Tom Silva sealing air gaps in windows with canned spray foam
Photo: Anthony Tieuli

For Efficiency's Sake

John Stone and Sally Peterson knew they had a big renovation on their hands when they bought a three-story 1887 Queen Anne in Cambridge, Massachusetts. It needed not only a new layout to accommodate their family of four but also, not surprisingly, overhauls of its drafty windows, underinsulated walls, and century-old boiler-and-radiator heating system. With a project of this scope, just bringing the house up to modern building codes would have provided dramatic improvements in energy usage. But as long as the walls were being opened up, the homeowners opted to invest in a number of efficiency upgrades—some simple, some more complex. "Making our house energy efficient is going to minimize our monthly bills and keep us more comfortable in winter and summer," says John. Here's a brief overview of the systems they've chosen to achieve these goals.

Sealing The Envelope
As with any home built before the days of insulation, house wrap, and double-pane windows, there'd be little point in installing high-efficiency HVAC equipment without first buttoning up the leaky exterior shell. TOH TV general contractor Tom Silva applied spray foam insulation, which yields slightly-better-than-code R-43 in the roof and R-21 in the walls. The foam, which requires professional installation, is about two to three times the cost of fiberglass batts but offers two to three times the effectiveness. And because it fills every crack and void, creates a vapor barrier, and won't settle over time, it eliminates drafts, too.

But a wall is only as airtight as its windows. Fixing the existing ones proved too expensive, so Tom replaced the rattly old sashes with high-performance wood units by Marvin that have simulated divided lights, insulating argon gas between the panes, and an invisible metallic low-emissivity, or low-e, coating that blocks heat loss. Windows like these typically start at $600 to $700 each but can reduce energy loss by 30 to 50 percent.

Shown: TOH general contractor Tom Silva uses canned spray foam to seal air gaps around new Marvin windows. To accommodate the local historic district's request that the windows look authentic, he ordered units with a putty detail on the outside—a flat, diagonal profile around each simulated light that mimics the look of the glazier's putty once used to hold panes of glass in place—instead of the usual quarter-round molding.
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