Low-E stands for low emissivity and it’s one of the most significant improvements in glass technology in years. It’s a microscopic, metallic coating applied to a surface of glass, much like the reflective coating on a mirror. However, since the coating is only a few atoms thick, most visible light will pass through it. Much like a regular mirror will bounce back your reflection, a Low-E coating reflects and re-radiates heat energy.

When it’s hot outside, it reflects heat energy back to the outside. When it’s cold outside, it reflects heat energy back into your home. Low-E coatings reflect 40 – 70% of the heat that is normally transmitted through clear glass. As a result, Low-E saves on the energy required to heat your home in the winter and cuts your air-conditioning costs in the summer. Glass with multiple layers of Low-E coatings generally perform better. However, they may have a very slight effect on the amount of visible light that passes through.

Low-E coatings can also help reduce furniture and carpet fading by reducing the amount of ultraviolet (UV) radiation that enters your home. Ultraviolet radiation can alter the chemical structure of dyes and other colorants.

There are different types of Low-E coating which have differing performance levels, so don’t let anyone try to convince you that all Low-E glass is the same. With the energy saving’s benefits to be realized, you should not invest in a new window that does not have a Low-E coating.