Windows can be the most attractive features of a house, but they also can be the least energy efficient. Glass is not a great insulator, which means that windows are a major source of heat escaping or entering a home. How your windows are glazed can make a big difference in this dynamic.
Windows are rated according to how much heat can escape through the glass, measured by R-value, and by how much heat can escape through an entire window per hour, the U-value. Windows with a high R-value allow less heat to escape; a low U-value means a window conserves more energy.
These days, many windows are double-glazed—they have two panes of glass separated by a thin space—and some are even triple-glazed, along the same principle. The space between glass panes may be filled with air or an inert gas such as Argon. This, as well as thin "low-E" (low-emissivity) coatings, help reduce heat transfer.
Homeowners in hot, sunny climates frequently choose windows with UV (ultraviolet) coatings that keep the sun’s rays from fading curtains, furniture, and carpets. Some UV coatings come tinted, which also helps to keep the house cool.
Easy-Wash Windows
Special polymer coatings on windows can repel dirt, reducing the need for window washing.
