When preserving historic architecture, which brings so many benefits to a community, including sustainability, windows and doors carry particular importance.

Often, the owners of historic homes don't realize just how important these features are to the design of their home, or to the overall character of a community.

Windows and doors are often the pieces, that if not repaired or replaced properly, can severely impact a historic façade, risking the integrity of the entire building.

One challenge in a community such as ours is that our architectural inventory includes Georgian, Federal, Victorian, and Colonial style structures, with a varying range of window styles and configurations.

Late 18th and early 19th century buildings often had rectangular, double-hung and sash style windows, with small panes of glass separated by wood muntins.  Typically, the panes would be 6-over-6 or 9-over-9 lights, and doors would be of solid paneled wood.

Victorian era houses, meanwhile, often featured taller, double-hung windows with a single piece of glass in one or both sections. Sometimes each sash was divided vertically in a 2-over-2 layout, or a more decorative arrangement that incorporated stained or leaded glass. Gothic elements such as a signature peak were also common.

Casement or "swinging" windows became more prevalent in the early 20th century as architects and builders were inspired by British and North European domestic architecture.

Fenestration style is an essential character-defining feature within each building, no matter the date of its construction. It is unique to each architectural style and period and is integral in maintaining a building's integrity.

The mistreatment of these features can not only result in the loss of a building's history but can impact a historic building's overall value.

If you are considering restoring or replacing existing historic windows, here are some things to review:

Plan on speaking with a skilled restoration expert to identify the style and construction. If replacement is the only option, seek professional architectural or preservationist advice before speaking with window salespeople.

If energy efficiency is your primary goal, consider reducing air filtration by sealing around windows and door frames, adding storm windows, or hiring a specialized company to double-glaze existing windows.

Select window and door styles compatible with the original shapes, light division, frame profile, and color range.

Today's windows can be large sheets of insulated glass rather than using "snap-in" muntins (the vertical and horizontal elements that divide the window into a grid). Inexperienced homeowners may be convinced that this is acceptable. However, experienced owners of historic structures can spot this error from blocks away.

Understand the difference between true divided lights (TDL) and simulated divided lights (SDL).  Always choose true divided lights, compatible with the style of your historic home.

Unless you are replacing steel windows, which are often black, or working with a modern or contemporary house, avoid black frames and muntins, which become almost invisible when viewed from the exterior and erase the visual impact of the appearance of those all-important true divided lights, which are so crucial to the character of the façade.

Choose a window color that is compatible with the historic architectural style. These days, almost all paint companies provide a historic paint color palette from which to choose.

Porch doors and glazed infill panels often feature larger panes of glass, distinguishing the porch from the main body of the house. When converting such a porch, resist using smaller windows, solid walls, or solid doors to retain a porch-like character.

If shutters are inherent to the architectural style, make sure they are sized as if they would cover the entire window when closed. A pair of 15 inch shutters on either side of a 60 inch window, for instance, is not appropriate.  Wood shutter material is always preferable to vinyl.

Reach out to the expert preservationists at the Chestnut Hill Conservancy, to learn about the history of your home and its placement on our National Register of Historic Places.

Remember what a privilege it is to reside within a national historic district and consider the responsibility we have to preserve and maintain the features that contribute so greatly to that honor.

Architect Jean McCoubrey contributed to this article.

Patricia Cove is Principal of Architectural Interiors and Design in Chestnut Hill and can be reached through www.patriciacove.com.