The historic Oakland Museum building, originally designed by Eero Saarinen and Kevin Roche, is a three-story, concrete structure with layered rooftop gardens, fish pools and large indoor galleries. As part of a major effort by the City of Oakland to promote Green Building Design, we were hired to dramatically lower energy use and provide better environmental controls for the building while maintaining its historical integrity. Rumsey Engineers joined CommAir mechanical as a design/build team, which turned over the new mechanical to the Museum after full commissioning and testing. We received a national award from ASHRAE for our work on the project, which resulted in an overall 65% annual energy savings (over $70,000,) and secured $250,000 in energy efficiency rebates.