Common materials and their architectural properties

Because of its high translucency (approximately 95% over a wide spectrum) there is a growing tendency to use ETFE (ethylene-tetrafluoro-ethylene) foil either in place of, or in combination with, coated woven textiles. Illustrations of a selection of membrane and foil materials and coatings, and a table giving an overview of properties, are presented by Pudenz (2004). 

Ti = transmittance of the external layer T2 = transmittance of the internal layer rj = reflectance of the inner surface of the external layer r2 = reflectance of the outer surface of the internal layer (Chilton et al., 2004, p. 106). 

A similar effect occurs on the outside of the enclosure where, unless shadows, for instance from masts and cables, are cast on the membrane surface, its contours may not appear well-defined. 

Internal illumination, for instance by upUghters, can be used highly effectively to highlight the surface curvature and increase the readability of the form. At night, light reflected off the inner curved surface of the membrane is dispersed throughout the enclosure. Simultaneously, transmittance through the membrane surface allows the enclosure to become an illuminated beacon in the landscape. 

8 Pattern of welded seams seen from the inside of a membrane roof at the Palenque, Seville, Spain (photo John Chilton). 

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