It's true; using a dishwasher consumes less water and energy than washing dishes by hand and letting the water run. Just be sure you get an energy- and water-efficient dishwasher to be extra safe.

To compare the efficiency of your options, look for the yellow and black EnergyGuide label. In addition to noting the specific model's estimated annual energy usage and estimated annual dollar operating cost, the label also includes low and high estimates for similar appliances.

The energy efficiency of dishwashers is measured by the average number of cycles they go through per kilowatt hour per year. This is called the Energy Factor, or EF, and the higher it is, the more efficient the dishwasher. Per federal appliance standards, a standard dishwasher (one that holds at least eight place settings and six serving pieces) must have an EF of 0.46, while a compact dishwasher must have a 0.62 EF.

Dishwashers that qualify for the Energy Star program-signified by a blue-and-white logo featuring a star-exceed the federal efficiency guidelines by 41 percent, for an EF of 0.65 for standard dishwashers and 0.88 for compact models. The Energy Star Web site, www.energystar.gov, offers more information about home energy efficiency, including special offers or rebates and a list of Energy Star qualified appliances.

A dishwasher's energy is spent mostly on heating up the water. Dishwashers vary in how much water they use, depending both on the model and the cycle selected. The amount ranges from 3 to 15 gallons per load, with an average of about 9 gallons, according to the American Water Works Association. The more water the dishwasher uses, the more energy that is being used.

Features that make a dishwasher more energy efficient include: