The dramatic, 647,000-square-foot PNC Firstside Center in downtown Pittsburgh boasts a magnificent facade of curving glass, steel, and stone overlooking the Monongahela River. The winner of several design awards, the building rises from a large plaza graced with waterfalls and fountains. Its airy, light-filled interior has 11-foot ceilings, floor-to-ceiling windows, an atrium, an open floor plan, and all the latest building system technologies, including individual climate controls. What most observers don’t realize is that this is a “green,” or environmentally and economically sustainable, workplace—and that it costs 20% less per square foot to operate than its comparably sized “standard” sister building in Philadelphia.

A version of this article appeared in the June 2006 issue of Harvard Business Review.