Property: People can live in grass houses

The straw house built by the little pig in the fairy tale, which was huffed, puffed and blown down by the wicked fox, has had a bad press. The truth is that this pig's dwelling may have been centuries ahead of its time.

Buildings made out of straw bales are no longer seen as the wacky creations of pastoral dreamers. They have become serious constructions in their own right, from their early manifestations as utilitarian storesheds to today's growing number of full-blown family houses. Straw bales are cheap at pounds 1.50 each, easy for self-builders to use, and are good insulators.

Perhaps the most ambitious bale project yet is in southern Ireland, where a family of four lives in a round, three-storey house - but its location is a closely guarded secret. The plan for another straw house envisaged by architects Jeremy Till and Sarah Wigglesworth is just as impressive, but in a very different way: it is slap bang in the middle of New Labour's heartland - Islington, north London, just off the Caledonian Road, to be exact.

Islington Council has approved plans for their three-bedroom house to be built on a derelict patch of former railway land. Construction is due to start in May next year. Although the couple are building it as a house to live in, at a cost of about pounds 220,000, they are treating it as a research project. As university lecturers in architecture, they want to demonstrate that living an energy-efficient and green lifestyle can be normal - indeed must be so, if the planet is to be self-sustaining.

"We want to get away from the idea that you have to be a back-to-nature dreamer to be environmentally sound," says Mr Till. "There is a middle ground which uses techniques that are appropriate, sometimes quite sophisticated, at other times very simple. To that extent this house is a piece of propaganda."

Walls of straw bales are usually plastered inside and out. But the walls of the planned Islington house will be treated only on the inside, the external face being covered by a translucent rain screen so that the bales remain visible.

The roof is perhaps the most radical aspect of the house. The twine on the straw bales, which will lie over a waterproof timber deck, will be cut so that the straw becomes loose and is left to rot for six months. A thin layer of compost will be spread over the top, and the "hairy roof" will be planted with strawberries.

There will be underfloor heating and windows will be triple-glazed. There is the option of later installing photo-voltaic panels on the roof - a highly efficient form of solar heating. In addition, the couple plan to install composting lavatories.

"Straw, contrary to belief, is one of the safest building materials - it is not highly combustible because the straw is packed so tightly," says Mr Till. "Nor does it attract vermin. It may well be the building material of the future. We hope that with this house we can show that low-energy buildings don't have to be boring."