To make the London 2012 Olympic Stadium the most sustainable for the Olympics to date, Populous has turned to fabric as a strategic part of the overall strategy
Not wanting to leave a burdensome legacy on the host city or its people, the Olympic Delivery Authority asked sports facility designers Populous to make the new main Olympic venue—the London 2012 Olympic Stadium—as green as possible. The architects succeeded in large part by reducing the materials used and making it one of the lightest stadia of the modern era. They accomplished this by using lightweight tension structure technology to minimize the weight of the structure, which, in turn, minimized fabrication time and allowed for rapid construction and later dismantling.
The challenge, says Populous associate principal Tom Jones, was in creating a structure that is both temporary and permanent. “The efficiency of the design allows the embodied energy within the structure and fabric roof to be kept to an absolute minimum, and therefore making it one of the most significant environmentally sustainable aspects of the stadium design.”
Early in the design development stages, in an effort to optimize wind performance levels and to ensure the end design solution could meet the wind conditions of the site, Populous ran computer modeling to test a number of roof coverage options. Test results helped determine that the amount of roof needed would cover approximately two thirds of the spectators’ seats. To support that amount of roof, several structural concepts were explored, including conventional cantilevering of rigid materials. As the stadium’s elliptical shape of the seating bowl—which allows 80,000 spectators to be close to the action on the pitch—factored into these calculations, the design team chose to use a bicycle-wheel form of rim and spoke configuration, an extremely efficient design both in terms of the materials used and the cost. A delicate-looking truss around the top perimeter of the stadium is pulled into compression by a ring of cables at the inner edge of the roof cover and radial cables that extend toward the center point of the playing field. Supporting this bicycle wheel superstructure is a canted ring of diagonal columns that stabilize the overall structure. The fabric covering is a PVC-coated polyester cut in preshaped panels approximately 1mm thick and clipped to the cablenet and tensioned into the final anticlastic 3-D form.
With big international sporting events like the Olympics, television influences all design aspects, both in front of and behind cameras. For this reason, very high light levels on the field of play are required to permit high definition, as well as slow-motion, HDTV coverage. To prevent glare for the spectators and players, and any lens “flare” for TV cameras, designers carefully controlled placement of a series of 14 triangular lighting rigs above the inner edge of the roof. These rigs (or lighting “paddles”) were placed on top of the inner tension ring at the edge of the fabric roof.
Framing this structure is a graphically dynamic fabric wrap composed of inverted wedges that help define entrances at the ground level. This porous, translucent printed fabric allows the building to breathe naturally using a minimum of fixed mechanical systems. [See “London 2012 Olympic Stadium sustainable wrap“.]