A full refrigerator uses less energy to operate than an empty one.
Remember that dishwashers use less water than washing dishes by hand, about 6 gallons less per load; dishwashers also use hotter water than you would use if you were washing the dishes by hand, so they can do a better job of killing germs.
According to the U.S. Department of Energy, in 1997 the average house spent over $1300 in energy costs. 44% of those costs, or about $600, came from heating and cooling. Yet, by setting the thermostat down just one degree a home could, over an eight-hour period, reduce energy costs by 1%. Doesn't sound like much? Look at the math: If you set the thermostat back by 10 degrees for the eight nighttime sleeping hours, and did this for a whole month you could lower your monthly bill by 10 percent. Do the same for the eight hours you're at work and you're looking at 20 percent. For the average home this could mean a $20 savings on the monthly heating costs with similar savings for the cooling season. A programmable thermostat can ensure those savings and pay for itself in one season.