Glazing is a transparent part of a wall structure and is usually made of glass or plastic, also known as the glass part of a window. The glazing is mounted with glazing putty and a support frame that holds the glass in place.
Common types of glazing include:
- low-emissivity and heat mirror glass
Previously, all windows were single glazed with one pane of glass. Single-pane glazing provides little protection against heat or cold. Because of the advancements made in glazing, single-pane windows are typically only used for their decorative look. Modern energy-efficient windows now come with glazing systems, which incorporate glass panes, gas fillings, and heat-sensitive coatings. These glazes include double-pane glazing, which are also referred to as insulated glass. Double-pane glazing contains a layer of inert gas, typically argon or krypton, sealed between the inner and outer glazing. Because the gas is a poor thermal conductor, it slows the flow of heat through the glazing and eliminates the need for storm windows. Triple-glazed windows are even more efficient than double-paned, as they include an extra layer of gas within the frame. In addition to providing improved thermal protection, triple-glazing can also provide sound-reduction qualities. Low-emissivity (low-E) and heat mirror glass is another option when choosing glazing. This type of window glazing includes a low-E coating and an invisible layer of metallic oxide, which reduces the amount of heat passing through the glass. Depending on location, low-E glazing may be adjusted to allow the sun’s energy in, or to block it out. Low-E glazing has been estimated to reduce energy costs by about 25% compared to single-pane glazing. Most new windows today offer low-E glazing. Additionally, heat mirror glazing systems typically meet or exceed the energy efficiency provided by triple-paned windows without the additional weight. Heat mirror glazing is made by suspending a sheet of low-E film between the insulated glass panes. Superglass, a material known as being one of the best insulators on the market, suspends two layers of heat mirror between the glass panes with gas-filled spacers.
When considering window and glazing options, it is important to consider:
- building type
- utility rates
- heat gains and losses
- visual requirements
- shading and sun control
- thermal comfort
- ultraviolet exposure control
- condensation control
- acoustic control
- color effects
- energy requirements
Other considerations may also be necessary when choosing the correct glazing.