retrofit for the future -...

sustainability

showhouse February 2011 |35

Nearly 27 millionhomes need low-

carbon retrofits. Hugeopportunities, but much to

learn, reports ROGER HUNT.

RETROFITFOR THE FUTURE

BELOW Follett Street, the completed,retrofitted house is to the right

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When the government launched its £17 million Retrofit for theFuture programme in February 2010 to fund low carbonretrofits, one of the architectural practices to respond was PRP.Like many, this multi disciplinary firm, with offices across theUK and in Moscow, Abu Dhabi and China, sees retrofit as ahugely important area, and one which is enjoying renewedinterest since the government pledged to cut 80 per cent of UKcarbon emissions by 2050 over 1990 levels. To meet thesetargets, domestic emissions from residential buildings will needto be cut by 29 per cent over the next ten years.Existing stock generates 27 per cent of total CO2 emissions and,with at least 60 per cent of the housing needed in 2050 already built,retrofitting existing housing to be more sustainable is essential.Currently these homes have an average EPC (Energy Performance

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Certificate) rating of D/E, with more than fivemillion homes managing only F/G. To achievethe required emission reduction targets, theaverage EPC rating for all housing will have to bebrought up to band B or better, a level currentlyachieved by only one to two per cent of homes.With up to 26.65 million homes needing low-carbon retrofits, this is far from straightforward.To be successful in the long term, best practice,standardised retrofit solutions need to beunderstood and implemented. This is whereRetrofit for the Future (RftF) comes in. The RftFprogramme is facilitated by the TechnologyStrategy Board (TSB), a non departmental publicbody established by the government. After anopen competition, which saw social landlords,local councils, architects and other specialistsuppliers come together to develop a range ofprototype solutions, 86 projects covering a totalof 119 dwellings across the UK were awardedcontracts to carry out whole house retrofits onaffordable rented homes.

This means that a huge insight into the retrofitprocess will be gained, explains Ian Meikle, theTSB’s head of low impact buildings. “The projectis seeing how far we go and how much thatmight cost.”With innovation a key component, RftF ismore than just a large scale demonstrator.Meikle emphasises that “kick starting” thesupply chain is a key aim. “We’re also lookingfor the holistic approach to carbon reductionso it’s as much about the systems andprocesses as anything else.”PRP is part of five of the project teams: FollettStreet, Beach Road, Willow Road, NailsworthCrescent, and Byron Square. Notably, PRP isalso involved with the BRE Victorian Terraceretrofit project at Watford and CoRE (Centre ofRefurb Excellence) in Stoke. As with the wider RftF project, the PRPschemes embrace a spread of house types andhave tested various retrofit methods andinnovative materials and technologies whileseeking to improved indoor comfort and achievean operational CO2 reduction target ofapproximately 80 per cent over existingperformance.

Each demonstrator house will be monitoredand evaluated by the Energy Saving Trust for atleast two years after completion of the work tounderstand the residents’ energy usage andcomfort, together with the environmentalperformance of the occupied house and thetechnology used. Ultimately the results of theprojects will be carefully evaluated and shared toidentify the potential for lower cost volumeimplementation across the UK housing stock.Key features of PRP’s approach have included:sensitivity to residents needs, maintaining theusability of the home, simplicity inimplementation and operation and the ability toreplicate the techniques in other similar houses.Further considerations were future proofingagainst climate change, fuel sources and energysupply technologies and the need to besympathetic to heritage, culture and aesthetics.

THE PROJECTSAll five of the projects undertaken by PRP have,

sustainability

“We should never trustthe records of the

house and we shouldalways do thorough on-

site surveys”


showhouse February 2011 |37

where appropriate, certain features in commonincluding: low-energy ventilation, loft and floorinsulation, real time energy display, energyefficient appliances, LED lighting, sun pipes fornatural light ingress, photovoltaic (PV) andsolar thermal panels, flue gas heat recoverylinked to high performance boilers and wastewater heat recovery.Follett Street, Tower Hamlets, London, is a

solid wall Victorian terrace house in aConservation Area. Key features include:aerogel internal wall insulation and doubleglazed windows.Beach Road, Sea Palling, Norfolk, is a turn of

the century Victorian coastal cottage and wasthe only house unoccupied during the retrofit.Adaptions were made to the front entrance toallow a ‘draught lobby’ to be created facing thesea. Key features include: aerogel internal wallinsulation, push fit ground source heat pump,wet underfloor heating and triple glazedwindows and doors.Willow Road, Dartford, London, is a pre

World War Two mid-terrace house with cavitywalls. The project saw one of the first domesticuses of combined PV and solar thermal in theUK – ‘PV-T’ high efficiency hybrid solar panels.These increase PV efficiency by water coolingthe PV panels and adding the waste heat to thesolar thermal circuit. Key features include:insulated external render and triple glazedwindows and doors.Nailsworth Crescent, Merstham, Surrey, is a

post-war, brick-built end of terrace house. A key

innovation was the linking of the solar thermal(ST) system to a ground source heat pump(GSHP). Although yet to be proven on this site,this is designed to allow surplus heat, generatedby the ST system, to be pumped around theGSHP loop to store the heat in the ground forfuture use. Key features include: externalphenolic wall insulation covered with bespokebrick slips to maintain the appearance of thebuilding, existing chimney flues capped and filledwith polybead insulation and triple glazedwindows and doors.Byron Square, Trumpington, Cambridge, is a

1947 steel frame semi detached house. Keyfeatures include: external phenolic wall insulationand triple glazed windows and doors.

LESSONS LEARNTWhile it is too early to draw definitiveconclusions, the TSB’s Ian Meikle explains thatconsiderable amounts of data will be freelyavailable at the end of the monitoring period.“We are going to monitor for two years and aregathering lots and lots of data points so will haveboth qualitative and quantitative data.”At PRP, Andrew Mellor, the firm’s environmentaldirector, explains that PRP’s aim was to developan energy reduction solution that was innovativeyet replicable and economically viable. “Earlyconsideration of how to solve delivery issuesalong with funding, incentives, residentawareness and quality control was imperative.” One of the key lessons learnt is that existinghouses hold secrets. “Therefore we have to

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OPPOSITE PAGETOP LEFT At Follett

Street, floorboards weretaken up to install

insulation on externalwalls between joistsTOP RIGHT Follett

Street, ready for internalinsulation in one of the

bedrooms MAINIMAGE Byron Squarefollowing the retrofit

THIS PAGELEFT Nailsworth

Crescent before theretrofit TOP RIGHT

Willow Road followingthe retrofit BOTTOM

RIGHT At Follett Street,photovoltaic (PV) andsolar thermal panelswere installed on the

roof


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CONTACTSPRP www.prparchitects.co.ukTSB www.retrofitforthefuture.org

Read Roger Hunt’s blog: www.huntwriter.com or follow him: www.twitter.com/huntwriter

depends on technologies which inevitably addsignificantly to the overall cost.Mellor acknowledges that “the whole industryhas a lot to learn”. Issues such as interstitialcondensation, poor internal air quality andsurface condensation on uninsulated party wallsare all very real. So, while there are are hugeopportunities for the industry in rolling out retrofitprogrammes on a large scale, those tasked withsurveying and preparing the specification for thehomes will need to be well trained and the workexecuted with consummate skill.

allow a contingency both in terms of programmeand cost. We should never trust the records ofthe house and we should always do thoroughon-site surveys,” says Mellor.With all the projects the main contractor workedwith subcontractors and this posed problemsbecause of the difficulties of ensuring that thenature of the work was understood and thatconstruction details were followed, especiallywhen it came to such things as insulation andairtightness. It is also clear that the supply chainneeds to be developed as some products arenot readily available; typical examples beingtriple glazed windows and wall insulation of therequired thicknesses.Crucially, Mellor believes that the length oftime for projects needs to decrease andresidents need to be properly informed on howthe process will impact them. “Even thoughwe – and I mean the contractor, PRP and theclients – thought we had spent enough timewith the residents explaining the process tothem we hadn’t. Six to eight weeks work forthem was a lot, they were ripping their hair outin some cases.” Ian Meikle raises the question of whether it isreally practical to do a whole house retrofit withpeople in situ. “There are some challengesaround that. Do we need to decant everybodyor can we get smarter with the way weprogramme things so we do certain areas ofthe house at a time?”As well as being disruptive, the time involvedpushes up costs. “We need a process more akinto a shop fitting exercise: fast, efficient and witha quality end product,” says Mellor. The figures currently being quoted for the basicpackage of insulation and other works to cutenergy usage are around £25,000 to £30,000 butthis only achieves a 55 to 60 per cent reductionin emissions; to achieve further reductions

TOP THREEIMAGES FollettStreet, aerogelinternal wallinsulation

LEFT BeachRoad – the

elements of theretrofit

BELOW FollettStreet, internal

insulation meansspace is lost withinthe home. This can

raise particularissues in alreadynarrow areas suchas on staircases

sh

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