STRUCTURAL GLASS FACADES - USC School of Architecture

pieces of glass with a ½” air space, for an overall panel size of 1”. (Point-fixed applications
may sometimes require larger thickness in one or both pieces of glass, increasing the overall
size of the panel.) Thus, the overall sealant site-line (corresponding to the glazing grid) is
over 1-3/4” wide. Framed glazing systems can approach this same dimension, and are
sometimes selected over point-fixed systems in these applications as they may provide
improved economy at little or no relative loss of overall facade transparency.
The thermal performance of glass is at odds with transparency. The offsetting attribute of
transparency, however, is daylighting. The balancing of these behaviors is a challenge in the
design of any enclosure with a large glazed area. Too often this problem has been dealt with
by the MEP engineer specifying some massive HVAC equipment. Fortunately, the façade
designer has an increasing array of materials and techniques. This topic, while of critical
importance, is not central to this thesis and the material beyond the scope of this document.
It is imperative however, that the designer understand the performance issues involving
glass, a primary material in the technology of structural glass facades. Toward that end,
what follows is a definition of key terms and concepts taken from the Viracon website that
every designer must understand in order to select and specify an appropriate glass material
on any façade project.
The following informative definitions and information are from the Viracon website, a
valuable resource for the façade designer. (Viracon 2008e)
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