Willis Headquarters, 51 Lime Street
London, UK, 2003-2007
Foster + Partners
Image Source: Foster + Partners
The new headquarters for Willis is located in the centre of the City of London. The project comprises of two separate buildings, a 29 storey building and a 10 storey building, which are located on a common plaza. In this project, I worked on the design of an environmentally responsive facade, the design of a parametric soffit under the tall tower, and the design of an elegant, doubly-curved mechanical grill on the lower tower.
Image Source: Foster + Partners
I was responsible for assisting with the design of an environmentally responsive facade. This involved carrying out environmental analysis of the facade and designing parametric shading elements. The design reduces the amount of solar insolation on the glazing while maximizing key views of London and the Thames. This optimisation balances environmental forces with the desires of the occupants. The amount of shading provided by each component at each location of the facade relates to the amount of solar insolation that that panel receives. I wrote a custom computer program to link the environmental analysis software, Ecotect, to Microstation, and drive the geometry of the facade components using the local environmental conditions.
Image Source: Foster + Partners
Image Source: Foster + Partners
I carried out many design studies for the soffit under the tallest office tower. The irregular plan form of tower, together with a complex sectional arrangement, made it a challenge to smoothly transition from the edge of the tower to the enclosed central core of the tower. Many different strategies were studied that harmonized the form and design intent of the architects with the practical considerations of structural and mechanical installations. The parametric design of the soffit was done in Microstation using DDD (dimension-driven design), a precursor to Generative Components, and custom written computer scripts.
Image Source: Foster + Partners
As the top of the lower tower can be clearly seen from the offices of the taller tower, it was necessary to carefully design the grill over this mechanical space. I was responsible for generating the form, geometric set-out, and blade detailing for the doubly-curved grillage over the mechanical area on the lower tower. The form was initially generated using an algorithm that "inflated" a virtual cable-net to create an elegant form that could account for the irregular plan form as well as the various heights of the equipment under the grill. Many different forms and structural studies were carried out. Due to construction constraints the form as built was a combination of two different rotational surfaces, which allowed for planar facets and therefore simpler detailing.