The Difference in Energy Savings Between Storm Windows & Double Paned Windows

Reinforce your old, wooden-paned windows with storm windows to keep out the elements.

In these trying economic times, most people are tightening their wallets, and some are making budget-wise -- and environmentally-friendly -- changes to their lifestyles. One of the best ways to accomplish both tasks is to reevaluate the energy efficiency of your home. Windows are often a big source of heat or cooling losses in places with harsh climates, and picking the right windows for the job can mean the difference between shelling out hundreds of dollars in energy bills or sitting pretty on a hefty wallet.

Double Paned Windows

Double-paned windows are significantly more expensive than their single-paned counterparts, but they insulate twice as well. This is because there is a vacuum-sealed space of air between the panes of glass which trap heat from the sun in the winter and prevent cool air from escaping in the summer. The double-paned window is the best option for energy-efficient home-building, assuming you choose a window which comes coated with low-E (emissivity) material. Low-E windows block UV light while limiting heat loss.

Storm Windows

Storm windows are an upgrade and are cheaper than installing double-paned windows in place of your outdated single-paned windows. However, unless you are installing the storm window on an existing double-paned window, it will not be as energy-efficient. You will also need to pay attention to the quality of the storm window; some are simply weak sheets of plastic which will not do much to insulate during harsh weather conditions. However, some storm windows come coated with low-e and can reduce your heating and cooling costs. If your primary windows are old and have wooden panes, an exterior storm window is the best choice.

Energy Performance Criteria

To help in choosing the most energy-efficient storm or double-paned windows for your home, check the manufacturer's label. There are plenty of performance criteria that will help you decide. For example, make sure the window has a low U-factor. This represents the rate at which your window will allow non-solar heat to flow through. Also, check for a low air leakage rating; high light-to-solar gain means that your window can take in summertime light but not allow it to overheat the room.

Ratings

For all windows, check that the product has been approved by the National Fenestration Rating Council. The NFRC rates windows in even more categories than listed above and can tell you exactly how efficient your window models are. Since the energy efficiency of storm or double-paned windows is often determined simply by quality instead of type, pay attention to the ratings guide for specific information.

References

• Green Builder: Choosing Windows
• U.S. Department of Energy: Energy Performance Ratings for Windows, Doors, and Skylights
• Saturn Resource Management: Storm Windows Can Save Energy
• Lower My Energy Bill: Double Paned Window