The U-factor of a window basically tells you how quickly or slowly a window loses heat. Learn more here.
The U-factor of a window basically tells you how quickly or slowly a window loses heat. The lower the U-factor, the more resistant to heat flow the window is. This means a window with a low U-factor will keep the heat in during winter, and the heat out during summer, which ultimately improves the energy efficiency of your home. There are also two other number ratings companies give windows so you can compare which windows have a higher energy efficient ratio. These factors are R-value and the air infiltration value, which we will discuss in another FAQ. Read more about U-factor here.