Insulating glass (IG), more commonly known as double glazing(or double-pane, and increasingly triple and quadruple glazing/pane), 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.

Insulating glass units (IGUs) are manufactured with glass in range of thickness from 3 to 10 mm (1/8″ to 3/8″) 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.

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.

In addition to the improved solar performance, insulating glass offers a greater availability of coatings. Low-E coatings which cannot be exposed, and therefore cannot be used with monolithic glass, can be used inside the insulating unit where they are protected by the hermetically sealed space.

Modern window units with IG typically completely replace the older double-hung unit, and include other improvements such as better sealing between the upper and lower windows, and spring-operated weight balancing that removes the need for large hanging weights inside the wall next to the windows, allowing for more insulation around the window and reducing air leakage, provides robust protection against the sun and will keep the house cool in the hot summer and warm in winter. These spring-operated balancing mechanisms also typically permit the top of the windows to swing inward, permitting cleaning of the exterior of the IG window from inside the building.

Parameters For IGU: (Annealed Glass and Solar Control Glass)

Parameters For IGU: (Energy Saving Glass – Low-E, Single Silver)

Parameters For IGU: (Energy Saving Glass – Low-E, Double Silver)