A house made from straw didn't work out so well in The Three Little Pigs, but maybe it's not such a bad idea after all. Sustainable building firm BaleHaus recently unveiled a number of new energy-efficient homes that feature a prefabricated straw insulation system, and promise a heating bill 90 percent lower than that of an average home.
BaleHaus is a group comprised of three firms: Cadan Developments, ModCell (responsible for the straw insulation), and White Design. The homes completed so far come in a number of shapes and sizes, including three-bedroom terraced townhouses and one-bedroom apartments, proving the versatility of the straw building system.
The sustainable technology installed in the homes varies greatly too, and includes roof-based photovoltaic arrays in several sizes, rainwater harvesting, and air-source heat pumps. The walls, roof and floor of a ModCell-equipped home have a U value of 0.15 W/m2K, while the triple-glazed windows and doors have a U value of 1.16 W/m2K.
A ModCell rep told Gizmag that the 90 percent reduction in heating bills claim is based upon hard data gathered from the completed LILAC housing project in Leeds (seen above). In this development, the four-month heating bill over winter for a one-bedroom apartment came in at just £18.00 (US$27.50), whereas the same bill for a four-bedroom house was a still impressive £50.00 ($76). We're still awaiting confirmation on how these homes fare cost-wise compared to similar-sized non-straw properties, and will update this article if and when we hear back.
It's good news with regard to fire performance and structural integrity too, as fire resistance tests on a prefabricated ModCell panel came in at over two hours – or four times the requirement for UK building regulations. Should a big bad wolf come knocking, wind resistance was tested at hurricane force winds of up to 193 km/h (120 mph) with no issue.
Perhaps more significant than the completed houses is the actual ModCell system of insulation itself. While straw bale construction has been around for a long time, the ModCell system offers prefabricated panels that – put simply – comprise a timber frame with deep straw bale insulation packed inside and topped by a wood fiber breather board. These modular units can be used to create a sustainable home with relative ease and finished with wood, brick or slate cladding.
Besides the completed LILAC project and the "BaleHaus at Bath" research project which was developed at Bath University and now serves the university's hospitality department, a development is also currently underway in Bristol and Cornwall, and another 50 homes are in the planning stage for the Bristol Area.
Update March 9: This article incorrectly stated that the straw homes are Passivhaus certified. Though ModCell does now offer a Passivhaus-certified panel, it was not used for the houses in Bristol. This error has now been corrected.