Window Know-How: A Guide to Going Green

To live green at home, and reduce your monthly energy bills, it’s important to evaluate windows. If you live in an older residence, don’t assume that replacement windows are the only option. Historic wooden windows are remarkably efficient as long as they’re well maintained. (And there’s nothing greener than preserving what you already have.) Conversely, manufacturing and installing replacement windows consumes enormous amounts of energy. Keep these tips in mind as you consider your options:

Older is Better: Old windows were fabricated from old wood. It’s generally denser and lasts longer than the new wood used for modern windows.

Caveat Emptor: Some salespeople promote replacements as cure-alls, but even the highest-quality replacement units can fail. In addition, experts note that new vinyl or PVC replacement windows can release toxic byproducts into the atmosphere.

Watch Your Pennies: Tearing out existing windows to install replacements is expensive and wasteful. Although you may achieve some energy savings, it will take decades (or centuries) to recoup your investment. Plus, you’ll have to dispose of the old windows, adding to the nation’s waste management woes.

Maintenance is Key: A well-sealed, tight-fitting window saves energy.

Check for Condensation: It can rot window sills and rails.

Use Storm Windows: They increase energy efficiency. Monitor them for clues about your house. Cold air leaking in through a storm window can create condensation on your window panes. Warm air escaping from your house can cause a storm to fog up.

Insulate: More heat is typically lost through the roof and walls than through windows. Adding just 31⁄2 inches of insulation to your attic can save more energy than new windows.

Install Window Treatments: Something as simple as a conventional window shade mounted inside the frame and touching the sill, with no more than a 1⁄4-inch gap at the sides, can reduce heat loss by as much as 27 percent. A shade with a reflective coating will provide even more protection.

Remember to. . .
1. Keep all exterior surfaces painted. A coat of paint protects wood. Pay particular attention to horizontal surfaces, such as window sills, where water collects.
2. Replace glazing compound (the putty that holds panes in place) when it dries out. Missing or cracked compound results in air infiltration. Always paint glazing after it has cured.
3. Maintain window locks Functioning locks hold rails tightly in place. A tight fit reduces air exchange.
4. Keep movable surfaces free of paint buildup so that sashes slide freely.
5. Replace any cracked or broken panes promptly.
6. Add or renew weather stripping where it makes sense. When correctly installed, weather
stripping can increase a window’s efficiency by as much as 50 percent.
7. Watch for water. Whenever you use storm windows, remember to clear the weep holes at the base to allow condensation to drain away.
8. Check seals around exterior storms and caulk well.
9. Test for air leaks. On a windy day, hold a lighted birthday candle or incense stick near the window frame to detect drafts.
10. Think about safety. Evaluate emergency exit routes before sealing windows with caulk or adding storms.

To learn more about saving your windows and weatherizing your home, visit the National Trust for Historic Preservation’s resources for homeowners.

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2 Comments

Filed under Historic Preservation, Sustainability

2 responses to “Window Know-How: A Guide to Going Green

  1. Agreed, but the one wrinkle is the requirement within the City of Portland for a percentage of a building addition (or perhaps even a new building) to meet current energy code. In our recent project, we had to obtain special permission to even reuse a single pane window that we moved as part of our addition. Everything else had to be new, although we made sure it was wood. I suppose we could have found some old single pane windows and simply raised them to meet new energy standards.

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