What is ENERGY STAR®?

ENERGY STAR® is a voluntary partnership between the U.S. Department of Energy, the U.S. Environmental Protection Agency and the fenestration industry.
It is designed to assist consumers in the recognition of energy efficient products and promote the environmental and economic benefits of these products with the ENERGY STAR® label and other program activities.
How do products qualify for ENERGY STAR®?
Consumer products (such as major appliances) receive the ENERGY STAR® label when they exceed the minimum federal energy consumption standards. These figures vary from product to product.

How do windows qualify for ENERGY STAR®?
Window products qualify by meeting certain criteria set forth by the National Fenestration Rating Council (NFRC).
All windows must be NFRC rated, certified and labeled for both U-factor and Solar Heat Gain Coefficient as well as Visible Light Transmittance.

What is a U-factor?
A U-factor measures the rate of non-solar heat transfer from one side of the window to the other. Heat transfers to both heat loss out of a living space during cold winter weather and non-solar heat gain into a living space during hot summer weather. This energy transfer, measured in BTUs, is know as conduction.
The lower the U-factor of a window, the higher it's R-value.

And what is Solar Heat Gain Coefficient?
The Solar Heat Gain Coefficient measures the amount of solar heat that gets through a window. The lower the SHGC, the better a window is at reducing heat gain, and in the end, the cooling costs that go along with it.

What is the NFRC?
The National Fenestration Rating Council is a non-profit, public/private organization created by the window, door and skylight industry. Their primary goal is to provide accurate information to measure and compare the energy performance of window, door or skylight products.

What are those qualifications?
The program has established three climate regions with one recommended product designation for each.

Northern Region Criteria

• Windows must have a U-factor rating of 0.35 or below.

Central Region Criteria

• Windows must have a U-factor rating of 0.40 or below. . .
• With a Solar Heat Gain Coefficient (SHGC) of 0.55 or below.

Southern Region Criteria

• Windows must have a U-factor rating of 0.75 or below. . .
• And an SHGC of 0.40 or below.

What's so special about 21st Century’s Window Systems?

Since 70% of a window is glass, real energy savings come from improved glass performance.

Low-E Glass and Argon Gas significantly improves energy efficiency and cuts the damaging effects of the sun by an additional 78% over clear insulated glass units.

In winter, it lets in maximum free solar heat and helps hold warm air inside, increasing R-value by an extra 104%

 In summer, an additional 48% solar heat gain coefficient helps cut air conditioning costs.