Aaron Peskin was working on the Green Building Ordinance last year, the big question was how to create incentives encouraging people to reuse historic buildings. They devised a system awarding points toward their mandated green building requirement for retaining historic features, and keeping the windows represents a big chunk of the points.

"It's about the truth of the building and the preservation ethos," said Cara Bertron, Page and Turnbull's cultural resources specialist. "Those are really hard things to articulate to people who may see the energy savings as worth it."

For more information, including details on upcoming events on greening historic homes, visit www.aiasf.org and www.builditgreen.org.