ETFE Architecture: A Photo Journey

Eden Project, 2000

The Eden Project in Cornwall, England was one of the first structures built with ETFE, a synthetic fluorocarbon film. The British architect Sir Nicholas Grimshaw and his group at Grimshaw Architects envisioned the architecture of soap bubbles to best express the organization's mission, which is this:

"The Eden Project connects people with each other and the living world."

Grimshaw Architects designed the "Biome buildings" in layers. From the outside, the visitor sees large hexagon frames holding transparent ETFE. Inside, another layer of hexagons and triangles frame the ETFE. "Each window has three layers of this incredible stuff, inflated to create a two-metre-deep pillow," the Eden Project websites describes. "Although our ETFE windows are very light (less than 1% of the equivalent area of glass) they are strong enough to take the weight of a car." They call their ETFE "cling film with attitude." 

Skyroom, 2010

ETFE was first experimented with as roofing material — a safe choice. In the rooftop "Skyroom" shown here, there is little visual difference between the ETFE roof and the open air — unless it's raining.

Every day, architects and designers are inventing new ways to use Ethylene Tetrafluoroethylene. ETFE has been used as a single layer, transparent roofing material. Perhaps more interestingly, ETFE is layered in two to five layers, like phyllo dough, welded together to create "cushions."

2008 Beijing Olympics

The public's first look at ETFE architecture may have been the 2008 Summer Olympic Games in Beijing, China. Internationally, people got an up-close look at the crazy building being erected for the swimmers. What became known as the Water Cube was a building made with framed ETFE panels or cushions.

ETFE buildings can't collapse like the Twin Towers on 9-11. Without concrete to pancake from floor to floor, the metal structuring is more likely to blow away buoyed by ETFE sails. Rest assured, that these buildings are firmly anchored to the earth.

ETFE Cushions on the Water Cube

As the Water Cube was being built for the 2008 Beijing Olympics, casual observers could see the ETFE cushions sag. That's because they are installed in layers, usually 2 to 5, and pressurized with one or more inflation units.

Adding additional layers of ETFE foil to a cushion also allows light transmission and solar gain to be controlled. Multi-layer cushions can be constructed to incorporate movable layers and intelligent (offset) printing. By alternatively pressurising individual chambers within the cushion, we can achieve maximum shading or reduced shading as and when required. Essentially this means that it is possible to create a building skin which is reactive to the environment through changes in climate. — Amy Wilson for Architen Landrell

A good example of this design flexibility is the Media-TIC building (2010) in Barcelona, Spain. Like the Water Cube, Media-TIC is also designed as a cube, but two of its non-sunny sides are glass. On the two sunny southern exposures, the designers chose an array of different types of cushions that can be adjusted as the intensity of the sun changes.

Outside the Beijing Water Cube

The National Aquatics Center in Beijing, China showed the world that a lightweight construction material like ETFE is structurally feasible for massive interiors required for the thousands of Olympic spectators.

The Water Cube was also one of the first "whole building light shows" for the Olympic athletes and the world to see. Animated lighting is built into the design, with special surface treatments and computerized lights. The material can be lighted on the surface from the outside or backlit from the interior.

Allianz Arena, 2005, Germany

The Swiss architecture team of Jacques Herzog and Pierre de Meuron were some of the first architects to design specifically with ETFE panels. The Allianz Arena was conceived to win a competition in 2001-2002. It was built from 2002-2005 to be the home venue of two European football (American soccer) teams. Like other sports teams, the two home teams that inhabit Allianz Arena have team colors — different colors — so the stadium can be lighted in the colors of each team.

Inside the Allianz Arena

It may not look like it from ground level, but Allianz Arena is an open air stadium with three tiers of seats. The architects claim that "each of the three tiers is as close as possible to the playing field." With 69,901 seats under the cover of ETFE shelter, the architects modeled the sports stadium after Shakespeare’s Globe Theatre — "spectators sit right next to where the action takes place."

U.S. Bank Stadium, 2016, Minneapolis, Minnesota

Most fluoropolymer materials are chemically similar. Many products are marketed as "membrane material" or "woven fabric" or "film." Their properties and functions may be slightly different. Birdair, a contractor who specializes in tensile architecture, describes PTFE or polytetrafluoroethylene as "a Teflon^®-coated woven fiberglass membrane." It's been the go-to material for many tensile architecture projects, such as the Denver, Colorado airport and the old Hubert H. Humphrey Metrodome in Minneapolis, Minnesota.

Minnesota can get mighty cold during American football season, so their sports stadia are often enclosed. Way back in 1983, the Metrodome replaced the open air Metropolitan Stadium that had been built in 1950s. The Metrodome's roof was an example of tensile architecture, using a fabric that famously collapsed in 2010. The company that had installed the fabric roof in 1983, Birdair, replaced it with PTFE fiberglass after the snow and ice found its weak spot.

In 2014, that PTFE roof was brought down to make way for a brand new stadium. By this time, ETFE was being used for sports stadia, because of its greater strength than PTFE. In 2016, HKS architects completed the U.S. Bank Stadium, designed with the stronger ETFE roofing.

Khan Shatyr, 2010, Kazakhstan

Norman Foster + Partners were commissioned to create a civic center for Astana, the capital of Kazakhstan. What they created became a Guinness world record — the world's tallest tensile structure. At 492 feet (150 meters) high, the tubular steel frame and cable net grid form the shape of a tent — traditional architecture for the historically nomadic country. Khan Shatyr translates as the Tent of the Khan.

The Khan Shatyr Entertainment Center is very big. The tent covers 1 million square feet (100,000 square meters). Inside, protected by three layers of ETFE, the public can shop, jog, eat at various restaurants, catch a movie, and even have some fun at a water park. The massive architecture would not have been possible without the strength and lightness of ETFE.

In 2013 Foster's company completed the SSE Hydro, a performance venue, in Glasgow, Scotland. Like many of the contemporary ETFE buildings, it looks very normal during the day, and is filled with lighting effects at night. The Khan Shatyr Entertainment Center is also lit at night, but it is Foster's design that is the first of its kind for ETFE architecture.

Sources

• Architecture at Eden, http://www.edenproject.com/eden-story/behind-the-scenes/architecture-at-eden
• Birdair. Types of Tensile Membrane Structures. http://www.birdair.com/tensile-architecture/membrane
• Foster + Partners. Project: Khan Shatyr Entertainment Centre Astana, Kazakhstan 2006 - 2010. http://www.fosterandpartners.com/projects/khan-shatyr-entertainment-centre/
• Herzog & de Meuron. Project: 2005 Allianz Arena Project. https://www.herzogdemeuron.com/index/projects/complete-works/201-225/205-allianz-arena.html
• Seabright, Gordon. Eden Project Sustainability Project. edenproject.com, November 2015 (PDF)
• Wilson, Amy. ETFE Foil: A Guide to Design. Architen Landrell, February 11, 2013, http://www.architen.com/articles/etfe-foil-a-guide-to-design/, http://www.architen.com/wp-content/uploads/architen_files/ce4167dc2c21182254245aba4c6e2759.pdf