Select Committee on Environmental Audit Written Evidence


Memorandum from Zed Factory Ltd

  1.  Zero heating specification homes and workspace can be built at no additional cost if economies of scale of around 5,000 units/year can be achieved within a UK sourced supply chain. BedZED cost more than standard construction because it is a prototype. With 1,000 units/year extra cost is reduced to around 15%. This figure is easily matched by the increased sales value on private for sale units.

  See section 1 in evidence submission—tender showing 20% cost reduction over BedZED

  2.  Lightweight steel framed or timber framed Modern methods of construction that do not incorporate high levels of thermally massive storage will require carbon intensive air conditioning within 30 to 50 years. The ZED building physics model developed with Arups allows new homes to take advantage of passive solar gain in winter meeting around 30% of winter space heating requirements, and passive cooling storing night-time coolth in the building fabric to compensate for the hot day temperatures. There is an urgent need for the sustainable communities programme to address climate change, recognising that the latest DEFRA and DOE predictions for summer temperatures in London in 2080 are likely to be similar to those found in Marseilles today.There are no lightweight homes or offices built in Mediterranean climates. Changes in the gulf stream that could produce colder winters are likely to be 300 to 500 years away.

  See section 2 in evidence submission—slides from DEFRA/DOE climate change conf.

  3.  Renewable energy sources can only meet national demand towards the end of this century if ZED standard load reduction exercises are adopted in new construction. The BRE Ecohomes excellent specification only offers a 35% carbon reduction on the current building regulations legal minimum. The maximum environmental performance specification recognised by English Partnerships is EcoHomes excellent. It is hard to see how the low standards embodied in this standard can deliver long term government targets. Despite repeated requests to the BRE to raise this standard to ensure zero heating specification fabric is a minimum reqirement, no progress has been made. ZEDfactory are now setting a new independent ZED standard, fully integrated with environmental performance targets for every part of the supply chain which will form the new industry standard—in much the same way that the Soil Association has regulated and maintained organic food standards. We would like to do this with government support, rather than as a private initiative. The Supply chain needed to build new ZED urban fabric can also be used to renovate existing buildings.

  See section 3 in evidence submission—the A to ZED supply chain book supplied

  4.  ODPM sponsored urban design codes based on traditional urban values as promoted by staff from the Princes Foundation are preventing the application of low environmental impact zero carbon development, as solar access is not given a high enough priority weighting. It is important that different aesthetics, building forms and building integrated renewable energy systems are allowed to inform the development of urban coding. It should be noted that BedZED breaks almost every urban code system currently being used, and yet it is very popular with the public and residents, has won a Civic Trust award, and shows how a low impact lifestyle and workstyle creates new urban layouts.

  There is considerable public demand for aspirational ZED communities, and there is already a large waiting list despite no advertising and no new communities being available to the public. Now that one exists, the public know what to ask for.

  See section 4 in evidence submission—examples of urban coding compared with BedZED

  5.  Using innovative design to increase density without sacrificing amenity, at the same time as providing good solar access and a garden for every home. On sites where a traditional approach has set a maximum density of around 45 homes/ha (typical on English Partnership sites in Milton Keynes) it is possible to achieve around 70 homes/ha using the ZED approach—with the increased density compensating for the increased construction costs of a zero heating specification—whilst providing exactly the same number of affordable homes and the same site land value that a conventional approach would achieve. No loss of private gardens or public open space was achieved, whilst meeting the 2050 carbon targets.

  See Section 5 in evidence submission—case study of Broughton bid in Milton Keynes.


  Carbon complacency, Urban design, cash, and modern methods of construction within the sustainable community's programme—the need for joined up thinking and a holistic industry "Vision".

  At almost any point in the history the UK construction industry there has been healthy debate between those proposing reduced environmental impact, and the majority of the developers, consultants and their supply chain who have just got used to the previous change in minimum legislative standards—and want to practice business as usual—undisturbed. This is only natural as predicting out turn construction cost, minimising planning risk and minimising sales risk is how a volume house builder can guarantee profit on new developments. The truth that planners and developers refuse to admit is that ordinary affordable housing [whether private or public sector] cannot be specially designed for each site. To cut costs and deliver to tight margins—it is necessary to invest in a highly refined product with as much standardisation as possible between different sites. Only cladding materials and roof forms can really be changed from site to site, producing a formula capable of convincing local planners, but in reality achieving a mono culture of similar estates from Cheshire to Wiltshire.

  This has produced a volume house building industry in the UK that works with a very limited number of standard house types, carefully engineered to skim through the building regulations legal minimum construction standards, with standardisation of architectural form maximising the opportunities for supply chain economies of scale, and with the final product honed by marketing professionals to offend the least number of potential customers. Flying over almost all of our major cities—it becomes obvious that a very limited number of standard house types built in relatively short periods of time over the last 150 years account for most ordinary homes in the UK.

  Each mass housing boom and its associated typologies have been derived from the prevalent social, economic and technological conditions of the period. The UK government is currently proposing unprecedented expansion of our current housing stock—fuelled by increasing house prices, and a lack of affordable homes, especially for key workers. The current shortage of housing stock is generally attributed to increased lifespan, marital breakdown, and immigration, with little or no notable increase in the indigenous UK population. So before setting on the next major housing boom and planning to build around four million new homes by the early 2020s—it is really important we anticipate the major resource challenges awaiting UK society in the C21.

  Accelerating climate change will mean summertime temperatures in the South East will approximate to Marseille sometime between 2050 and 2080. Affordable coolth will become a larger issue than affordable warmth with many thousands already dying from overheating in the urban heat islands of Paris and London in summer 2003. Any lightweight building without high levels of thermal storage will require carbon intensive air conditioning to be habitable throughout a UK summer. Current government policy promotes lightweight prefabricated modern methods of construction with virtually no passive cooling qualities. There are no examples of lightweight homes or workspace in Mediterranean climatic zones.

  Almost all timber based lightweight construction concepts have originated in Northern America, Scandinavia or northern Europe—where overall average temperatures tend to be significantly cooler and summer overheating is rarely a problem. It is important that the UK construction industry plans for the worst case scenario of the Scandinavian winter combined with the Mediterranean summer. The long term scenario of climate change redirecting the Gulf Stream away from our shores could still take place—however experts predict this is likely to start affecting UK climate after around 150 years of intense warming, with the effects beginning to be felt over a 300 year period. (source DEFRA—climate change conference—London March 2004) The challenge for UK will to combine the construction and urban response suitable for a Scandinavian winter with the searing heat of a Mediterranean summer. Simply meeting one or the other will either produce cold gloomy buildings in winter, or cause problematic overheating in summer. Addressing such a new bioclimatic challenge will inevitably lead to new a new urban language for much of the UK—with summer shade and passive cooling strategies needing to be convincingly reconciled with the need to capture low angle winter sun for passive solar gain and maximise daylight in the gloomy winter months. Perhaps the new government championed urban design codes will champion the ordinary citizens right to be both cool in summer and receive a third of their winter space heating needs from passive solar gain?

  Global agricultural production will be in crisis, as climate change creates winners and losers with desertification affecting areas of Southern Europe. The UK imports 70% of its food today, so losing agricultural land to housing may not be the most sensible strategy. With around 11% of the surface area of the UK covered by urban sprawl, and with the average UK meal having travelled over 2,000 miles from farm to dinner plate, it may not be in the long term national interest to plan a large percentage of the four million new homes required by 2020 on prime agricultural land. We would certainly struggle to provide a subsistence diet for the current UK population from food sourced within our national boundaries, and with the human global population still expanding exponentially—it is likely to be increasingly difficult for the UK plc to find the resources to secure healthy low cost food on the international markets. This may be one of the most important reasons why the UK cannot contemplate a secure future without almost total dependency on the European Union breadbasket. The challenge here is to reconcile the densities found in the centre of a typical UK market town (100 to 120 homes/ha) with the amenity and private garden provision found in semi detached 1930s suburbia.

  Meanwhile the UK Government has a duty to be wise and farsighted (we hope) It has a public duty to the electorate to consult the best experts and plan ahead. Whilst future predictions about anything are notoriously fraught, just about the only thing that both experts and public awareness co-incide on is climate change and global warming. So achieving a democratic mandate to plan for climate change and the phased withdrawal from our near total addiction to carbon emitting fossil fuel—is unquestionably realistic. It is this thinking that produced the latest White Energy Paper, with it's startling statement that North Sea gas will run out in 5 years and North Sea oil in ten, making UK PLC totally dependant on fossil fuel imports from some of the most politically unstable countries in the world.

  Fortunately the UK Government has accepted the connection atmospheric carbon emissions and climate change and has signed up to an agenda that will deliver a 20% reduction in Carbon emissions by 2020 and a 60% reduction by 2050. So even if we found unlimited stocks of gas and oil, we couldn't really burn it!

  As collectively we have democratically reached this conclusion it becomes very important to debate the best way of deploying our limited natural resources to cope with an increasingly uncertain future. The billions of pounds spent on military intervention trying to secure political stability in the Middle Eastern oilfields could have been spent on fast tracking the UK's snail like process towards a low or zero carbon economy.

  So complacency about reducing carbon emissions is probably about the most anti—social, dangerous stance to adopt at this point in our islands history. We have to regard a low carbon diet as cultural priority or fight and be prepared to die for our perceived right to contribute more than our fair share of global warming.

  So the critics will say—"don't be ridiculous we could never afford this whole scale change of technology, cultural priorities and social change!" So the Government consults the construction industry, suggests sensible targets for reducing environmental impact and always finds any chance of progress hindered by the industry lobby. Our experience indicates the following standard responses are encountered in most circumstances when consulting the key industry stakeholders:

  "Planners" say—we cannot move away from our formulaic design codes—with our preference for perimeter block layouts and courtyard parking. We find the technical requirements of daylight, solar access, airflow, acoustics and renewable energy integration within the urban fabric hard to integrate within conventional urban design priorities. We know what has worked in the past so please use our design codes for masterplanning any new projects. In this case social stability is perceived to come from continuity with our historic past. Most people find comfort in urban form and architectural expression derived from a rose tinted view of our heritage. The danger is that this approach degenerates into sentimentality reconciled to an orgy of material and resource consumption that rapes the present without restraint or joy.

  "Architects" say—we cannot innovate easily, because there is no fee, time or client appetite for environmental innovation without coercive legislation. If left to our own devices, we really prefer maximising peer approval by building experimental artworks for wealthy clients, and avoiding unrewarding, high constraint social housing if at all possible. And anyway, how can we integrate solar technologies if the master planner or urban designer has ignored solar access?

  "Volume house builders" say—"the carbon emissions from new housing is relatively small—why not look at improving the existing building stock before making us change our product? Our standard house types have evolved from market demand—please leave us alone to get on with the job of increasing annual numbers of new stock". [Source Pierre Williams—house builders federation spokesman ]

  "Developers" say—Homes have a different market from workspace. Please let us build office parks near motorway junctions and keep housing on Greenfield sites away from complex urban communities on problematic Brownfield land.

  "The supply chain" says—We can only tool up and invest in new low environmental impact technologies and products if we have sufficient demand. Go and buy from Germany if you want this specification now! If all the industry wants is the legal minimum specification that is all we can realistically provide.

  "The legislators say"—We cannot persuade the market to embrace low environmental impact thinking without waiting for legislation, which will be unpopular and slow coming. We have to treat the industry like a child being given some bad tasting medicine that though initially unpleasant will provide a long term cure. Here are some nice, easy entry level standards, that won't taste too bad, and will start the process of removing the national addiction to fossil fuel. We cannot push ahead with reducing environmental impact too fast without attracting a vociferous industry lobby.

  "The government says"—Our short term target is to build more affordable homes as soon as possible. Environmental innovation costs more. Let's just build as many homes as possible to the minimum plausible ecohomes standards. Speed and delivering the maximum number of affordable homes is far more important than carbon, so lets promote lightweight modern methods of construction to overcome perceived traditional skills shortages, and lets adopt non controversial urban design codes to accelerate the planning process. Building traditional looking homes is always populist, even if they are really made in factories using modern methods of construction.

  "The public say"—We want as many affordable homes as possible, whilst allowing the existing housing stock to increase in value, and without losing any green belt or agricultural land, and without creating higher density communities anywhere near my home. Just about the only politically expedient response to this challenge is building large numbers of new homes on unpopulated flood zone, preferably in the Thames Gateway. And if we must have new development, please make it look like something we are familiar and comfortable with—preferably Victorian or older.

  "The inevitable conclusion"—changes in the legal minimum standards regulating carbon emissions seem to always meet the predictable lobby against change from diverse organisations ranging from the Urban villages Forum to The House builders Federation, and those that stand to lose most from their physical or intellectual investment in the current status quo. Radical proposals such as zero heating spec homes are deemed unpalatable and before long we will be fighting our next war to ensure supplies of fossil fuel from outside our national boundaries.

  So if we know what the long term carbon emission targets we have to meet are, and we also know roughly what its costs us in military intervention outside our national boundaries to ensure supplies of fossil fuel—it should be possible to agree a phased programme of progressive legislative carbon reduction legislation, and could be interpreted through a planned tightening of building regulations minimum carbon emissions standards, or through planning legislation such as PPS22 (where new buildings have a minimum quota of their annual energy load met from building integrated renewables). The proportion of renewable energy generated on site will become very important, as almost all the capacity provided by green tariff electricity will be required to support our historic urban quarters—where the heritage culture lobby requires preservation in the interests of historic continuity. Renewable energy only makes sense if the demand has been reduced by excellent passive design. It will simply not be possible to run UK plc off renewable energy sourced within our national boundaries without adopting zero heating specification building fabric—or ZED standards. Once these national environmental performance targets for any new urban fabric have been agreed to be in the national interest, it becomes important to develop design codes that provide the planning system with an impartial assessment procedure for development control. Somehow environmental impact, ecological footprint analysis and carbon footprint need to be introduced to the governments current enthusiasm for design codes—currently designed to speed up planning approvals in the attempt to maximise the delivery of new affordable homes.

  Publishing this long term strategy of ever increasing carbon reductions would do wonders for the UK development industry. The planning profession can familiarise itself with the new urban morphologies and aesthetics created by a low or zero carbon cultural agenda. The supply chain could make long term investments in tooling for the new standards, research and development would flood back into the industry—and the cost of this new planned innovation would drop dramatically. Better still the government could recognise that best practice demonstration projects are an essential part of this continuous innovation programme. The carbon threshold provided by minimum legal regulations can only be increased if the government is sure that workable affordable upgrade solutions can be delivered at reasonable cost. Projects like BedZED are essential to show where the regulations and urban design codes could go over a five to ten year period. Initially these pathfinder projects attract higher "prototype" construction costs—just as a prototype car costs far more than a production run model. The building regs minimum pass specification will always provide the cheapest out turn construction cost simply because 99% of the industry builds to these standards—achieving massive economies of scale. It is absurd for industry critics to point to such projects—comment on the increased construction costs, and then lobby against any upgrading of carbon reduction legislation, or the introduction of meaningful solar access into urban design codes. Providing that the same carbon saving legislation applies to the entire industry, a "level playing field" is achieved—and any associated increase in construction costs effectively reduces land value, anticipating that no developer will accept a reduction in profit. Only those industry players with large existing land banks will object to this approach, but then they shouldn't be hoarding such a precious resource anyway. An easy way to phase in any renewable obligation under the planning system would be to make the exact percentage of building integrated renewables required on each site proportional to the rateable value or poll tax band. This would prevent the renewables obligation becoming a development tax making regeneration unviable in low value areas of the country.

  Understanding that small runs of zero heating specification homes would always attract higher construction costs, ZEDfactory have now value engineered the BedZED prototype to create a range of standard house types and associated urban design codes that could be tendered to achieve similar supply chain economies of scale to that achieved by the volume house builders. This is important, as it is virtually impossible to distinguish their volume product by company or brand, resulting in spectacular rationalisation of the house building industry. This approach does not mean that all zero heating spec homes have to look like BedZED, but that the integrated supply chain defined in the ZEDproducts range can now be used to create a variety of different generic forms capable of supporting a variety of different architectural palates. The results of applying volume discounts to the ZED supply chain are spectacular, with 100 homes/year costing about 30% above regs minimum, 1000 homes/year costing around 15% above regs minimum, and 5000 home/year providing no extra cost over regs minimum. Once this volume throughput has been achieved, the omission of the central heating system pays for the additional fabric investment [superinsulation, triple glazing, heat recovery etc] Almost all of the ZED supply chain can be used to upgrade existing buildings, potentially increasing its carbon savings by application to our existing stock of homes and offices. Perhaps large regeneration projects could look at the potential of volume discounted supply chains—ensuring a consistent standard of high performance components and locally sourced building materials, but with a number of different professional teams including urban designers and architects to provide variety and different forms of architectural expression.

  So why not use the government's Sustainable Communities Programme to pioneer some of these best practice demonstration projects, and kick start the supply chain economies of scale? If only 5,000 of the 160,000 new homes built in the UK each year were built to ZED standards, there would be no additional premium for meeting this carbon neutral specification for both homes and workspace. Instead the best we can hope for is the BRE ecohomes excellent pass specification—offering only 35% carbon reductions over a building regulations minimum specification. This is the maximum green specification that the government will countenance, based on consulting the conservative volume house builders. Most new homes will be built to Eco Homes "very good standard"—offering an even lower carbon reduction performance. Equally worrying is the official promotion for lightweight prefabricated construction under the modern methods of construction banner. With increasingly hot summers, it is likely that affordable coolth will become as important as affordable warmth as contributors to fuel poverty in under privileged households. The lack of internal radiant thermal mass in both timber frame and steel frame solutions virtually guarantees the need for air conditioning within a thirty year period—again raising carbon emissions. And it is no use relying on ground source heat pumps—the electricity consumption still rises spectacularly, incurring carbon penalties far in excess of proven passive cooling strategies. It could be proposed that to build the sustainable communities programme to these mediocre specifications ignoring climate change—would be an environmental liability, especially when the concept of creating new households without any increase in population is already a strategy virtually guaranteed to increase national carbon emissions.

  It appears that English Partnerships owns around 50% of the land proposed for the sustainable communities programme. It seems that many of the sites in Milton Keynes are being marketed with perimeter block master plans briefs requiring max densities of around 45 homes/ha.

  The ZEDinabox range of standard house types achieves between 80 top 90 homes/ha, with integral live/work workspace as required, and virtually every home having a private garden, and all family homes an integral conservatory. It looks possible to almost half the amount of agricultural land lost to new housing, achieve more balanced mixed use communities that encourage home working and shared facilities like car pools and still achieve the same financial receipt from the land sale, at the same time as building an aspirational carbon neutral community. Until the necessary economies of scale are achieved, additional density or planning gain is the best way of offsetting the additional construction cost, and creating a level playing field for the ZED developer. All that is required is a little vision. If the 5000 homes / year target was achieved over a three year plan, then there would be no financial penalty for constructing to the ZED specifications, and most volume house builders would automatically adopt these standards without concern—as is beginning to happen in other parts of Europe—particularly Austria. This would achieve a step change reduction in carbon emissions without any real investment. It is vital that we do not worry about the solar urban design breaking the rigid and out dated design codes currently being promoted by the neo conservatives from the Prince's Foundation—a new set of design criteria is bound to generate a fresh urban layout, a fresh aesthetic and a new ways of leading a one planet lifestyle. The UK replaced its homes and workspaces at around 1.5%/year over much of the C20, meaning national carbon neutrality could be achieved through the urban regeneration process alone—a target now possible before the start of the next century.

    So how does this potential reassignment of our cultural priorities translate into new urban form with carbon auditing and ecological footprint analysis beginning to inform fresh environmentally accountable urban interventions? The following examples show how the ZED supply chain and urban design approach can deliver different development solutions to match the urban and suburban context, without all the schemes looking like BedZED. If this supply chain was adopted by English Partnerships or some of the regional development agencies for even a tiny percentage of their development programme—somewhere between 2,000 and 5,000 homes a year will result in no additional cost for this aspirational step change specification. ZEDfactory wish to actively encourage other delivery teams to adopt this supply chain, and would prefer to work with the govt to make these standards accessible to the entire industry. It is important that this initiative is formulated to be in the national interest rather than to benefit any individual companies.


BedZED—the new English Garden City prototype

  BedZED tries to show how we can reconcile density with amenity—achieving a step change reduction in environmental impact at the same time as increasing most residents' quality of life.

  With a typical UK families annual carbon emissions being spent on a third for heating and powering the home, a third for transport, commuting and private car use, and a third for food miles—with the average UK meal having travelled over 2,000 miles from farm to dinner plate. There's just no point in addressing any one of these issues without addressing the other—so at BedZED we have tried to make it so easy and convenient to lead a near carbon neutral lifestyle that most people simply default into this way of living without conscious effort. Built to densities that mean we could meet almost all the new homes required by 2,016 on existing stocks of Brownfield sites—without losing valuable agricultural land and green belt to low density traditional development. At the same time as providing most new homes with both a garden, a south facing conservatory, and the opportunity to avoid commuting by working on site. BedZED re introduces the Victorian back to back, with housing facing south, and commercial space facing north. This very deep plan format provides two active frontages—minimising external wall surface area, and minimising the overall site area required by the super insulated wall thickness. This creates single aspect dwellings looking south over their own gardens, with high daylight levels maintained in a deep plan by triple glazed roof lights over stair voids. Wherever possible the housing ground floor level is raised 1,200 mm above the pavement and workspace, allowing residents to look down at workers and public passing in the mews streets. Terraces are never longer than six units—allowing the development to be porous to pedestrians and cyclists, whilst parking is flung to the perimeter of the site using Homezone principles.

  Environmentally benign innovation will cost more, so we have enabled the developer to buy a site with outline planning permission for a housing estate with a maximum permitted density, and then add an office park without having to pay for the land. We have placed gardens on the workspace roofs—which allow virtually every home to have a garden, showing how density can be increased at the same time as increasing amenity. The adjacent mid 1980's Laing homes development over the fence has the same residential density as BedZED, but without any private gardens on three storey walk up flats. The money the developer would have normally spent buying land for the office park is then re invested in the ZED super green specification. We have set a national precedent for this legally, by expanding a normal Section 106 planning gain agreement with the local authority to officially include reduced environmental impact targets. This is a real breakthrough, as it allows carbon neutral new mixed use development to be built without always requiring govt grants. Resale values at BedZED are a minimum of 15% higher than exactly the same size unit immediately over the fence, and often around 30% higher on larger flats and townhouses. Over 1,000 members of the public have registered an interest in moving to a ZED community.

Sky ZED Wandsworth

  How do you replicate as many of the social and environmental features of BedZED on a compact inner city site ? We found an unloved Wandsworth traffic island in public transport tariff Zone 2, with excellent public transport nodes, right beside an underused over ground railway station on the Waterloo line. The site had never been considered for housing, and is currently a pedestrian no go zone housing a large advertising hoarding. Wandsworth Council is currently occupying many short lease dysfunctional office buildings up the road, so we designed a four storey car free office plinth for the local authority, capped with a communal roof garden complete with creche and residents bar/café. Above two 35 storey aerodynamic blades house around 300 affordable key worker one and two bedroom shared ownership flats. The blades are connected every six floors with communal enlarged lift lobbies incorporating communal herb gardens and shared play space for residents. The homes are placed high enough above the traffic to dilute air pollution to normal London standards, and the super insulated, thermally massive construction with triple glazing and heat recovery ventilation not only reduces thermal requirements to about one fifth of a normal home, but also provides excellent acoustic isolation. Double glazed balconies with opening windows are provided for every home. The building has been designed to focus the prevailing wind onto building integrated wind turbines—providing all the homes annual electrical requirements from renewable energy generated within the sites boundaries. The same wind turbines can already be found in urban areas outside petrol stations and supermarkets in this part of London and make the same noise in high winds as a car passing in the street.. The careful shape of the building means that a SkyZED turbine in Wandsworth has the electrical output of the same unit sited on a hillside in Wales.

  The existing underpass system is renovated and a series of glazed courtyards created, making it safe and easy to cross from the station to the new Wandsworth riverside quarter, effectively healing the damage to the urban fabric done by traffic engineering in the 70s. SkyZED provides over 300 homes with no loss of open space in the borough at the same time as creating a landmark green gateway as the urban focus to one of the most important approaches.

ZEDquarter at Kings Cross

  Developer Argent St George have commissioned Bill Dunster architects to produce a feasibility study for a carbon neutral ZEDquarter on disused railway land behind Kings Cross station. We had to work within the constraints of the existing tunnels, incorporate a listed Victorian potato market arcade—and work within the rules set by the master planners. A two storey commercial base containing office and retail space is top lit by east/west axis central arcades feeding into the listed glazed street. Above roof gardens are placed wherever storey heights are restricted by underground tunnels, with south facing three storey family and live work residential accommodation above more solid load bearing zones. Reclaimed London stock brick will tie the new mixed use development into the tough street scene and existing historic railway buildings providing the urban context in this part of town. We believe this project shows how higher density solar urbanism can work in inner city areas with high land values.

Broughton Parcel D

  As climate change accelerates—it is increasingly important to plan urban quarters around the physical properties of the construction proposed. This is particularly important if lightweight timber framed or steel framed systems are proposed. Conventional lightweight construction places thermally massive brickwork or rendered blockwork on the outside face of any habitable space, effectively removing any potential for passive cooling or solar thermal storage in winter. With this construction it becomes important to use small windows to limit summer solar gain, and if possible keep to east/west orientation.

  Working within English partnerships design codes requiring perimeter block layouts, ZEDfactory have proposed placing thermally massive ZED standard housetypes on all terraces within 20 to 30 degrees of dues south, and conventional timber framed housetypes from a volume housebuilders standard range on all other orientations.

  The east/west facing homes all have individual gables maximising the surface area of south facing roof surface. This allows future installation of large areas of solar electric panels and the opportunity for every household to install solar thermal panels for domestic hot water at some stage in the future.

  By using the large areas of "green space left over after planning" for installing small 15 kw ouput windturbines (making more or less the same noise at 20 metres per second wind speed as a car passing in the street) we found it was possible to meet the government target of a 60% carbon reduction by 2050 at the targeted completion date for the project—autumn 2005.

  Thermal modelling by Arup of both timber frame and ZED housetypes shows ZED units to require 25% less winter space heating than exactly the same spec east/west facing unit. By combining the benefits of passive solar gain and the mounting opportunities for active solar collection, it is clearly beneficial to maximise south facing domestic frontage. By placing live/work and workspace units in the shade zone of the purely residential accommodation on the ZED units—it was also possible to achieve two active frontages, with parking courtyard homezones working well as a more commercial zone. The big difference between these ZED units and the original BedZED design is that all live/work units have their own roof gardens, allowing the Flexibility to move towards purely residential use if market conditions suggest this may be more appropriate. The flexibility to use the north facing units as community spaces, bars, café's, shops, offices, live work units—as well as residential will ensure that this community will adapt easily to a future suggesting far lower levels of private transport. Significantly, the Broughton masterplan proposed a density of 45 homes/ha. The ZEDfactory scheme achieved around 70 homes/ha, with the majority of homes having their own garden, and although requiring a higher overall construction cost to meet the low carbon specification—the residual land value still substantially exceeded that achieved by a more conventional EcoHomes excellent rating built to the original planning brief density. The target of 50% affordable was still met. Using this worked example, we believe it is possible to demonstrate how the government sustainable communities programme can be fitted on less land, with higher numbers of affordable homes, and with significantly lower overall carbon emissions.

June 2004

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