North Carolina’s historic windows are vanishing at an alarming rate. Property owners replace them because they are led to believe that replacement windows will bring instant energy savings or because they don’t realize that there are ways to repair and restore original sash. Yet once replaced, these historic artifacts are gone for good.

Here are some answers and resources on kinds of historic windows, how they can be energy efficient, how they can be fixed and who can help restore them.

Window basics

Double-hung, clerestory, casement-- historic windows come in all kinds. And different architectural styles employ different muntin profiles, casings, and other details.

Drawing by Amy Estep / reprinted courtesy City of Greensboro

• Excellent diagrams of window anatomy and basic window and door styles are available in the City of Greensboro’s historic district design guidelines (pp. 58-61) (PDF 17.2MB)

• Window Information Guide(Cambridge, MA, Historical Commission)

• Tip Sheet for Historic Wood Windows (National Trust for Historic Preservation) (PDF 1.2 MB) NEW!

Energy Efficiency

In terms of embodied energy, original windows are considerably greener than “energy-efficient” vinyl replacements. And with proper maintenance, sealing, and storms, historic windows can provide the same efficiency as replacements, with a much smaller environmental impact overall.

• Original sash is the greener choice! Historic Windows and Energy Efficiency by Sarah Wolff tells all . . . (PreservationNC.org)

• Forty-one years to pay back replacement window costs? Historic Omaha’s simple return calculator for replacement windows (PDF 57 kB)

• "What Historic Windows Can't Replace" from the Journal of Preservation Technology (PDF 127 kB)

• The National Center for Preservation Technology and Training has published an energy-performance study on wooden windows (PDF 2.9 MB)

Restoration

One of the great benefits of original windows is that they can be repaired, rather than replaced. That means long-term savings for the property owner and long-term benefit for the environment. With many replacement windows, “maintenance-free” means there’s no way to repair them. Once a seal breaks, the entire installation has to go.

Some resources for keeping your original windows in good working order:

• Basic advice on maintaining windows from the National Park Service

• Old House Journal holds a Sash Window Clinic

• Got a bungalow? The Historic Chicago Bungalow Initiative has practical advice for your windows. See, especially, Window Rehab, Window Restoration, and How to Remove a Window Sash.

• Several National Park Service briefs look at maintenance and repair of different historic window types:

• The Repair of Historic Wooden Windows
• The Repair and Thermal Upgrading of Historic Steel Windows
• An Analysis of Replacing Steel Windows with Aluminum on a Commercial Building
• The Use of Awnings on Historic Buildings

• How to make protective coverings for stained glass(Traditional Building magazine)

 

Professionals

• Double-Hung Historic Window Restoration (PNC Professional Associates Network) of Greensboro specializes in the repair of pre-1935 windows and doors

• Other PAN carpenters and craftspeople