What Is Insulating Glass?

What Is Insulated Glazing?

Insulating glass (IG) consists of two or more glass window panes separated by a vacuum[1] 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.

Advantages of Double-Paned Windows

Though glass itself isn’t much of a thermal insulator, it can seal and maintain a buffer from the outside. Double-paned windows offer a significant advantage when it comes to the energy efficiency of a home, providing a better barrier against outside temperatures than single-paned windows.

The gap between glass in a double-paned window is commonly filled with an inert (safe and non-reactive) gas, such as argon, krypton, or xenon, all of which increase the window’s resistance to energy transfer. Though gas-filled windows have a higher price tag than air-filled windows, the gas is denser than air, which makes your home significantly more comfortable. There are differences between the three types of gas that window manufacturers prefer:

• Argon is a common and most affordable type of gas.
• Krypton is typically used in triple-paned windows because it performs best within extremely thin gaps.
• Xenon is a cutting-edge insulating gas that costs the most and is not as commonly used for residential applications.

Tips for Improving Window Efficiency

No matter how well-designed they might be, double- and triple-paned windows can always be helped along to eliminate energy loss. Here are tips to help improve the efficiency of your windows:

• Use thermal curtains: Thick thermal curtains drawn across the windows at night significantly raise the window’s overall R-value.
• Add window insulating film: You can apply your own thin clear layer of plastic film to the window trim with adhesive. Application of heat from a hairdryer will tighten the film.
• Weatherproofing: Older windows may have hairline cracks or they are beginning to open up around the framing. Those problems let cold air enter the home. Using an exterior-grade silicone caulk can close up these leaks.
• Replace foggy windows: Windows that are foggy between the two panes of glass have lost their seals and the gas has leaked out. It is usually best to replace the entire window to regain the energy efficiency in your room.