Real-estate developers aren't exactly known as tree huggers. And a city-block-sized, mixed-use office-and-residential tower isn't exactly a yurt. But Mark Edlen, the managing principal of Portland, Oregon--based Gerding Edlen Development, figured that building the tower made him a conservationist since it saved the equivalent of 70 acres of suburban land. He has since gone on to develop nearly $4 billion worth of high-quality, environmentally sustainable buildings. One recent example: Oregon Health and Science University's new 16-story bioscience center (above) is on track to become the largest U.S. building ever to receive a Leadership in Energy and Environmental Design (LEED) platinum rating. For years, Edlen has been a passionate proponent of the notion that building green is not just the responsible thing to do but also the competitive thing to do. If today's commercial structures don't achieve radical savings in the energy and water they consume, he says, they'll soon be at a significant cost disadvantage. That's why he has set a goal of making all his new designs produce more energy than they consume and consume more waste than they produce within five years. Can he get there? "I'm 100% confident that if we don't try," he replies, "we won't make it."