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Shopping for new windows?

Whether the glare of the summer sun or the chill of winter winds is the problem, inefficient windows can affect the energy bills of a home or business. But going shopping for windows might not be necessary just yet.

“Replacing windows is an expensive process,” says Ken Hellevang, a North Dakota State University Extension Service agricultural engineer. “Look at how much you’re going to spend on the windows. If it’s strictly heat loss that you’re experiencing, how much difference will it make? How long will it take to pay for the windows with the amount being saved?

“It’s difficult to justify replacing windows based just on the conductive heat loss,” he adds. “If you’ve got air leakage around the window or rotting wood, then you could go ahead and make the switch, but realize it’s going to take a long time to get a payback.”

Here are some budget-saving ideas that will improve existing windows:

Condensation on windows occurs when air inside the house touches the cold surface of the windows and turns into condensation.

“That problem can be solved either by warming the window surface or lowering the humidity,” Hellevang says.

Keep the inside humidity level below 40 percent during the winter, he advises. An air exchanger will help with the overall air quality inside a building and control humidity. More information about window condensation and controlling indoor humidity can be found in an NDSU publication titled “Keep Your Home Healthy.” It is available at

If your windows are cold, one good option for warming the glass surface is to place a plastic window fi lm over the window with an air space between the plastic and window. A wide variety of window films that will reduce heat leaks and air infiltration around windows is available.

Insulated window treatments are another way to save a few dollars on heating and cooling bills.

Installed properly, window coverings can reduce heat loss significantly. The advantage of the window treatments is that they can be opened on the sunny side of the house to allow the sun to add free heat to the home. In the evening when the sun goes down, simply shutting the blinds retains the heat.

Window treatments also can aid in reducing heat gain during the summer. Close the covering when the sunshine is coming through the window.

Single-pane windows, rotting wooden frames and leaking window seals are indications that windows should be replaced. That’s when a window is inefficient and costing money.

As you shop for new windows, choices about materials, style and installation will all have an impact on your energy bill

But consider all your options first.

“Replacing the windows may be the correct choice, but sometimes there are other options, such as caulking and weather stripping to reduce infiltration, that you should consider when making a decision,” Hellevang says.

If replacing a window, select one rated by the National Fenestration Rating Council. The rating will list the following factors that should be considered when selecting a window:

  • U-factor measures the rate of heat transfer from inside a room. The lower the number, the lower the potential for wasted heating expenses.
  • Visible transmittance measures how much natural light can come into a room. A high number means more natural light.
  • Solar heat gain coefficient measures the amount of outdoor solar radiation heat that can enter a room. The lower the number, the lower the potential for wasted cooling expenses.
  • Air leakage measures how much air will enter a room through the window. The lower the number, the lower the potential for draft through the window.
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