ETFE

Summary

ETFE is ethylene tetrafluoroethylene, a fluoropolymer made into transparent film and foil. It is used in inflated cushions for long-span roofs and facades, with U-value and solar gain tuned by layers and frit patterns.

Cols

Image

ETFE: ethylene tetrafluoroethylene
Cushion / pneumatic panel: inflated layers of ETFE film
Frit pattern: printed pattern that adjusts solar gain
Brand names: Tefzel (DuPont), Fluon (Asahi Glass), Neoflon (Daikin), Texlon (Vector Foiltec)

History and demand

Invention

1970s: DuPont developed ETFE

First uses in construction

Eden Project: first large-scale architectural use (listed 2001)
Allianz Arena and the Beijing National Aquatics Centre (2008 Olympics): pneumatic ETFE panels
Tropical Islands: 20,000 m2 (215,000 ft2) ETFE window

Sourcing

Named ETFE suppliers include AGC and Daikin in Japan and Chemours in the United States (market research)

Properties

Mechanical

Tensile strength: about 42 MPa (6,100 psi)

Thermal and moisture

Working temperature range: -184 to 150°C (-299 to 302°F)
U-value: about 5.6, 2.5, and 1.9 W/(m2·K) for single, double, and triple layers (0.99, 0.44, 0.33 Btu/(h·ft2·°F))
Solar heat gain coefficient: 0.2 to 0.95, adjustable with frit patterns

Durability

Artificial weathering equal to about 30 years' exposure showed almost no film deterioration
Low friction coefficient sheds dirt

Uses in buildings

Building elements

Greenhouse and Canopy Glazing: inflated roofs and canopies
Skylights and Roof Windows: cushion roof glazing
Curtain Wall Systems: pneumatic facade panels

Pros and cons

Pros

Self-cleaning surface
Recyclable
Adjustable solar gain through frit patterns

Cons

Single layer U-value about 5.6 W/(m2·K); insulation needs multiple layers

Manufacturing and cost

Main manufacturers and suppliers

Sources

Wikipedia: Ethylene tetrafluoroethylene, https://en.wikipedia.org/wiki/Ethylene_tetrafluoroethylene
Wikimedia Commons: AWM-Munich-ETFE-Cushions-Photovoltaic.jpg, photo by MdCAlmeida Villafuerte (CC BY-SA 4.0), https://commons.wikimedia.org/wiki/File:AWM-Munich-ETFE-Cushions-Photovoltaic.jpg
MarketsandMarkets: ETFE market, https://www.marketsandmarkets.com/ResearchInsight/ethylene-tetrafluoroethylene-market.asp