VLT: Visible Light Transmittance

The visible light, with wavelengths between 380nm-780nm,
that is transmitted directly through a glazing system.

VLR: Visible Light Reflectance

The visible light is reflected by a glazing system.

Infrared Rejected (789nm<)

Infra red light from the sunlight is only a portion of the solar spectrum which provides heat through a glazing system. It is important not to confuse infra red rejection with TSER (total solar energy rejected) which is the true indicator of how much solar energy will be blocked by glazing system.


A measure of a surface’s ability to emit (reflect) long-wave infrared radiant heat energy (thermal heat, room temperature). Emissivity varies from 0 to 1 (0=no emittance, 1= 100% emmittance)