A diversity of windows on Boston’s Beacon Hill. Image credit: Kristina D.C. Hoeppner (CC BY-SA 2.0)

The original sash was retained in this restoration. There is no insulated glass, but a matching storm window has been installed. Image credit: Ric Panciera.
This restoration incorporated a modern vinyl window with flat muntins. The original sash has been removed. Image credit: Ric Panciera
Historic window with muntins and installed storm window, South Side Historic District, Corning, New York. Image credit: Stilfehler (CC-BY-SA-4.0)

Single-hung window with 15-lite top sash, South Side Historic District, Corning, New York. Image credit: Stilfehler (CC-BY-SA-4.0)

What Working with Historic Buildings Has Taught Me: Historic Preservation, Windows, and Sustainability

by Ric Panciera AIA, LEED AP
Friday, 10 September 2021

This is the first installment of a multiple-part discussion on historic buildings from ABA Senior Associate and Senior Technical Architect Ric Panciera. Ric guides ABA's quality control and assurance programs, and his deep expertise in building technology, materials, and construction systems shapes our studio's technical, preservation, and design approaches to historic buildings.

Historic preservation is an old topic, and I'm certainly not the first person to underscore the following preservation-related issues. But I'd like to present an inquiry into the obstacles that professionals, homeowners, and building owners face when forced to choose between maintaining original windows in historic buildings and the need to be responsible in terms of energy use and comfort. To say that these two issues are at odds with one another is an understatement. I have no immediate answers or long-term solutions, but I would like to open a discussion on the topic.

Many towns and cities have historic preservation boards, most of which are advisory, not regulatory. In addition, most local historic districts have guidelines that correspond to the Secretary of the Interior's Standards for Preservation and Rehabilitation. These standards, written long ago, are the cornerstones of the preservation movement that began when people realized we were losing many of our cherished older buildings to new construction. Something had to be done.

As a member of a local historic preservation commission, I'm often conflicted between interpreting the standards, which appear quite clear, and my obligation to be a design professional, whose responsibilities may not be clear at all. People looking for relief from the requirement to preserve what they perceive as leaky, damaged relics from the distant past look to the wisdom of the board, the members of which may also have differing opinions from one another on this subject. 

What's the deal with windows?

Preservation boards usually have jurisdiction only over the exterior of buildings, and even then, they usually can regulate only the parts that are visible from a public way, including openings such as doors and windows. On many historic buildings, the windows are perhaps the most identifiable character-defining feature. Original wood sash and frame windows, double-hung or casement, are composed of multiple panes of a single piece of glass, held fast by a mineral-based glazing putty in an amazingly thin wood muntin framing system. The glass sits in a wood frame that penetrates the building's wall with projecting wood sills and wide casings. If the windows are really old, the glass appears wavy, figured and unmistakably the result of hand-blowing and flattening.

Many historic windows were hand-made and glazed on the construction site. Much like weaving and barrel-making, casting glass for a window was a craft. Would you throw out a perfectly useable heirloom quilt or wicker basket? That's a good question, and this logic enters the realm of thinking for preservationists and architects quite often. But it's not nostalgia that drives us here, it's the loss of detail, of old-growth wood and hand-blown glass, of the shadow lines that define the construction of the sash. This potential loss feeds a longing to convince others that new is not always better.

Many of us aren't often fooled by modern historic-looking windows, which, despite all efforts to appear like the old sash, just don't duplicate the original feel and texture. Muntins are often wider and flatter in newer windows. Windowsills are only vestigial, or they've been removed entirely. There's often a noticeable reflection in the glass from insulated double glazing, and simulated divided lites are just that—an imitation. Gone is the craft and the delicacy.

Windows, Sustainability, and Climate Change

Local historic preservation and conservation boards, mostly staffed by volunteers from the design, real estate, and legal professions, are under full attack from the rapidly growing climate change army, whose arguments for high-performing envelopes in historic buildings shouldn't be ignored. Many of us preservationists argue, and we wave studies to prove our position, that an original single-glazed window, if restored, weather-stripped, and placed behind a decent storm sash, is just as good a thermal performer as a modern insulated glass window.

We also argue that reusing the original window is more broadly sustainable. With a traditional wood sash, you can simply remove the broken glass panel and reglaze the sash. Isn't saving the original window frames, made with dense, old-growth wood, greener than throwing material in the landfills and replacing it with quick-growing wood, which has a short life cycle, or synthetic materials, which consume energy to manufacture and transport, cannot be recycled, and only add to the problem of waste? Buildings do not have interchangeable parts like automobiles. It seems like madness to throw away an entire window assembly and replace it with a new one when the insulated glass panel fails.

At this point, the building scientist / nature-lover / be-gentle-to-Earth person in each of us begins to emerge. However, each preservation hearing delivers at least one applicant who reads and understands the preservation guidelines yet must have new windows. Notwithstanding research, testing, and an overabundance of building materials in landfills, we're rapidly losing ground on arguments based on sustainability and green practices. We're even being told that these aren't issues an historic preservation commission should be discussing. Here are the big reasons why we are challenged:

  1. Money. It costs a significant amount to restore, weatherstrip, re-install, and cover an old sash and frame with a storm window. Less expensive new windows flood the market and are readily available at home centers and lumber yards.
  2. Scarcity of restorers. Even in the Northeast, home to perhaps the greatest number of historic wood sashes still in service in the US, experts who do this work are few and in high demand.
  3. Marketing. It's hard for the homeowner to ignore commercials—the hype, the claims of better and stronger, the promise of more energy efficiency and no drafts, and the offers of "buy two and get two windows free" with "free installation." Eventually, even the greenest homeowner with the staunchest conviction to preserve and protect begins to drown in the deep waters of marketing campaigns.
  4. The myth that new windows save energy. True, windows that seal well and don't let cold air into a building do save some energy, and double glazing offers a minor performance improvement. In practice, however, window replacement isn't the first step to take if saving energy is the goal. Studies have shown it's better to insulate the walls first, followed by roofs, ceilings, and floors, before replacing windows.
  5. Lack of appreciation for owning a historic home. Many people who choose to own older houses may not be aware that buying a home in a historic district, or buying any older home, comes with some responsibility and appreciation for the building's history.

What to do?

Conflicts between preserving existing historic fabric and saving the planet are real. The practice of treating each case reviewed by the local boards on its individual merits, thankfully, is our salvation from being totally overcome by the sustainability movement and our own internal conflicts. When I wear my historic preservation hat, I sadly realize that we can't save every old window and every old house simply because they're old and have intrinsic historic character. We also shouldn't knock down and obliterate our past simply because it doesn't fit the values and the economics of the present. If we're to truly move into this century regarding historic preservation, progress needs to be made in our treatment of historic buildings so it strikes a balance between preservation and sustainability. We all want to live in safe and comfortable places, admire the character of the historic buildings we live in, and to continue to appreciate those buildings that compose the durable character of our neighborhoods and communities for our lifetime and years to come.

Historic windows are a hot-button issue for homeowners and historic boards, and despite the guidelines, there are no easy answers. Applying logic and economics may steer the conversation but not solve the problem. Stewardship of historic buildings is sorely missing when it comes to windows, but there isn't a "one-size-fits-all" approach. It will take some breaking down of the rigid requirements set in motion many years past before we find our way forward. Helping people understand the historic significance of their homes is a first step. Sharing research on energy efficiency in historic buildings more broadly may also help. There are options for preserving the character-defining features of older buildings while allowing for modifications that enhance the energy performance, yet without a clear understanding of these options, historic windows may still end up a casualty. As community members and experts in preservation, we can help homeowners understand the value of their property and help establish priorities that may lead to conservation of significant historic features.