Look for the Energy Star® Label
Rite Window is an Energy Star® Partner. Energy Star is a U.S. government program managed by the U.S. Department of Energy. Over the past 15 years Energy Star® guidelines have doubled the energy efficiency of the windows they endorse. To qualify for Energy Star® certification window brands must meet strict energy-efficiency standards.Beginning January 1st, 2016 replacement window manufacturers will be required to meet an even greater level of energy efficiency in order to be Energy Star® certified. The previous U-Factor rating requirement of 0.30 will be lowered to 0.27. Rite Window products currently meet or exceed the new 0.27 U-Factor requirement. Be sure to confirm that any window you’re considering meets the new Energy Star® standards.
The U-Factor rating shows how well a window product prevents heat from escaping.
The lower the U-Factor number the better its resistance to heat flow and the better its insulating properties. U-Factor ratings generally fall anywhere between 0.20 and 1.20. (oddly, the lower the U-Factor number the better)
As shown by the chart, the type of materials used in window construction can effect the U-Factor rating, and a significant improvement in U-Factor values is seen with windows using Low-E coated glass.
Beginning January of 2016, all Energy Star® qualified windows must have a U-Factor rating equal to or less than 0.27. This is the same rating needed for the window to qualify for a tax credit.