Insulating glass refers to glass that is made to prevent significant heat transfer into or out of a home or building. It consists of multiple pieces of glass separated by spacers made of either metal, such as aluminum, or structural foam. The space between the glass is sometimes filled with a noble gas, such as argon or krypton. Insulating glass is often abbreviated IG and is sometimes called double-glazed or double-pane glass. As technology evolves, triple-paned or quadruple-paned glass is now available as well.
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[citation needed] but special applications such as acoustic attenuation or security may require wide ranges of thicknesses to be incorporated in the same unit.
Insulating glass is comprised of several components: multiple pieces of glass, materials that create and maintain space between the glass and any gas added to the space between the glass. All of these pieces are assembled into a single, sealed unit that holds the entire system together and helps prevent changes, especially to the air (or gas) between the glass. These complete units are called insulating glass units, or IGUs.
Your IG unit will typically be made with low-E glass, which has a coating that reduces the ultraviolet and infrared light that passes through a window. It helps regulate temperature (and energy consumption) within a home by redirecting heat back in the direction from which it is coming. Low-E coatings are made of microscopically thin coatings of materials that reflect heat much better than it absorbs or emits it.