Olympic swimmer Michael Phelps was the darling of the 2008 Summer Games as he knocked down world records like bowling pins and won eight gold medals at Beijing's new National Aquatics Center. Dubbed the “Watercube” for its futuristic cubic shape, this energy-efficient venue was a collaborative design by China State Construction Design International (CCDI), PTW Architects in Australia, and international engineering firm Arup. It was built by the China State Construction Engineering Corporation (CSCEC). Reflecting the traditional square shape of houses in China, the structure is clad with a skin of inflated, pale-blue ETFE cushions (ethylene tetrafluoroethylene — a lightweight polymer) that cover the façades to create a profusion of shimmering blue water bubbles.
The dynamic lighting design, conceptualized by Arup Lighting, allows every bubble to take any color. Approximately 500,000 Cree XLamp® bars, each with eight to 16 red, green, and blue LEDs, are embedded in the steel structure of the façades in between the bubble layers. Each LED bar is individually addressable, allowing the pillows to become giant pixels.
Rogier van der Heide, global leader of Arup Lighting, explains, “We developed the scheme in very close collaboration with architects PTW. The renderings of the concept stage show these gorgeous watery colors that blend so well with the semi-opaque, slightly milky ETFE cushions. Every bubble is a double-layer façade system by itself and equipped with LED bars in between the layers. The light distribution comes only from one side of the bubble, creating a decrease in light intensity that emphasizes the three-dimensionality of the bubbles.”
Considered a building material for the future, ETFE has other benefits, as well. “It weighs only 1% of a glass façade, which means Arup could keep the structure light and airy, and it is recycled material which is another important addition to the building's sustainable properties,” adds van der Heide. “Including the heat that is being reused to warm up the pools, it is estimated that the ETFE façades save about 30% in energy. This is equivalent to what a fully clad roof with photo-voltaic panels could achieve.”