R-5 Standard

For homeowners who want superior energy-efficiency in their windows, ABC GLASS AND MIRROR offers a selection of R-5 products. These windows surpass even standard Energy Star windows in their ability to insulate.


The R-value of a window is an indication of how well it insulates – the higher the R-value, the more heat the window keeps in your home. To put R-5 in context, a typical Energy Star window is R-3. Research indicates that upgrading from R-3 to R-5 can mean cutting back on heat loss by more than 30%.


Another indication of a window’s energy-efficiency is U-factor. This is a measurement of how much heat can escape through the window, so the lower the U-factor the more energy-efficient the window. A regular Energy Star window has a U-factor of 0.3, while the U-factor of an R-5 window is around 0.2.

Triple-Pane Glass

One characteristic that sets R-5 windows apart and makes them better insulators is the use of triple-pane glass. Each pane on an R-5 window is really an insulated unit consisting of three pieces of glass with space between them and a seal around them. This three-part glazing gives R-5 windows an edge over standard double-pane units.

Argon and Low-E

Top-quality R-5 windows may also include argon gas and/or Low-E coatings. When argon gas fills the spaces between the three panes, the window’s ability to insulate gets an additional boost. Low-E coatings applied to the appropriate glass surface also cut back on energy loss.

8395 Euclid Avenue, Suite B
Manassas Park, VA 20111-5215
Telephone: (703) 257-7150
Fax: (703) 257-7131

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