The new nature center at my alma mater, Calvin College, sounds pretty cool:

The Bunker Interpretive Center is a largely self-sustaining entity, independent of the city's sewer system and taking more than 60 percent of its operating power from a photovoltaic array on its roof. Much of the center - including paneling, insulation and interior trim - is built of recycled materials. On days the weather permits, the windows open automatically to heat and cool the building. Gray water (from sinks) is recycled through a biomass, a large window box filled with plants that filter the water and return it to preserve ponds. Waste is processed through chemical composting toilets. The soil from those toilets, processed by worms, will eventually enrich the center's landscaping - all indigenous plants grown in the preserve.