Storm Windows By the Numbers

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Many of us know that storm windows can make a huge difference in the comfort of our homes. The fine folks at Chicago Green Windows, a window rehabbing company, have compiled some studies that explain how storm windows can help and what qualities to look for when investing in some.

The following articles and studies are available to download in PDF form:

Measured Winter Performance of Storm Windows

From the study’s conclusion: “The addition of low-E storm windows to the prime window provided performance very similar to that of the replacement window…” Field Evaluation of Low-E Storm Windows From the study’s abstract: “Overall heating load reduction due to the storm windows was 13% with the clear glass and 21% with the low-e windows. Simple paybacks for the addition of the storm windows were 10 years for the clear glass and 4.5 years for the low-e storm windows.”

Home Energy Magazine – Windows __ Storm Windows Save Energy

An excerpt from the test results: “As shown in Figure 1, energy flow was substantially reduced in both windows after the storm windows were installed…For comparison, the storm window on Window One was removed, and a weatherization crew was asked to weatherize the window as they typically would in the field. The crew selected for the work was one that frequently encountered and repaired leaky windows. The crew: squared up the window frame, allowing a tighter fit for the sash; replaced the rotting sill and part of a stop; glazed the panes; caulked cracks in the frame; and installed a sweep at the bottom of the window and a new window lock to improve  closure. The same four tests were then run on the weatherized window. The results are shown in Figure 3. They indicate that  the weatherization was somewhat less successful at reducing leakage than was adding the storm window. Evidently, there were leakage sites that could not be located and repaired by weatherizing the window, the effects of which could yet be alleviated by adding the storm window.”