We have double pane windows and are thinking about installing storm windows in front of them. Would that be a cost efficient way to save on our energy bills? -Jessica

Hi Jessica,

While you could add storm windows to your existing double pane windows, the energy savings would not be nearly as great as installing them over single pane windows. You also should check your window warranty, since some warranties may void the coverage on your glass due to the possibility of heat build up between the storm window and insulated glass.

When used over single pane glass in colder climates, storm windows can reduce heating costs by 13% and pay for themselves in 10 years. If a low-E coating is applied to the storm window, the savings increase to over 20%, with payback in less than 5 years.

Since you already have insulated glass windows, the payback period would be much longer in your case.

To increase the energy efficiency of your existing windows, be sure the sash are a tight fit in the casing and the weather stripping around the window blocks air infiltration. If you decide to install storm with a low-E coating, make sure it is the proper type for your climate.

Good luck with your project,

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