysavingtrust.org.uk/Easy-ways-to-stop-wasting-energy/Energy-saving-grantsand-offers.62

17 Cost estimates prepared for the Committee on Climate Change by Element Energy: ‘Uptake ofEnergy Efficiency in buildings’ (2009) include capital and time costs of floor insulation installed inan 80m 2 property at the lower estimate represent installation on a DIY basis with upper endestimate being for installed cost.18 English Heritage, ‘Energy Efficiency and Historic Buildings, Application of Part L of the BuildingRegulations to historic and traditionally constructed buildings’, see www.englishheritage.org.uk/partL19 http://www.energysavingtrust.org.uk/Easy-ways-to-stop-wasting-energy/Energy-saving-grantsand-offers.20 Costs Estimates from Sturgis Carbon Profiling and Samson Associates21 Based on estimates from a range of sources including those prepared for the Committee onClimate Change by Element Energy of £5,600 (capital cost only) rising to £5,761 (including surveyand time to empty room). Note this did not include costs of recommissioning electrics,redecorating or costs of removing/refitting a kitchen or bathroom. EST estimates a range of 5,500-8,500 and DECC estimate between £5000-7000. These all also exclude associated internal worksto bathroom or kitchen and redecoration.22 English Heritage, ‘Energy Efficiency and Historic Buildings, Application of Part L of the BuildingRegulations to historic and traditionally constructed buildings’, see www.englishheritage.org.uk/partL23In line with DCLG Permitted Development for Householders Technical Guidance (January 2013)24 http://www.energysavingtrust.org.uk/Easy-ways-to-stop-wasting-energy/Energy-saving-grantsand-offers.25 Costs Estimates from Sturgis Carbon Profiling and Samson Associates26Based on estimates from a range of sources including those prepared for the Committee onClimate Change by Element Energy £6,800, rising to £8,356 (which would include scaffoldingcosts for a two storey house), but not any recommissioning of electrics or redecorating costs. ESTestimates a range of £10,500-14,500 for a three bedroom semi with gas heating.27 http://www.energysavingtrust.org.uk/Easy-ways-to-stop-wasting-energy/Energy-saving-grantsand-offers.28 Costs Estimates from Sturgis Carbon Profiling and Samson Associates, here based upon cost ofrefurbishing a sash window in a listed building.29 Based on cost estimates prepared by Keegans for the report: ‘Energy Efficiency in FlattedBuildings’, (ECD Architects on behalf of Dolphin Square Foundation and Westminster CityCouncil), 2010, for professionally draughtproofing a sash window.30 English Heritage, ‘Energy Efficiency and Historic Buildings, Application of Part L of the BuildingRegulations to historic and traditionally constructed buildings’, see www.englishheritage.org.uk/partL31 http://www.energysavingtrust.org.uk/Easy-ways-to-stop-wasting-energy/Energy-saving-grantsand-offers.32 Costs Estimates from Sturgis Carbon Profiling and Samson Associates, here based upon cost offixed lightweight seasonal secondary glazing taped for the lower estimate or a system with anindependent frame with a sash style opening at the upper end of the estimate.33 English Heritage, ‘Energy Efficiency and Historic Buildings, Application of Part L of the BuildingRegulations to historic and traditionally constructed buildings’, see www.englishheritage.org.uk/partL34 As set out at Town and Country Planning (General Permitted Development) (Amendment) (No 2)(England) Order 2008 SI 2362, Part 1 Class A.363

35 Town and Country Planning (General Permitted Development) (Amendment) (No 2) (England)Order 2008 SI 2362, Part 1 Class A36 http://www.energysavingtrust.org.uk/Easy-ways-to-stop-wasting-energy/Energy-saving-grantsand-offers.37 Costs Estimates from Sturgis Carbon Profiling and Samson Associates, here based upon cost ofrefurbishing a sash window in a listed building.38 Town and Country Planning (General Permitted Development) (Amendment) (no.2) (England)Order 2008, SI 2362, Part 1 Class G.139Town and Country Planning (General Permitted Development) (Amendment) (No 2) (England)Order 2008 SI 2362, Part 1 Class A, A.1(i)(iii) and Part C, C.1(c)(i)40 http://www.energysavingtrust.org.uk/Easy-ways-to-stop-wasting-energy/Energy-saving-grantsand-offers.41 Sturgis Carbon Profiling and Samson Associates42 http://www.energysavingtrust.org.uk/Easy-ways-to-stop-wasting-energy/Energy-saving-grantsand-offers.43 Sturgis Carbon Profiling and Samson Associates.44 Sturgis Carbon Profiling and Samson Associates.45 Town and Country Planning (General Permitted Development) (Amendment) (England) Order2011 SI 2056, Part 40, Class F46 Town and Country Planning (General Permitted Development) (Amendment) (England) Order2011 SI 2056, Part 40, Class F47 http://www.energysavingtrust.org.uk/Easy-ways-to-stop-wasting-energy/Energy-saving-grantsand-offers.48Sturgis Carbon Profiling and Samson Associates.49 Town and Country Planning (General Permitted Development) (Amendment) (England) Order2011 SI 2056, Part 40, Class C50 Town and Country Planning (General Permitted Development) (Amendment) (England) Order2011 SI 2056, Part 40, Class C51See the results of the EST field trial of heat pumps:http://www.energysavingtrust.org.uk/Generate-your-own-energy/Heat-pump-field-trial52http://www.energysavingtrust.org.uk/Easy-ways-to-stop-wasting-energy/Energy-saving-grantsand-offers.53 Energy Saving Trust figures54Subject to the restrictions and conditions set out at Class G.2 and G.3 in The Town and CountryPlanning (General Permitted Development) (Amendment) (England) Order 2011. In a conservationarea this may not be on a wall or roof fronting a highway, and may not be sited so that it is nearerto any highway than the part of the dwellinghouse or block of flats which is nearest to the highway.It should be used for heating only, and should minimise its impacts on the external appearanceand amenity of the area.55 Outside a conservation area an air source heat pump is not permitted development where it isinstalled on a wall which fronts a highway and is above ground level.56 See the results of the EST field trial of heat pumps.57 http://www.energysavingtrust.org.uk/Easy-ways-to-stop-wasting-energy/Energy-saving-grantsand-offers.58 Energy Saving Trust figures59 Town and Country Planning (General Permitted Development) (Amendment) (England) Order2011 SI 2056, Part 40 Class A64

60 Town and Country Planning (General Permitted Development) (Amendment) (England) Order2011 SI 2056, Part 40 Class A61 http://www.energysavingtrust.org.uk/Easy-ways-to-stop-wasting-energy/Energy-saving-grantsand-offers.62 Sturgis Carbon Profiling and Samson Associates.63 Town and Country Planning (General Permitted Development) (Amendment) (England) Order2011 SI 2056, Part 40 Class A64 Town and Country Planning (General Permitted Development) (Amendment) (England) Order2011 SI 2056, Part 40 Class A65 http://www.energysavingtrust.org.uk/Easy-ways-to-stop-wasting-energy/Energy-saving-grantsand-offers.66 Sturgis Carbon Profiling and Samson Associates.67 Schedule 2, Part 1, Town and Country Planning (General Permitted Development) (amendment)(No 2) (England) Order 2008, ‘Development within the curtilage of a dwellinghouse’, Class C ‘Anyother alteration to the roof of a dwellinghouse’.68Schedule 2, Part 1, Town and Country Planning (General Permitted Development) (amendment)(No 2) (England) Order 2008 Class A ‘The enlargement, improvement or other alteration of adwellinghouse’ A.3 (a) states that the materials used in any exterior work shall be of a similarappearance to those used in the construction of the exterior of the existing dwellinghouse. TheCLG technical guidance offers some clarity suggesting that this would probably only apply topitched roofs and that flat roofs would not need to accord with this, meaning that a pitched roofwould not be permitted development.69 Schedule 2, Part 1, Town and Country Planning (General Permitted Development) (amendment)(No 2) (England) Order 2008, ‘Development within the curtilage of a dwellinghouse’, Class C ‘Anyother alteration to the roof of a dwellinghouse’.70See note 6771 http://static.london.gov.uk/mayor/strategies/sds/docs/living-roofs.pdf72 Sturgis Carbon Profiling and Samson Associates.73CE192 Making Private rented housing energy efficient – the Flagship Home case study, EnergySaving Trust (2006)74Performance of the Flagship Home, Rickaby Thompson Associates, August 2007Further InformationContact 020 7641 2531 or see the planning permissions section of the council’s website atwww.westminster.gov.uk/services/environment/planning/permission for information on obtainingpre-application advice.65