Material for an Architectural Revolution

ETFE, a fluorocarbon-based polymer, is a durable, adaptable plastic that's opening horizons for builders at the Beijing Olympics and beyond

by Elizabeth Woyke

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Imagine a swimming arena made out of bubbles. Or a stadium knit from steel girders like a bird's nest. Or even an enormous tent, proudly covering over a million square feet of space. A decade ago, such buildings might have existed only in the imagination. Today, they're being built in Beijing as China's new National Stadium and National Aquatics Center and as the Khan Shatyry Entertainment Center in Astana, Kazakhstan. All thanks to innovative architects, adroit engineers—and the unusual properties of the material called ETFE.

ETFE may be about to get its moment in the architectural spotlight, but in fact, it has been around since the 1970s, when DuPont invented a fluorocarbon-based polymer, Ethylene Tetrafluoroethylene, for use as an insulation material in the aeronautics industry.

The interesting property for architects is that the resin can be spun into a thin, surprisingly durable, film, which manufacturers such as DuPont (also Asahi Glass Company, which calls its version Fluon) pack in rolls—like a sturdier version of plastic cling-wrap. It can be used in sheets or inflated into pillows, and with its incredible versatility, it has become the go-to material for those in search of an alternative to more traditional materials, such as glass.

Sweeping Europe

As it happens, DuPont didn't really care about pushing ETFE to architects at all. That fell to Stefan Lehnert, a German mechanical engineering and business administration student and avid sailor, who stumbled across the material in his search for new sail technologies. Having discounted it as inappropriate for his sailing needs, he nonetheless saw building-material potential in its transparency and its self-cleaning and structural properties.

In 1982, he founded Vector Foiltec—a design and manufacturing company specializing in the use of ETFE—in Bremen, Germany, and began shopping the material around to architectural firms. The company's first project, the roof of a small pavilion at a zoo in Arnheim, Holland.

Since then, ETFE has become increasingly popular, especially in Europe. The 1990s saw it used in office atria, university buildings, medical facilities, exposition halls, and zoos across Britain and Germany. In 2000, the Eden Project, a huge environmental complex in Cornwall, Britain, containing two gigantic geodesic conservatories covered in ETFE, was unveiled. Designed by Grimshaw Architects, the construction was widely acclaimed as an engineering marvel, and created a wave of global interest.

Bubbles and Twigs

With the spotlight on the Beijing Olympics, designers expect ETFE to go mainstream at last. Certainly there's no better illustration of the material's ability to turn architectural fantasy into reality than the Beijing Olympic Green, located at the north end of the central axis of Beijing City. There, less than 500 meters apart, sit the rapidly rising National Stadium and National Aquatic Center.

The two structures could not look more different. The Herzog and de Meuron-designed stadium is crafted out of woven steel and resembles a sturdy but intricate bird's nest. The Aquatics Center, nicknamed the Watercube, is refined and delicately detailed, an iridescent box covered in what appear to be bubbles. When completed later this year, both will showcase innovative uses of ETFE. To protect spectators from rain and wind, the stadium will feature red ETFE cushions inserted in the spaces between the "twigs" of its "nest." The 750,000 square foot Watercube, the largest ETFE project ever, will be clad entirely (roof and four walls) in blue ETFE cushions.

Given the extensive size and expense (an estimated $100 million) of the Watercube project, it's surprising to note that this will be the first time that Sydney, Australia's PTW Architects have actually used the fabric. They're that confident. John Bilmon, managing director at the company, says they chose ETFE over glass and fiberglass because it satisfied the project's engineering needs. Some bubbles in the design span 30 feet without any internal framing—a distance that wouldn't be possible with other materials.