Super-duperstore

Supermarkets are regularly hailed by architects as the modern equivalent to churches or museums, though it's not often that you see shoppers taking the time to admire the handiwork of a carefully stacked shelf or kneeling in reverence at the foot of the fish counter. At the same time, they are widely accepted to be a beast of a building type, at best mediocre and at worst offensive. While some go for the gnome-infested faux-cottage effect, providing a Toytown of banking, gardening, clothing and eating services intended to keep you there all day, others plump for the less sickly but utterly dismal stripped-down, pile-'em-high formula, designed to have you in and out in half an hour.

Developing their practice's earlier work with Tesco at Hemel Hempstead, Herts, and Brent Cross in London, Michael Aukett Architects have responded to a growing demand for well-made supermarkets, and claim to have "taken the boundaries of supermarket design a major step further forward". Their new store in Sheffield, one of the three winners of this year's RIBA award for the Yorkshire region, falls into the rather unattractive category of "edge of town" development, being by the side of a railway track in Sheffield's well-to-do Abbeydale suburb. It is, however, one of several recent designer creations - notably, the new Sainsbury in Plymouth - which try to better the down- and-out image of out-of-town shopping. The idea is that an award-winning design not only raises the profile of the supermarket chain, but also guarantees that, unlike its easily-dismantled counterparts, the building will have a long life.

The front of the pounds 7m Sheffield building gleams, but gives little away. Stacks of trolleys and a blisteringly big and red Tesco sign overshadow its finer features - the sprouting pillars, the completely glazed facade. And the costly- looking floating steel roof is virtually invisible from the car park, which is the only approach. The roof is actually best viewed from the Sainsbury store on the other side of the railway, its pristine finish showing up Sainsbury's in all its boring brownness.

But the roof commands most admiration from the interior, and the neglected subtleties of the outside are repeated to greater effect indoors. The architects have done away with the standard suspended ceiling that exists in most superstores, and much is made of the warehouse-sized single-storey space, lending the building an airy feel, elegantly enhanced by the wave design of the roof (below). The waves are achieved by "cold-rolling" steel sections into half-pipes, which are then bolted together. Long seams of glass running the width of the roof divide the beams, allowing in plenty of natural light, which makes for a welcome alternative to the usual phosphorescent glare of strip-lighting. With its glassy facade, the building's entrance and cafe areas are absolutely flooded with light even on the greyest of days - though all the light in Sheffield couldn't entice me to sit down for a cup of tea in the place where I'd just stocked up on bleach.

The tubby pillars are encased in reconstituted stone. Because they are so sturdy in comparison to the roof, they seem to be holding it down rather than keeping it up. Each column sprouts four spindly iron beams at the top - viewed from a distance, it all resembles a field of whirligig washing- lines. Look up at them long enough against the dizzying angles of the roof, and they certainly start to spin.

The building's capaciousness does offer a more-pleasant-than-usual environment for the weekly shop. There's more aisle space than usual, and more room between the checkouts - but there's no getting away from the fact that the size of the building has created difficulties for product advertising. Colossal croissants and boulder-sized baguettes hang from the roof to help customers pinpoint the bakery, and the dairy section is identified by a series of Friesian-cow backsides with swaying tails - each of them 6ft tall.

Such architectural effort, however, has not been carried through to the frugal landscaping and barren car-park area outside. The shed-shaped building ensures that you can't mistake it for anything but an out of town supermarket, crammed with fresh-frozen, vacuum-packed, tinned, boxed and bagged goods that are a bore to buy. But it is a much improved version and the burgeoning pursuit of a new architectural language for supermarkets certainly marks a step in the right direction.

Lightness on the edge of town: the glazed facade (top), and (above) the tubby pillars, which appear to hold down the floating glass-and-rolled- steel roof