Sir Alexander Fleming Building, Imperial College

The impact of the research zone, seen from an upper level, is immediate and dramatic – one is inevitably reminded of great commercial atria, like that of Foster's Hong Kong Bank or Rogers' Lloyd's. Natural light enters from the heavily glazed north elevation and from above. Instead of dealers' desks, there are, however, banks of study carrels for boffins on the second and fourth levels, heavily occupied, when I visited, by figures intently tapping away at computers. As in Foster's own office – compared by one critic to a nineteenth-century mill – the fixed furniture provides an ordered framework, keeping a mass of papers, files and books under control.

A strict building management policy forbids the random fixing of posters and notices to the building or the ends of the carrels – the rules seem to be observed. Laboratories and other highly serviced technical spaces, plus some cellular offices, occupy the east and west flanks of the building, where they are close to the main service risers, and the south end of the block. The use of timber, as on the lower floors, for partitions and doors, plus carpeting in the carrels, contributes to an aesthetic which is welcoming and far-removed from the more clinical fit-out of the labs. On the northern edge of the forum there are open areas, provided with comfortable seating and served by kitchens, where informal meetings can take place. One of the underlying aims of the project was to encourage interaction and communication between departments – this as much the world of the 'new office' as of conventional laboratory design. This is an all-hours building – come here late at night or on a Sunday morning and there will be people at work.

User reaction to the building seems positive – its success, says Ian Caldwell, is being used to spearhead further building campaigns at the college and to attract funders. (A second Foster building is about to go on site.) IC's older buildings contain laboratories arranged along corridors, making interaction difficult but providing greater privacy and insulation from noise and other distractions. Yet the noise level of the forum seems to be a constant, murmurous hum – rather like that which prevailed in the old British Museum reading room and an agreeable background to concentrated work. It helps, says Caldwell, that everyone working there is part of a research ιlite – there is an implicit code of behaviour. The undergraduates can peer upwards through the glazed screen and aspire, perhaps, to a PhD or even a post on the faculty.

As project director Andrew Thomson points out, lessons from other Foster projects, including Stansted, have been applied in the use of natural light in the building. At Stansted, a calm and regular light is occasionally interspersed with shafts of sunlight which 'lift' the interior, providing an element of sparkle. A similar strategy was adopted at ic, where a series of rooflights, baffled by sculpted 'waves', provide a steady north light, with the occasional burst of direct light. As at Stansted, consultant Claude Engle advised on the natural lighting strategy as part of the overall energy programme for the building.

Engle is a regular Foster collaborator. So, increasingly, is the Dane Per Arnoldi, responsible for the strong element of colour in the IC building. Arnoldi's first collaboration was at Commerzbank in Frankfurt and, more recently, he has had an important role at the Reichstag. At IC, Arnoldi strengthened the architect's own colour proposals. The south wall of the central forum is painted in increasingly intense yellow hues, which integrate with the exposed concrete and timber panelling to give the space a glowing focus. Elsewhere, the use of a deep blue effectively marks out social and interactive spaces

.As university buildings, in terms both of procurement and design, increasingly learn from the world of commercial architecture, the results are mixed. But Foster's addition to the (increasingly civilised) Imperial College campus is remarkable not only for its use of a constrained site, in an area where major national institutions contend for land, but also for its inspired adaptation of space-planning and management techniques learned in the world of office design. This is a highly sociable building, which recognises that scientists are people and provides a comfortable, even inspiring, milieu for innovation.