It's hard to overstate the potential (and necessity) of greening our existing building stock. Buildings account for 73% of electricity consumption in the U.S. and 38% of CO2 emissions. Can you imagine the dent we can make with added efficiency in this sector - environmentally and economically? Plus, existing buildings are all around us. Chances are, you're inside of a building (an existing one) as you read this blog entry - talk about an accessible opportunity.