Far from being a new material, ethylene tetrafluoroethylene (ETFE) first appeared on the scene in the 1970s when DuPont invented it as an insulation material for the aeronautics market, according to Reliable Plant. However, the wonder polymer is now being touted as "the building material of the future," as this fluorocarbon-based polymer is finding its way into some of the most innovative examples of design. In fact, it may soon experience a surge in notoriety thanks to its major role in the design and structure of some recent worldwide sporting events, including last year's World Cup and next year's Beijing Olympics.

ETFE is a transparent plastic that has been selected in lieu of glass and plastic for the construction of many future-forward buildings and concepts, due to the material's unique properties.

A mere 1 percent the weight of glass, ETFE can cost 24 percent to 70 percent less to install. Compared with glass, it transmits more light and is also a better insulator. It also boasts extraordinary resilience. ETFE can be stretched to up to three times its length without losing its elasticity. (If the film does tear, it can be patched with other pieces of ETFE.) Where a large glass panel might measure 10 feet by five feet with extensive internal framing, ETFE can span 30 feet or more without any trussing.

The recyclable material (simply melt and reuse) is also self-cleaning: dirt, sleet, rain and snow slide off its nonstick, nonporous surface. If exposed to fire, ETFE shrinks from the heat, providing a vent for smoke to escape.

It can carry 400 times its weight, with an estimated 50-year lifespan.

The interesting property for architects, according to BusinessWeek:

[The] resin can be spun into a thin, surprisingly durable, film, which [some manufacturers] pack in rolls. It can be used in sheets or inflated into pillows, and has become the go-to material for those in search of an alternative to more traditional materials, such as glass.

ETFE has become increasingly popular since the 1980s, especially in Europe. Architects began working with ETFE some 15 years ago. The material will be used for the 2008 Beijing Olympics, where it is an integral part of the distinctive designs of both the Beijing National Stadium and Beijing National Aquatics Center — slotted for completion later this year.

The stadium is crafted from woven steel and resembles a sturdy but intricate bird's nest, according to BusinessWeek. 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 Aquatics Center — aka the Water Cube — however, is the largest ETFE project to date. It is refined and delicately detailed, "an iridescent box covered in what appear to be bubbles," as BusinessWeek puts it. When complete, the Water Cube's walls and roof will be clad in more than 100,000 square meters of blue ETFE pillows a mere .008 of an inch thick. The ETFE pillowing will allow greater light and heat penetration than traditional glass, resulting in a 30 percent reduction in energy costs. The Water Cube is designed to gather heat passing through its ETFE walls and roof — energy that can be used to heat the building's water systems or expelled through vents if the building gets too hot.

Beijing National Aquatics Center, dubbed the Water Cube, will host swimming, diving, water polo and synchronized swimming events at the Beijing Olympics in 2008.
Credit: Foiltec

The material is available in different finishes, colors and prints, and can be lit from within using LED lights or decorated with projections. For example, at the start of the 2008 Olympic Games, the Water Cube's exterior walls will turn into a kind of movie screen, showing projections of the swimming competitions inside.

Other large ETFE projects include Munich, Germany's Allianz-Arena, finished in April 2005 and the host of last year's World Cup. More than 2,800 ETFE-film air panels cover its exterior, and the arena's "skin" can be illuminated at night, glowing red, white or blue, depending on which team is playing.

Credit: Allianz Arena

And the Khan Shatyry Entertainment Center — a 1,076,000-sq. ft., tent-shaped recreational complex in the capital of Kazakhstan — is due for completion next year.

Yet for all its celebrated properties, ETFE is by no means a perfect material.

Two or three layers typically are welded together and shipped flat to the job site, where they are inflated into panels or "cushions." These cushions require semi-continuous air pressure — to keep them stable and give them thermal properties — so most systems include thin hoses that plug into the cushions' sides.

According to BusinessWeek:

These air-supply lines connect to a computerized system that monitors the pressure within the cushions. This system can also feed air into, or eject air from, particular chambers or layers to let in more light or create more shade, meaning the ETFE cushions act as a dynamic puffer jacket for buildings. In some installations, this is done automatically using light sensors.

Yet its unique properties sure are making it a pliable material for engineering and architectural expression.

Earlier: Recipe for World-Class World Cup Stadium

Resources

The Miracle Polymer for the New Millennium
by Elizabeth Woyke
BusinessWeek, April 24, 2007

Transparent plastic turns design fantasy into reality
RP news wires (via Reliable Plant), April 2007

Tefzel — ETFE Specifications
Boedeker Plastics, Inc. (see comment below) and [redacted]

Ethylene Tetrafluoroethylene (ETFE)
RTP Company