Architecture: It's a bug's life - but with all mod cons

London Zoo has new, hi-tech, energy-efficient accommodation for Britain's creepy-crawlies, from field crickets to jellyfish.

AS TRICKY clients go, the British field cricket leaps ahead. They like a dawn chorus so they make noisy neighbours. At least the jellyfish are quieter, but their water bills are high and they do need particular saline levels. The praying mantis is devout but the locusts swarm and their heating bills really mount up.

London Zoo's new house for creepy-crawlies is ready for occupation by many different species. Architects Phil Wharmby and Mike Cozens have applied so many different temperature controls on 80 showhouses that, like their faddy clients, they are getting really adaptable. They have to be, to survive as architects of the newest building at London Zoo to support Conservation in Action.

They don't like their grandly named Web of Life to be called the bug house - because it's got crayfish in it. And butterflies, accommodated in a huge glass vase open only at the top, ringing the double height of the south-west face.

North-east, the building nosedives below ground to nestle in a paddock full of anteaters, who can gaze at ants in the showcases below. This part of the insect house is for the really small members of our food chain.

The pounds 4.4m Web of Life, housed in this new building at London Zoo, promises to be a good visitor attraction, sandwiched between the llamas and the lions on one side and the wolves' park on the other. The wolves have been wintering in Edinburgh to avoid the building work.

"Creepy-crawlies don't rate high on the list of must-haves for architecture," says Mike Cozens. "But they should - because so many insects are under threat. Did you know that 95 per cent of all living things in the world are insects? Just one of them dying out has a dramatic impact on us because of their role in the food chain."

The floor plan of the Web of Life spirals like a snail shell, with display cases that explain the importance of the insects and how they evolved using all sorts of survival techniques, such as camouflage.

But it is nice that the architects have paid just as much attention to buggies as to bugs. Wrapping around that gentle spiral is a ramp for parents pushing their children, and for wheelchairs. In the core of the spiral are the kitchens and the keepers' air and water temperature controls.

The Web of Life is a hi-tech building that manages to look organic, with its canopied skin stretched like a caterpillar on ribs within - while the outer roof is made of galvanised steel that will corrode and rust to an agreeable autumnal colour. Big awnings swoop down from this roof so that shelter for queues is provided at all times. The architects say that this reminds them of a big barn but it's more organic than that - with tapering pale blue and green columns that look more like mushrooms.

The building is what the architects call "environmentally progressive". They had two conflicting principles to resolve in their design - lots of glass, and saving energy.

Big ventilation chimneys resembling camels' noses move air through the building. In order to cool the glass during the summer, deciduous trees were planted. In winter when the leaves drop, the sun reaches through the glass.

The timbers have been sourced from sustainable forests: this is not just a glib aside but a genuine pledge to find hardwoods grown in Malaysia under controlled conditions. The architects actually flew there to check it out.

A borehole was sunk 70 metres to pump cold water into a heat exchanger at the top of the building, sucked up there in a big red tube and down to underfloor channels that zigzag below the concrete floors. The structure, which is scheduled to open on 29 April, is arguably the most energy-effective building to be completed in the UK in 1999.

On Wednesday the Tourist Board launches the building as part of the Millennium City trail. The Millennium Commission awarded the centre pounds 2.2m in 1995, just two years after London Zoo itself had been threatened with closure.

Wharmby and Cozens had already helped the Zoo to establish a master plan, and their children's playground was a popular crowd-puller.

This is in contrast to the penguin pool by Bernard Lubetkin, the Grade 1-listed building which might be every architect's favourite example of early Modernism but is nevertheless seen as unfriendly by the public.

"Something about penguins makes people think they have human characteristics, and so people think they wouldn't like to live there, even though their breeding programme shows they are happy," Phil Wharmby explains.

He has already designed a second house for the penguins, which has an underground viewing chamber so that you can see them swimming. So far, however, the project has not been given the green light.