Material Review: One to Watch

Now that the show is over, here’s a question: Who got the gold—in architecture—at the 2008 Summer Olympics in Beijing? Was it PTW Architects for their luminescent, bubble-clad Watercube, also one of the world’s most energy-efficient buildings? Or was it Herzog & de Meuron for the steel-entwined Bird’s Nest? Glowing from within, it became the iconic building of the event to billions of viewers around the world. Both buildings broke records, architecturally speaking, in pushing the limits of manmade construction. The Watercube’s skin replicates the random pattern of bubbles of foam, and the Bird’s Nest envelope takes on the lightness of loosely woven twigs. Interestingly, both organic forms owe credit to the same synthetic material: a fl uorocarbon-based polymer named Ethylene Tetrafl uoroethylene (ETFE). Pillows made from ETFE fi lm clad the entire exterior of the Watercube and fi ll the spaces between and above the twigs of the Bird’s Nest. Showing unprecedented fl exibility—lightness, durability, and both environmental and cost efficiency—ETFE may have been the real hero of the 2008 Summer Olympics’ architecture.

ETFE Comes to Market
The possibilities of ETFE may seem utterly 21st century, but it’s not a newfangled product. The formula was originally developed in the 1970s by Dupont for use as an aeronautic insulation material. Made from a waste product of lead and tin mining, the resin in its raw state “looks a bit like sugar,” if you ask Ben Morris, who, along with Stefan Lehnert, figured out how to use it to improve the building envelope. To develop and distribute ETFE in the building market, Morris and Lehnert founded Vector Foiltec, Ltd., in 1981. Today, the company has offices in 13 countries around the world, and its team of researchers is constantly exploring new ways ETFE can be used in construction.

Here’s how: After ETFE is heated up and extruded into a paperthin film, it can be welded into large sheets that can themselves be used as building skin or can be woven together into cushions pumped with air. The ETFE sheets are transparent, like glass, but are one percent of the weight of glass, transmit more light than glass, and cost 24% to 70% less than glass to install. ETFE sheets are also chemically inert, so they don’t degrade under UV rays. Since the chemical compound of ETFE is related to that of polytetrafloroethylene (i.e., Tefl on®), ETFE film is also nonstick, so it keeps itself clean. Sweetening the deal in today’s eco-conscious building market, ETFE is recyclable: At the end of its useful life—thought to be at least 50, but possibly up to 200, years—it can be melted down and reused. When ETFE sheets are fused into pillows and pumped with air, the material takes on both stability and high insulation properties, and the design possibilities are seemingly endless, according to Morris. “You can manipulate the number of layers to the cushions so you can change the insulating calculations. You can print graphics onto it or manipulate the sunlight going through it to your heart’s content. By printing patterns on different layers and then moving the layers, you can create kaleidoscopes that change and react to sunlight.”

And Morris and his team aren’t done. “What’s interesting is that it’s a new technology, rather than a new product,” says Morris.

Only now, with the airtime recently devoted to the Watercube and Bird’s Nest in Beijing, will the world at large see how this sugary resin can push the envelope in modern architecture. In reality, though, ETFE has already been stretching the limits of design—mostly in Europe—for the past decade. Nicholas Grimshaw & Partners used ETFEs in the Eden Project (2001), a 30,000-square-meter complex of ETFE pillow-clad domes housing a rainforest in Cornwall, England. Herzog & de Meuron’s St. Jakob’s Park in Basel, Switzerland (2001), is surrounded by ETFE pillows, some tinted red to spell out the name of the stadium, others able to be illuminated with logos, images, or colors—likewise with the Allianz-Arena in Munich (2005), also by Herzog & de Meuron. Opening this year, Foster + Partners’ Khan Shatyry Entertainment Center in the capitol of Kazakhstan will be covered by a curtain of ETFE that will keep the space warm enough for year-round use.

Closer to home, Daly Genik Architects and Bruce Mau used patterned ETFE film on skylights for the underground Art Center College of Design in Pasadena in 2004. The ETFE skylights in Fox & Fowle’s 2005 renovation of the 1903 Bronx Zoo Lion House adjust for shading and temperature as the sun moves, allowing ultra-violet light for plants and animals but blocking excessive heat. Upcoming high-profile ETFE-based projects that are close to completion in the U.S. include the LeMay Museum in Tacoma by L.A.-based Grant Architects. On the boards but already garnering a lot of attention: a whale-shaped New York Aquarium in Coney Island by Cloud 9, a Barcelona-based firm that’s known less for what it has built than the ideas it has conceived. Collaborating with the landscape architectural firm WRT, Cloud 9 has designed an ETFE cover that would be draped over the existing aquarium and new pavilions like a fishing net. Playing on the colorful history of Coney Island, red LED lights are woven through the ETFE fabric, and the steel frame supporting it looks like a roller coaster.

Cloud 9: A Patent Change
Now in its tenth year, Cloud 9 has only three completed buildings to its name, but nine patents for building technology. The firm’s name refers both to the airborne habitats that Buckminster Fuller proposed in the late 1940s, and to its mission. “We are an office trying to build clouds,” says principal, Enric Ruiz-Geli. And more than any other, Ruiz-Geli is testing and exploring the architectural capabilities of ETFE. Born in 1968 and schooled in Barcelona and at Columbia University’s Graduate School of Architecture, Ruiz-Geli sees the role of today’s architect as part inventor. “In the past, we architects were paid by our responsibility: we were paid by square meters; we were paid 10 percent of the budget. Now we are paid by the added value of ideas.” The firm patents its ideas not necessarily to protect them, but to register them, “and later on, to share,” says Ruiz-Geli.

Ruiz-Geli terms this rethinking of the role of the architect as “the economy of architecture.” Fitting neatly into that matrix, he says, is an economical material like ETFE. “It belongs to this low economy. We are going from a market where the knowledge is really low and the material is really high—like marble—to high engineering, high knowledge, but the material itself—the chemical, the physics, the whatit- is-made-of—is very cheap. Architecture has to take that path. More money to the hands of people—to the brains— and less money to the materials.”

Interestingly, it’s not uncommon for brainstorming at Cloud 9 to be done in collaboration with material manufacturers, often from the beginning of a project. Manufacturers financially support the firm’s research. “They help us economically on the research and development, just to pay to visit the lab and to know what’s going on, what’s in the future, because they know that later on they are getting projects,” Ruiz-Geli says.

“We want to go to bed with our clients early,” explains Ben Morris of Vector Foiltec. “My company is architects and engineers and artists and scientists and batty people. Really the only difference between us and Enric is that Enric sells his knowledge, and we embody our knowledge in a technology. So we like to work closely with architects and engineers very early in the process and learn from them.”

It also makes sense for architects using ETFE to collaborate early with the manufacturer because ETFE turns the typical design strategy inside-out. Most designs start by setting the structural grid and then identifying the cladding. “All the architects are nurtured on their mothers’ knees with this concept,” says Morris. But because ETFEs are so lightweight, architects can take a different intellectual journey. What loads will the cladding take? How big can you make the cushions? The structural grid is derived from that load analysis. “So it’s completely the other way around from what you’d normally do,” Morris says. With ETFEs, the grid may go out the window all together. Morris explains, “If you invent a cladding system in which the whole surface is flexible, then you don’t need any movement joints on the edge, you just spread it across the skin. And that completely changes how you think about designing a building. Suddenly you have a system that is so flexible that you can have bendy buildings.”

Ruiz-Geli credits ETFE’s flexibility as one of its best attributes. “It allows us to fold and unfold this material as if we are designing a costume. You can build curvy shapes, organic shapes. We do complex geometries. I like it that my architecture moves and performs. We need material that can follow.”

One curvy Cloud 9 project not yet done, but already winning high praise from the likes of The New York Times, is the Villa Nurbs, a private residence that hovers like a series of otherworldly pods in the suburbs outside of Barcelona. Cloud 9 has developed a patented ETFE system for the roof of the villa. In addition to taking on an organic shape, it filters light; plus it can monitor energy use and open or close accordingly. The homeowners can also opt to open the roof if they simply want to look at the stars. Ruiz-Geli explains, “It’s as close as we can come to clouds.” It’s a project that would be inconceivable with glass. “Glass is not smart enough,” says Ruiz-Geli. On a project that uses this kind of new technology, architects have the added job of educating their clients. “Their first reaction is very dreamy, very ‘wow,’” says Ruiz-Geli. “Then it takes time to transfer this knowledge. You need to take them to see buildings.” Admittedly, part of the attraction of ETFE, for clients, is the novelty of the material. “ETFE helps clients have an iconic building. The material is helping you lead architecture.”

No wonder. In Ruiz-Geli’s hands, ETFE is being made to perform like a living organism. Cloud 9 has another project under construction in Barcelona too, a science museum. In the Media-TIC building, Ruiz-Geli wraps triangular pillows of ETFE around a 10-story cube. The panels open and close like gills depending on temperature and light.

Going one step further is the Thirst pavilion, a small and temporary project the firm just completed in Zaragoza, Spain, for Expo 2008, an international expo on water and sustainable development. What’s so smart about this unairconditioned pavilion? In a dome shape that mimics the geodesic domes of Buckminster Fuller, Cloud 9 designed a skin of fiberglass between three layers of ETFE cushions. As with Villa Nurbs and Media-TIC, the ETFE sheets monitor temperatures and adjust insulating properties accordingly.

But there’s more. Borrowing the biological principal of human cooling, Ruiz-Geli has designed the skin to “sweat.” When the sun heats the pavilion, the ETFE sends salt water to the outside of the building. The water immediately evaporates in the heat, and the salt crystallizes. “We are building an igloo of salt, and each time the building sweats, it becomes thicker and thicker,” Ruiz-Geli explains. “It’s a very sustainable principal. Our exterior material is salt. It’s not stone, it’s not marble. When there is rain, the pavilion will get a shower. We dissolve the salt, collect it again, and put it back to the system.”

Buildings that move, breathe, and, now, sweat? The next Olympics should be interesting.

About the Author

Hannah McCann is an editor at large for Architect magazine.