Mud: building block of the future

New homes built of mud or straw, with a lawn on the roof, sheep fleeces for insulation and heat from the ground or a boiler fired with sawdust – this is one vision of the future for our green and pleasant land. The Government wants carbon dioxide emissions to be halved by 2050. It also wants all new homes to be zero carbon by 2016, and once that target is reached, it then aims to build 240,000 a year. But at present, the construction of a zero carbon house costs 15-30 per cent more.

Help is at hand in Wales, where for more than 30 years a team of scientists and volunteers has been exploring and developing – or eliminating – alternative building and energy methods. Many of the ideas thought radical years ago are now common practice.

The Centre for Alternative Technology (CAT) in Machynlleth, the ancient Welsh capital, opened in 1975. The centre, in a former slate quarry, is blessed with mountain streams, which help fire up some of the energy projects.

Many of the techniques currently being explored are not new – indeed, much of the work at CAT revolves around materials and methods that have been used for centuries. It is often a case of “looking forward to the past”.

There’s nothing new about rammed earth walls, for example. Ancient cob cottages built by labourers trampling mud and straw have survived for hundreds of years, provided they had “a good hat and boots” (roof and footings).

Some of the techniques being tested at CAT may sound bizarre, but the policy there is to be thorough in the quest for a more environmentally friendly lifestyle, including not just energy savings and generation but also conservation of wildlife and an organic approach to food production.

Lucy Stone, a spokesman for the centre, is in no doubt that the world is, at last, listening. “The Government’s declared quest for zero carbon homes by 2016 must spur the construction industry to give greater priority to the energy performance of housing,” she says. “If and when total energy use is reduced, then the renewable element can be met by smaller, cheaper systems.”

Among the energy-saving building techniques being developed and used in public buildings are grass roofs and rammed earth bricks covered with hemp and lime render. These, unlike traditionally fired bricks and clay tiles, use hardly any energy in their manufacture.

Telegraph