Windows bring light and the view from outside into the house, but they also transfer heat and cold. The construction of a window greatly affects how much heat is lost or gained. If you are replacing windows, knowing a few basics about window insulation can save you money and make your home more comfortable.
Problems with Poorly Insulated Windows
Windows with higher insulation values save money on heating bills in winter and cooling bills in summer. In addition, when windows are constructed with more than one pane of glass, they are less prone to having problems with condensation.
Condensation happens when the warm air inside the building hits the colder surface of the glass in a single pane window. When the window is a double or triple pane, the inner pane stays warmer, reducing or eliminating the condensation of moisture on the glass.
Drafts are also eliminated with well-insulated windows.
If you have ever sat by a window and felt a cold draft, you may have thought it was due to a lack of weather stripping around the window. This may be true, but a drafty feeling coming from a window can also be due to single pane construction. Single pane windows allow your body heat to escape through the glass, causing what feels like air movement and a draft.
The Construction of Well-Insulated Windows
Double and triple paned windows add insulation value because there is an air space trapped between the panes. This air space acts as a buffer to heat transfer, keeping hot and cold temperatures from affecting the comfort level inside.
Some windows provide even more insulation value by replacing the air with an inert gas, usually argon or krypton gas. Krypton gas does a better job of insulating windows with a smaller space between the panes, and argon gas works more effectively when the space is larger.
The material used for the construction of the window frame also has a large effect on how well-insulated the window is. Aluminum frames easily transfer heat, unless they are made with a urethane thermal break-strip. Wood, vinyl, and wood-clad vinyl are more resistant to heat transfer, providing better insulation value.