The study of light is subjective in some specific aspects, like color and glare, but very objective in aspects like direction and reflection. Basic optics laws tell us that when a light ray travels in a medium and finds a glass surface, for example, part of the incident ray is reflected and the rest is transmitted to the other side of the glass. Depending on glass characteristics and some other factors, the light transmitted exhibits a different range of phenomena such as heat-gain. This document provides education on design considerations to reduce the possible effects of the reflective characteristics of exterior cladding materials and glazing systems used in building construction.

The Technical Services Division of the National Glass Association (NGA) has produced this Glass Technical Paper solely for informational purposes. This Paper was developed by dedicated member volunteers and subject matter experts. The original version of this document was published in 2018. This version of the document was updated and published in September 2023.

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