For all the talk about sustainable building in new construction, a more pressing issue often missing from the conversation is America’s existing stock of energy-inefficient housing units. The Glanville Residence in Newton, Mass., used to be one of those houses—until Boston-based ZeroEnergy Design (ZED) gave it a high-performance energy upgrade.

The 4,570-square-foot Craftsman, which Boston architect James H. Ritchie designed for himself in 1912, was in relatively good architectural and structural shape. Ritchie included many of the latest features and construction technologies available to him at the time, and the home’s second owner—another architect—made minor improvements and renovated the kitchen.

Still, the house was built in the 20th century and clearly needed to be brought into the new millennium. “Using infrared cameras, we found that the wall insulation wasn’t too bad and wasn’t sagging,” says project architect Stephanie Horo­witz, AIA, ZED’s managing director. “But the roof insulation was barely meeting code and was a great source of energy loss.” The firm also performed blower door tests to obtain a more complete energy-performance picture.

Armed with the data, the ZED team removed the roof’s existing wool insulation, sprayed 6 inches of foam into the ceiling, and insulated the basement walls. They also completely overhauled the mechanical system, adding a high-efficiency boiler and installing new ducts in the conditioned attic space. A new heat recovery ventilator helps bring in fresh air, and 54 Energy Star–rated windows tighten the building envelope. For good measure, they added low-flow fixtures, recycled glass tile in the remodeled bathrooms, and a rainwater collection system.

Updating an old house—especially one whose life history spans nearly a century—is a challenge, but not in the way you might think. The technology is readily available, Horowitz says, but budget limitations can complicate matters considerably. Building a home from the ground up “achieves greater efficiency and higher levels of [energy] performance,” she admits, but if it’s done in the right way, upgrading an old house can significantly benefit both the environment and the client—as it did in this case. “The occupants are comfortable, the home isn’t drafty anymore, and the livability is very much improved.”