World's greenest office building opening in Seattle

Tenants are now moving into Seattle's Bullitt Center, said to be the largest structure in the world yet to qualify for the Living Building Challenge, a particularly rigorous standard in sustainable building. Greenness means that the building can not contribute any waste to the environment. The structure can only use as much water as it can collect. And it must be powered only by as much energy as it can generate itself. In addition, all the heavy building materials like concrete and steel must come from within 300 miles of the site.