A window with two or more pieces of glass is a great way to save energy and enhance indoor comfort. But are three panes better than two? The verdict is in: Triple pane windows are far more energy efficient but because the cost is considerably higher, it’s important to look at the details to determine if the investment is worth your while.
Features of Double Pane Windows
Dual glass panes come with mounting flange, insulated frame, and superior air seals. By virtue of containing two glass panes, these windows reduce heat loss by up to 50 percent during winter, and keep the energy bill much lower by incorporating a Fiberglass frame, increasing the overall energy efficiency of your Fiberglass windows.
But when it comes to evaluating window performance, it is the space between the glass panes that makes the real difference. Double glass panes have space in the middle that does not necessarily have to contain air.
Instead, manufacturers are opting to cover one of the glass surfaces in the middle – so it is protected – with Low-E coating, which is a metallic cover that can reflect unwanted sun radiation, allowing the indoors to stay cooler in the hot summer while protecting furniture and carpets from direct sunlight.
Alternatively, some manufacturers put a special gas in the space between the glass panes to slow down the transmission of heat. The gas used can be argon or krypton, and allows the window to reach much higher insulation values than single glass panes.
Double Pane Versus Triple Pane
Triple pane windows contain one more glass pane and an extra gap that can be filled with argon gas or the Low-E coating for even more insulation. This may make the window heavier, but sliding it up and down should still be fairly effortless. If your new triple pane windows are hard to open, it could be because they don’t fit in the opening properly, or there is something else impeding their motion.
Compared to double pane windows, triple pane offer significantly higher energy efficiency (higher R-value) and greater energy savings (a lower U-value). Below is a comparison of three types of windows:
The R-value for a single pane window is about 1; and a U-factor of 1
The R-value for a double pane window is about 3.3; and a U-factor of 0.3
The R-value for a triple pane window is about 8.3; and a U-factor of 0.12
Although triple pane windows offer significantly more energy savings than double pane windows, triple panes cost more upfront so the ROI is not very encouraging, which makes double pane windows the more common option. But if your home is properly insulated, with an efficient heating and cooling system, and you have more heating degree days than cooling degree days, you should consider triple pane windows.