China´s new National Aquatic Center, called the Water Cube, uses multiple layers of a modified ETFE copolymer to produce the “membrane cushions” that encompass the building’s exterior. The structure will be home to the Olympic swimming, diving and water-polo competitions. (Vector Foiltec photo)

“The realization of `green Olympics’ in the Water Cube project sets a good example for other Olympic venues and the construction of Beijing´s urban projects,” according to Yu Xiaoxuan, deputy director of the Venue and Environment Department of the Beijing Organizing Committee for the Games of the XXIX Olympiad (BOCOG). He noted that the building absorbs solar radiation and reduces thermal loss, makes maximum use of natural ventilation and lighting to ensure temperature and humidity control, features an advanced water treatment system and an efficient water-recycling system, and employs “innovative energy-saving materials and products” to reduce inside and outside pollution.

Vector Foiltec of Germany and Yuanda Group of Shenyang, China, won the contract to undertake the membrane project in January 2005. Construction of the facility, which will be able to seat 17,000 when completed by the end of this year, began in December 2003. The work on the concrete and steel structures was finished in July 2005, and installation of the membrane cushions began last Aug. 1.

On its Web site, Vector Foiltec explains how its “climatic envelope” system works: “The Texlon cladding system comprises a number of layers of the UV-stable copolymer ethylene tetrafluoroethylene welded into cushions or foils. The cushions are restrained around their perimeter by aluminium extrusions, which are in turn fastened to a supporting primary structure. The cushions are inflated with low-pressure air to provide insulation and to resist wind loads.

“A Texlon cushion comprises at least two layers,” it continues. “However, more layers can be added into the system to enhance the cladding´s insulation properties. Each foil can be treated with a variety of treatments to control and manipulate the aesthetics quality of the roof, the visual transparency and the level of solar gain.”

Vector Foiltec also indicates that it uses both Hoechst AG’s Hostaflon and DuPont Co.’s Tefzel ETFE foil products, but does not specify which is used in the Water Cube project.

The blue bubbles outside the National Aquatics Center comprise more than 3,000 pneumatic cushions, with sizes ranging from 9 square meters to less than 1 square meter per piece. These cushions look like an single structure, but actually are relatively independent from each other, providing for convenient replacement of individual cushions when needed.