Saving Energy with Low-E Glass

Low-E Glass Windows Will Keep Your Home Cooler During the Summer and Warmer During the Winter

By Mark J. Donovan

All glass panes in windows are not the same. Just because a new window is double pane doesn’t mean you’re necessarily buying the most energy efficient window. Yes, a double pane window is a step up in saving energy and keeping your home more comfortable during the cold winter months due to increased insulation performance. By itself, however, a double pane window doesn’t help to keep your home cooler during the summer. By selecting windows with energy savings low-E glass, that are also double pane, you can ensure year round energy efficient windows.

Low-E glass, or low emittance glass, is a special type of glass that has spectrally selective coatings applied to it.

The thin film coating is specifically designed to allow only certain wavelengths of the solar spectrum to pass through the glass and enter the home, while restricting others. More specifically Low-E glass prevents solar ultraviolet wavelength energy from entering the home. The ultraviolet light is what actually warms the surface of objects that it comes in contact with. Ultraviolet light also causes furniture fabric, carpeting, and wood floors to fade over time.

Low-E glass is unlike the dark shaded glass that was produced decades ago. The energy saving Low-E glass of today has so fine of a film coating on it, it is nearly imperceptible to the naked eye. Low-E glass appears effectively clear, thus it will not reduce the amount of natural light into your home.

Moreover, today’s low-E glass film coatings are specially designed and applied so that they help keep homes cooler during the summer months and warmer during the winter months. As a result, when combined with double pane window technology, Low-E glass windows provide the maximum in energy savings.

When purchasing energy saving Low-E glass windows make sure to select ones appropriate for your climate region. Not all Low-E glass windows are the same. There are several types of spectrally selective Low-E film coatings, and none are ideal for all climate regions. For example, there are some types of Low-E glass coating windows that are more appropriate for the southwest United States, while there are other types more appropriate for the northeast. As a matter of fact, the Energy Star program identifies four unique climate zones in the United States.

With each climate zone, they recommend a specific type of Low-E glass to be used in the windows. As a result, for those homeowners and builders participating in the LEEDs program to build energy efficient rated homes, they must use the specific type of Low-E glass windows for their region, as recommended by the government.

For example, the Energy Star program recommends homes built in the North and Central regions of the United States to use “Moderate Solar Gain Low-E Glass Windows”. These types of windows are specially designed to screen out a high percentage of the sun’s ultraviolet light during the summer months, and a lower percentage during the winter months when the added solar heating is desired.

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In the southwest portion of the country, however, the government’s Energy Star program recommends using “Low Solar Gain Low-E Windows”. These windows let in even less ultra-violet sunlight and heat during the summer months.

To learn more about spectrally Selective Low-E glass, and other ways to make your home more energy efficient visit

If you need more help on choosing the right window replacement for your home, contact one of our pre-screened window installation contractors. They can help you select the replacement windows that are right for your home and budget, and perform the installation.

For more information on Installing Replacement Windows and Interior Window Trim

  • See the Installing a New Window Ebook from  The Installing a New Window Ebook provides easy to understand, step-by-step instructions, on how to remove an old window and install a new one. Pictures are included for every key step in the process.
  • See the Installing Interior Window Trim Ebook from  The Installing Interior Window Trim Ebook provides easy to understand, step-by-step instructions, on how to install interior window trim around a window. Pictures are included for every key step in the process.

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