Insulated glass

Insulating glass (IG) consists of two or more glass window panes separated by a vacuum or gas-filled space to reduce heat transfer across a part of the building envelope.A window with insulating glass is commonly known as double glazing or a double-paned window, triple glazing or a triple-paned window, or quadruple glazing or a quadruple-paned window, depending upon how many panes of glass are used in its construction.

Insulating glass units (IGUs) are typically manufactured with glass in thicknesses from 3 to 10 mm (1/8" to 3/8"). Thicker glass is used in special applications. Laminated or tempered glass may also be used as part of the construction. Most units are produced with the same thickness of glass on both panes but special applications such as acoustic attenuation or security may require different thicknesses of glass to be incorporated in a unit.