December 1, 2007


So-called double-façades (DF) or ventilated façades, environmental second skins, etc. have attracted great interest as modern building enclosures. The DF label actually covers a wide range of different enclosure types. In most cases, a DF has three layers of glazing with ventilation and solar control devices between the outer two glazing layers, although some ventilate the space between the inner glazings. In most cases, the airflow through the glazing cavity is driven by natural buoyancy (hot air rises) aided by wind pressure differences, although some systems use small fans (often driven by photovoltaics). In hybrid systems, HVAC supply or exhaust air streams are directed through a glazing cavity before connecting with the outside. Reprinted with permission from Journal of Building Enclosure Design, 2007, pages 48-53.