Johnson Window Films Dealer Resource Center

Dry Shrink Shaping

As discussed, the Solar Spectrum consists of radiation ranging from 300nm to 2500nm wavelengths. The spectrum is divided into 3 Spectral Regions:

When heat passes through a glazing system, it is called Solar Heat Gain (SHG). To better measure the total amount of heat that passes though a glazing system, you first need to understand the amount of energy that each of the 3 Spectral Regions contributes to the Solar Heat Gain.

Measuring total heat control performance for glazing systems is an important part of the window film business. The industry accepted measurement for total heat control is called the Solar Heat Gain Coefficient (SHGC). The lower the SHGC number (less heat gain), the better the solar control performance. Please note the SHGC includes contributions from all 3 solar spectrum regions – UV, VIS and IR.

Therefore, to receive an accurate heat control performance measure between different glazing systems, the SHGC should be utilized because it takes into account all 3 spectral regions. Heat control performance data that only considers one spectral region, instead
of all 3, is not considered an accurate measure of SHGC.

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