Low-E (Low Emissivity) coating is a microscopically thin, nearly invisible film of metal or metallic oxide layers deposited on the glass pane surface.

The Low-E coating reflect the infrared radiation, therefore, does not allow for radiant heat passing throungh windows, while letting visible light pass.

This results in more energy efficient glazing because radiant heat orginating from indoors in winter is reflected back inside, whike infrared heat radiation from the sun during summer is reflected away, keeping the cool inside.