The Green Microgym is the first renewable–energy-generating gym in the United States. The flooring is cork. The wall art is local. The paper is made of recycled materials. The toilets are low-flow and dual-flush. The equipment is low-energy. But the biggest energy savings come from the gym's two cardio rooms. The grid-tied treadmills, ellipticals, and spin bikes actually generate electricity and pump it back into the gym, a perfect energy complement to the solar paneling on the roof. When you run, so does everything else, from the TV to the music to the lights to the ceiling fans.