Reusing existing buildings is inherently sustainable, but it’s often messy, and the old South Hills High School was no exception. Imagine shoveling out 10 tons of avian waste and abating, piece by piece, oak floors and doors ruined by rain. (The behemoth building had sat vacant for 35 years while the roof rotted and birds flew through.)

Yet transforming it into 106 affordable and market-rate seniors apartments was more than a symbolic gesture. The design team calculated that the embodied energy saved was equal to roughly 5 gallons of gasoline per square foot, translating into 15 years of projected energy expenses for the landmark building.

To make the project work financially and programmatically, a dimly lit shop wing and auditorium were removed, though the balcony’s ornate hand railings were salvaged. R-50 closed-cell foam sprayed on the existing roof deck boosted insulation values.

Brick wall interiors were layered with 2 inches of spray foam, then stuffed with R-19 fiberglass batts between metal studs. And the gas-powered cogeneration plant, combined with a 26-kW PV array, is projected to reduce operating costs to $161,000 per year, from $237,000 for an ASHRAE-compliant building.

Despite the building’s gifts—tall windows and grand volumes—many developers, daunted by the construction challenges, had passed on this project.

“To get it accomplished, our client had about seven funding sources; it wasn’t a slam dunk,” says architect Laura Nettleton of Thoughtful Balance. “I feel best about the quality we achieved for the amount of money spent. It feels like a boutique hotel.”