Microscopically thin, virtually invisible, metal or metallic oxide layers deposited on a piece of glass and sealed in an insulating glass unit to reduce the U-Factor. The radiant energy (heat), i.e. long wave infrared, is in effect reradiated back toward its source.

Microscopically thin, virtually invisible, metal or metallic oxide layers deposited on a window or skylight glazing surface, primarily to reduce the U-factor by suppressing radiative heat flow through the window or skylight.

Microscopically thin, virtually invisible, metal or metallic oxide layers deposited on a window or skylight glazing surface primarily to reduce the U-factor by suppressing radiative heat flow. A typical type of low-E coating is transparent to the solar spectrum (visible light and short-wave infrared radiation) and reflective of long-wave infrared radiation.