Double Glazing

Double Glazing

Insulating glass (IG), more commonly known as double glazing (or double-pane, and increasingly triple glazing pane), consists of two or three glass window panes separated by a vacuum space to reduce heat transfer across a part of the building envelope.

Insulating glass units (IGUs) are manufactured with glass in range of thickness from 4 to 10 mm or more 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 used on both panes but special applications such as acoustic attenuation or security may require wide ranges of thicknesses to be incorporated in the same unit.

Spacer

The glass panes are separated by a “spacer”. A spacer, also known as a warm edge, is the piece that separates the two panes of glass in an insulating glass system, and seals the gas space between them. Historically, spacers were made primarily of metal and fiber, which manufacturers thought provided more durability.

However, metal spacers conduct heat (unless the metal is thermally improved), undermining the ability of the insulated glass unit (IGU) to reduce heat flow. It may also result in water or ice forming at the bottom of the sealed unit because of the sharp temperature difference between the window and surrounding air. To reduce heat transfer through the spacer and increase overall thermal performance, manufacturers may make the spacer out of a less-conductive material such as structural foam. A spacer made of aluminum that also contains a highly structural thermal barrier reduces condensation on the glass surface and improves insulation, as measured by the overall U-value.