INSULATED GLASS consists of two or more glass windows separated by a vacuum or gas filled space to reduce heat transfer through a portion of the enclosure. A window with INSULATED GLASS is often referred to as a double-glazed or double-paned window, a triple-glazed or triple-paned window, or a quadruple-glazed or quadruple-paned window, depending on how many panes of glass are used its structure.

Insulated glass modules are usually manufactured from glass with a thickness of 3 to 10 mm. Thicker glass is used for special applications. Laminated or tempered glass can also be used as part of the structure. INSULATED GLASS manufacturers tell you that most units produce the same thickness of glass in both panes, but special applications such as acoustic attenuation or security may require different thicknesses of glass to be incorporated in one unit.
Insulating glass was developed from older technologies called double-hung windows and storm windows. Traditional double-hung windows use a single pane of glass to separate interior and exterior spaces.
INSULATED GLASS manufacturers tell you that during the summer, a window screen will be installed on the exterior to slide over double-hung windows, keeping out animals and insects.
In winter, the glazing is removed and replaced by storm windows, which create a two-layer separation between the interior and exterior spaces, increasing the window's thermal insulation during cold winter months. To allow ventilation, the storm window can be suspended on removable hinge rings and opened using folding metal arms. INSULATED GLASS manufacturers tell you that although insects are generally inactive in winter, screening through open storm windows is usually not possible.