In fact, that's only part of the art. What BedZed also attempts is more ambitious: to do all the sustainable stuff while still being a place - a tightly-packed village, really - which has a sense of style, which appeals to a wider market, which is not for beard-and-sandal initiates only. As a consequence, BedZed is the first ever Stirling Prize candidate that you can buy into. Because there are a few homes there, out of 100 in total, that are for sale.

Basically, these are long housing terraces - but not on the Victorian model, where houses face each other across the street. At Bed Zed, nearly all the homes face one way: south. The tall fully-glazed south-facing facades have conservatory-like "sun spaces" behind those facades and contain photo-voltaic cells to generate some of the estate's electricity. So that the houses behind can get an equal share of the sun, the backs of the terraces swoop down low. Set into them are little roof gardens, reached by arching steel bridges from the street behind. So you might have a house or flat in one row, but your garden might be on the roof of the row in front. Where the sequence of terraces ends, the back of the row is given a rounded treatment. Materials are simple, with many of them recycled: steel, timber, brick, glass.

I'm shown round BedZed by the affable Toks Ajetumobi, general factotum to the estate. Everybody knows Toks: he knows everybody. Toks points out the pavilion where electricity is generated out of waste trimmings from trees, and where the estates' sewage is processed in a greenhouse full of wooden vats of living reeds. The development happens to have been built on a former sewage treatment site. The downside of that - I don't know if it's the result of the former processing activity or the present one - is that there is still a faint whiff of sewage about the place on the baking hot day that I visit, which is slightly though not massively offputting.