Back in the 1970s, efficiency was about turning out the lights. Today, says Paul Scheckel, author of The Home Energy Diet, "it's about taking advantage of technology to do the same things better." Largely as a result of technological advances, the U.S. now uses 47 percent less energy per dollar of economic output than it did 30 years ago. Unfortunately, because of supply-side inefficiences, a lot of the energy we make is wasted by the time it reaches our homes and offices. Consumers can't do much about that, but it's easy to make an effort at home-and to see it pay off in lower bills. "I call it â€negawatts,' " says Amory Lovins of the Rocky Mountain Institute. "There's no cheaper or cleaner power than the power you don't produce."