What’s the Difference Between Double-Pane and Triple-Pane Glass Windows?

When it comes time to buy new windows for your home, you will need to decide on how many panes of glass you want. Most homeowners opt for at least double-pane glass, which is constructed from two glass layers with gas trapped between them. It helps insulate your home better, and even reduces noise from outside your home. Advancements in window construction have allowed more panes of glass to be inserted in a window, with triple-pane glass being an upgrade you may be considering. Before you get your windows installed with three panes of glass, consider how it compares to a double-pane glass window.


The R-value measures a window in terms of heat flow. Windows with low R-values will not effectively prevent heat from transferring through the glass, while windows with high R-values will be very effective. If your primary concern is picking windows that will do a great job at keeping the heat inside your home during the winter, you will want windows with the highest R-value possible.

A typical double-pane window with a quarter inch spacer will have an R-value of 1.72 in the winter, while a similarly constructed triple-pane window will have an R-value of 2.56. For comparison, single-pane windows have a .9 R-value. The triple-pane window is going to be much more superior at keeping the warm air inside where it belongs.

Solar Heat Gain Coefficient

You must also look at the SHGC rating of new windows when making comparisons. This factor will help determine how effective the window is at blocking the solar heat from the sun. The rating scale is the opposite of R-value, where lower is actually better.

A triple-pane window has a SHGC of .19, while a double-pane window is .70. This means that three panes of glass will block 80% of solar heat gain, while two panes of glass only block about 30%.

When looking at the SHGC ratings, you must consider the climate in your area as well. Southern climates may be better off with windows that have a low SHGC, as you want to block as much heat from the sun during the hot summer. If you are in a cooler northern climate, a higher SHGC might be ideal to let heat in all year round.

Now that you know how a double-pane and triple-pane window are different by looking at their ratings, you can decide on which one is best for your home. Contact a local window supplier in your area, with any questions.