in Greener Homes on 2 May 2010
Modular houses can be green, if you choose carefully.
For most buyers, prefabricated homes have three big pluses: a set product, a set price, and construction in double-quick time.
The factory-built process can also result in far less waste. Architect and environmental design consultant Chris Barnett, from Third Skin Sustainability, says that even if prefab companies aren’t eco-minded, they’re likely to use materials efficiently.
“Supply chains can be refined and controlled to reduce waste – there’s an alignment between waste saving and cost saving,” he says. “Also, the site impacts, noise and ecological disturbances will all be cut down if the on-site construction time is short.”
But it’s a mistake to assume that modular always means green. Most modular houses use steel framing, which has much higher embodied energy than timber. Another potential disadvantage of prefab is the lack of thermal mass, meaning the homes can’t store the heat from winter sun or the cool from summer nights. Quality modular buildings compensate by adding extra insulation so they require little energy to stay comfortable.
Homebuyers need to assess a modular dwelling’s design and performance just as they would conventional on-site builders and plans. “Look at the building fabric and the star rating, as well as the energy and other environmental impacts of delivery,” he says. “If it’s a green modular house, it should have a high star rating and low energy demand through smarter appliances and lighting.”
Mr Barnett is developing SmartSkin, an innovative manufactured housing system that uses timber wall panels that are both structural and insulating, and a factory-built technology pod. He expects to complete the first home by the end of the year.
“We’ve been building the same way for hundreds of years – we still get handed the same piles of sticks and nails,” he says. “Over the next 20 years we are going to see significant changes. The efficiency of manufactured and component-based construction will be crucial in creating greener housing that remains affordable.
“There aren’t many sustainable options on the market now, but products are starting to come from overseas and Australian manufacturers are beginning to gear up.”
One Australian manufacturer taking sustainability seriously is Eco Villages Worldwide, based in Bendigo. They sell Eco Pods – flat pack homes that are assembled on-site in three weeks. “When someone buys one, I make an order and it creates a list of every product needed,” says Bryce Tonkin. “It’s a manufacturing process for the building and that has massive ramifications for efficiency, and reducing waste, time and effort.”
Mr Tonkin says the market for prefab homes has grown over the last few years. “More and more, people want buildings quickly. Our path has been to design those homes for their eco-friendliness and energy efficiency.”
Eco Pods are rated at 7.5 stars, which means they need about two-thirds less energy than standard five-star homes. Among the carefully selected materials are compressed-straw wall panels made locally in Bendigo, recycled carpets and decking made of old milk bottles and sawdust. The three-bedroom design sells for $230,000.
“There are a lot of people who want to reduce their carbon footprint and ongoing energy costs, but it’s complicated if you’re starting from scratch,” Mr Tonkin says. “We’re trying to make it easy for people to get something they can move into now.”