Low emissivity (Low-E) glass is glass that has a low-emissivity coating applied to it in order to control heat transfer through windows. The use of Low-E glass in double glazing can reduce energy loss through windows by as much as 30-50%. A Low-E coating is a microscopically thin, virtually invisible, metal or metallic oxide layer deposited directly onto the surface of glass.

This coating reflects longer wavelength heat from radiators and room surfaces back into the building and allows in warming short wavelength solar energy. These incoming short wavelengths of solar energy are re-radiated by internal building surfaces as longer wavelengths which are then reflected, by the coating, back into the room.

Double glazing using Low-E glass has good energy conservation properties and many other advantages as listed below: