May 8, 2015 3:59 pm
his year David Martin will test an ambitious plan: to see if he has successfully constructed the world’s first carbon-positive prefabricated home.
Martin, a director at Australian modular building company ArchiBlox, will move to the coastal village of Cape Paterson, southeast of Melbourne, in the Victorian countryside. There he will live in his own creation with his two small children for 24 months.
The Archi+ Carbon Positive House prototype, unveiled in Melbourne last month, produces more energy than it uses, claims ArchiBlox. Energy produced in its lifespan of an estimated 105 years is the eco-equivalent to taking more than 300 cars off the road for one year, or planting almost 7,000 native trees.
The breezy, open-plan timber structure has a vertical garden made of sliding walls covered with pots to grow vegetables and herbs. There is no mechanical heating or air-conditioning. Instead, a roof planted with indigenous shrubs adds thermal insulation and in-ground cooling tubes pull air from the floor for ventilation. The house is solar-powered and uses recycled rainwater.
Multiple living spaces are squeezed into a tiny 77 sq metre space. Sliding doors transform functionality: a hidden loft acts as a spare bedroom and there is a “shladder”, or combined ladder and shelf. What is more, the entire structure can be assembled in just six weeks. It is “designed big but built small — it’s compact, versatile living,” says Bill McCorkell, architect and director at ArchiBlox.
The Archi+ Carbon Positive House, priced from A$260,000 ($204,000), is the first new-build standing home in Australia to receive a platinum rating by the life-cycle assessment company eTool. Yet McCorkell and Martin are acutely aware of the jump between an experimental prototype and making a house perform under the pressures of day-to-day life. “We really want to practice what we preach,” says Martin. “We [want to] look at how people are going to live rather than pick a model off a plan.”
Energy produced in the house’s lifespan allegedly equates to taking 300 cars off the road for a year
Prefabricated houses, whose parts are assembled in factories rather than on-site, first proliferated after the second world war to meet housing shortages. By 1949 more than 150,000 had been built in Britain alone. Prefab, however, has become associated with cheap bulk manufacturing, mobile homes, and Portaloos. Few of the wealthier baby-boomers have wanted, or needed, identikit “cookie-cutter” homes.
That view is changing. The image of prefabs as a “hut on the back of a truck,” needs to be erased, says Martin. “Now they’re more luxury and sustainable.”
There is a shift “from mass production to mass customisation,” agrees Masa Noguchi, an associate professor in environmental design at the University of Melbourne. With the rise of new technologies, prefab homes now offer cutting-edge architecture mixed with high eco-credentials. They take less time to erect than traditional bricks-and-mortar homes, they can be entirely custom-made and are often much cheaper than an architect-designed traditional home.
Japan is one country with a thriving contemporary prefab market. Last year, retail company Muji, which is branching out into architecture, designed Vertical House in Tokyo, a prefab three-storey home built on a minuscule plot of land. Large north-facing windows provide light, making it feel more spacious, as does the lack of interior walls or doors.
Traditional Japanese architecture provides inspiration for the carbon positive house. A sunroom spans the width of the structure. This buffer zone creates a pocket of air that both envelops the house in warmth in winter and protects the inside rooms from the searing sun in summer. Psychologically these “lungs” act like an engawa, the wooden strip of flooring that divides the interior of a Japanese machiya house from the noisy world outside.
“It’s about physical health as well as mental health. The house is used like a Japanese garden, because it integrates you with plants, [merging] the outdoors and indoors,” says Martin. Meanwhile, natural timbers and the insulating earth berm, which runs up the back and over the top of the house, blends easily into the environment. This is architecture that wants to deliver results rather than make an artistic statement.
“The design is a bit like Dr Who’s Tardis — it packs a lot of spatial experiences and places within a very tiny building,” says Clare Newton, an associate professor in architecture at the University of Melbourne. “It looks modest but is effectively a high-performance machine in terms of materials, orientation, air movements and efficient planning.”
Not all prefab homes are hard-wired to be eco-efficient. But construction in a factory means less waste, combined with a higher level of control over the finished product. Re-usability — with steel-framed prefab homes able to be disassembled and reassembled on another site — is another advantage.
At the end of the day sustainable building is about energy efficiency, not just bamboo floors and low-flow shower heads
Over the past six years, UK company Ecofloat has created more than 15 customised floating homes, starting from about £150,000 with fittings. They are made off-site in a workshop in Hertfordshire then towed by boat to their UK destination.
One of its creations now floats on the Thames at St Katharine Docks in London. Floor-to-ceiling glass sliding doors lead out to a deck to form a living space with expansive views over the water. Topping the rectangular home is a roof terrace planted with sedum to insulate and absorb rainfall. The structure is made from sustainable timber. Interiors are fitted with LED lightbulbs and furnishings are recycled or created from reclaimed wood.
“This is a much gentler, lighter way to live,” says founder Mike O’Shea, who customises each home. Most people want to minimise water movement. But even that can be varied: O’Shea recalls building one house with lighter weights in the foundations for a client who liked the sensation of swaying with the swell.
Seattle-based Method Homes sources half of its business from custom-building one-off prefab projects. One of its bestsellers is its Cabin series. With prices starting at $289,760 for a two-bedroom unit, features include light-filled bridges connecting the bedrooms, floor-to-ceiling windows and a garage.
The building company has worked with architects and engineers to push the prefab envelope, creating large cantilevers of up to 16ft, vaulted two-storey rooms, and structural steel components. The end-product is also more economical to operate. “At the end of the day sustainable building is about energy efficiency, not just bamboo floors and low-flow shower heads,” says co-founder Mark Rylant.
Back in Australia, prefab still only accounts for a fraction of the building market. In a country with a vast land mass and low-density population, minimising living space is not a concern for most. While the Archi+ Carbon Positive House may attract plenty of publicity, can people actually be persuaded to buy it on home turf?
It is a “high risk for developers”, admits eTool cycle-assessment engineer Patrick Hermon. Half the battle is “changing the mindset” that big is best.
Meanwhile, Noguchi’s experiences in building Canada’s first “net zero-energy” prefab, the Eco Terra house, might provide a lesson. Noguchi admits that in theory the house was zero energy but in reality that faltered when people actually moved in. He recognises that there “is a gap between simulation and post-occupancy [due to] unpredictable aspects like people and climatic conditions”.
Martin, for one, is unperturbed. For now he is excited about “chilling out with the kids on the daybed soaking up the north sun and watching the vegetables grow”. This, he insists, is just “the first step to something much more”.
Photographs: Getty Images/Hulton Archive; Picasa
Slideshow photographs: Dominic French; Getty Images/Hulton Archive; Alpinfoto; ArchiBlox; Picasa
The new prefab: why factory-built homes are now cutting-edge - FT.com