The ENERGY STAR^® label was created as a joint effort by the U.S. Department of Energy and the U.S. Environmental Protection Agency. The ENERGY STAR^® Window Program is designed to help consumers identify energy efficient windows and doors. ENERGY STAR^® qualified windows and doors save you energy and money, increase the comfort of your home, and protect your valuable possessions from sun damage. They are also better for the environment because lowering your energy use means less air pollution from power plants.

What makes ENERGY STAR^® qualified windows and doors so efficient?
Some of the technologies that window manufacturers can use to fabricate ENERGY STAR^® qualified windows include:
• Improved framing materials such as vinyl
• Two or more panes of glass with a Low-E coating that blocks UV rays and reduces solar heat
• Warm edge spacers, such as foam, that keep the panes separated without acting as a conductor to help fight heat loss and reduce condensation
• Argon or krypton gas fills between the panes provide better insulation. These gases are odorless, colorless, and non-toxic

Who decides if a window is energy efficient?
The energy performance of all ENERGY STAR^® qualified windows, doors, and skylights must be independently tested and certified according to test procedures established by the National Fenestration Rating Council (NFRC).

NFRC is a third party, non-profit organization that sponsors certified rating and labeling programs to help consumers compare the energy and performance features of windows, doors, and skylights.

NFRC’s programs do not distinguish between "good" and "bad" windows, set minimum performance standards, or mandate performance levels. This is where ENERGY STAR^® comes in. ENERGY STAR^® enables consumers to easily identify NFRC-certified products with superior energy performance.

Performance Ratings
The NFRC label, which can be found on all ENERGY STAR^® qualified windows, provides performance ratings in a number of categories:

U-Factor measures the rate of heat transfer and tells you how well the window insulates. The lower the U-Factor, the better the window insulates.

Solar Heat Gain Coefficient (SHGC) measures the fraction of solar energy admitted and tells you how well the product blocks heat caused by sunlight. The lower the SHGC, the less solar heat the window transmits.