PROVIDENCE — Margaret Lewis had an old, drafty window in the attic of her Sheldon Street home. The window was rotted around the edges and the wall and floor under the window were water damaged.

Lewis replaced the window with a double-pane model she bought at Home Depot. Shortly thereafter, she received a letter from the Providence Historic District Commission informing her that a lien had been placed on her home, and that it would only be lifted when she replaced the new window with a replica of the original single-pane window.

Providence is a city that prizes its historic buildings and streetscapes. Benefit Street, on the city’s East Side, is advertised as “a mile of history.” Created in the mid-18th century, it features dozens of examples of 18th- and 19th-century wood-framed houses, practically uninterrupted by modern development. Off the south end of Benefit Street, Sheldon Street, shares Benefit’s historic character.

To ensure the protection and preservation of the city’s historic character, the Providence Historic District Commission (PHDC) was created in 1960. The commission oversees Providence’s eight local historic districts, which encompass more than 2,500 buildings. The commission has the authority to regulate development, and reviews and then approves or denies proposed exterior repairs or renovations to any property within a local historic district.

While the commission has helped maintain the character and beauty of the city’s most historic places, it comes at a cost to those property owners. Applications must be submitted to the commission for most external renovations or repairs, along with an application fee that ranges from $15 to $120 depending on the project’s complexity. The commission then has 45 days to determine whether to approve or reject the application. Minor requests usually take no longer than a week, and most applications are ruled on within 30 days, according to the commission’s website.

During the past 15 years, Lewis has been replacing her home’s windows a few at a time. Each historic replica costs about $600, so she can’t afford to replace all the windows at once. She has filed at least five applications — at $15 an application — with the PHDC and has replaced 16 of about 20 windows in the home.

Lewis also has replaced a mahogany and walnut railing, and will soon replace her front door, which she expects will cost about $2,000 to match the size and style of the existing door.

“It’s hard to sustain the cost of a historic home,” she said.

On the corner of Washington Street and Canal Walk, more than 100 windows were recently refurbished in the Rhode Island School of Design’s Illustration Studies Building. This was not the original intent of the project, according to Jack Silva, RISD’s head of facilities.

Prior to being refurbished, the windows were “falling apart” and different in style depending on the face of the building, according to Silva. RISD proposed replacing all of the windows with aluminum framed, energy-efficient models, which would have looked more historically appropriate than the existing windows and weren’t all original to the building anyway, he said.

The proposal was rejected by the Rhode Island Historical Preservation & Heritage Commission, which was asked to reviewed the project during the Coastal Resources Management Council’s review process. As a result, the institution invested $350,000 to refurbish the mismatched windows.

“I understand and value preservation, but the rigidity makes it hard for businesses to (upgrade their buildings),” Silva said.

The historic preservation standards Providence uses are the accepted standards nationwide, according to Robert Azar, the city’s deputy director of planning.

“It’s important to note that within historic districts, the look and the actual materials a building is made of are considered to be character-defining elements,” Azar said. “We consider these houses to be architectural masterpieces.”

Maintaining original single-pane windows, or at least replicas, is an important part of stewarding these masterpieces, he said. Depending on the era of the building, the original windows may be handmade and unique in terms of shape or size.

“They can’t be easily replicated,” Azar said. Even double-pane windows that replicate the division of glass differ in appearance upon close inspection, he said.

“For historic districts, we (stress) maintenance and repair. Under certain circumstance it can be more expensive to maintain a property within a historic district,” Azar added, “but property values are usually higher.”

He also noted that a historic property owner’s neighbors play by the same rules.

“You have to maintain your property, but all the properties around you are being maintained as well,” Azar said.

While the rules and costs associated with living in a historic district can be burdensome, many residents choose to locate there because they see the value of stewarding the city’s history.

“They see these buildings outlasting themselves, and remaining in tact for generations to come for the benefit of the residents and the public,” Azar said.

Of course, from an energy-conservation perspective, replacing old single-pane windows with new single-pane windows isn’t the optimal approach. As anyone who has stood in front of a single-pane window on a cold winter night can attest, the air feels as though it comes right through the glass. Installing double- or triple-pane windows can mitigate that problem.

Lewis, of Sheldon Street, said she is replacing the windows in her home to keep warmer, save money and stop water from leaking into her house. RISD’s Silva said he saw an opportunity to improve conditions in the Illustration Studies Building and save on energy costs.

The PHDC does permit storm windows and weather stripping to improve insulation. By using storm windows and weather stripping, historic windows can achieve a level of insulation that approaches that of a modern window, according to Azar.

Of course, for Lewis that means buying 20 storm windows on top of the relatively expensive replacement cost of her single-pane windows.

Double- and triple-pane windows lose their effectiveness over time as their weather stripping and seals wear out, and are usually replaced — at significant cost — every 20 to 30 years, according to Azar. He said a wood-framed, single-pane window can last more than 100 years.

“It’s less expensive to maintain your windows and get storms then replace them,” Azar said.

From an environmental perspective, this means less windows sent to the landfill and less energy used to make new windows, according to Azar. He also noted that the commission doesn’t regulate interior upgrades, and encourages improving energy efficiency by adding insulation, for example.

While installing double-pane windows in RISD’s historic buildings would result in energy and cost savings, it isn’t the low hanging fruit in terms of energy efficiency, according to Silva. Ensuring the buildings and windows are airtight is more important, he said. The real savings, according to Silva, are accomplished by replacing inefficient machinery with new, energy-efficient technology. His crew has converted all but a handful of the campus’ old oil burners to high-efficiency gas burners, for example.

“Preserving an existing building is the most (environmentally friendly) kind of development there is,” Azar said.

He said the city’s historic districts are dense and walkable by nature, and include many of the sustainable patterns of development that cities across the country are now trying to replicate.

“There is an ongoing conversation to make sure the (PHDC) is fulfilling the goals of protecting the city’s unique historic character, while also responding to the needs of property owners,” said Bonnie Nickerson, Providence’s director of planning and development.

In recent years, homeowners living in local historic districts have been adopting solar panels. This sparked the commission to engage in a public process that resulted in guidelines for adding solar panels to historic homes. The guidelines were followed by a series of regulations, which have helped homeowners clearly understand how to appropriately incorporate solar panels on their properties.

Since the regulations were enacted, no application for solar panels has been denied, according to Nickerson.