City of Alexandria, VA
In early 2010, City Council directed the Boards to convene a work group to develop policies for the appropriate use of modern and sustainable materials in the historic districts. As part of that work, the BAR review process in Alexandria was also significantly streamlined to reduce the time and cost for approval of many minor architectural elements, including roofing and windows, by allowing Staff administrative approval.
With regards to windows, please be assured that the all of the property owners in the historic district may either retrofit their existing windows to be more energy efficient or may install new historically compatible modern windows. Because the alternatives are not always obvious, Staff is happy to help owners and contractors identify historic windows in the field and to suggest replacement window types, where appropriate, which meet the policy for administrative approval on different age buildings. Owners with unique and unusual cases which do not comply with the adopted policies are encouraged to apply to be heard by the Board.
The Board does require that historic windows with “wavy glass” be retained and repaired, where ever possible, because so few remain. However, these original windows may often be completely restored, weather stripped and have Low-E storm windows installed, with no City approval required, for the same cost as new high quality wood windows. In addition, studies show that a properly restored window has almost the same efficiency as a modern window and that the energy cost savings of new windows can take many decades to recover.
Staff estimates that 70% to 80% of the original windows in the historic districts were replaced in the late 20th century, often with low quality products now themselves in need of replacement. In these cases, staff may administratively approve new double-glazed windows with Low-E glass and simulated divided lights. The only time single glazing must be used is on the facades of 18th and early 19th century buildings which abut the public sidewalks because there is such an obvious visual difference when viewed from this close distance. However, modern single glazed windows from several manufacturers are available with energy panels built into each sash which provide the same insulation and convenience as double glazing. This exception applies to a relatively small percentage of the buildings in Old Town and secondary elevations of these early buildings may still use normal double glazed windows.
In all cases, the simple application of weather-stripping and the addition of storm windows can substantially improve the energy efficiency of existing windows and the addition of insulation in the attic has a much greater rate of return than window replacement. Attached is a small sample of web links that address historic windows and window replacement: