In the discussion of energy conservation, a great deal of attention has focused on mandated efficiency standards for cars and energy-using household appliances. (In this article, I will use the term "appliance" in a generic sense to cover household durables). Unfortunately, the estimates of energy savings predicted to result from these mandated standards are derived mechanically.' When mandated standards raise the appliance efficiency by 1 percent, demand is predicted to drop by 1 percent; when they raise efficiency by 2 percent, demand is predicted to drop by 2 percent; and so on. Examples of such results are found in reports by the Department of Energy (1979a, 1980) and by the Staff of the California Energy Commission (1979) on energy demand in California in the coming two decades.