Energy Efficiency in Conservation Areas - Westminster City Council

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Energy Efficiency in Conservation AreasEnergy Efficiency in Conservation AreasInsulationRoof InsulationRoofs can be easily and cost effectively insulated.Where possible, use vapour permeable sarking toavoid the need for visible external vents. Whereadditional ventilation is required, ensure thatexternal vents at eaves, ridges and down the pitchare sympathetically designed and specified.Loft insulation• should completely cover all ceilings belowand overlap any wall insulation• must allow good ventilation to the loftspace without blocking eaves or soffitvents• results in colder loft spaces so water tanks& pipes should be insulated or removed toavoid freezingRoom-in-the-roof insulation• can be applied in-line with the sloping rooffrom inside behind a vapour checkplasterboard• usually needs a continuous ventilationgap above it• can be added above existing timbers fromoutside• should be continuous with insulation in theceiling above and in the walls belowFlat roof insulation• can be applied to existing roofsparticularly when renewing a roof deckand finish• needs a continuous ventilation gap to bemaintained above it when laid betweenjoists• can be added on top of an existing deck(without ventilating below it) orunderneath existing ceilings• refer to LSA manuals for lead roofs (seeglossary)Key: Figure 51 Continuous line of insulation with ZODP2 Minimum 50mm ventilation gap maintainedunder existing roof or vapour impermeablesarking3 Equivalent of 25mm continuous eavesventilation gap, with insect mesh4 Wall and ceiling finish usually with a vapourcheck membrane behindAvoiding Thermal BridgingThermal bridging occurs where insulation is notcontinuous or is bridged by materials such asmasonry or timber with a higher rate ofconductivity. Then heat loss increases andcondensation can be a problem. It is not aplanning issue and it should be carefullyconsidered when insulating.Care is needed particularly with internal insulation:around openings, at the junction of wall and roofinsulation, and where intermediate floors andpartitions meet external walls. Thermal bridgingcan be avoided by:• carrying insulation around all window and doorreveals up to the frames• ensuring roof insulation reaches the top ofexternal walls without blocking ventilation• applying a metre of insulated dry lining to bothsides of internal walls as they join external walls• insulating in the ceiling cavity below a parapetgutter before the flat roof insulation can begin• insulating in ceiling cavities under intermediatefloors at the break in the wall insulation• ensuring rooflights are detailed to avoid thermalbridging, including conservation productsFigure 5Typical room-in-the-roof detailing showing in-lineroof insulation with loft and internal wall insulationA sustainable approachSustainability issuesAll buildings, in their construction and in their usehave a significant impact on the environment.Demographic trends, projected to 2016, show thenumber of households per head of populationdoubling from 1861. The current and futurechallenge in the maintenance and construction ofall housing is to balance or reconcile its impactswith the benefits gained.In addition to energy efficiency and waterconservation, the main sustainability issues toconsider when refurbishing traditional buildingsinclude:Use of local labour & skills• to support local economies and theviability of local businesses• to encourage traditional building skills andcrafts using local materials• to reduce reliance on transport leading toa reduction in energy use and pollutionPreventing pollution• by employing energy efficiency measures• by using products that do not containCFC’s/HCFC’s, VOC’s, heavy metals orPVC• by avoiding equipment that contributes toacid rain, produces NOx or airborneparticulates• includes avoiding products fromcompanies responsible for pollution in thedeveloping worldBetter buildings for health• by designing correct thermal & ventilationlevels• by using non-toxic materials &components, such as organic-basedpaints and stains• by avoiding VOCs - e.g. urea -formaldehyde foam insulation which hashealth hazard concerns• by considering the design of domesticelectrical systems to avoid ElectroMagnetic Fields (EMFs)• includes considering the health of buildersChoice of materialsThe environmental selection and use ofconstruction and finishing materials must beappropriate for traditional buildings. It is a largesubject and is discussed on the next page.Energy AdviceWhilst a building can be designed to be energyefficient, it is how the building is used that willultimately determine how efficient a building willbe. It is good practice to complement the energyefficiency improvements with an energy adviceprogramme. This will enable occupants to:• understand their heating & controlsystems• reduce their fuel bills & budget for fuel• alter their behaviour to save energyRSLs are in a unique position to undertake anenergy advice programme, containing forexample:• simple system-specific energy advicehandbooks• home visits by a qualified energy adviser• energy advice surgeries for problemsolving• energy advice talks at residents’associations• tips and advice incorporated in RSLnewsletters• a show house used as a demonstratorEnergy advice to occupants should include:• how to use heating controls &programmers• recommended temperature settings• controlling condensation• efficient use of appliances & low energylights• grants for energy efficiency improvementsContractors should also be educated to giveenergy advice that is consistent with the aboveprogramme. Contact the Energy Efficiency AdviceCentre for more information (See Contacts)5 14
Energy Efficiency in Conservation AreasEnergy Efficiency in Conservation Areas13Water conservationMains water useOver half the 33 billion litres of water extractedeach year in the UK is used by the domesticsector. It is important to address waterconsumption in homes due to rising environmentalconcerns. Water costs can be more than thecombined cost of gas and electricity in a wellinsulated house.Water saving appliances can be fitted into existingbuildings to make 24% to 47% savings without anyimpact on the external appearance. As withenergy, water efficiency is determined by theactivity and habits of occupants. Further advicecan be sought from the Environment Agency (seecontents).Rainwater useRainwater collection can be considered for WCflushing, cleaning and watering to save up to 50%of household mains water consumption.Rainwater package systems are now readilyavailable which comprise of a centrifugal filter,storage tank, pump and controls. Tanks can belocated underground or in a basement. Rainwatercan be pumped to WCs directly or to a holdingtank inside.Manufacturer’s instructions and water authorityregulations should be followed at all times.A specialist can be consulted for further advice.Rainwater system components - a downpipe filter(left) can be fitted easily into an existing drainsystem & an underground filter (right) is usuallypart of a new system: both filter out particles &debrisWater conservation adviceThe Environment Agency’s factsheets entitled‘Conserving water in buildings’ providescomprehensive guidance on all aspects of wateruse and appliances: see Contacts on the backpage.WCsSome WCs can use 9 litres of water a flush. Newerlow flush WCs have 2 to 4 litre flushes. Waterlessor vacuum toilets may only be appropriate inparticular circumstances. It is sometimes possibleto reduce the flush of existing WCs with adisplacement or delayed fill device, though not ifthe WC then needs to be flushed more than once.Baths, showersand tapsTapered and insulatedbaths save water andenergy.Showers should be fittedwith thermostatic mixervalves and low water useheads.Spray taps save up to 80%of the water and energyused by standard pillartaps and aerators reducesplashing and give theillusion of greaterwater flow.InsulationWall InsulationExisting walls can be insulated in a number ofways. All walls should be fully surveyed to currentBritish Standards and deterioration corrected priorto insulating. Traditional walls have a greaterability to ‘breathe’ (explained on page 15), so theimpact of any insulation on the overallperformance of the building should be fullyassessed at design stage. Planning guidance isgiven below.Internal wall insulation• is recommended for solid walls using aninsulated dry lining system (usually withvapour control) which does not affectexternal facades• is easy to install and can accommodatenew service ducts and conduits (see right)• avoids thermal bridging (see page 5) andinterstitial condensation when correctlydetailed• can cause additional problems if any timberused is not isolated from external walls usinga DPC• improves draught-proofing of a buildingwhen sealed around its edges, see alsopage 7• should be carefully detailed to avoiddamaging internal features e.g. aroundwindows & doorsCavity fill insulation• is recommended where masonry cavities exist• should not use materials that are a healthhazard• can damage facades during injection unlesscare is taken when positioning and drillingholes• should be installed by a manufacturers’approved contractors using a testedand certified product (e.g.with a BritishBoard of AgrÈment Certificate)External wall insulation (EWI)• is not preferred if existing externalfeatures and facades need to be retained• can be used to reproduce lost originalfeatures where traditional materialscannot be used• provides the highest insulation levels androom sizes are not reduced• easily avoids thermal bridging andprovides protection to existing walls• makes use of thermal mass in existingwalls• should be undertaken by a manufacturer’sapproved contractor using a testedproduct with third party certification (suchas BBA)Watch points• Prior to insulating, ensure that existingstructural, damp and rot problems havebeen eliminated• Never block existing ventilation holesunless an adequate ventilation method isto be provided• Always ensure that any timber used isisolated from external construction by aDPC• Always use non-PVC conduit, particularlynext to polystyrene insulation which canreact with itPlanning GuidanceGuidance should always be sought for majorrefurbishment works. Where there is no legislativecontrol, good practice in the care of historicbuildings should still apply. SPAB publishes suchtechnical guidance, see Contacts on the backpage.The following general guidance is given:• Floor and basement insulation isacceptable by following good practice forhistoric buildings• Dampness and rot problems should notbe treated unnecessarily with chemicals,see page 15• Internal insulated dry lining is acceptablewhere internal features are not historicallyimportant• Cavity wall insulation is acceptableprovided care is taken making injectionholes• External wall insulation should only beconsidered in consultation with thePlanning Department• Loft insulation combined with vapourpermeable sarking eliminates the need forvisible roof vents• Flat roof insulation can add thickness thatshould be kept below original upstandsand parapets6
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Energy Efficiency in Conservation Areas - Westminster City Council

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