Your building has the potential to change the world. Existing buildings consume approximately 40 percent of the energy and emit nearly half of the carbon dioxide in the US each year. In recognition of the significant contribution of buildings to climate change, the idea of building green has become increasingly popular. But is it enough? If an energy-efficient building is new construction, it may take 10 to 80 years to overcome the climate change impacts of the building process. New buildings are sexy, but few realize the value in existing buildings and how easy it is to get to "zero energy"...