STRUCTURAL GLASS FACADES - USC School of Architecture

combined to provide an even broader range of affect. Many glass fabricators provide unique
color choices.
Optical distortions were discussed as an evaluation criterion in section 6.2. Heat-treated,
insulated and laminated panels will all display subtle variations of color. Evaluating
reflections is an important aspect of glass appearance; the primary way we see glass is
through reflections on its surface. Optical distortions can be very apparent in the reflections.
Some designers find this objectionable.
The appearance should be evaluated both from the inside and outside, in daylight hours and
during artificial lighting conditions.
6.4.1.6 Visible Light Transmission
High daylight levels in a building’s interior are an increasingly popular strategy among
designers to reduce energy consumption from artificial lighting. The visible light transmission
property of a glass type determines the natural light levels in the interior. The provision of
high levels of natural light must be balanced against the need for solar control. Colored and
coated glass is used to limit the amount of visible light transmission providing a range of light
levels.
6.4.1.7 Solar Transmission and Absorption
The solar heat gain coefficient (SHGC) is the primary measure of the total solar energy
passing through a glazed opening; measuring the full spectrum of solar energy as opposed
to just the visible light specturm. A low SHGC coefficient will lower the solar gain and lower
air cooling costs. A high coefficient will raise the solar gain, potentially reducing heating
costs. Local climate becomes an important evaluation criterion; if heating costs are higher
than cooling costs, a high coefficient may be a better choice, and the opposite if cooling
costs are higher than heating costs. The potential for harvesting daylight to offset artificial
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