This week the first straw eco homes go on sale in Bristol. The traditional red brick homes may look ordinary on the outside but they are at the cutting edge of low carbon technology. Plus, they are not only cheaper to buy than the average Bristol home, but they also promise fuel bills of up to 90 per cent cheaper than brick built houses.
Previously the idea of a house made out of straw would be more appropriate in a fairy tale, than in reality, due to a lack certified materials and concerns about durability, however, when the University of Bath developed a factory-built straw insulating panel, it meant that developers and house buyers could now insure and mortgage buildings which use this sustainable construction material.
Developers Connolly and Callaghan built seven townhouses in Bristol using the innovative Modcell® straw panels, in which an engineered timber frame encloses the compressed straw bale insulation. Constructed using the load-bearing straw panels within an airtight design, the super-insulated straw walls provide three-times greater insulation than required by current UK building regulations.
The Q mark industry certification is the result of the University of Bath’s three-year EUR 1.8m EuroCell research project, funded by the Executive Agency for Small and Medium-sized Enterprises (EASME) jointly with industry partners Integral Engineering Design and architects White Design.
To receive certification the University research tested the ModCell® straw panel’s energy efficiency, fire safety, durability and weather-resilience, including exposing the panels to heavy rain and extreme temperatures ranging from -20oc to 50oc.
Professor Pete Walker, Head of the Department of Architecture & Civil Engineering at the University of Bath, led the research, which previously entailed building the innovative prefabricated straw bale building called the BaleHaus as a test site in 2009.
Commenting, he said: “The construction sector must reduce its energy consumption by 50 per cent and its carbon emissions by 80 per cent by 2050, so radical changes are needed to the way we approach house building. As a construction material straw is a low-cost and widely available food co-product that offers real potential for ultra-low carbon housing throughout the UK. Building with straw could be a critical point in our trajectory towards a low-carbon future.”
In the UK up to seven million tonnes of straw remains after the production of wheat flour, and up to half this amount is effectively discarded due to its low value, to be used as animal bedding. This ‘leftover’ 3.8 million tonnes of straw could be used to build over 500,000 new homes, as an average three-bedroom house needs 7.2 tonnes of straw.
As well as utilising an agricultural co-product, straw has significant environmental benefits. Rather than releasing carbon dioxide (CO2) during the process of producing a building material, as brick or cement does, it absorbs CO2 as it grows. As a result, straw homes have one of the lowest carbon footprints available, with many buildings being net carbon-negative.
Craig White of ModCell commented: “The Q mark industry certification means that straw is now a viable, affordable means of tackling the housing crisis in the UK. Using a ‘fabric first’ approach is ideal for private homes, social housing, and new, innovative projects such as custom-build. Straw now offers a simple and effective home-grown solution to the UK’s housing needs.”
So, despite what the Big Bad Wolf says, building a house out of straw is safe, durable, fuel-efficient and affordable building method - far better than any brick-built house.
See the video about the project: http://vimeo.com/118929904