The shape of homes to come

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15 June 2007


By Jan Carlos Kucharek


BRE’s Offsite 2007 show reveals the strides carbon-efficient housing has made.
Pictures by Peter White, BRE



Looking like Brookside Close in a parallel universe, the Innovation Park at this week’s BRE Offsite 2007 show aims to highlight moves being made by the construction industry to meet the government’s Code for Sustainable Homes.
It’s a warm day and we’re sitting in the cooler and more comfortable interior of the Osborne House, finished in June 2006, opened by John Prescott, and awarded an Ecohomes “excellent” certificate. “When it was launched last year, this was an exemplary house showcasing a whole range of innovations,” says BRE’s director of enterprise and innovation Jaya Skandamoorthy. “However, under the Code for Sustainable Homes, even this only achieves code level 3.”
It just goes to show how fast the industry is prepared to move to ensure it meets the regulations.
Levels 1-5 of the energy code represent improvements of 10-100% over the 2006 building regulations, with code 6 being zero carbon in terms of construction and operation.
All houses here claim to meet energy codes 4-6, with extra credits gained by adding such extras as water recycling, environmental considerations or waste management.
“Previously, most volume housebuilders wouldn’t think of going beyond building regulation requirements, and ones that did had to convince clients of the extra value they were getting for the increased cost,” says Nick Hayes, director of sustainability at BRE.
“The code is part of a holistic approach to construction, and the lack of elemental solutions has forced far more free thinking out of housebuilders. They now have to play with new ideas, innovations and options.”
Offsite 2007’s overriding message is that construction for energy efficiency is the way forward.
Ahead of the legislation

It is encouraging to see volume housebuilders making serious attempts to pre-empt regulatory requirements.
If anything, the worry is that it shows the construction industry is in a position now to move to far higher standards than legislation demands, calling into question the value of current standards.
For Hayes, the build process has been part of a steep learning curve for manufacturers too. “Housebuilders are already demonstrating that they can build to U-values of 1-1.5,” he says. “The real challenge for them is the workmanship to achieve adequate thermal detailing and airtightness.”
Offsite 2007 allows us to see new approaches to housing with global warming in mind. But the real onus will be on the BRE to provide empirical, scientific data to allow these designs to be evaluated objectively. The housing industry has been proactive in pushing ideas forward, and with its innovation and construction methodologies is laying claim to the higher echelons of the Code for Sustainable Homes.
But it is the BRE’s job to put these rookies through their paces.
Sigma Home

Architect PRP Architects
Manufacturer Stewart Milne Group
Bedrooms Three
5/5
The Sigma Home is aiming for a code level 5 rating. The structural build-up for the walls uses an advanced closed-panel timber frame of 140mm studwork, timber rainscreen cladding, glass wool insulation between the studs sheathed with 9mm oriented strand boards on both faces, vapour barrier and internal face ready for services and dry lining. It also uses Du Pont’s innovative Energain phase change panel, dramatically increasing thermal performance. The build-up achieves 0.15W/m sq K for the walls, and a projected air tightness of 1** m/hr/sq m. While it is an offsite MMC approach, with a zinc-clad cassette roof, cassette floor system and triple-glazed windows, the house has additional insulation on the walls applied on site to achieve the rating. The building uses renewable energy by way of solar thermal and photovoltaic panels, roof-mounted wind turbines, and solar gain. Active heat exchange is part of a passive system, using stack effect with heat exchanger above the stairwell. Shower and basin water is recycled for toilet flushing. Designed as an urban townhouse, it has generous height dimensions, ticking all the boxes for its target market.
Hanson 2

Architect TP Bennett
Manufacturer Hanson Building Products
Bedrooms Three
5/5
The Hanson 2 House uses thermal mass and purely passive ventilation. Unlike 2005’s traditional-looking Hanson 1 House, this is a contemporary take on a traditional form of construction. The house has a novel plan and aims to achieve code level 4 using modern masonry details. Wall construction is offsite panels of stack-bonded brick/solid brick bonded using cementitious glue, damp-proof membrane, insulation and internal finish, giving a wall U-value of 0.18. The zinc-clad asymmetrical roof with hidden gutter detail has an integral ventilating roof lantern. It is true to the principles of mitigating solar gain through mass, and the plan assists this, with bedrooms at the cooler ground level and living on first. These are connected by a stairwell that allows passive ventilation to occur through warmed air being exhausted up through the roof lantern and for cooler air to be drawn in from below. Partition walls are dense blockwork panels with intrinsic sound and fire resistance. Ground source heat pump underfloor heating and solar collectors are integral.

Hanson 2 shows a savvy understanding both of the conservative nature of the suburban market and of how to work within the constraints of the modern idiom. If the market warms to the distinctive roof, with a few permutations to the elevations this could be a goer.
Osborne House

Architect Baily Garner
Manufacturer Vencil Resil
Bedrooms Two
3/5
The Osborne House is the older sibling of the group. This building uses a load-bearing structural insulated panel system (SIPS) comprising outer cladding, weather barrier, 250mm of insulation, and internal finishes, giving an overall width of 450mm, manufactured offsite. Current performance achieves a 40% reduction in carbon emissions against Part L regulations, the walls having a U-value of 0.15W/m sq K. The house is 10 times more airtight than existing requirements, and uses an active heat exchange system to condition the house, tempering incoming air with heat from the outgoing. It has a cassette roof, underfloor heating, triple glazing, and integrated skirting “wire” perimeter heating. Smart technologies see every room wired up for audio and data via a centralised control box by digital plumbing. A disabled lift has been incorporated into the design as a nod to the concept of lifetime homes. Good use of technology, but in terms of the performance of the newer homes, trailing the others.
Lighthouse

Architect Sheppard Robson
Manufacturer Kingspan Offsite
Bedrooms Two
4/5
This 93sq m house is the only house in the group that aims to achieve code level 6 under the Code for Sustainable Homes. The Kingspan Home is a strategic joint venture in conjunction with Barratts and Wimpey Homes.
“Kingspan wants to build 30,000 homes in the next year, as it has the investment, capacity and infrastructure to build in volume,” says Jaya Skandamoorthy, BRE director of enterprise and innovation. “It can factor in economies of scale to allow for quality, choice and adaptability.”
Like the Osborne House, it uses a highly insulated 284mm-thick SIPS panel, giving it an overall U-value of 0.11W/m sq K.
“Kingspan uses renewable and sustainable technologies, including passive cooling and ventilation, plus mechanical ventilation with heat recovery, and integrated PV panels. Wider agendas push it into the code 6 band,” says BRE director of sustainability Nick Hayes.
“It has rainwater harvesting and greywater recycling, and is offsetting excess rainwater into a constructed ‘swell’, helping with runoff attenuation and contributing to sustainable landscaping principles,” he adds. “Credits like that allow it to score higher in terms of overall performance, forcing developers to consider all aspects of the design.”
Sheppard Robson is already proposing permutations to the basic form to bring diversity in look, and more bedrooms for larger developments.
Organics House

Design EcoTech
Manufacturer EcoTech
Bedrooms Three
3/5
EcoTech’s Organics House, says BRE’s Nick Hayes, uses a “closed-panel construction timber stud system with steel volumetric units forming bathroom units and kitchen pods brought to site and lifted in. There are no wet trades at all.”
Achieving code level 5, it has high levels of thermal efficiency, with a U-value for the 240mm-thick walls of 0.18W/m sq K, something to be expected of a Swedish constructor, but it is lacking imaginative design. Active heat exchange is used to condition the building.
EcoTech says a variety of surface finishes and internal layouts using a standard system are offered to create visually distinctive communities. It markets itself as a “turnkey solution”, and comes with all white goods, remote monitoring, security systems and fully finished Swedish timber wood floors. The ground floor aims to minimise thermal bridging at the floor perimeter, maximising thermal performance.
Volumetric House

Architect Proctor & Matthews
Manufacturer Spaceover
Bedrooms Two
4/5
As soon as Offsite 2007 is over, Spaceover’s container-shaped modules will be installed in an hour-and-a-half on one of its social housing schemes. “We have already built 35 houses in the first phase of the scheme, and these are part of the second phase of 43 units of keyworker housing,” says Spaceover technical manager Tony Fox. “We have an overall U-value of 0.23, we’re using ground source heat pumps, and high-specification glazing. We will make code level 6 if we add photovoltaics to the modules.”
Spaceover’s units are built offsite using a light-gauge steel frame, external cladding, insulation and internal finishes brought in by lorry. Units sit on top of each other, with steel feet at the corners; an acoustic bearing acts as a damper. “There is no flanking sound, and our acoustic separation means we can raise the regulation sound insulation from 45dB to 53dB,” adds Fox. Unclad and giftwrapped for the show, it’s hard to judge aesthetically, but it is performing and is already being specified by the market.

Fonte: bdonline