U.S. energy consumption is typically broken out by sector as in the above left. But some big brained people associated with Architecture 2030 recognized the importance of separating out the impact of buildings — a big chunk of the industrial, commercial, and residential sectors — and created the pie on the right, which shows that buildings account for just about half of total U.S. energy consumption. Methinks the majority of the public is not aware that buildings have such a large impact. We seem much more inclined to focus our attention on transportation. Since CO2 emissions are roughly proportional to energy use, our biggest opportunity for reducing GHG emissions is to make our buildings more efficient.