Glazing

Natural light, views, a visual connection with the outdoors: glass makes possible many of the best features of houses. But as the amount of glass used in a house increases, energy efficiency usually decreases simply because glass windows and doors are not as effective as walls at insulating. For that reason, a great deal of research has taken place in recent years to improve the efficiency of glazings.

Now when you buy or replace a window or glazed door, you can choose from a variety of glazings. Generally speaking, the more energy-efficient the glazing, the more expensive it is.

Heat loss through glass is typically measured by an R-value . The higher the R-value, the more efficient the glass.

U-value measures the amount of heat that can escape per hour through a given window. Two U-values are typical--one for the glass and one for the entire window, including the frame. The lower the U-value, the more energy-efficient the window.

Though single glazing (a single sheet of glass) was once the standard, dual glazing or insulating glass is now more common for quality windows. This type of glass consists of two panes of glass separated by a thin air space. Though a single-glazed window offers an insulating value of about R-1, a dual-glazed model provides twice the value at R-2. You can also buy even more effective triple glazing with dual air spaces.

MORE ABOUT:
/ Insulation / / Types of insulation / / R-values / / Exterior doors / / Window types1 / / Window types2 / / Window parts / / Glazing / / Skylights / / Skylight shafts /

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