Saving Energy with Energy-Efficient Windows

According to the US Department of Energy inefficient windows can be responsible for as much 35% of the energy lost in a building.


How much summer heat is coming into your home through your windows?

The California Energy Commission estimates that as much as 40% of the cooling requirements of a typical building are due to solar heat absorbed into the building through the windows. Considering this information, it stands to reason that a large portion of energy expenses could be saved by making sure the windows of a building are well maintained and energy efficient with the right type of glass installed.

Old windows allow for warm air within the building to escape outside and on hot days the heat from the outside is easily absorbed. Replacing these with top of the line energy efficient windows is sure to lower the costs of your next energy bill while keeping the interior of the home as comfortable as possible.

If you are considering replacing the windows of your home it is important to keep in mind that a lower cost and lower quality window may end up costing you a more in the long run. Quality windows offer superior energy saving features that can eventually pay for themselves, lower quality options only look new. Windows that qualify to certain stipulations may be eligible for Government rebates and special incentives.

Understanding Window Energy Ratings

In order to best avail yourself of all that a top quality energy efficient window can offer you it is important to understand the energy rating labels. This will help you to understand the efficiency of the various products with which you will be presented.

-The U Factor — This Solar Heat Loss Coefficient is best if below 0.3

-The SHGC (Solar Heat Gain Coefficient) This is indicated on a scale of 1 through 10, Hotter Climates will want to pick lower SHGC’s)

Certain brands may include such information as visible light transmittance, air leakage and condensation resistance on their labels. You may also find the coefficients for cooling and heating. The National Fenestration Rating Council, or NFRC, label for windows includes and energy performance number.

Condensation Resistance coefficient

— Expressed as a value from 1 to 100, measuring the resistance the window has to condensation forming on it. The higher the number the better.

Air Leakage Coefficient

— Measured from 0.00 to 1.00, indicating how much air can pass through a single foot of window, skylight etc. through cracks and spaces, the lower this number is the better.

Picking the Right Glass

In addition to the numbers discussed above it is also important to consider these points:

-Single Pane Glass is not as efficient as other options, not only does it allow for a great amount of heat to enter it also allows for a lot of heating energy to be lost to the outside. Single pane glass usually has a U-factor of 1.1, which is much too high.

-2 or 3 Pane Glass is the most advisable selection for saving energy and keeping out excessive heat from the sun. The U factor here is about 0.3 which is more efficient.

-Argon Filled Glass windows make much better insulators than the conventional option. These are very high quality products designed to save energy and last a long time.

-Low E coating glass is perhaps the most well-known type of energy efficient glass. The low U-factors on this type of window means that those living in cold climates can retain more interior heat.

-Low E2 glass is also known as Spectrally Selective Glass or Solar Low-E. This type of window option is especially good for those living in warm areas where only a little sun light is desired inside, thus effectively lowering the cost of AC units.

-VT Glass (Visible Transmission) has the nice advantage of being able to reduce glare and heat which is very appropriate for downtown locales and those living in snowy regions.

-Got Kids? Impact Resistant Glass can resist impacts ranging from stiff winds all the way to the accidental baseball. If living in a particularly windy location or where security may be an issue, Impact Resistant Glass is for you.

-Tinted windows can add a measure of privacy and also control the amount of glare reflected into the house.

Installation Notes

Even the best windows and top-of-the-line features are only as good as the workmanship that set them up. After making sure the windows you have selected meet all the NFRC rating standards, be sure you rely on competent personnel to set them in place, the risk of attempting a DIY job here is that without proper professional installation, these precision pieces of architecture will not function properly.

When your windows lose their seal and let air leaks in, out or around the window it’s time to repair them.

When condensation or fogging occurs on or between glass panes or your windows are painted or nailed shut and virtually impossible to open – you’ll want to replace those too.