The SALFORD low-e n e r gy ho u s e : Lea r nin g fro m ou r p a s t

Brow n, P, Bu rk e, ME, Mo r ris, GJ a n d Webs t er, PJ

Tit l e The SALFORD low-e n e r gy ho us e : Le a r nin g fro m ou r p a s t

Aut h or s Brow n, P, Bu rke, ME, Mo r ri s, GJ a n d Webs t er, PJ

Typ e Mo nog r a p h

U RL This ve r sion is available a t : h t t p://usir.s alfor d. ac.uk/id/e p rin t/35 8 7 7/

P u bl i s h e d D a t e 2 0 1 0

U SIR is a digi t al collec tion of t h e r e s e a r c h ou t p u t of t h e U nive r si ty of S alford. Whe r e copyrigh t p e r mi t s, full t ex t m a t e ri al h eld in t h e r e posi to ry is m a d e fre ely availabl e online a n d c a n b e r e a d , dow nloa d e d a n d copied for no n-co m m e rcial p riva t e s t u dy o r r e s e a r c h p u r pos e s . Ple a s e c h e ck t h e m a n u sc rip t for a ny fu r t h e r copyrig h t r e s t ric tions.

For m o r e info r m a tion, including ou r policy a n d s u b mission p roc e d u r e , ple a s econ t ac t t h e Re posi to ry Tea m a t : u si r@s alford. ac.uk .

Dr Philip Brown

Dr Maria E Burke

Gareth Morris

Professor Peter J Webster

—

Funded by theVice-Chancellor’s IconicProject with theCity of Salford 2010

The SALFORDlow-energy house:Learning from our past

The potential national energy savings that would result from anadoption of the SALFORD, or an equivalent efficient design, areimmense. Conversely, failure to build to the SALFORD standardwill impose a massive unnecessary burden on national energyresources that will be carried forward well into the next century

‘The SALFORD low-energy house’Energy Efficiency Office, Report No. ED 179/59,1987

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In the UK the Domestic sector uses nearly 20% of national energyfor Space Heating. The SALFORD houses, designed in 1976 forSalford City Council, and extensively monitored in 1980, consumeabout 25% of that of the general UK housing stock, and less than60% of current, 2010, Building Regulations.

Thirty years on this survey shows that the SALFORD design is stillleading and is one of very few that will be able economically tomeet, in both urban and rural locations, the near-zero Carbon‘Code for Sustainable Homes’ that is to become mandatory in 2016.

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Space heating energy required for UK housing 1976-2016 relative to 2010 Regulations

The SALFORD low-energy house was designed in the late 1970s for Salford CityCouncil in a joint project with the University. A semi-detached experimental pairand a prototype terrace of six mixed dwellings were built and extensively monitored.The results showed substantial energy savings and occupant satisfaction. The passivedesign, which incorporates a high thermal capacity internal structure protected by ahighly insulated, well-sealed envelope, provides a high level of continuous thermalcomfort at low cost whilst being fire, rot, damp, mould and vandal resistant.

In the early 1980s, about 200 other SALFORDhouses were built for the Council, withingovernment ‘yardstick’ cost limits, for sociallyrented housing and a further 50 or so werebuilt by a local developer for the privatesector. In the mid-1980s councils had to stopbuilding due to cuts to the funding of housingin the public sector. The SALFORD design andexperience did not become widely known andwas not implemented to any great extent bythe private sector that had taken over theprincipal house building role.

To mark the University’s focus upon thecross-cutting themes of Energy and SocialJustice a new study was launched in 2010to explore the long-term performance ofthe SALFORD dwellings. This 2010 studyshows the houses continue to perform well.Average space heating energy use for the30-year old SALFORD houses is less than25% of the UK average, and less than 60%of that required by the current 2010 UKBuilding Regulations. The house designdetermines the basic capital cost and theaverage level of energy consumption.

However, individual occupant choice ofequipment and comfort temperaturedetermines actual overall costs and theenergy consumption which varies widelyfrom less than 5% to more than 50% ofthe average. This study has demonstratedthat the SALFORD design continues to beahead of its time. It also suggests thatlegislation and publicly funded housingdevelopments are the principal drivers inachieving energy-saving improvementsin the housebuilding industry and at anindividual household level.

Dwellings designed to the SALFORD houseprinciples are expected to be able to meetthe proposed 2016 near-zero CarbonRegulations at competitively low capital cost.

Overview

1

In the mid 1970s Salford CityCouncil owned, and managed,approximately 40,000 renteddwellings. They were of differentdesigns and styles but many of themsuffered from a range of problemsincluding: condensation, mould-growth and poor thermal comfort.The energy crisis of the 1970s onlyadded to the conclusion that thehousing stock was too expensiveto heat. This was compounded bythe fact that many of the tenantswere on low incomes and wouldtoday be classed as ‘fuel-poor’.

In 1975 the City Council approached theUniversity of Salford for help in jointlydesigning a new low-energy dwelling thatwould address these issues. Dr J E Randell,Senior Lecturer in Building Services Engineering,in the Department of Civil Engineering atthe University, and J M A Hoyle, architectin the City Technical Services Department,were the project team. Together theyestablished the basic physical principlesand then incorporated them into the finalarchitectural design and saw them throughto construction.

The City Council laid down thefollowing specifications:— The cost of the dwellings should,

if possible, be within social housingcost ‘yardstick’ limits.

— Established construction methods,materials and techniques should be used.

— The dwellings must place no limitations onthe normal living patterns of the tenants.

— Heating costs and energy consumptionshould be substantially lower than thoseof existing housing.

— General maintenance costs should notexceed those of existing housing.

— The dwellings should be adaptable todifferent types of fuel and heating appliances.

Randell and Hoyle arrived at a basic‘SALFORD house’ design philosophy of ahigh thermal capacity internal structureprotected by a highly insulated, well-sealedenvelope. In combination these three factors,with attention to associated details, result ina ‘passive’ structure that can maintain constantequable temperatures with controllableventilation, low in winter to conserve heatand high in summer for cooling [1].

The Council first built an experimentalpair of 2-bedroomed semidetached houses,followed by a prototype terrace of fourhouses and two flats. After successful detailedmonitoring they went on to build a further200 or so dwellings in Salford.

Unfortunately the radical changes tohousing policy in the 1980s brought thenumber of homes built by local authoritiesto an effective stop so Salford City Councilbuilt no more. However, elsewhere in Salford,a private builder adopted the design for asmall estate of about 50 flats and housesand a local Housing Association incorporatedthe principles into the design of a shelteredhousing development.

Background

The SALFORD low-energy house: Learning from our past2

Design detailStructure and thermal capacityThe thermal storage capacity of a buildingis largely determined by its internal mass.In the SALFORD design high mass is providedby constructing the internal walls of denseconcrete blocks and the floors of suspendedconcrete beams with block infill topped offwith sand and cement screed. The resultis an internal mass, and thermal capacity,about four times traditional values. The innerwalls were wet plastered to ensure goodair-tightness and good thermal admittance.The large thermal capacity that results enablesmaximum use to be made of incidental gains,reduces temperature fluctuations and permitsflexibility of heating strategies. This is inmarked contrast to lightweight houses, suchas most timber-framed constructions, thatcan have a thermal capacity of around aquarter of traditional values and consequentlycan suffer large temperature excursions.

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Cross-sections of the insulation anddense structural and high thermal storagecomponents of the SALFORD house [3]

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Insulation and ventilationIn the SALFORD design the thermal insulation thickness is nominally 200 mm all round.In the experimental and prototype houses this comprised 200 mm glass fibre loft insulationwith 200 mm polyurethane granules under the ground floor and in the 173 mm wide externalwall cavities. The windows used were proprietary, sliding, dual-glazed units made of treatedtimber finished with a microporous stain, with trickle ventilators in the heads. ‘Cold-bridging’was avoided by design details, and external doors were draught-stripped and separated frommain living areas by a lobby or hall. Mechanical extract ventilation facilities were provided inthe kitchen, bathroom and toilet to remove water vapour and odours at source.

Cross-sections of the SALFORD house [3]

3

Heating systemsDuring the experimental stages severalheating systems were tested. These includedexperimental heat-pumps combined withheat recovery from extracted air, a gas boilerand both underfloor and warmed-air heating.These technologies all involve relativelyhigh capital cost items with accompanyingsignificant maintenance potential that isdifficult to justify when the maximum heatingdemand, around 2 KW, is so low.

The production houses were heated with justone, or sometimes two, balanced-flue gasconvector heaters, delivering in total between1.5 and 2.5 KW, one in the living room toprovide optimum comfort and the other inthe hall to ensure equable whole-housetemperatures. Conventional central heating,using water-filled radiators distributed underwindows in each room, was not installedin the production houses because it couldnot be economically justified and is notnecessary to maintain comfort conditions [2].

CostHistorically Salford City Council built traditional social housing within government ‘yardstick’costs. The new SALFORD dwellings were designed, giving priority to factors that involved long-term gains and saving on the non-essential, to the same financial constraints and Council QuantitySurveyor’s estimates for the design were close to those for their traditional houses. Tenders wereinvited from seven builders in 1982 to build a small estate of houses to both traditional and thenew SALFORD designs. The tenders for the traditional design averaged out at ‘yardstick’ with aspread of ±10%. The SALFORD design average was 107% of ‘yardstick’ ±8%. Consequently theCouncil were able to build within their ‘yardstick’ specification. It is to be expected that prudentbuilders would factor into their estimates an additional amount for unknowns when tenderingto build to a new unfamiliar design, and that costs could be reduced as they gained experiencewith the design. With or without this factor there was very little difference in cost between thetraditional and SALFORD designs.

External appearance and orientationThe external house appearance of brick walls with tiled pitched roofs is normal for the UK butis not critical to the design. Overall window area is also normal but, as the road on which thedwellings were built runs NE-SW, the most southerly facing elevation, that to the SE had the mostglazing, about 25%, and the NW about 10%. This enabled maximum solar gains to be receivedvia the SE windows and for transmission losses through the NW facade to be minimum. Theexternal doors on the NW face were also sheltered with a porch and outhouse. The NE and SWwalls are unglazed brick-faced end walls to the exterior, or are internal concrete block party walls.

The SALFORD low-energy house: Learning from our past4

SE elevation of the experimental semidetatched pair and prototype mixed terrace [3]

The NW facade of the prototype terrace in 1980 [3]

Monitoring results 1980-82The prototype terrace was extensively monitored through 1980-82, by Salford UniversityIndustrial Centre Ltd., as part of the Government’s Energy Efficiency Demonstration Scheme.The results were published as a full Report [3] and as an outline Expanded Project Profile [4]in 1987. The annual average energy used for space heating, water heating and for all otheractivities as measured for the SALFORD terrace in 1980-82 were compared with values calculatedfor an equivalent group of dwellings built to the 1976 Building Regulations then in force, andto 1985 Regulations introduced later. It was assumed that energy for water heating and otheractivities would be the same for all equivalent dwellings. In the dwellings built to 1976 Regulationsabout two-thirds of the total energy is used for space heating. In the SALFORD dwellings spaceheating energy consumption is reduced to about a quarter of that of dwellings built to the1976 Regulations, so that space heating, water heating and other uses are each of comparablemagnitude. Overall energy savings in the SALFORD dwellings are about 50%. Typically the lengthof the heating season, the period of a year in which heating is required to maintain comfortableinternal temperatures, is also reduced from the UK average of about 7 months to around3-4 months in the SALFORD dwellings.

A large majority of the tenants indicated satisfaction with the SALFORD dwellings. As wellas being very economic to heat, about £1 per week at 1980 prices, the houses are inherentlyresistant to fire, rot and vandalism, and were reportedly quiet with reduced internal and externalnoise transmission. As internal surfaces are maintained at equable temperatures day and nightcomfort is increased and condensation problems are minor. Even without heating, in UK wintersthe risks of house freezing are virtually eliminated.

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Auunal energy use in 1980-82 for SALFORD houses (% of 1976 Regulations)

The SALFORD low-energy house: Learning from our past6

30 years on...Apart from the monitoringactivity performed in theearly 1980s little attentionhas been paid to the housesin the intervening period.Indeed, residents from theoriginal monitored terracehad been assured of nofurther inconvenience anddisruption from any moremonitoring by researchers.

The houses and their occupants though posea unique opportunity to better understand– over the long-term – whether the housescontinue to be energy efficient, how theresidents use them, what they think aboutthem, and whether lessons could be takenfrom this experience nationally.

Quite a lot has changed in the 30 years. In themid-1970s the housing concerns of Salford CityCouncil were the plight of their low-incometenants and the inadequacy of their housingstock to meet their needs. Now, the Councilhas little direct involvement with new-buildhouses which have become the responsibility ofHousing Associations and private developers.

For the first 20 years there was little changein the UK Building Regulations related to theconservation of energy. It is only in the last decadethat there has been any significant improvementand it will be only in the next decade that newRegulations will become effective and requireexpert design to meet. There is now significantconcern for the environment, climate change,CO2 emissions, and an emphasis on ensuringsustainability in development. There is alsoa national commitment to meet impendingrequirements of EU legislation and internationalagreements related to sustainability andnear-zero Carbon buildings.

The specific objectives of the new study were to:— Assess how the SALFORD house has

performed, and how it conforms to currentand proposed building standards.

— Analyse the current energy consumptionof the SALFORD house.

— Determine what maintenance andrefurbishment has been required.

— Determine the various views, experiencesand everyday behaviours of residents living indwellings built to SALFORD house principles.

The SALFORDhouses today - Surveyresults 2009-10It remains unclear exactly how manyproperties were developed in Salford to theSALFORD house design. One of the mainproblems in tracking them down was thelack of awareness about their existence bycurrent officers within Salford City Council.Officers and Councillors who were contactedtended to know of the existence of the housesbut were unsure how many were developedand where these might be. Indeed, oneCouncil development of SALFORD houses,in Lower Broughton, had been demolished,along with a number of surroundingdilapidated properties, to make way fora large-scale urban renewal project.

Also, as their external appearance isintentionally conventional, and no limitationswere placed on normal living patterns,many of the current occupants - as well asexternal agencies such as the local authority,regeneration partners and estate agents- are unaware of the exceptional natureof their properties. However, through acombination of conversations with CityCouncil staff and the publication of a pressrelease about the study, a number of peoplecame forward who had direct knowledgeof the houses of interest to the study. Threesites were located and studied; the originalexperimental semi-detached house andprototype terrace adjacent to the University;a Council built estate of houses in Pendleton;and a mixed private development in Ordsall.Some of the former Council properties arenow privately owned or let.

Interviews were organised with as manypeople as possible who had experience ofthe properties. In total 18 people wereinterviewed, 15 of whom still lived in thehouses, one had recently moved to anotherproperty and two had been forced to leavetheir properties as a result of the urbanrenewal initiative that required thedemolition of the houses.

Most of the interviews lasted for around30 minutes and covered:— Their awareness as to the background

of the development of the house design.— Length of habitation and reasons for

moving there.— Views on how the house compares to

other properties they have experience of.— Views on comfort.— Installation of any energy efficiency

related modifications.— The heating season of the house.— Duration of daily heating usage.— How they used the property.— Overall satisfaction with the house.— Their actual or approximate energy use.

The occupantsFour of the people interviewed were the original tenants of the houses when they were builtin the early 1980s. The others had lived there for various periods of time from just a few monthsto many years. Interviewees ranged in age from 18 to 85. Dwelling occupancies ranged fromindividuals to a household of four with young children. Seven interviewees were owner occupiers,three were privately renting and eight were existing or former Council tenants.

The heating systemsThe original heating systems, of one or two gas convector room heaters, had been replaced byconventional central heating in all the properties, either by the Council or by the private owners.

There was a distinct divide amongst occupants who had experienced the houses both pre- andpost-central heating. Two expressed the view that those who complained about the lack of centralheating did not understand how to use the house. Another long-term resident reported thatpeople who moved into the houses ‘moaned’ as they expected central heating and saw the housesas being in that respect inferior to other properties. It was reported by a number of people thatthe original heating system was more than adequate as they found the properties warm in winterand cool in the summer. There was some suggestion that the people who were satisfied with theoriginal system tended to be the people who had lived in the properties from the beginning andwho had been taught to use the heating system correctly. Those who did not like the originalsystem were often later occupiers. However, there were people who had moved into thehouses when built in the early 1980s but who did not share the enthusiasm for the properties.One person described the houses as ‘difficult to heat’ and ‘draughty’ until they had installedcentral heating and fitted a secondary external door to the porch.

There is anecdotal evidence from private developers, at the timethe houses were built, that it was difficult to sell the houses withoutcentral heating installed as potential buyers considered that theylacked an essential amenity. The idea that central heating is notessential for comfort, but is generally only necessary to compensatefor inadequate thermal design, was not, and is still not, generallyunderstood or accepted.

7

Condensation, damp and mouldSome problems with condensation and mould were reported but they were not endemic orsevere as had been common to houses in the 1970s. All the Council-built production propertieswere fitted with extractor fans in the kitchen, and in them no damp or mould problems werereported. No fans were fitted in their bathrooms originally, one tenant has since installed one.Another, without a fan, complained of mould growth in the bathroom. In the mixed privatedevelopment the bathrooms in the flats are situated in the middle of the property and haveno windows. Some of the bathrooms have a fan and others not and condensation and mouldgrowth is a problem. One person just opens doors and another uses a dehumidifier. Problemsof mould were not reported from the private houses that have bathrooms with windows.

Condensation forms on surfaces in rooms in which there is anexcess of water vapour and inadequate ventilation to remove it.Most commonly, in traditional dwellings, condensation forms on thecold inner surfaces of poorly insulated external walls even when thewater vapour concentration is not high in absolute terms, becausethe surface temperature is below the dew-point and the relativehumidity is then 100%. If condensation persists mould will inevitablyform and may grow rapidly, especially if it is warm, as it is likely tobe in an internal bathroom. Insulating the outer walls substantiallyreduces the traditional problem but has no effect when the cause isnot cold but is lack of adequate ventilation. The solution is to provideappropriate ventilation facilities and for them to be used.

WindowsOriginally the Council fitted proprietary, sliding,dual-glazing, with a treated timber framefinished with a microporous stain as it wasthermally efficient with an estimated 60-yearlifetime. Its cost was about the same as that ofa single-glazed, hinged, painted wood windowwith an estimated lifetime of 10 years, that wascommonly fitted at the time. The uPVC-frameddouble-glazed units that are now ubiquitous,were then much more expensive and sealantfailure within 10 years was common.

Without exception all the people interviewedreported that the original windows thatwere installed were unsatisfactory. There weretwo principal problems, ease of opening andcleaning. Although they were not as easy foroccupants to open as hinged windows theywere not as secure and could be openedwithout too much difficulty by intruders fromthe outside. This failing was not acceptable tooccupiers and some had difficulty obtaininghouse insurance. Some occupants used toremove panes for cleaning between theoverlap. This was hazardous as some paneswere large and difficult to handle andbreakages occurred.

Years later, the Council replaced all the windowsin their properties with uPVC double-glazedunits. Private owners have done the same,except in one upstairs flat where the originalunit is still in use and is serviceable 30 years on.

The SALFORD low-energy house: Learning from our past8

The heating season and annual spaceheating energy consumptionsThe traditional heating season in the UK isabout seven months, from early Octoberthrough to May. For the SALFORD houses itis less, typically about half, from aroundmid-November through to March on average,as incidental gains are sufficient to heat thehouses through much of autumn and spring.Also, on heating days the space heatingdemand is on average about half that oftraditional housing. Overall the annual spaceheating requirement is about a quarter oftraditional, as it is approximately proportionalto the product of the daily demand and theheating season length.

As daily demand and heatingseason length are approximatelyproportional to each other thesquare of either can be used asa measure of annual spaceheating energy consumption.

The 1980-82 study involved detailedtemperature monitoring at half-hour intervalsin six dwellings over two years. It produceddetailed results which showed thatconsumptions by different households variedby about a factor of five, from about 10% to50% of traditional with an average of near25%. In this 2010 study energy consumptionwas calculated from the heating seasonlengths and space heating costs estimated byeach interviewee. The results were groupedaccording to location; the original terrace,the estate of Council production propertiesand the private development, then averagedand all compared with the equivalent for aTraditionally built dwelling as reference.

The estimated average energy consumptionis almost exactly the same as was measuredfor the 1980-82 seasons; just over 25% ofTraditional. However, large fluctuations areobserved, from below 5% to near 85%. Atleast four of the 14, from across the locations,have very small consumptions, each less than5% of Traditional and less than a fifth ofthe SALFORD average.

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In 1980-82 House 3 in the terrace had by far the highest energy consumption, about 50%of Traditional. In 2009/10 the same house had the lowest at well under 5%, less than a tenth ofpreviously. A similar reduction is shown by Flat 6, but the opposite trend is shown by House 4in which consumption has risen from about 20% to near 30%. All three dwellings had differentoccupants in 2009/10 from those in the 1980s. In contrast House 1 has the same occupants,but they are 30 years older. In 80-82 House 1 averaged just under 20% and in 09/10 about30%, a much smaller change but a rise, as would be expected for older retired occupants whogenerally have higher heating demands than the young and more active.

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The differences in space heating energy use in the SALFORD dwellings are largely due to the different internaltemperatures chosen by the occupants. A one degree increase in the average internal temperature throughthe heating season could account for the increase in consumption in House 1. Minimum comfort temperatureis often considered to be 18˚C, with 23˚C being very comfortable. At a steady internal temperature of 23˚Cthrough a UK winter a SALFORD house consumes around 25% of the space heating energy of that for aTraditional house run at the same peak temperature, but the latter would have lower nighttime temperaturesas a result of using energy-saving intermittent heating. A SALFORD house run at a steady 18˚C would, over aseason, consume only about a quarter of one run at 23˚C. Thus it is not surprising that there is such a variationin energy consumption when occupants can choose to live in acceptable comfort at minimal cost, or verycomfortably at a quarter of the cost of normal. Furthermore, if one house in a SALFORD terrace is unheatedits temperature, during cold spells, could be elevated by up to an additional 5 degrees by heat transferfrom neighbouring houses through the uninsulated party walls.

The power requirements andinternal temperature responses forSALFORD, Traditional and timber-framed dwellings are very different.Calculations for houses intermittentlyheated for eight hours to achievea comfort temperature of 21˚C,for an external temperature 0˚C,after a morning 2-hour boost andfor a further six hours throughthe evening are illustrative.

Traditional and timber-framedwellings save energy by intermittentheating but at the expense of lowerinternal temperatures. The Traditionaldwelling drops below the comfortband within four hours of switchingthe heating off and the timber-framedwelling in less than two hours.The SALFORD dwelling would stillbe within the comfort zone twodays later so there is no need forthe heater to be sized for boostpower or significant advantagein intermittent heating.

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The SALFORD low-energy house: Learning from our past10

Internal temperature and heating power Chart and Table for SALFORD,Traditional and Timber-Framed Dwellings intermittently heated to 21oCby 2-hour boosts morning and evening for an external temperature 0oC

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Comparison to other propertiesand UK Building RegulationsThe two former social housing tenants whohad recently been moved from the SALFORDhouses and had been rehoused in the newlarge-scale development, were critical of theirnew homes. They regarded their old housesas being far superior to their new propertieswhich they described as; draughty, noisy,difficult to keep warm, and expensive to runwhen compared to their old SALFORD houses.

Presumably the recently built new propertiesin the large-scale redevelopment comply,as a minimum, with the 2006 UK BuildingRegulations. The 40-year comparison of thespace heating energy requirements and usagefor UK housing since 1976 shows that theSALFORD house requires less than 45%of 2006 Regulations, which supports thecomments of the former tenants that theirnew houses are relatively difficult to keepwarm and expensive to run.

In the twenty years from 1976 the Regulationsrelated to space heating tightened by about15%. It is only in the last decade that therehas been any significant attempt, in responseto serious environmental concerns, to usethe Regulations to conserve fuel and power.In 2003 the average housing stock was only8% more efficient than 1940s cavity wallstandard constructions and, regardless of newbuild, it will require substantial refurbishmentof the existing stock, and decades, beforeefficiency improves much further.

The SALFORD design is exceptional incomparison. It is over 40% more efficientthan the current 2010 Regulations and 25%better than the proposed 2013 Regulations.With a few practicable improvements, toensure compliance with the new sustainableenergy sourcing requirements, dwellingsdesigned to SALFORD house principles shouldbe able economically to meet the proposednear-zero Carbon 2016 Regulations.

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The social significance of the SALFORD designAlthough the SALFORD houses are demonstrably superior in comfort, energyefficiency and lifetime costs to most UK houses that is not enough for them,or for equally efficient innovative designs, to be routinely built. The bulk ofnew housing stock – around 80% - is built by private developers for sale onthe open market. For houses to be built in the private sector they must beprofitable for the builder or developer who must compete in the existingmarket which requires them to take a short-term view of a long-terminfrastructure investment – namely a house or dwelling.

These dwellings, and how they are used by occupants, will determine levels of energy consumptionwhich will have an impact for decades or possibly centuries. These are important considerationsas domestic space heating accounts for nearly 20% of UK energy consumption. In the past thepublic council house sector could, and did, take a more socially considered longer-term view,although it was still constrained by stringent capital cost limits. It was only because the public sectorwas then active that the SALFORD houses were built in the late 1970s. Further building, andexploitation of the innovative technological advancement, ceased when councils were effectivelystopped from building in the 1980s; a direct if unintended consequence of national political policy.

Due to the short-term pressures at play in a market economy, private sector developersgenerally cannot competitively build to much better than current Building Regulations as itusually involves an increase in costs, which it is difficult for them to recover because purchasersrarely appreciate, or are prepared to pay for, the superior long-term or energy efficient features.The prime determinants for private house purchasers have typically been: ‘location, location,location’, mortgage constraints, perceived property desirability and the view they take of the‘housing ladder’. The average mortgage length is historically only seven years but for youngerfirst-time buyers it will be less as they tend to move more frequently. Older owner occupiers tendto be less active in the housing market as for them social factors tend to supplant financial andcareer move considerations.

The SALFORD low-energy house: Learning from our past12

Estate agent marketing tends to reflectpotential buyers’ interest priorities and, at thesame time, serve as a means of maintainingsocial norms for purchasers and vendors asto what is deemed ‘important’ or ‘desirable’features in a new home. Although the issuesof sustainability and energy-efficiency areachieving greater prominence in our economythe references to energy use in theadvertisements of estate agents are minimal.Virtually the only references to energy use orcomfort are comments such as “the propertybenefits from having gas central heating anddouble glazing”. In general terms there is littleor no interest in energy efficiency from housebuyers. At least one of the SALFORD houseswas placed on the housing market at the timeof the study and no mention was made ofthe unique characteristics of the property byeither the vendor or the estate agent.

Efforts have recently been made bygovernment and most properties, whenbeing built, sold or let, are required to havean Energy Performance Certificate (EPC) or,in the case of new build housing, be ratedagainst the Code for Sustainable Homes.Regardless there remains generally little orno interest in energy efficiency from housebuyers and, as yet, there is no evidencethat EPCs or the energy rating of a houseis having a major impact on how homesare marketed or bought.

It is, however, a positive step and is likely thatthey will start to have some impact, as hasgradually happened for similarly energy-ratedconsumer durables and cars. Only when thecost of fuel is prohibitively expensive willconsumer demand lead to any increase in theattention placed on initiatives like the EPC.Until then it appears that only by legislationto enforce minimum standards will the privatesector be able to meet the sustainable andsocial need. Developers and providers of socialhousing however tend to driven by differentobjectives – such as tenant and communitywelfare – with more attention placed on thelong-term investment in their stock. As thisstudy, and other findings, show social housingproviders tend to be inclined to invest inimproving housing standards as well as beingkeen to explore new ways to tackle issuessuch as energy-efficiency and fuel poverty.

UK governments have historically not legislatedto any real extent to decrease the use of fueland power in dwellings until the last few years,and the building industry has not sought topush them in this regard. We are now in themidst of a decade of rapid change driven bythe concerns over the consequences of climatechange and the requirements placed uponthe UK by EU legislation. In the 1970s SalfordCity Council responded locally in a socially justand innovative manner to the urgent needsof their tenants. This led to the developmentof housing which was decades ahead of itstime. Thirty years on it is, once again, urgentnecessity that is the driver for EU, nationaland local action.

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The SALFORD low-energy house: Learning from our past14

— In the main the occupants are well satisfiedwith their properties and enjoy a highstandard of thermal comfort at muchreduced cost.

— There are a few instances of mould growthbut they could be eliminated by using anextract fan.

— The properties are inherently resistant torot, fire, vandalism and noise transmissionand maintenance costs are relatively low.

— There has been some refurbishment inresponse to occupant demand. The originaldual-glazed windows, and room heaters,both adopted by the Council on the groundsof their satisfactory thermal performanceat minimal cost have been replacedrespectively by uPVC double-glazed unitsand conventional central heating. Theoriginal decision was cost optimal butclearly the users prefer the more expensivebut more convenient alternatives forthese items.

— A marked feature of the results is thevariation in energy consumption bydifferent households. This can be explainedby householders operating their homesat different temperatures. A SALFORDhouse could be habitable throughout theyear without any space heating at all,comfortable at 10%, and very comfortableat 25% of normal consumption.

— Strategically the much shortened heatingseason required by houses built to theSALFORD design could, in the long-term,if they are built in large numbers, affectthe seasonal demand patterns for fueland power. In the short-term their toleranceto zero heating provides security foroccupants in case of extended power,or fuel delivery, failure.

— There is little difference in capital costbetween traditional thermally inefficientbuild and the relatively simple SALFORDlow-energy design. They employ traditionalbuilding methods and materials, andmaintenance costs are correspondingly low.

— Legislation, or renewed public sectorinvolvement, is necessary to furtherenergy-saving improvements in thehousebuilding sector.

ConclusionsThis survey has shown that dwellings built to the SALFORDdesign over 30 years ago continue to perform to specification,using about 75% less energy than the UK average for spaceheating and over 40% less than for houses built to the latest2010 Building Regulations. Houses built to the SALFORD designprinciples, of a high thermal capacity internal structure protectedby a highly insulated, well-sealed envelope, should be able tomeet the near-zero Carbon Regulations to be introduced in 2016.

Although good thermal design is necessary to enable substantialenergy savings it is not sufficient to ensure it. Individual residentbehaviour and a lack of understanding about how to use dwellingscan make an enormous difference to how efficient a low-energyhome is. In order to obtain optimal benefits the design must also beintuitive for occupants to use and match their habitual behaviours.

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References[1] J E Randell and J M A Hoyle, Low energyhousing - Salford’s answer, Building Servicesand Environmental Engineer, June 1979.

[2] J E Randell, Domestic heating systems andtheir selection, BSER&T 4 No. 2 1983, 52-61.

[3] P J Webster, The SALFORD low-energyhouse, DoE Energy Efficiency DemonstrationScheme, BRECSU Report No ED 179/59,December 1987, 1-48.

[4] P J Webster, The SALFORD low-energyhouse, DoE Energy Efficiency DemonstrationScheme, BRECSU Expanded Project Profile 59,February 1987, 1-4.

AcknowledgementsDr John E Randell, formerly Senior Lecturerin Building Services Engineering, in theDepartment of Civil Engineering at theUniversity, and J Martin A Hoyle, formerlyarchitect in the City Technical ServicesDepartment, were the project team taskedto design what was to become the SALFORDhouse. Together, in 1976, they establishedthe basic physical principles and thenincorporated them into the final architecturaldesign that has stood the test of time.

We wish to acknowledge their originality,innovation, expertise and achievement.We also wish to offer our gratitude to theoccupants of the houses who took the timeto talk to us – more than once in somecases – about their experiences of living intheir homes.

Finally, we are grateful to the University ofSalford for providing the VC Iconic awardthat allowed this study to take place.

The SALFORD low-energy house: Learning from our past16

SE aspect 1980

SE aspect 2011

Salford Housing & Urban Studies UnitCollege of Science & TechnologyUniversity of SalfordBusiness HouseSalfordM5 4WTUnited Kingdom

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