Glass Glossary

Visible Light Reflectance (VLR)

Last Updated: November 23, 2023

Visible Light Reflectance (VLR) is the measure of how much visible light (wavelengths typically ranging from 380 to 750 nanometers) is reflected off the surface of a material, such as glass. It is expressed as a percentage, representing the proportion of incident visible light that is reflected away from the material’s surface. VLR is an important factor in determining a material’s appearance, visual comfort, glare, and the quality of visibility through the glass.

It is important to note that it is beneficial to have a low VLR on the indoor surface of the glass. Low indoor VLR enhances visibility when viewing objects outdoors, particularly in overcast or nighttime sky conditions, as it reduces the amount of light reflected back into the observer’s eyes. This makes it easier to see through the glass without the interference of reflected light from the interior.

On the other hand, high VLR on the exterior surface can help reduce glare from direct sunlight, but may also make the glass appear more reflective and less transparent, potentially impacting the building’s aesthetics and views from the outside.

Visible Light Reflectance is a critical parameter in the selection of window and door glass, affecting both visual comfort and aesthetic considerations. It should be evaluated in conjunction with other factors like visible light transmittance, solar heat gain coefficient, and ultraviolet protection to achieve an optimal glazing solution for each specific application.