Voyage to the centre of the earthship

It's the purple beret that gives Mischa Hewitt away. Put him in a business suit and he could pass for a financial adviser. Indeed, he once was a financial adviser. Now he's given that up to work for the Low Carbon Network, an organisation that promotes the use of low carbon technologies and that has just built one of Europe's greenest buildings. The beret is the badge that marks Hewitt's transformation from office-bound rat racer to Britain's greenest project manager.

Stanmer Park, Brighton

The result of Hewitt's work is a community centre just outside Brighton that it makes the celebrated zero-carbon development BedZED look positively profligate. For a start, the only utility connected to the building is the telephone: its power comes from on-site renewable energy generators, its drinking and washing water come from filtered rainwater and all its wastewater is treated on site. As you'd expect, much of the building is constructed from recycled materials, but this project takes ecological sensitivity a stage further by making its walls from a product that is too hazardous to send to landfill - car tyres.

Used car tyres are a real headache in terms of waste management because there are so many of them and they are so hard to get rid of (see "The problem with tyres" below).

"In the UK we throw away 40 million tyres a year and there is no adequate solution to this problem," explains Hewitt. "It will get worse from June this year as European Union legislation will ban tyres from going into landfill sites. A solution is urgently needed for this problem and we believe we have the perfect answer."

The single-storey building is located just outside Brighton at Stanmer Park, and will act as a community hub for Stanmer Organics, an organisation that leases land for organic food production and other green activities. But this is no hippy hut in the woods; it was designed and built by a professional construction team and is intended as a learning resource for the industry and general public alike.

The building is the first English example of an "earthship", and the inspiration for it was supplied by Michael Reynolds, the founder of the earthship movement, who has built about 800 of them in Taos, New Mexico. According to Hewitt, Reynolds said if he was given millions of dollars to develop the perfect building block he would have come up with the car tyre. Inspired by the lecture, Hewitt joined the Low Carbon Network with the aim of building one of his own.

But constructing buildings out of old car tyres is easier said than done. The Environment Agency blocked the idea as it classifies them as toxic waste. "It took a lot of lobbying on our part to get them to change their minds," says Hewitt. "I suppose they were concerned that anyone could get rid of old car tyres by using them to build a wall, then putting a roof on top and saying it was a building."

In the UK we throw away 40 million tyres a year and the problem is getting worse. We believe we have the perfect answer

Mischa Hewitt, Low Carbon Network

The Low Carbon Network lobbied the Environment Agency while it was raised money, sorted out the design and acquired planning permission. Waste management specialist Biffa donated £180,000 and specialist gases company BOC donated another £25,000. The US design was modified by Reynolds to suit the UK climate. For example, the roofs of the New Mexico Earthships are designed to catch snow for the water supply but the Brighton earthship only needed to collect rainwater. Architect RH Partnership prepared the detailed drawings and BEP Consulting engineers took care of the structural engineering.

Work started in April 2003 using skilled members of the Low Carbon Network. Reynolds came over from the USA to get the team up to speed on the construction technique needed for the tyre walls (see "Building a house of tyres", overleaf). These form the main back wall that retains the hill behind the site. Behind the wall is up to 2 m of compacted chalk, a layer of insulation and finally a dampproof membrane to stop water percolating into the building. The mass of chalk will act as a gentle storage heater, warming up in the summer and helping to heat the building in the winter.

The rest of the building is timber-framed. The tyre wall supports timber roof trusses at the rear of the building, which are supported at the front by timber posts. This is the only wall in the building that sits on a conventional concrete foundation. Glazing is inserted between the posts to maximise light and solar gain. Beyond this is a sloping glazed wall that creates a sun trap.

By the end of 2003 the external envelope was finished - and so was the money. It took until the following spring to obtain a grant from Network for Social Change, and that was enough to get work going again. The inside of the tyre wall was plastered with adobe, a mixture of sand, clay, soil and chopped straw. The floor slab was cast using "ecocement", made from a combination of magnesium oxide and conventional cement. "The advantage is that you use two-thirds less ordinary Portland cement, which is environmentally damaging," says Hewitt. A low wall inside the building was built using pink granite blocks salvaged from a company that was closing down. The flooring in the sunroom came from an even more unusual source. "We found a funeral director in town that threw away a skipful of waste granite every month so we got them to dump it here," says Hewitt.

Then the money ran out again in the winter of 2004, and this time it took a £21,000 grant from EDF Energy and some money from the DTI and the Energy Saving Trust to refinance the project. By 2005, however, a wind turbine had been fitted, as had photovoltaic and solar panels and a biomass heater, all of which were intended to demonstrate a wide range of renewable technologies. Power is stored in batteries, which can keep the building going for 10 days.

With the building almost complete, the money has run out yet again: another £20,000 is needed to finish off the interior. The final cost of the building will be £280,000 but Hewitt says the next earthship should be cheaper, as this project is a prototype. The good news is that earthship principles are already filtering through to mainstream construction. Architect RH Partnership has designed another earthship as a park ranger office and conservation centre for Kerrier council in Cornwall. A main contractor is being sought for this job and work will commence this summer. The revolution is happening faster than Hewitt expected.

Anyone who would like to visit Earthship Brighton, make a donation to help finish the project or develop other projects should contact Mischa Hewitt on 07974-122770, email mischa@lowcarbon.co.uk.