There are three important wavelengths to consider when selecting windows and glass: UV, visible light, and infrared. UV wavelengths can cause sunburns and fading in fabrics, and should be blocked; visible light is light that we see and should not be blocked; infrared wavelengths transfer heat (these are the wavelengths that make your car too hot when it’s parked all day) and these also should be blocked.

The image above shows the light that the human eye can see (visible light) and its relationship to UV and infrared. A common goal in selecting a glass package should be to find one that allows, or transmits, the most visible light, while blocking UV and infrared.

Source: McCluney, 1996

The image above shows how different glasses transmit different wavelengths – The spectrally selective glass does the best job at blocking UV and infrared, and still has a high Visible transmission (>70%).

It is important to note that stopping (or blocking) the transmission of infrared doesn’t just keep heat out during the summer, it keeps heat in during the winter.

Alpen HPP offers a variety of glazing options to minimize or maximize infrared transmission to suit your climate and building type.