Research carried out at the University of Bath has resulted in the UK’s first affordable and mortgageable straw bale homes going on sale this week. Illustration - Leeds co-housing project which used the same straw filled panel building system

Promising fuel bills up 90 per cent cheaper than an equivalent brick-built house, and costing less than the average to buy, the first straw houses, which have gone up for sale in Bristol, offer an affordable, low carbon and fuel-efficient means of house building.

"Straw is much warmer than other materials so the houses will not use as much energy to heat, and they will stay warmer for longer," said a spokeswoman for the university.

"It is also more breathable, so the houses feel nicer, it is a much nicer feel," she said.

The work by the university means home owners can now get a loan or mortgage on straw houses, as researchers proved to financiers they were durable and low risk.

Previously straw bale houses have not been eligible for finance, due to a lack of certified materials and concerns about durability, but a new factory-built straw panel design developed at the University of Bath has received BM Trada’s Q mark certification, meaning developers and house buyers can now insure and secure mortgages against homes, schools and offices built using this sustainable construction method.

The seven Bristol townhouses were built by developers Connolly and Callaghan using the innovative ModCell straw panels, in which a timber frame encloses the compressed straw bale.

Built with the load-bearing straw panels within an airtight design (plus triple glazed windows) the new houses will need significantly less conventional heating.

Their super-insulated straw walls provide three times’ greater insulation than required by current UK building regulations so fuel bills are anticipated to fall by up to 90 per cent.

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 and civil engineering at the University of Bath, led the research.

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."

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."

Credits:: www.bathchronicle.co.uk