Straw houses: builders hope past will inspire greener, warmer future

http://www.theguardian.com/society/2015/feb/09/straw-houses-builders-home-green-warm-energy

Version 0 of 1.

The jokers inevitably bring up the tale of the Three Little Pigs, while naysayers wonder if the walls will really be strong enough to support the roof – or might turn out to be a terrible fire risk. But a team building seven townhouses in Bristol with walls of straw rather than bricks – or even sticks – insist that as well as creating cosy family homes, their project could eventually help solve the UK’s housing crisis.

“Yes, we’ve heard all the jokes,” says Finlay White, whose company specialises in making walls out of straw bales. “But we know that our buildings will withstand hurricanes, never mind the huffing and puffing of a big bad wolf. We get the jokes every day. We like to reply by saying the children’s story is a bit of clever PR from the bricks and mortar side of the industry.”

More seriously, White argues that wattle and daub, and straw, served very well as building materials for many centuries. “We’re turning the clock back by using those more environmentally friendly materials now. We like to to think building is turning full circle.”

Over the past few years buildings such as schools, offices and some homes have sprung up around the country partly constructed out of straw. What the developers say is different about these townhouses is that, finally, they have been able to achieve the standard construction certification that they believe will give high-street lenders the confidence to hand out mortgages on them.

It means that when they are finished in a few weeks time, they can be offered on the open market to any buyer rather than through housing schemes. “I should think buyers will still be asked a good few questions by the mortgage companies,” says White, a member of the business development team at the specialist Bristol-based architects. “But we’re confident we have the answers.”

The houses in Shirehampton are certainly handsome. The exterior walls are made of compressed straw held in an engineered timber frame, but they are clad in red brick and topped in red tile to match the neighbouring semi-detached houses.

Their top floors enjoy views across to the cliffs of the Avon gorge, but according to the developers the other hugely attractive feature is that their fuel bills will be 90% cheaper than an equivalent brick-built house thanks to the insulation the straw provides.

They are not too expensive, either. The two-bedroomed versions are expected to go for around £220,000, the three-bedroomed ones for £235,000 – just a little more than the conventional neighbouring semis.

The project has been developed together with the University of Bath’s department of architecture and civil engineering. Prof Pete Walker, who led the work at the university, said: “The construction sector must reduce its energy consumption by 50% and its carbon emissions by 80% by 2050, so radical changes are needed to the way we approach house building.

“Straw is a low-cost and widely available food co-product that offers real potential for ultra-low carbon housing throughout the UK.”

As part of the EU-funded project, Walker and his colleagues tested and refined the technology, including examining the structural and weight-bearing properties of straw, and its thermal insulation.

“Over the past three years of research we have looked at various aspects of the performance of straw,” said Walker. “Two that particularly come to mind as concerns or apprehension from potential users of straw are fire resistance and weather resistance.”

The straw panels were exposed to heavy rain and extreme temperatures ranging from -20C to 50C, and to hurricane-force winds. Walker also said their fire resistance was “remarkably good”, and because the straw is encased in wood, mice will not be able to make a meal of the walls.

According to the researchers, up to 7m tonnes of straw remains after the production of wheat flour in the UK. They say half is used for animal bedding, but argue the other half could, in theory, be used to build more than 500,000 new homes.

Manjit Kaur, the estate agent in charge of selling the Shirehampton straw houses, said she was being inundated with inquires. “I think the only problem we’re going to have is that we don’t have enough of them,” she said. “The interest is already huge before they are even finished.”