A couple of types of gas are commonly found inside windows. In order to maximize heat resistance and improve insulation, modern windows are made with two or even three layers of glass. Sometimes, gases are pumped between those layers in order to further insulate the window for better energy-efficiency.
The Science
Windows are a weak point in a home’s insulation system since they are open to the outside world, and architects have been trying to improve window insulation for a very long time. A window composed of multiple layers of glass separated by spaces filled with air was significantly more efficient than single-pane glass. That is because air conducts heat much worse than glass does. However, the gases that make up the air we breathe such as nitrogen, oxygen and carbon dioxide still conduct heat much better than some other gases like argon and krypton.
Inert Gases
Argon and krypton gases are very non-reactive and consist of single atoms. That makes them very bad at transferring heat and very safe if exposed to people. That is why those two gases make perfect insulation between window panes. Krypton is a better insulator than argon, and it works well in three-pane windows that don’t have a lot of space between each of the panes. Argon, on the other hand, insulates better in double-pane windows with plenty of space between the two layers of glass. Because of those two factors, argon-insulated windows are not as efficient as krypton-insulated ones but are a little more budget friendly. Both, however, are a huge improvement over simply using air as an insulator.
Measuring Insulation
The effectiveness of insulation in a window is measured by two related measurements – the R-value and the U-factor. The R-factor measures a window’s resistance to heat, while the U-factor measures how well it conducts that heat. A well-insulated window has a high R-value and a low U-factor, while a poorly-insulated window sports the reverse. Here, Energy Guide shows some sample U-factors for various windows. As you can see, a quadruple-glass krypton-insulated window can have a U-factor of as low as 0.22, while a regular single-pane glass window has a U-factor of as high as 1.30. As you can see, the values vary not only based on the gas and glass used in the window, but also on the materials in the frame and window size. It is also important to think about the design and layout of your home as well. While the triple-glass argon-insulated window is almost as well insulated as the quadruple-glass krypton-insulated one, it is almost twice as thick. That means it will be harder to fit into your project without proper planning.
Other Considerations
It is important to choose the best window for each situation. The right window for your project depends on many factors such as the insulation used in the house, the area and climate and even what sort of frame surrounds the window. However, the type of gas found inside the window can make a huge difference in the efficiency of your home.
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