The building has a steel frame structure with profiled metal deck and concrete floors, and a central concrete core which houses lifts and staircases. Its ovoid shape is created by inclined perimeter columns.
The facade is a series of storey-height, triple-glazed and insulated cladding panels which are faceted and inclined to follow the shape of the building.
The panel fixing system had to accommodate differences in panel size and structural movement of the building as it reached its final shape and loading. Each panel is fixed at its corners by 'cup-and-ball'connectors mounted on horizontal flanges which allow vertical adjustment. The base connectors support the panels and the upper connectors provide restraint.
A head truss bolted to the floor slab and connected to the lower 'cup-and-ball' connectors takes vertical wind load and slab load.
The panels exceed the requirements of Part L of the Building Regulations. Each panel comprises an outer rainscreen of 10mm toughened glass with a 103mm cavity behind, vented to create a stack effect, and an inner layer - double-glazed units with Low E coating between insulated aluminium-faced panels.
Horizontal aluminium louvres are set in the cavity between the glazed areas.
At each floor level the panels overhang a continuous recess with highlevel fresh air vents to the floor below. They are linked to open in conjunction with fresh air vents in the cladding panels. They also open for smoke purge and air pressure relief in the event of fire.
The panels were preassembled in Switzerland by Schmidlin, transported to site and lifted onto the facade.