Preserving Original Windows
First published in The Pelham Weekly, October 30, 1998; revised & reprinted, October 21, 2011
Windows are to a house, what eyes are to a person: from the inside, they are the means for looking outward, but from the outside, they are the single most revealing component in understanding the essence of what is within. While the original windows in an historic or vintage home are the most significant architectural component, they also have become the most vulnerable as homeowners have often been misled to believe that replacement windows will “improve” the house and produce energy savings that will pay for them. In fact, replacing windows can ruin the architectural integrity of a home, while the energy savings are usually never realized.
Window Types
The type, size and configurations of windows varied dramatically through the history of American architecture. They are a critical indicator of the age, style and architectural expression of a building. “Casement” windows (which swing on a side edge hinge) represent the earliest design for a non-fixed window. They are used in the various “English Revival” architectural styles found in Pelham, including Tudor Revival, “Jacobethan” Revival, English Vernacular and “Cotswald Cottages.” In the earliest examples, these windows typically had wood frames, but by the mid-1920s, architects began to rely on steel casements dressed with fancy brass hardware. In both cases, the window itself was often a leaded glass panel, with the width and configuration of the lead varying depending on the age and style of the home. In marked contrast are single and double-hung windows, typical for Colonial Revival houses.
Within these two general window types, are hundreds of window variations, which reveal even more about the architectural style of a house. The window size and proportions, the number of glass panes and the thickness of the window mullions vary dramatically according to style and cannot be replicated by standard “replacement” windows. For example, within the general category of “Colonial” architecture, the Federal Style typically had over-sized windows with extremely slender mullions and fewer panes of glass. The earlier Georgian Style, in contrast, can be identified by its smaller windows, chunkier mullions and many more panes of glass. These distinctions were often followed in the revivals of these styles n the late -19th and early 20th centuries.
Similarly, windows varied dramatically within the all-encompassing “Victorian” styles. The Shingle Style is known for having a multi-paned upper sash (sometimes with as many as 36 panes of glass) over a single pane lower sash, while the Second Empire Style rarely had more than one or two panes of glass separated by an over-sized mullion. At roughly the same time, the Queen Anne Style employed a free-form window configuration, often with a single pane of clear glass surrounded by multiple smaller panes of colored glass.
Antique Glass
The technology of making glass has also changed over time, creating a dramatically different appearance for antique glass. The oldest homes in Pelham (pre-1880s) contain “crown glass,” made by spinning blown glass, which left “bubbles” and a heavy “rippling” effect. Later 19th and early 20th century window glass was made through a rolling process that left some rippling and gives historic windows a unique character and texture that can be seen from both inside and outside the house.
Pelham has an outstanding collection of historic architecture, due in no small part to the fact that many homeowners have retained original windows. Decisions to restore and preserve, rather than replace original windows demonstrate good judgment not only as a matter of historic preservation, but economics as well.
The Myths of Energy Efficiency
The Preservationist magazine publication of the NYS Historic Preservation Office once reported that studies show double-glazed windows usually offer only marginal reductions in heat loss over single-glazed windows. Heat conducts rapidly through all windows – regardless of age – because glass has such poor insulation value. Heat conduction is measured as an “R-value,” with single-pane windows having an R-value of about one and most double-glazed windows having an R-value of two, versus an R-value of 13 for a typical insulated wall. The Preservationist cites a 1996 Vermont Study (“Testing the Energy Performance of Wood Windows in Cold Climates”), which concluded that to recoup the cost of replacement windows through energy savings would take 27 years for old windows in the worst condition. For old windows that have been properly sealed and weather-stripped, it would take 375 years to recover the new window cost through energy savings.
In fact, where old windows are inefficient, it is not from higher heat conduction through the glass, but from air infiltration around the window. A tighter fit can be achieved in older windows by removing the sash, stripping the paint, adding weather-stripping and re-hanging the window. When steel casement windows prove to be too drafty, the better solution to replacement is the installation of an interior wood storm window.
The cost of these solutions is far less than replacing with an equivalent new wood window. It is also a greener solution than installing vinyl replacement windows, which are not designed to last as long and require substantially more energy in manufacturing materials, assemblage and transportation than is necessary to restore an existing wood window.
Preservation Trends
After many years of a trend toward replacement windows, there have been modest gains toward preservation. Not long ago, Christopher Gray, author of a weekly architecture column in the Sunday New York Times Real Estate section, reported on the work of Scarsdale-based “Seekircher Steel Window Repair,” which is dedicated to restoring and preserving steel casement windows. The owner, John Seekircher,” is quoted as stating that in the last decade, “people have seen that the energy savings were illusory, and that removing historic windows actually diminished the property value, especially in a single-family house.The Pelham Preservation Society encourages the preservation of original windows and for many years has salvaged antique windows in order to make the glass available to owners of historic homes. Recently, when the Pelham Picture House decided to replace the building’s oculus windows, the Pelham Preservation Society got behind the project. While the window deterioration was so severe as to make preservation impossible, the organization provided a grant to create an exact replica of the frame, including the profile of the mullions, and installed original salvaged glass from the 1920s to match the period of the building.
Links to Preservation Briefs on Preserving Windows:
Leaded & Stained Glass Windows
Link to Historic Window Restoration Contractors
Report on the Myth of Window Energy Savings
How other communities are working to preserve historic windows in: