Don’t Tear Down That Old Building: Retrofit For Energy Efficiency

“The most sustainable building is the one you don’t build,” says Tamar Warburg, director of sustainability at Sasaki, a Boston design firm specializing in Architecture, Interior Design, Planning and Urban Design, Landscape Architecture and Space Planning, among other disciplines.

Very old structures were built with regard for energy efficiency, but when heating fuel became cheap and easily available, the regard shifted to views through big windows, large rooms flowing into each other, high ceilings and big boilers laboring wastefully in basements.

Then air conditioning became commonplace, and all regard for what we now call ‘sustainability’ went, well, out the window.

“Buildings built before the popularity of air conditioning had openable windows, ceiling fans, passive strategies for cooling like porches,” Warburg says. “Thermal comfort is now dependent on high energy use.” 

She points out that one half of carbon emissions globally come from the built environment.

“Before you begin any building project, you have to consider the carbon embedded in the materials, as well as the operational carbon in things like heating systems,” she says. “Consider the source of the energy, not just the amount. Don’t just look at the investment cost, look at the overall lifetime cost and determine: where’s the break-even point?”

“If we re-use and upgrade existing buildings, we are greener on every front.”

Rebecca Berry is the president of Finegold Alexander Architects, a Boston firm that received the first AIA Honor Award for Extended Use for the 1976 conversion of Boston’s Old City Hall to a private office and restaurant use. Other notable projects include Ellis Island National Monument and Museum and Boston’s Bulfinch-designed Massachusetts State House.

“Retrofitting buildings creates jobs,” says Berry who, over 50 years, has worked on hundreds of historic buildings, including more than 40 structures on the National Register of Historic Places. 

“Different buildings present different levels of opportunity to fine tune them,” she says. “Generally speaking, when we talk about making an older building energy efficient, we think about the envelope: the windows, walls, door openings, etcetera. 

“With windows, the first line of action is always to repair, preserve and seal the original windows. For example, a few years ago, we worked on a small – only 15,000 square feet – but historically important building at Boston University. All the old wood windows were taken off site, repaired and then sealed. In another project, that was impossible – the old windows had been replaced. We replaced them with double-paned replicas of the originals.”

Walls are surprisingly problematic. Stone, for example, is porous. When used as a house’s exterior wall, it is meant to breathe.

“In those cases, we do careful calculations and figure out how we can add interior insulation,” Berry says.

Both she and Warburg recommend replacing outdated heating and cooling systems in older buildings with heat pumps. 

“We want to get away from electric resistance heat like electric radiators, which are not very efficient and very expensive to run, and use variable flow electric technology, like heat pumps.

“Heat pumps are great as long as you have a good building envelope.”

Berry also touts the use of energy recovery ventilators to boost the efficiency of cooling systems.

She says that the most difficult architectural style to retrofit for energy efficiency is that of a 1960s Brutalist building.

“The concrete envelope and the structure are one, and very porous. The only way to do it is with mechanical changes, like windows.”

Tamar Warburg sees the design landscape trending green.

“A lot of thoughtful, sustainable building is happening today, especially along the coasts in California and the Northeast, the Pacific Northwest, Chicago and other places,” she says. “Renewable energy is at a strong level of consciousness all across the country, at all levels. In fact, in 2020, 20 percent of U.S. electricity came from renewable sources.”

The trend towards old buildings is very real: Sasaki is moving from its long-term offices in Watertown, a Boston suburb, to a historically important 1890s building in the heart of Boston’s downtown.

This post first appeared on Forbes.com. To see the original, click here.