Green building and historic restoration are sometimes at odds, but never do they conflict so much as with windows. Preservationists are hard-pressed to replace a wavy piece of historic glass with a new energy-efficient window. Likewise, leaving any part of a building leaky and uninsulated is anathema to most green builders. Even in less historically significant homes, the cost of replacing all or even some of the home’s windows can be a major expense.
Storm windows offer a great compromise between cost, energy efficiency, and historic considerations. Improvements in storm windows are comparable to those made in new windows, and include reflective coatings and improvements in sealing—these are not the junky aluminum pieces of yesteryear.
While the air space between the original single-pane window and the storm window has not been shown to have much insulating benefit, the great reduction in air leakage (and outside noise) along with cutting back radiant heat transfer can effectively double the R-value of older windows. (Granted, this amount is only from about R-1 to R-2 once storm windows are added.) Especially for historic homes, interior storm windows add a green upgrade while preserving the home’s exterior character and beauty.
Interior storm windows improve the efficiency of old windows without sacrificing the historical aesthetic.