Replacement Windows: Energy Efficiency

If You Make the Wrong Choice
When Replacing Windows,
You’ll Hate Tearing Open
Your Energy Bill Every Month…

It’ll Just Remind You Of Lost Savings


If most window companies claim to install energy efficient windows, how do you know how to get the best value? One of the best ways is to educate yourself on the terms and ratings used when talking about energy efficient windows. To start, understand the 3 basic ways energy escapes from windows: infiltration, conduction, and radiation.

If you feel drafts when you stand near your windows, you are having INFILTRATION issues. Cold air seeps in during the winter as warm air and money escape out.  CONDUCTION is Mother Nature heating or cooling the glass outside while your furnace or AC battle the heat or cold from the inside. With poor windows, your furnace and AC are at a big disadvantage.  RADIATION is the term for heat or cold radiating (escaping) directly through the window pane.


New advances and designs have allowed for dramatic improvement in the energy efficiency of windows. If you have older windows, you should upgrade and stop leaking money. (And, unfortunately, new construction is no guarantee you have good windows. Builders often use low quality windows to save on overall costs).

There are now a number of values and factors that you can use as a guide when determining how efficient a window really is.

Terms To Understand:
R-Value – The R-Value measures the resistance that your window has to heat flow. If a particular window has a high R-Value, it will lose less heat than a window with a lower R-Value. NOTE: BECAUSE SOLACE WINDOWS USE A SPECIAL ULTRA-CORE WINDOW SYSTEM, THE R-VALUES ARE OFTEN DOUBLE OR MORE WHEN COMPARED TO OTHER FRAMING MATERIALS.

Low-E Glass – Low-E (low emissivity) glass reflects the heat on the outside and the inside of your home. It decreases the UV light entering your home. Quality windows will have Low-E glass.

U-Factor – U-Factor is a measure of the rate of heat loss of the entire window. Lower is better when it comes to U-Factor. In a cold Midwest winter, you’ll be happy to have a lower U-Factor that reduces the percentage of heat that leaves your house.

Solar Heat Gain Coefficient – The Solar Heat Gain Coefficient refers to the rate of heat gain through a window. Lower “Solar Heat Gain” means less heat will enter your home from the outside. This is important during summer months when you use your air-conditioner.

Energy Star Label – The Energy Star label is a certification developed by the U.S. Department of Energy and the EPA that verifies a product meets energy performance criteria. Since the energy efficiency windows will vary in different parts of the country, four different climate zones are designated for measuring performance.

The National Fenestration Rating Council (NFRC) – The NFRC is a non-profit organization and it provides a Window Energy Ratings System that measures U-Factor, Solar Heat Gain, Visible Light Transmittance and Air Leakage.

HIGHLY RECOMMENDED: Always select replacement windows that have both the Energy Star and the NFRC labels.


Remember, it is not enough to select quality, energy-efficient windows. You also need to get a professional, craftsman-level installation for maximum effectiveness. It is beyond disappointing to go to the time and expense of hiring a contractor only to end up still feeling drafts around your windows. Don’t hire the guy working out of the back of his truck who has done “some” windows. Hire an established local company with a PROVEN reputation.

Have more questions about energy efficiency and windows? Contact us to schedule a free consultation