ETFE is the acronym for ethyl tetra fluoro ethylene, a strain of fluoro polymer. Here are a few of its characteristics:
- It weighs 1% of glass (for the same size)
- High level of transparency to visible UV light
- High resistance to degradation by sunlight
- Lifespan of up to 50 years
- Can support 400 times its own weight
- Better insulation properties than glass
- Classified as a recyclable material
Additional ETFE information
- With a Teflon-like surface, dust and dirt generally do not settle on its surface; when they do a small amount of water is sufficient to remove them.
- ETFE Foil unaffected by UV light, atmospheric pollutants on and other forms of environmental weathering.
- ETFE foil weighs 1kg/m2 (or approximately 4.3 pounds per square yard). This characteristic makes sound waves that are not reflected back.
Energy transmission and translucence
The amount of solar energy transmitted through glazing such as traditional glass is referred to as a G value expressed between 0 and 1. A higher value indicates a higher amount of solar energy through the glazing.
For a lower G value (less solar energy transmittance) multiple ETFE layers (pillows) are used. Another solution is to print on ETFE, also known as “fritting”, using differently sized patterns, ink color and density.
Standard glass has a G value around 0.88, specially-treated glass can have a G value as low as 0.46. An ETFE roof can have a G value of 0.48 with a 2-layer system and a printed (fritted) surface. A 3-layer configuration can give an approximate G value of 0.35
ETFE and Insulation properties
- A single layer of ETFE has an approximate U value of 5.6 w/m²°K.
- A typical 3-layer ETFE pillow can achieve a U value of 1.96 w/m²°K, a value significantly better than achieved with triple glazing when used horizontally
- Glazing manufacturers use values for vertical glazing which give more favorable figures
- ETFE cushions can be made more insulating with additional ETFE layers or by treating the ETFE with specialized coatings to enhance the thermal properties.
ETFE pillows: structural stability and thermal resistance
ETFE is a new and very strong material which can be used in layers to increase structural characteristics, thermal resistance and other related aspects.
The approximate air pressure in an ETFE pillow is 220 Pa and gives it structural stability and insulation properties.
ETFE comes in extruded film or foil form. A main use for it is in construction of air-filled “pillows” supported by frames (note: ETFE pillows are made from between 2 and 5 layers with thermal resistance comparable to glass, and with a maximum size of 4-5 metres (12-16 feet). ETFE-based materials are rated as non-fragile and offer excellent fire ratings and is self-extinguishing.
Single Layer ETFE
Double Layered ETFE
This configuration provides efficient insulation with U values as low as 2.3U(W/m2K).
Triple Layered ETFE
An outstanding characteristic of EFTE foil is its exceptional shear and tear resistance.
In situations where required repairs are minor, such as a small puncture, adhesive ETFE foil can be used to patch the area.
For major repairs the modular frame configuration of structures using ETFE makes it simpler to fix the problem. Often a section can be easily and quickly removed, repaired and then put back into place.