ETFE-Foil structures – the flexible glass

ETFE-technology – innovative, durable and efficient

Modern architecture is hard to imagine without use of transparent structures for facades and roofs. Besides glass structures, innovative structures made of ETFE foil are increasingly gaining significance.

Ideal applications include sectors where the conventional approach would often be to use glass (swimming pools, water parks, atriums, skylights, zoos, greenhouses and palm houses etc..

Structures made of multi-layered ETFE foils

ETFE (ethylene tetrafluoroethylene) is an innovative material which is used in building as extruded foil with thicknesses from 0.1 to 0.3 mm (100 to 300 µm).

ETFE as non-fabric-reinforced material, ETFE foil is used primarily in the form of air-filled cushions. The foil cushions can be equipped with multiple air chambers to attain low U-values.

Heat from sunlight can be reduced by printing on the foil cushions.

The so-called "pillows" are held in shape by air pressure in the cushions (approximately 300 to 800 Pa – 0.0435 to 0.1160 PSI). Depending on the cushion geometry and the external loads, the individual cushions can span 4.50 meters (14.76’), with no other supporting structure. Much greater spans are possible with additional tensile structure reinforcement. The supporting air supply and the control is fully automated. Custom design concepts can provide the optimum solution for each project.

ETFE-cushion constructions retain their stability due to a pneumatically-generated synclastic design.

  

ETFE
Ethylen-Tetrafluor-Ethylen 
 Base material  Fluorpolymer  
 Total weight (g/sq.m)

 175 or 0.036 lbs/sqft (at 100 μm)

 Tensile strength (N/mm2)

 Longitudinal direction  51 - 58 
(7396-8412 PSI)
 Lateral direction  53 (7687 PSI)

 UV-resistance  very good
 Stain-resistance  very good
 Translucence  approx. 90 %
 Colour  highly transparent
 printing and dyeing possible
 Fire classification  DIN 4102 B1 
 flame retardant
 EN 13501-1 / B-s1,d0

Single-layer ETFE foils

ETFE foils can also be installed in single layers. The material-specific properties of relatively low elastic deformation and high plastic deformation, as well as high ultimate strain must be taken into account when doing so. Normally the foils are supported by thin steel cables (8 – 12 mm, 0.315” – 0.472”). The spacing and layout of the steel cables are specified according to the structural requirements.

  • Especially high light transmitting capacity of approx. 90% in the visible wavelength range
    (from 400 – 700 nm/UV)
  • High UV transmissibility, depending on the material thickness
  • Good thermal insulation: U values, depending on the number of foil layers
  • G value between 0.10 and 0.85 depending on the design and alignment of the printing pattern
  • Low weight of foil cushions, thereby facilitating light, intricate substructures
  • Very good mechanical properties: High tensile strength/tear resistance and hail resistance
  • Flame retardant – ETFE foils burn off without dripping
  • Low maintenance costs due to anti-adhesive surface with self-cleaning effect
  • Interesting design options offered by printing, e.g. shading without additional construction
  • Long service life of at least 25 - 35 years
  • Cost savings in comparison with conventional transparent roof constructions
  • High recyclability

 

 

 

ETFE roofing - Hitachi Power Office in Duisburg/Germany

By partially coating the foils, it is also possible to produce a shading effect.

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Example of shading - "media tower" Hamburger Meile shopping mall