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Houses out of sand and water

Buildings are expected to feature as a crucial area for energy-saving in the UN’s third report on climate change this week BBC new reported.

Encamped on the edge of London’s docklands development, a bazaar of corporate stalls is pursuing the green pound in Britain’s ever-hungry construction industry. Production of concrete, that staple of modern building, alone accounts for up to 10% of man-made greenhouse gas, US scientists believe. Then there is the energy spent on shipping the materials, and finally the power needs of the finished buildings. Yet with a bit of clever substitution and sourcing, and some deft adjustments to the existing housing stock, environmentalists believe that CO2 emissions could be reduced anywhere in the world.

House of straw
If the number of “green” consultancy companies at London’s Think 07 trade fair is anything to go by, environmentally-friendly architecture is becoming big business in the developed world. Among the items on display are designer energy-saving bulbs and an ingenious-looking tube for piping daylight from your roof into your house’s darker rooms. Most tangible of all, at an event dedicated to the UK’s property and construction industries, are the wood fiber and cement building-blocks stacked in one corner.

Sustainable rotation crops like hemp are the cost-effective future of building, according to Tom Woolley, a professor of architecture at Queen’s University Belfast. One hectare of land can produce enough hemp stalk to build a house, he told the BBC News website, and using about 12% of the UK’s set-aside land, you could grow enough hemp to build the 200,000 new houses the country needs. Then you have the fiber and oil for other products.

He picks out the Eco Depot in York, a new cityFrance. council building, as a good example of green architecture, pointing to the straw bale panels used for its walls and its “breathable” lime render. Its “low-impact” design means the need for heating or cooling is minimal, he says. With existing buildings, he believes that the crucial thing is to improve insulation, for example with a mixture of hemp and lime on old brick buildings, a technology used in

Solid sea and sand
Home to 80% of the world’s population, the developing world has access to less than 20% of the world’s construction materials, according to figures from the UN’s industrial development agency (Unido). Unido’s technology promotion unit seeks out cheap, energy-efficient construction technology and introduces it to some of the poorest regions on Earth, suggesting novel ways of using local materials to cut the financial and environmental costs still further.

“The owners of the technologies often do not know how to market them while those looking for the technologies don’t know where to find them,” Vladimir Kozharnovich, the unit’s program manager, told the BBC News website. “We seek to provide people with technological options which can be adapted to their specific environment.” In Herat, Unido has planned a model village of 100 energy-efficient homes, designed by Indian and Chinese architects in consultation with the local authorities.

The homes each cost a projected €2,578 ($3,500) and are equipped with bathroom, toilet and solar-powered electricity. Building costs are reckoned to be 30-50% cheaper than existing dwellings. However, the plan is at a standstill while Unido awaits approval from the donor, Japan. Slow donor approval is a common problem, Kozharnovich says, but already he is working on a new, similar Afghan project, this time for the province of Baghlan, with EU funding. Unido promotes Indian portable brick factories as one answer to cheap construction materials. Another project, now under discussion with Namibia, is a Russian technique for manufacturing building blocks out of sand and seawater.

“The precision is very good - it’s like Lego,” says Kozharnovich. “It is a proven technology which cuts production costs five-fold, and can be used in both hot and cold regions.” One example of Unido’s hi-tech thinking about sourcing local materials is in Botswana, where the agency has proposed melting locally available basalt as a replacement for expensive imported steel rods in concrete buildings. Unido, Kozharnovich stresses, does not seek to change local architecture, but to find more efficient ways of using local materials which will be acceptable locally. It could, he says, mean a traditional timber frame with non-traditional wall panels made of wild grass.

Priorities
Prof Woolley notes that unfired mud brick (adobe) technology has taken off in the US, dispensing with the energy used in firing traditional clay bricks. Sun-dried bricks were a mainstay of construction among the indigenous peoples of the Americas for thousands of years, and go back centuries in Africa, an example of the return of a trusted old technology. One modern trend Tom Woolley bemoans in the UK is what he says is over-emphasis on green energy creation.

“Somebody has very cleverly got the vast majority of politicians and the public to think that sustainable buildings is about sticking extremely expensive renewable energy equipment on the roof of the building, which is actually the last thing you should be doing,” he says. “The first thing is to reduce the demand and produce buildings which are breathable and well insulated and airtight.” The architecture professor admits that pioneering projects with organic materials can be expensive but confidently expects that the costs will fall once the new technologies go mainstream. (news.bbc.co.uk)