Did you know that energy loss attributed to windows accounts for 25 to 30 per cent of the annual heating and cooling costs for both new and existing homes?
If you have an older home with single pane windows and wood frames, you might find that the windows are drafty and don’t block out outside noise or UV light. Newer homes, too, may have windows that don’t seem to be particularly well made or sturdy.
It’s easy to tell if your windows are inefficient. Do you feel a draft when you are close to the window? Feel your windows — are they hot or cold depending on the season? Do they fog up? In the warm weather, does your HVAC system run all day just to keep your home comfortable?
If so, maybe you’ve started thinking about energy-efficient replacement windows. There are a number of benefits to energy-efficient windows, including:
- Lower heating and air conditioning costs
- Less condensation so less mold
- Less fading of drapes, carpets, and furniture
- Less noise from the outside
Understanding Window Ratings
Windows are given two important ratings that tell you how well they perform. If you’re choosing new windows to replace those that are damaged or low-performing, you should look at these ratings carefully.
The science around this technology can be complex. We won’t get too technical here but there are a couple of phrases that describe window ratings that are commonly used — U-factor and R-rating.
The U-factor is a measure of thermal conductivity. You want a window that does not conduct heat. An energy-efficient window will keep heat in or out. The lower the U-factor, the better the window. Look for a U-value below 0.5. According to the U.S. Department of Energy, a window with two panes of glass and a half-inch of space between will have an average U-factor of 0.48, while one with quadruple glass can increase your efficiency to a U-factor of 0.22.
Another rating that you’ll see is the R-value. This tells you how resistant the window is to heat conduction. You want to look for windows with a high R-value, which indicates that they will resist heat conduction well.
There are a couple of certifications that good quality energy-efficient windows should have. Look for these labels:
- NFRC: National Fenestration Rating Council tests and certifies windows and doors for U-Factor, solar heat gain coefficient and visible light transmission.
- Energy Star certifications are based on minimal standards that windows must meet in a specific climate to ensure low energy costs.
Here are some of the features and materials that you should look for when shopping for energy-efficient windows.
Double Pane Glass: This is made up of two individual panes of glass and is the most commonly used. If you use low-e coating and either argon or krypton gas, this should prove quite sufficient in moderate climates. Double pane glass blocks UV rays 90 percent more effectively than single pain glass.
Triple Pane Glass: These are the most energy efficient as long as the low-e coating and argon or krypton gas is used. They are great for climates with extreme weather and are the best for reducing noise and resisting condensation. They can be used for rooms in the home that face busy streets or are very close to neighbours.
Quadruple Pane Glass: Are used in the coldest climates. They are very expensive but save on heating and energy cost significantly if installed correctly. These windows are very heavy and need strong framing.
Single pane glass: Are the least energy efficient type. They only keep the elements out and provide very poor insulation.
Argon and krypton are odorless and colorless gases used between the panes to add energy efficiency to your windows. Krypton is usually a little more expensive. Both gases act as an insulator to help minimize heating and cooling loss, and both work well with low-e coating.
Spacers are Important
Double spaced or triple spaced replacement windows manufactured today are separated by a spacer. These are either made from aluminum, stainless steel and foam, or all foam.
They have 3 basic duties:
- The spacer absorbs stress from thermal expansion and contraction
- They help prevent condensation from forming by increasing the temperature of the insulated glass edges
- They help to seal the glass to keep the gas between the panes from leaking out and also to keep moisture from getting in
Most sources recommend all-foam spacers because they do the best job of reducing the transfer of heat or cold from the glass. They also expand and contract along with the glass
What About the Frame?
If you have an older home your window frame may be made of wood. Newer Frame materials include fiberglass, vinyl, and aluminum.
Wood frames offer great insulation but also need upkeep. You’ll need to seal every 12 to 18 months.
Vinyl is a budget-friendly, air-tight option. Their efficiency is almost as good as wood. Some people consider that their appearance is not as attractive as other types.
Aluminum is strong, light, and requires almost no maintenance. On the down side, aluminum conducts heat very quickly and does not provide good insulation.
Fiberglass window frames are very stable and strong and last a long time. They have air cavities that can be filled with insulation. They are a slightly more expensive option.
Installation of New or Replacement Windows
Your best bet is to hire a trained professional to ensure you get the maximum benefit of energy efficiency and comfort and to secure your warranty.
Another Energy-Saving Measure
One effective step you can take immediately to reduce your energy bills is to call Forney Air for inspection and maintenance of your HVAC system. Call us at (214) 924-9745 for prompt and reliable service.
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