Questions About Buying New
Windows, Doors or Skylights?

The National Fenestration Rating Council (NFRC) is a nonprofit organization that empowers consumers who are in the market for energy efficient windows, doors, and skylights. When you see the NFRC label on these products, this is your assurance that it’s going to perform the way it’s advertised to perform.

NFRC Label

Under our program, windows, doors, and skylights – otherwise known as fenestration products – are independently tested, certified, and labeled. Our label does not recommend which products to buy. It simply provides you with information on how the product will perform so you can decide for yourself if it’s right for you. 

Compare Product Performance

The NFRC label provides information on how a window performs. The two most importantNFRC Label energy ratings are U-factor and Solar Heat Gain.

By reviewing the label information, consumers can make an informed choice about the product that is best for their individual situation.

See Windows 101 for more details on U-factor and Solar Heat Gain.

Look For The ENERGY STAR® Label

The U.S. Department of Energy and the U.S. Environmental Protection Agency have developed an ENERGY STAR® designation for products meeting certain energy performance criteria. Since the energy efficiency performance of windows, doors and skylights can vary by climate, product recommendations are given for four climate zones: a mostly heating zone (Northern); two heating and cooling zones (North/Central and South/Central); and a mostly cooling zone (Southern).

For more information about ENERGY STAR windows, see

What is Fenestration?

Fenestration refers to any opening in a
building's walls, such as a window, door, or skylight.

It is based on the Latin word for
windows – "fenestra"


Did You Know? .
  • FENESTRATION refers to any product that fills an opening in a building and includes windows, doors, skylights, and curtain walls?

    These products are designed to permit the passage of air, light, vehicles, or people.
  • that many local building codes require egress windows in some rooms to be considered a bedroom?

    Find out if your bedroom windows qualify in Windows 101.
  • it's a good idea to have fire drills at home to make sure all of the home's occupants – including children – know how to operate escape windows in the event of an emergency?
  • a study of schools found that more daylight in the classroom resulted in improved performance on math and reading tests. (Heschong Mahone Group Study, August 20, 1999.)

    For information on how Daylighting can affect home life, see Windows 101.
  • some areas require impact resistant windows or window coverings in building codes?

    Does this "impact" you? See Benefits of Improving Windows for additional information.
  • special windows that can prevent break-ins and even stop bullets are available from window manufacturers?
  • all ENERGY STAR® qualified windows are required to display the ENERGY STAR label?

    If there is no label, it does not qualify for ENERGY STAR.
  • some utility companies offer rebates for home improvements such as new windows?

    Check with your local utility to find out about rebates and to ensure you purchase qualifying products.
  • in order to qualify for ENERGY STAR®, fenestration products must be rated according to procedures established by the National Fenestration Rating Council (NFRC).
  • products carrying the NFRC Label have been independently tested and certified by the manufacturer?

    This is a voluntary program that allows you –the consumer – to accurately compare unbiased product ratings
  • the National Fenestration Rating Council (NFRC) was founded in 1989.

    The first rating procedure – for U-factor – was adopted in 1991; test procedures for Solar Heat Gain Coefficient (SHGC) and Visible Transmittance (VT) were adopted in 1993.

    Energy Ratings will explain the numbers on the NFRC Label and what they mean to you!
  • there are many different styles of windows?

    See Windows 101 for a list of some of the more popular options so you know exactly what you want when you shop!
  • that poor quality windows can cause color fading of your carpets, furniture, and artwork?

    See Windows 101 for information on what causes fading and what you can do to reduce it.
  • that you have more options about windows than just style?

    Anatomy of a Window will provide you with the information you need to make informed choices.
  • your local building codes may require new windows be to specific standards.

    Our Shopping Guide discusses what you need to know about codes.