Synopsis: For many homeowners looking to improve the energy efficiency of a house, one of the first things considered is the windows. Old windows can have lots of drawbacks: broken glass, poorly operating sashes, wood damage, worn jambs. The big question then becomes whether to replace or to repair the old windows. Although replacements could be the right answer, don’t discount the idea of repair, according to FHB associate editor Rob Yagid. Replacement windows can have an extremely prolonged payback period. Old wood windows, however, were built to be repairable. An illustrated problem-and-solution guide will help you to determine your best option.

Old wood windows are as charming as they are maddening. While they offer appealing craftsmanship and an authentic sense of home, they typically leak like a sieve. With rising fuel costs, an unstable economy, and a catatonic housing market, it’s simply becoming more and more difficult to look at those old units with pride.

If you live in a historic district, you may not have the option of installing replacement windows. If you live elsewhere, however, you may be tempted to ditch the whole preservationist mentality and hop on the vinyl replacement train in hopes of reaping all the green rewards and cash savings of a modern home. Don’t – not without carefully considering your options first.

By assessing your existing wood windows and making the right upgrades, you might be able to restore them to rival the performance of a standard replacement at a fraction of the cost.

Consider the potential of your existing windows

You might make a window-replacement contractor’s head spin if you tell him that you’re going to repair rather than replace an old, drafty wood window. After all, thanks to progress in building technology, tight windows with astonishingly high insulating values – Serious Windows, for example (www.seriouswindows.com) – are now available. But not every advanced building solution or product makes sense for everyone. For many, repair work is a desirable alternative to replacement.

In a collaborative effort, the Vermont Energy Investment Corporation, the University of Vermont’s Department of Civil and Environmental Engineering, and the U.S. Army Cold Regions Research and Engineering Laboratory set out to test the value in wood-window repair. In their 1996 paper, “Testing the Energy Performance of Wood Windows in Cold Climates,” they assessed the performance gains accrued through various wood-window upgrades, including the addition of storm windows. Through testing and modelling over 150 windows across the state of Vermont, they found that the difference in annual energy savings between a properly restored wood window and a typical replacement unit amounted to only a few dollars.

The findings that were published in that paper are still supported by experts researching the issue. Michael Blasnik, an independent consultant for over 25 years specializing in energy efficiency, building science, and weatherization-program evaluation, has looked more recently at the energy impact of replacement windows. “The numbers just aren’t as high as you would hope to see,” he explains. “There is actually little data that supports the idea that replacement windows save any significant amount of energy in typical homes.”

Blasnik studied the energy bills of a small sampling of houses in Upstate New York. He looked at their energy bills before and after replacement windows were installed. No other building improvements were made. The findings were less than impressive. On average, the homeowners saved about $40 on their annual heating bills. Consider the expense of replacing all the windows in a house, which could cost as much as $10,000, and replacement hardly seems sensible or economical. By dividing the total investment by the annual energy savings, you get a shocking payback period: The owners of these Northern homes won’t see net cost savings for another 250 years.

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