Skin or structure? What is so remarkable about the use of EFTE (Tefzel) in the Beijing Olympics Swimming Stadium (the Watercube) by Arups and Australian Architects Peddle Thorp Walker (PTW), is the ability of the material to act as a primary structural element, lightweight skin, green material, fire resistant and remain faithful to the design intent all at the same time.
Contemporary architectural material expression could be seen as a homogenisation of surface and structure, all folding together. The play of materiality seen in the work of late post modernist architects that separated skin & structure, wall and roof, has generally disappeared. The challenge for EFTE is to act in all of the above and adapt for variations on the building (there are 7 variations of bubble forms), including as a roof without change in material or appearance (and to withstand snow loads).
Using the metaphor of the soap bubble structure (explored originally by Frei Otto and rediscovered by Irish Professors of Physics at Trinity College, Weaire and Phelan) the building consists of an inflated cavity structure of bubbles 3.6m thick into a space frame structure 177m x 1771m x 31m high. The skin is inflated, such that the tensile strength of the bubble enables it to resist the loads on the building. Previously EFTE has been used in nuclear power plants, space technology & underwater, but owing to its translucent appearance and high strength (10x stronger than other fluropolymers) was the appropriate choice for Beijing.
2-4mm thick sheets of EFTE is ‘tailored’ like clothing to the bubble profile (possibly computer controlled laser cut which would give this material great potential for non standard geometry applications), inflated and continually kept under pressure to keep the bubble shape. The material has excellent insulative properties, the ability to resist temperature extremes (considering China has a temperature of -30C in winter) and readily admits daylight, so that it saves on both lighting (55% saving) and heating (30% saving) requirements. Nothing in the company websites comments on the environmental impact of the material manufacture.
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