Could 200-Year-Old Windows Be More Efficient Than New Models?



Good news for historic home owners: Your vintage windows may be just as energy efficient as newer models. This is according to a study by Shannon Kyles and colleagues at Mohawk College in Ontario, Canada. The researchers found that restored 200-year windows actually prevented heat loss just as well as updated models, despite many older homes’ reputation for being drafty.

Treehugger reports that the study involved an eight by 12 foot tiny house. The house had two new windows and two 200-year-old windows. They were all installed with foam insulation by John Deelstra, Professor of Carpentry at Mohawk College.

The results? They found no difference in efficiency.

“The test results demonstrate that there is no difference in air infiltration between new windows and restored pre-war windows,” Kyles said in a statement to Treehugger.

However, “restored” is the operative word in that sentence; most old windows aren’t professionally restored with foam insulation.

So while there are other factors to consider, these results speak to the effectiveness of restoration. And since 45% of the average energy bill goes toward heating costs, according to the Department of Energy, it pays to choose the best window option for your home. Kyles also writes in the study that potential air leaks aren’t the only factors to consider, since other types of energy go into window production and transportation.

“An existing 200 year-old window essentially consists of wood and glass with paint or varnish,” she writes. “The energy needed to restore it is minimal. Comparing this to a new window, one must consider first the embodied energy required to extract raw materials to produce the new product, then the direct energy used to remove the existing window and dispose of it in a land fill. More direct energy is needed to then take the new window to the building.”

According to Treehugger, some cheap replacement windows are manufactured with lower standards than those crafted several hundred years ago. While this has sparked a debate in the historic preservation community, window industry data shows that the market for energy efficient windows is predicted to increase by almost 9% between 2017 and 2021.

Preservationists, perhaps this is your chance to close the blinds on this debate.

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