Steven Chu, Ph.D, the U.S. Energy Secretary, has a Facebook page. I have no idea if it's actually him posting, but I'm still a fan, meaning I get regular updates. Yesterday, he posted this chart that shows exactly where the 40% of energy used in the U.S. by buildings goes. This is not new information to me--I've heard it several times before in various ways--but it is an unusually powerful graphical representation. You can see immediately that while heating is a big energy hog in residences, lighting is the big deal in commercial buildings. I love this kind of graphic: it's simple, straightforward, and contains a whole lot of information that easily accessible. Now, if only the psychrometric chart were this easy!