Casual followers of architecture and building construction would be able to recognize the bubble-like membranes that comprise the exterior of some of the world's most famous sports complexes. But the lengthy chemical name referring to the flourine-based plastic polymer, ethylene tetrafluoroethylene (ETFE), 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.

Eden Project, image by Flickr user Tim Parkinson via Creative Commons

DuPont originally invented ETFE as an insulation material for use by the aerospace industry. Its first headline-grabbing 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 being 16 years old, the hexagonal cells of the structures appear newly built, as the material's nonstick surface lends a self-cleaning ability to the membrane.

Allianz Arena, image by Flickr user Sönke Biehl via Creative Commons

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 and the Beijing National Aquatics Centre. The 2,874 ETFE-foil inflated panels that define the design can be illuminated individually, making the arena the first 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 is the biggest single installation of the material in the country.

Beijing National Aquatics Centre, image by Flickr user Garrett Ziegler via Creative Commons

While ETFE is still a relatively nascent building material, its growing reputation as a recyclable, tensile, enduring, and cost-effective alternative to traditional cladding is rapidly becoming a favourable option within the toolkit of international architects.

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