They don't make 'em like they used to.
Lloyd Alter
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Steve Thomas recently wrote a post entitled Convince Your Local Historic Commission to Go Green, and noted that "I'm very much in favor of historic houses. I think that historic commissions have to expand their thinking a little bit and let homeowners make green upgrades." He also noted that the Historical Commission in Salem, where he lives, won't let him change his windows. Finally he writes "historic commissions will need to upgrade their technological thinking on it and allow homeowners to green their historic houses."
Steve is right, and a lot of people are trying to do just that—to look at the technological thinking about how old buildings work, and what we can do to bring out the best green things about them as well as adapting them to new technology. I thought it might be a good idea to expand on the subject and explain why preservationists like old windows. I approach this subject not just as an architect or a writer about green design for TreeHugger and Planet Green, but as board member and incoming President of the Architectural Conservancy of Ontario, a 75-year-old organization with 24 chapters and a lot of volunteers dedicated to preserving historic buildings.
In this series, I will look at the issues of windows, insulation, technology and the changing nature of Historic Preservation Societies in this era of concern about sustainability. First up, windows:
Windows
Windows are a critical part of the look of an historic home, but they are often sacrificed on the altar of supposed energy efficiency and convenience. Window salespeople are particularly aggressive and promise huge savings in energy. They are lying toads.
The National Trust for Historic Preservation writes:
There is an epidemic spreading across the country. In the name of energy efficiency and environmental responsibility, replacement window manufacturers are convincing people to replace their historic wood windows. The result is the rapid erosion of a building's character, the waste of a historic resource, and a potential net loss in energy conservation. Typically replacement windows are vinyl, aluminum, or a composite with wood, and none will last as long as the original window. Repairing, rather than replacing, wood windows is most likely to be the "greener option" and a more sustainable building practice.
And they have the data to prove it. Study after study show that changing windows is one of the least cost-effective things that one can do to save energy. One report concluded:
Our study of old windows showed that the energy savings are similar for a variety of retrofit and replacement strategies. Rates of return on investment for energy improvements are quite low when starting with typical or tight windows with storms in place, but are significantly higher when renovating loose windows with no storm.
The difference in annual energy savings between renovating an old sash and replacing it with a new one was very small--retrofits saved only a few dollars.
And given the fact that the old windows might be old, very solid and strong wood, and the replacement might be vinyl or finger-jointed wood made out of lots of small pieces glued together, the older window will probably last a lot longer. As Donovan Rypkema summarizes:
- Properly repaired historic windows have an R factor nearly indistinguishable from new, so-called, "weatherized" windows.
- Regardless of the manufacturers’ "lifetime warranties", thirty percent of the windows being replaced each year are less than 10 years old.
- One Indiana study showed that the payback period through energy savings by replacing historic wood windows is 400 years.
- These houses were built hundreds of years ago, meaning those windows were built from hardwood timber from old growth forests. Environmentalists go nuts about cutting trees in old growth forests, but what's the difference? Destroying those windows represents the destruction of the same scarce resource.
Then there is the economic impact. Fixing old windows is a labor intensive job, so the dollars are spent locally instead of at a distant manufacturing plant. That's economic sustainability, also part of sustainable development.
Finally there is cultural sustainability, part of sustainable development. Maintaining the original fabric and character of the houses is what makes historic neighborhoods viable and maintains their value.
In the end, the greenest window is the one that's already in the wall.
Stay tuned for the next installment: Insulation and Historic Houses
More in TreeHugger and Planet Green:
Noooo Edinburgh, Don't Lift Ban on Changing Windows in Historic Structures
Noooo Edinburgh, Don't Lift Ban on Changing Windows in Historic Structures
Renovation Uses Twice As Much Labor, Half as Much Material as New ...
Building the Green Modern Home: Looking at Windows
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