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Windows can be one of your home’s most attractive features, providing daylight, heat from the sun in winter and cool breezes in the summer. Unfortunately, windows also can account for significantly raising your heating or cooling bill by letting heat out during cold weather and hot sunlight in during summer.

If your home has single-pane windows, you may be surprised at the energy savings you’ll gain by replacing them with high-performance, double- or triple-pane windows. While it may take many years for new windows to pay off in energy savings, the benefits of added comfort, improved aesthetics and functionality can offset the cost.

Replacing old windows with Energy Star® qualified models can lower your household energy bills by an average of 12 percent. In addition, new windows can help reduce chills and drafts, condensation on the glass, and fading of furniture, carpets and window coverings.

Choose your windows

The choices you make about style, materials and installation could have a big impact on your comfort and energy bill.

  •  Cost: Price per window ranges from a few hundred to a few thousand dollars, depending on materials, features and installation costs.
  •  Materials: Wood frames offer good insulation, but they’re heavy and need extra maintenance. Vinyl and composite frames insulate well and don’t need painting.
  •  Style: Single-hung, double-hung and sliding windows leak more air than casement, awning and hopper windows.
  •  Glass: Some types of glass provide better insulation, light and condensation resistance. Windows with low-emissivity (low-e) coatings often are more energy efficient.
  •  Cleaning and maintenance: Some materials and features make windows easier to care for. Tilt-in sashes, for example, make cleaning easier.

Keep these points in mind

A few years ago, five companies that sold replacement windows were found to be making exaggerated and unsupported claims about the energy efficiency of their windows, as well as how much money consumers could save on their heating and cooling bills by having them installed. The settlements with the Federal Trade Commission prohibit those companies from making these types of deceptive claims. However, that doesn’t mean that there still aren’t some companies that are less-than-truthful about the performance of their products, so compare carefully when shopping for windows.

  •  Look for the Energy Star label.
  •  Choose high-performance windows that have at least two panes of glass and a low-e coating that lets in light, but reduces heat gain. The coating also can protect your valuables from harmful, fading ultraviolet light (by up to 75 percent) without noticeably reducing visible light.
  •  Select windows that are gas-filled to reduce heat loss.
  •  Consider the highest efficiency windows your budget allows. Look for the National Fenestration Rating Council label, which gives the efficiency details as determined by an independent industry rating system for the energy performance of windows, doors and skylights. (See information on next page.)
  •  Select windows with both a low U-factor and a low Solar Heat Gain Coefficient (SHGC) to maximize energy savings during both cold and hot seasons.
  •  Look for U-factors and SHGCs for the entire window, rather than center-of-glass U-factors and SHGCs. Whole-unit numbers more accurately reflect the energy performance of the entire product.
  •  Think about buying windows with impact-resistant glass if you’re concerned about flying debris from storms.
  •  Go to to find out about tax credits in Iowa. Also ask your local electric cooperative about rebates or weatherization programs available in your area.

Buying the right windows is only half the job. Your new windows must be installed properly to achieve maximum energy savings and maintain the warranty, so have them put in by trained professionals according to the manufacturer’s instructions.  

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