FAQ Knowledge Articles

Conventionally, it has been thought that the better a window is at blocking UV rays the better the window will be at preventing fading of furniture and upholstery. While blocking UV is important in the prevention of fading, it has been found that light in the visible spectrum will also cause fading. Therefore, two other scales have been developed to measure fading potential: The Krochmann scale and the ISO-CIE scale.

The chart below is based on two pieces of 1/8” glass in an insulated glass make-up. The lower the percentages the better the glass is at preventing fading.
Glass Make-UpUV TransmissionKrochmann ScaleISO-CIE Scale
Clear/Low E129%42%63%
Low E2/Clear16%33%55%
Low E3/Clear5%21%43%
Low ELR/Clear2%13%27%
For a more thorough treatment of this subject see this Cardinal Technical Service Bulletin.