The Bay School of San Francisco is an independent high school with an academic emphasis on science, technology, and ethics—and their crucial interrelationships. This conversion of a historic landmark Army barracks into a start-up independent high school weaves together historic preservation, adaptive reuse, and environmental responsibility, creating spaces that teach. Designed to serve a student body of 400 with 22 classrooms and seminar spaces, six sophisticated laboratories, art and music spaces, a 22,000-volume library, student center and dining room, the high performance design integrates resource-efficient design strategies, building systems and materials throughout and is estimated to require less than half the energy consumption required to construct and operate a new school building of comparable size.