Replacement Windows: Two-Pane vs. Three-Pane

Gas

• To make a window more efficient and better-insulated, an inert gas is trapped in the space between its panes. Different gases are used in two-pane and three-pane windows. In windows with two panes, argon gas is inserted between the layers. Argon is used in three-pane windows as well, but it is mixed with krytpon, another inert gas. This helps increase the insulating properties of the air layers.

Low-E Coatings

• More efficient windows are covered with a very thin layer of metal that helps reflect heat away from the window. Each pane of glass in a window can be coated with a low-E coating to make the window more efficient. Therefore, a triple-pane window with low-E coating can provide a house with slightly more heat resistance than a window with only two layers of the coating.

Cost

• Triple-pane windows cost more than double-pane windows. For some, the initial higher cost of installation may make double-pane windows seem like the most affordable option. However, you should consider the future savings that triple-pane windows might net you. The initial cost is offset by the fact that your energy consumption will be reduced in future years thanks to the insulating properties of triple-pane windows.

Weight

• Another consideration is that triple-pane windows typically weigh more than their double-pane equivalents. If you are installing a particularly large window, this can become a concern. The heavier weight may mean that you need to build a more thoroughly reinforced frame to make sure that the window is stable. Moving and installing triple pane windows can also be more difficult because of the added weight.