Historic windows, already one of the most vulnerable elements of historic buildings, are in danger of extinction. Misinformation during the current sustainability campaign has painted historic windows as poster children for inefficiency. As a result, rehabilitators are increasingly quick to discard old windows for new replacements. The current plethora of financial incentives for home efficiency improvements, such as the tax credits for home weatherization included in the Economic Reinvestment and Recovery Act (ERRA), have exacerbated the situation to an alarming degree.
Windows are one of the most character-defining architectural elements of a building. The size of window panes and types of glass used offer not only aesthetic detail but historical clues, such as the building’s date of construction or architect. Many historic window types are no longer produced- their loss quite literally constitutes the loss of something irreplaceable.
Like so much historic craftsmanship, damaged historic windows can often be repaired and rehung. Further, when augmented by the addition of storm windows, historic windows can attain levels of efficiency equal to those of new windows. Historic windows are composed of old-growth lumber with a life expectancy that far exceeds the 15-20 years estimated for new windows. Further, the landfill waste created by a wholesale window replacement project easily outweighs the increased energy efficiency to be reaped. Accounting for the energy involved in the production of new windows, transport to the site, and landfilling of old windows, the payback period for replacement windows can be up to 200 years! Simply adding a storm window will have a payback period of fewer than 10 years. Holistically viewed, window replacement is not only detrimental to the historic character but is often actually much less environmentally responsible than is retention and repair.
Prolific misinformation coupled with unmatched promotion of efficiency upgrades is obscuring the facts. Literature promoting efficiency improvements does not properly explain or encourage non-replacement options. Many homeowners remain unaware that there are alternatives to wholesale window replacement, and that these alternatives can result in a final product that is equally as efficient, for a fraction of the cost and time, in addition to being architecturally appropriate. The current increased interest in home efficiency improvements and the pressure to complete projects in time to secure financial incentives makes the present situation particularly threatening.
PNJ encourages anyone rehabilitating a historic building to think carefully and consult multiple sources before moving forward with window replacement. Consider not just the promised short-term energy savings, but how significant a role historic windows play in the building’s integrity, and how much waste wholesale replacement would create. Preservation and augmentation of historic windows is an option, and potentially, the approach that best serves the building, the environment, and the project budget.
Preservation New Jersey
Ron Emrich, Executive Director