The College's Center for Environmental Studies was selected by the Department of Energy as one of the 30 "milestone" buildings of the twentieth century, and would be LEED Platinum-certified had it not been built before the advent of the LEED system. The building design was spearheaded by renowned environmental studies professor David Orr, who also chairs the College's environmental studies program. The building has enough solar panels to supply excess energy to the local grid. An innovative "living machine" provides a closed-loop water use, cleansing, and re-use system. The Environmental Studies Laboratory is registered under the LEED certification program, part of the College's policy requiring all new building to meet LEED Silver certification, at a minimum.