Swiss Re is one of the worlds leading reinsurance companies. This new building will bring together all the companys London-based staff. Located on the site of the former Baltic Exchange in the City, the tower rises 41 storeys and provides 45,000 square metres of accommodation, including offices and a shopping arcade accessed from a new public plaza.
The project takes a radical approach - technically, architecturally, socially and spatially - to create the capitals first ecological tall building.
The tower has a radial plan with a circular perimeter. In profile it widens as it rises and tapers towards its apex. This form responds to the constraints of the site: the building appears more slender than a rectangular block of equivalent size; reflections are reduced and transparency is improved; and the slimming of its profile towards the base maximises the public realm at ground level. A diagonally braced structure supports the building at its perimeter, allowing column-free floorspace and a fully glazed envelope which opens up the building to daylight.
Each of the floor-plates is rotated with respect to the one below it. This allows the spaces between the radiating fingers of each floor to combine to form spiralling lightwells. Socially these spaces break down the scale of the building. Environmentally they help to regulate the internal climate, becoming the buildings lungs. Fresh air is drawn in at each floor via slots in the cladding. Exhaust air can be recycled to provide heating to the building, or vented to the outside.
The spiral form of the atria generates pressure differentials that greatly assist this natural flow. The system is so effective that air conditioning will not be required for a significant proportion of the year. As a result, energy consumption is dramatically reduced in comparison with conventional office buildings.