University at Buffalo - The State University of New York

Published: August 7, 2008

By PATRICIA DONOVAN
Contributing Editor

UB architect Annette LeCuyer’s recent research is on a remarkable material that is changing the way architects and engineers think about building performance.

UB architect Annette LeCuyer has written a book about ETFE, an amazing new building material that was used to construct the National Aquatics Center in Beijing.

The material, ETFE, is being showcased at the Beijing Olympics as the material used to construct the National Aquatics Center.

ETFE is an extraordinarily thin, lightweight, flexible, self-cleaning polymer that, when used in air-filled cushions, is extremely strong—even when its resin is spun as thin as Saran Wrap—and has extraordinary energy-saving, insulation, acoustic, light-transmission, fire-engineering and structural-behavior qualities. It also is environmentally friendly and can be very beautiful.

“ETFE foil cushions have recently become an important material for the cladding of such technologically sophisticated and innovative buildings as the spectacular National Aquatics Center for the 2008 Olympic Games in Beijing,” LeCuyer says. Popularly known as the “Water Cube,” the center’s beautiful iridescent surface was inspired by the geometry of a continuous array of soap bubbles.

The polymer, whose full name is ethylene tetrafluoroethylene, is the subject of LeCuyer’s new book, “ETFE—Technology and Design” (Birkhauser Verlag AG, 2008), in which she presents an in-depth introduction to its characteristics in the context of the recent history of pneumatic buildings.

LeCuyer, professor of architecture, teaches a course on design and construction technology in the UB School of Architecture and Planning. Her research focuses on materials and the impacts of digital design and fabrication on building construction.

She notes that the manifold appeal of ETFE is due to a variety of exceptional qualities. It is 1 percent the weight of glass, transmits more light than glass, is a better insulator, costs from 24-70 percent less to install than glass, is very strong, has a long life span and is not only self-cleaning, but recyclable.

“Unlike many building materials, ETFE is not degraded by exposure to ultraviolet light,” says LeCuyer. It is able to elongate up to 400 percent before failing. While other building assemblies rely on rigidity for strength, air-filled ETFE cushions readily deform under variable wind, rain and snow loads without loss of structural strength or stability. Because of ETFE’s light weight, it can span much further than glass and requires less supporting structure.

She notes that the ETFE cushions on the Aquatics Center, while made of foils that are only eight one-thousandths of an inch thick, can span 30 feet without intermediate support, a feat that is not possible with glass. The innovative envelope of the Water Cube also works hard environmentally. Conceived as a thermal duvet, it comprises a double skin of multi-layer cushions with a 3.6-meter-wide air cavity between, which will potentially reduce energy costs by 30 percent.

If the film tears, it can be patched with other pieces of ETFE and, when exposed to fire, it softens and shrinks away from the heat, naturally venting smoke out of a building. In fires, earthquakes, storms or explosions, ETFE—unlike glass—does not shatter and so helps to mitigate risks to life safety. Its naturally nonstick, nonporous surface has chemical properties similar to Teflon. It is so slippery that dirt, snow and rain just slide off.

“ETFE cushion enclosures,” she says, “initially became known to a wide public through the Eden Project in the UK by Grimshaw Architects, the largest plant enclosure in the world, and the Allianz Arena in Germany by Herzog & de Meuron.” The material also can be seen in several proposals for the 2012 London Olympics.

Vector Foiltec, a British/German company that specializes in using ETFE architectural-cladding technology—including its use in the Beijing Aquatics Center—will build eight projects in the U.S. next year and has more than 100 other commissions slated worldwide. Vector Foiltec has carried out a number of projects in the U.S., including skylights for the Art Center for the College of Design in Pasadena, where multi-layered ETFE cushions that are printed with patterns employ variable air pressure to alter the shading coefficient and thermal insulation of the building envelope in response to changing daylight and weather conditions.

She notes that ETFE has been around since the 1970s when DuPont commercialized it for use as an insulation material in the aeronautics industry. Later, it became a popular tie and cable insulator used in the nuclear industry.

In the 1980s, she says architects and engineers were drawn to the fact that ETFE allows for more light and heat penetration than traditional glass. She notes that, because of its unusual structural attributes and sophisticated and tunable environmental performance, ETFE cushion technology holds the potential to construct very large climatic envelopes like those proposed by such 20th-century visionaries as R. Buckminster Fuller, Frei Otto and Walter Bird. Unlike many traditional building materials, ETFE also measures up well in terms of sustainability.