ETFE, a material fluorocarbon-based polymer ethylene tetrafluoroethylene, is quickly gaining popularity in North America and being used on some of the continent’s most innovative and prominent projects.
The material has many attractive attributes, combining design practicality and structural cost saving with a new aesthetic quality and creative usage possibility.
What is ETFE?
ETFE is a fluorine-based plastic that, like many future-looking materials, was originally developed by the aeronautics industry for its high resistance to corrosion and temperature variations.
Repurposed for architectural use in the 1970s, ETFE’s highly transparent and remarkable lightweight quickly set the material on the path to being a low-cost and more customizable glass substitute for long span structures and building facades.
In its early days, mainstream use of ETFE in construction projects has been largely limited to Europe, but the material is quickly finding popularity in the Americas as more prominent projects have opted for its use to stunning aesthetic and performance results.
Key Benefits of ETFE Foil
Weighing in at roughly one percent of the weight of glass, significant reductions in structural costs are made possible by employing ETFE.
The material films can also be up to 95 percent transparent and allow for the passing of ultraviolet light, which is responsible for the promotion of photosynthesis and facilitating plant growth. The amount of solar shading and transparency can be changed by adjusting the translucency, density and number of layers, as well as with the use of frit patterns.
Much like a glazed system, increased thermal performance is also possible with a multi-layered ETFE material approach.
When foils are formed into cushions, the pressurized air serves to stabilize the film and provides structural performance in addition to the thermal performance of the system.
Add this to the fact that ETFE material has a high resistance to deformation, high elasticity, is self-extinguishing in flames and can transmit acoustically and it becomes clear why so many large stadiums and projects are embracing the material.
ETFE vs Glass
In general, the basic enclosure performance of the ETFE system is much like a curtain wall glazing system. Weighing in at roughly 1 percent of the weight of glass, it can reduce the cost of the structural support system significantly.
Even with the addition of the extra foil layers to produce an inflated cushion, an inflation tubing system and aluminum extruded components and flashings, roof weights are often reported to be considerably lighter when compared to a glazed system.
Despite the potential cost-saving and design aesthetic benefits, ETFE is not an equal substitution to glass or other roofing systems in many respects.
In laboratory testing, ETFE has proven to be surprisingly puncture resistant. Despite excellent performance under these conditions, ETFE is not overly resistant to being cut and it is not recommended as vertical railing and should not be used at street or pedestrian levels as it cannot prevent intrusion.
Much like safety films that are placed on glazing, the ETFE material is, unlike glass, a stand-alone film that cannot shatter and is therefore much more suited for deflection than puncture resistance.
Access, repair and maintenance for ETFE are also not routine due to the unique characteristics and damage risks of the ETFE system. Because of this, the specialty design-build contractor will usually sign on for an extended warranty/maintenance period to perform this work.
ETFE vs PTFE
With both ETFE and PTFE being polymer plastics used as innovative building materials, chemically similar enough that only a letter separates the materials in the design and construction industries, they are easy to confuse.
While ETFE is most commonly utilized as an architects ‘future roof’ material, PTFE is more common in the construction industry as a highly specialized water resistant film most often used in insulation and as a friction and heat reduction solution.
PTFE, often referred to as Teflon®, has seen its highly specialized water, heat and friction resistant characteristics grow its popularity as a technical solution in industrial applications, especially electrical cabling.
Both ETFE and PTFE are relative fresh faces in the building industry. This formulative infancy paired with the materials’ respective unique combinations of chemical characteristics has many specialists expecting new innovative applications to continue to be uncovered and explored.