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ETFE foil: Time to shine

March 1st, 2008 / By: / Feature

For 25 years, ETFE foil has been used to grand effect in structures throughout Europe. The United States is finally catching on.

It can certainly be said that the development of ETFE (Ethylene Tetrafl uoroethylene) took a dramatic step in evolution. During the early stages of space exploration, Dupont, working with NASA, developed ETFE as a thermo plastic version of Teflon. It was designed to have high corrosion resistance and the durability to hold up under oppressive cosmic radiation that NASA would expose it to.

But it took the innovation of a professional yachtsman to turn ETFE into an architectural application. Dr. Stefan Lehnert, a mechanical engineering student at the time, was looking for better foils for his sails. When he experimented with ETFE, Lehnert realized he found an ideal building material — transparent, self-cleaning, durable, and flexible to great lengths.

ETFE polymer is 1% the weight of glass, expands to three times its normal length without losing elasticity, and offers shade and insulation control. It can be laid out in sheets or billowed into pillows, giving it elegance and economy of scale. And on top of that, the material is easy on the earth.

World recognition

Lehnert founded Vector Foiltec in Bremen, Germany in 1982—a design and manufacturing company that turned ETFE into the Texlon Foil System.

Since then, ETFE has been in the toolkits of architects and builders throughout Europe. It’s used in such varied locations as atriums, exposition halls, universities, gas-station roofs, and sports stadiums. But two high profile applications have brought the use of ETFE into the global public’s interest. First was the Eden Project, a sprawling environmental complex of more than 28,000m2 of ETFE-covered bio-domes that opened to the public in Cornwall, U.K. in 2000. Th e second is two structures that will serve as centerpieces to the 2008 Summer Olympics games in Beijing—China’s National Stadium and National Aquatics Center. Th e former is dubbed the “bird’s nest” for its intricate, seemingly random thicket of girders hugging the main edifice. The spaces in between and on the roof are filled with inflated, waterproof ETFE cushions.

In almost cartoonish juxtaposition nearby stands the Aquatics Center, a geometric cube covered in what resembles oversized bubble wrap. Used as membrane insulation, it is considered to date the world’s largest ETFE project.

US market stuff

While the profile of ETFE continues to grow around the world, its use in the U.S. has been slow to catch on. “Before the year 2000, there were only a handful of people in the United States that actually knew about the technology and doing research,” says Edward Peck, lead designer for Foiltec North America. Peck was one of them. After the Eden Project, Dr. Lehnert looked to capitalize on the acclaim for the Texlon Foil System and decided to explore the U.S. market. Lehnert and Peck teamed with investors and in 2001 launched a North American office in Cohoes, New York.

But rather than pouring money into marketing it up front, Foiltec North America hit the test laboratories. “We knew how the system performed, but the European standards don’t hold water in the United States. We had to build a foundation of test data— sustainability testing, strength and load testing, all the way to hurricane testing,” Peck says. “The roomful of data we had in Germany didn’t mean anything over here.”

With its bases covered, the company set out on its other goal of educating architects about the technology and to assist them in evaluating potential applications. It the meantime, the company’s Texlon Foil System has been used to striking effect in structures in the United States.

The Art Centre College of Design in Pasadena, Calif., added a new campus that was renovated from an industrial wind tunnel. California design firm Daly Genik Architects (DGA) transformed the 8,360m2 complex into gallery and design space for the school. Above the studio space, DGA designed three sculptural skylights using the Texlon Foil System—with its three layers of ETFE foil, two of which featuring custom patterns designed by graphic designer Bruce Mau—to clad the faceted forms. The patterns allow the skin to visually transform, while altering its light transmission. The skylights glow softly at night, like a beacon of lanterns. In 2006, DGA won an Honor Award for design from the AIA California Council.

The Massanutten Aquatic Centre, located in the Shenandoah Valley in Virginia, was completed in 2005. The stand-alone indoor watermark, designed by Aquatic Development Group, resides within the mountain resort. The central aquatic area features a pyramid enclosure—a network of timber frames, with Texlon foil filling in the spaces and providing rich views to the surrounding landscape.

The most recent Foiltec NA project is the U.S. Federal Building. Architect Moshe Safdie designed a sprawling atrium to connect three blocks of offices that provide light and connectivity to the highly secured building. According to Peck, the plans called for unilateral trusses to span from one side of the atrium to the other with no additional structure. The Texlon ETFE System allows for a three-dimensional curve as it follows the curved footprint of the atrium—a feat that traditional materials cannot achieve without segmented straight or flat elements.

The result is maximum transparency and acceptable load specifi cations that past muster for post 9-11 blast requirements in government buildings.

A green selling point

While ETFE’s properties off er wide-ranging potential as a building material, it’s the environmentally friendly factor that Peck says is raising eyebrows in the United States. Increasingly, the LEED® (Leadership in Energy and Environmental Design) Certification, awarded by the U.S. Green Building Council, is a feather in the cap of architects, builders, and communities. The Art Centre College of Design was the first structure in Pasadena to be granted a LEED certification, due in large part to its ETFE elements.

“We knew that sustainability was a major element to push,” Peck says. “This product gives you a lot of opportunities as far as day lighting, reduction of steel for support structures, savings on transport. If you reduce the tonnage of steel, reduce the raw building materials, we have a real capacity to lighten up a building.”

The Texlon Foil System has very low energy consumption during its manufacturing process (much of which includes recycled materials). The complete system can weigh between 50 and 90 percent less than other systems with comparable properties.

Gaining momentum

In addition to Foiltec, other companies outside the U.S. have embraced ETFE foil in a number of applications and markets. Foiltec NA has eight more projects slated to be built in the U.S. this year. European companies Covertex and Hightex GmbH continue to apply the material to structures great and small. It’s the great structures, however, that have had an unforeseen affect on architects here who began to associate ETFE with high-end money projects.

“This is what we’ve been struggling with since the international recognition we got with the Eden project in 2000,” says Peck. “These are the projects that are in the public eye. But most architects here are thinking, ‘When am I ever going to win a competition or be awarded a contract to design a billion dollar project? In my lifetime that’s not going to happen.’ Our challenge is to make it grounded, and make architects realize that any project can incorporate ETFE foil. Whether its an office building with an interesting atrium or a lobby with a skylight, or a factory with a series of skylights, or a small high school stadium with a canopy roof. These are all realistic.”

Jeff Barbian is a freelance writer and editor who frequently writes about design and architecture. His piece on the Alnwick Garden pavilion appeared in the May/June 2007 issue.

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