HARVESTING HOUSES FOR THE PLANET

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

Russian design for houses made from sand and seawater blocks (image:
Unido) Unido says Russian sand and seawater blocks fit like Lego

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.

Sustainable building: York Eco Depot

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 fibre 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 fibre and oil for other products.

He picks out the Eco Depot in York, a new city 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 France.

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 programme 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 $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, Mr
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 Mr 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, Mr 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.

Tom Woolley's latest book, Natural Building, is out now.