You won’t see this polymer used as the cladding for any buildings in Toronto that we are aware of, but ETFE has become a cladding of choice around the world for buildings where the architect wants a modern look, and either provide a glow from within at night, or the transmission of light through the walls during the day, such as in a greenhouse, and where they are looking more for translucency than for the greater transparency of glass.
Casual followers of architecture and building construction will, however, recognize the bubble-like membranes that now comprise the exterior of some of the world’s most famous sports complexes. But the lengthy chemical name for ETFE, Ethylene tetrafluoroethylene, a flourine-based plastic polymer, would likely elude even the most fanatical observers of the industry. Only since the new millennium has the practice of coating structures in this lightweight building material really gained ground across the globe… well, except for here it would seem.
DuPont originally invented ETFE in the 1970s as an insulation material for use by the aerospace industry, but its first headline-grabbing architectural application came in 2001 with the completion of the Eden Project in Cornwall, England. The selection of the material allowed each of the geodesic biomes to regulate environmental and solar conditions for the flora within, since transparency to ultra-violet light is among ETFE’s primary benefits. Despite now being 22 years old, the hexagonal cells of the structures still appear newly built, as the material’s nonstick surface lends a self-cleaning ability to the membrane.
After experiencing functional and aesthetic success with the Eden Project, engineering firm Arup expanded its use to sports stadia worldwide. Pneumatic panels — layers of ETFE that are filled with air — have famously clad the Allianz Arena in Munich (above) and the Beijing National Aquatics Centre (below). The 2,874 ETFE-foil inflated panels that define the arena design can be illuminated individually, making it the first building in the world with a full colour-changing external cladding system. The 4,000 cushions wrapping Beijing’s Water Cube contribute to its status as the largest ETFE-clad structure in the world.
In Minneapolis, the roof of the newly built U.S. Bank Stadium was the biggest single installation of the material in the United States, while its most recent splashy application was as the cover of the rolling roof of The Shed at Hudson Yards in New York City. We have yet to see cover a major building with it in the Greater Toronto Area.
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From 2015 to 2017, UrbanToronto and its sister publication, SkyriseCities, ran an occasional series of articles under the heading Explainer. Each one took a concept from Urban Planning, Architecture, Construction, or other topics that often wind up in our publications, and presented an in depth look at it. It’s time to revisit (and update where necessary) those articles for readers who are unfamiliar with them. While you may already know what some of these terms mean, others may be new to you. We are publishing or updating and republishing Explainer on a weekly basis. This article is an update of one that was originally published in 2017.
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