Working details A ROOFLIGHT WITH A CONCAVE ROOF SLOPE
The building is six storeys high, with a two-storey rooftop plantroom. It has a cast in-situ concrete frame with a steel roof structure. Laboratories are ranged around the perimeter, with desk spaces for researchers in open galleries set around three sides of a 20m x 40m atrium. The galleries have glazed balustrades and give views across, offering opportunities for interaction
The galleries receive natural light from a series of five large rooflights, each consisting of a vertical band of north-facing glazing and a convex roof which slopes down to meet the next rooflight. The convex roof is fitted with an 800mm-wide rooflight which faces south. In cross-section the rooflights form a saw-toothed profile running the length of the atrium. The rooflights are 20m wide.
The north-facing rooflight was designed to give light to the deep atrium. The light is diffused by a screen formed from 60mm-diameter steel bars set at 165mm-diameter centres which follow the shape of the convex roof. The south-facing light provides sparkle; the moving shafts of light it admits are tempered by the diffusing screen of bars.
Light studies ascertained the quantity of light produced by the northlight and tracked the path of the sun's rays from the south-facing light and established that glare would not occur. The convex roof reveals more visible sky and provides greater diffusion than a concave form. The glazing consists of a toughened-glass outer layer and a laminated-glass inner layer.
Each northlight is supported by a Vierendeel frame, to which are fixed a series of concave 305 x 165mm universal beams; these carry the roof. An insulated acoustic steel deck is covered with a standing-seam roof finish at upper levels and a Sarnafil roof at lower levels.