• Credit: Sarah Hanson

The greenest construction project starts with an existing building. That much is certain. Building reuse conserves resources and energy while diverting massive amounts of waste from the landfill—as preservation architects are quick to point out. In fact, the perspectives of architects who specialize in preservation and those who specialize in sustainability (often portrayed as contrasting) share a view through the same window. But it’s the frame of the window that’s up for grabs. Sometimes literally.

“With some of the certification programs like LEED, there’s been a huge emphasis on replacing windows in historic buildings, which I think is a mistake,” says Glenn Keyes, AIA, a preservation architect in Charleston, S.C. Keyes readily admits that new windows are more efficient, but are almost always clad in vinyl or aluminum and don’t match the historic windows.

“Windows are such a character-defining element in historic buildings,” he says. “Instead of replacing them, a second pane may be routed into the sash if it’s thick enough—which is often the case with early-20th-century buildings, for instance.” Another alternative, according to Keyes, is an interior storm window behind the historic window to improve efficiency without compromising integrity. Besides the window issue, there are other points of contention. The preservation community is often regarded as stubborn and unyielding to compromise—even when the expense of replacing features on buildings with authentic materials is hard to justify.

On the other hand, the sustainability camp is sometimes seen as shortsighted in its emphasis on measuring energy efficiency by square footage, which may encourage larger-than-necessary projects and the use of cheaper materials with shorter service lives, according to Jean Carroon, FAIA, a Boston architect, chair of the AIA Historic Resources Committee, and author of Sustainable Preservation: Greening Existing Buildings.

“The preservation community represents a kind of frontline protest against needless waste and our throwaway culture,” she says. But Carroon believes there are reasons for each camp to be encouraged. Many older buildings are inherently efficient, Keyes points out. “A lot of what’s being proposed today has been practiced historically before mechanical systems became prevalent for heating and cooling,” he says, noting that a lot of homes built between 1960 and 1990 are incredibly inefficient. “But even with inefficient buildings,” he says, “there’s a lot to overcome when you tear them down, and it’s almost always better all around to improve what’s there.”

Preservation Green Lab, a Seattle-based research initiative launched by the National Trust for Historic Preservation in 2009, agrees. In its January 2012 report, “The Greenest Building: Quantifying the Environmental Value of Building Reuse,” the National Trust claims that “it takes 10 to 80 years for a new building that is 30 percent more efficient than an average-performing existing building to overcome, through efficient operations, the negative climate change impacts related to the construction process.”

The benefits of reuse are harder to quantify. “I think the intangible quality that doesn’t fall strictly into sustainability or preservation is the role that historic homes play in the tapestry of a community,” says Kevin Eronimous, AIA, a sustainability architect in Denver who lives in a renovated 1908 bungalow in a neighborhood of older homes. “Living in a walkable neighborhood within five miles of downtown, connected by a bike path, has a value that can’t be measured in energy and materials.”—Ben Ikenson