Is your old house cold and drafty…but your utility bills make it look like you’re heating our Masonic Temple downtown? If so, read on. The next two Practical Preservation articles will focus on energy efficiency and the historic house. Today’s column is about embracing your original wood windows. They’re beautiful, and yes, energy efficient, if you treat them right.
Prior to mass production, windows were created by hand. The earliest homes in Farmington, dating from the first half of the 19th century, were built by the settler himself. The wood in these homes was felled on that property, and the house was built by the settler—plus, potentially, his family and neighbors. Their work can’t be replicated on a production line.
Or take the original windows still found on some of our beloved Victorian-era Queen Anne homes. At that time, the windows and trim were often some of the most decorative features of a home. Until World War II brought the need for fast, cheap home building, much of the construction of a house was highly individualized.
Pretty, yes. But are these beautiful windows really energy efficient?
Pella Has Nothing on Old Growth Wood
Most houses of the late 19th century, and many from the early 20th century, were built with old growth wood. Today, virtually no old growth wood remains available for new construction in the United States. Instead, new lumber is grown quickly without the time needed to create the density of old growth.
The Environmental Protection Agency has a section of their website dedicated to energy efficiency and older homes. It notes that windows from homes built before 1950 are likely to have “valuable and now-scarce old growth wood which is denser, more rot- and warp-resistant, and holds paint better than modern, plantation-grown wood.”
The wood windows used in older homes were meant to stand the test of time. And, with proper care, they do.
The misperception that wood windows aren’t energy efficient was addressed by a 1996 study in Vermont, conducted by engineers from the University of Vermont, Vermont Energy Investment Corporation, and the U.S. Army Cold Regions Research and Engineering Laboratory.
The report—titled “Testing the Energy Performance of Wood Windows in Cold Climates”—analyzed the heating costs of wood windows before and after upgrades, such as installing weatherstripping, using storm windows, and sealing top sashes. In conclusion, the study found little difference in energy savings when comparing new windows to upgraded wooden windows. However, the cost difference in purchasing new windows is much greater than the cost of rehabilitating original wooden windows.
A few basic steps can make a big difference in the life of wood windows.
Invest in Storm Windows
Storm windows can double a window’s efficiency, and insulated low-e glass in the storm can further optimize its thermal performance. Storm windows are most often used on the window exterior, but can be used on the interior as well. They can be purchased from home improvement stores if the window is a standard size or custom-made for those windows that are atypical.
“To be effective and compatible, storm windows must be tight fitting; include a sealing gasket around the glass; align with the meeting rail of the primary sash; match the color of the sash; and be caulked around the frame to reduce [air] infiltration.” (National Park Service Preservation Brief #3, Improving Energy Efficiency in Historic Buildings)
Weatherstripping comes in a variety of forms, depending on the window type. Foam, vinyl, and metal are typical materials, although felt can be used as well. The weatherstripping is applied to the perimeter of the window sash, generally in the form of a compression barrier when the window is closed.
Keep Up with Routine Maintenance
Routine maintenance includes interior and exterior paint removal, sash or frame repair, reglazing when necessary and repainting, according to the Preservation Brief #9 (The Repair of Historic Wooden Windows). Paint stripping and repainting should be done every five to ten years if quality paint and primer is used. Wood window sashes and frames should be monitored for repair needs. Extended exposure to sitting water on exterior sills can quickly lead to wood rot and need for repair. By keeping them properly painted, the life of your windows is greatly extended.
Window rehab can be undertaken by contractors in the Metro Detroit area, or as a DIY home repair project. (If this strikes your interest, take note: Preservation Farmington will be hosting a one-day, hands-on wood window rehab workshop this May or June.)
See our resources page for area window rehabilitation contractors.
-by Jena Stacey