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Light to Solar Gain (LSG)

The light to solar gain is an indicator of glass performance and is measured by the ratio of light transmittance to heat-transmittance (LSG = VLT / SHGC). Obviously, the higher the LSG, the closer the glazing performance is compared to the ideal glazing. Extremely high performance glasses can have an LSG of around 2.

In perspective with the above measurement tools, a highperformance glass should have a higher light transmittance, lower visible reflectance, lower SHGC and SC, lower U-Value and lower RHG. That said, the light transmittance and reflectance characteristics can be subjectively analyzed based on the architect’s design preference and in locations where intense direct incident sunlight forces the reduction of glare by using darker tints and coatings.