The past few years have made it abundantly clear that any building dedicated to public health research needs to be highly flexible, and quietly reassuring. The School of Public Health – the second project that Allies and Morrison has completed at Imperial College London’s new White City Campus in west London – is a ten-storey building that radiates calm and order, while packing in a huge amount of reconfigurable teaching and research space.
Situated on the west side of a new square of college buildings, the school has a formal, grid-like facade of white precast concrete, filled in with coppery pink metal panels and expansive glazing. This reveals the range of activities within: teaching on the first and second floors, offices and research on the five floors above, and on the public ground floor, community events, coffee and casual games of table tennis. The open spaces are characterised by a restrained palette of exposed concrete (lightened by the use of 50% GGBS), Douglas fir, perforated metalwork and muted pink finishes.
The site is hemmed in by rail lines, busy Wood Lane and the Westway, the main artery in and out of west London. Height was also restricted, with any new development limited to ten storeys: “Even though it was next to a 30-storey tower, we had to navigate the height from the neighbourhood Victorian terraces and step up to the higher scale,” says Laurie Hallows, director at Allies and Morrison.
As one of the earlier stages in Imperial’s evolving plans for a west London science and innovation district, the building’s end use was initially unclear. “It was an open brief, so from the first iteration we were designing with flexibility in mind,” says Hallows’ colleague Paul Eaton, a partner at Allies and Morrison.
An in-situ concrete frame with flat slabs helped to keep all options on the table: layouts and service runs could be reconfigured as the brief became more defined. It was the ideal blank canvas, says Eaton. “It’s still one of the best ways of creating a flexible shell, particularly when you factor in all the complexities around fire safety and encasement. When the brief for the School of Public Health was introduced, the building grew and changed, but that spirit of flexibility was maintained.”
The building may have been growing in terms of the brief, but the site constraints remained the same. Imperial’s expanding programme now required a ten-storey building, which exceeded the mandated height limit. The team began to rework the design, with a focus on rationalising the structure. A 10.5m x 7.8m grid became 7.8m in both directions. The shorter spans helped to reduce the slab thickness, cutting the floor-to-floor height from 4m to 3.8m, while maintaining ceiling heights of 2.7m. “This meant we were able to lower the overall height of the building while still squeezing in the floors we needed,” says Hallows. Less material also meant less embodied carbon.
The 7.8m x 7.8m grid offered other advantages, adds Eaton. “It works for different sorts of arrangement – open-plan offices, perimeter offices, but also larger meeting rooms and teaching spaces. It can be adapted to dry labs too, if they’re needed in the future.” It’s also divisible into 600mm units, which simplifies the design of finishes such as floor and ceiling tiles, as well as concrete joints. The frame was cast using a proprietary large-panel steel formwork system, adapted slightly to align the tie holes with the grid.
On the facade, the grid allows each span to be expressed as regular 3.6m bays within a vertical frame of 600mm columns – wider than a typical office elevation. These generous proportions help to mark out the public-facing, teaching building from some of the more introverted, lab-focused facilities on the Imperial estate. “It gives a feeling of openness when you look out, but also when you look at the building from the outside,” says Eaton.
Each facade responds differently to its orientation and surroundings. The north facade, which frames the main entrance on a campus side street, rises from a single-storey colonnade. The circular columns were cast in situ but, due to the 50% GGBS concrete, merge almost imperceptibly with the white precast concrete above. On the north-west corner, the final 7.8m bay has been cut out of the top five storeys, creating a setback that draws east light into the building and steps down to the Victorian urban scale of Wood Lane.
On the east and west elevations, the colonnade becomes solid, with delicately fluted precast panels that resolve the building at street level. To shade the interiors from the morning and evening sun, the window profiles are deeper on these facades, although designed with efficiency in mind. “We did a lot of work to optimise those elements,” says Eaton. “They have a C-shaped profile, removing concrete in the middle where you don’t need it, and maximising depth at the window reveals.”
The south facade is different again – stepped and opaque, with discreet east-facing windows turned away from the residential building opposite. This blank wall helps to shield the building from the Westway and conceals the main core, which is positioned at the south end of the building to make the floorplates as large and open as possible.
The precast elements are smooth in texture, highlighting the crisp junctions and shadow gaps between horizontal and vertical elements. “We wanted to keep the finish fairly simple,” says Eaton. “It’s a building where texture is less important than dimensions and proportions. Wood Lane is also a fairly busy traffic environment, so we wanted something that wouldn’t stain and was easy to maintain.”
This is a building designed to last far longer than the nominal 60 years, he adds. “We always try to think of our buildings like this. They have really important uses, but they will last for much longer than those uses. The nature of public health research will change over time, and the building will evolve too.”