Problems With Dishwasher Energy Ratings

Wouldn’t it be nice, in shopping for a dishwasher, if you could go down to your appliance store, review the EnergyGuide labels or Energy Star™ designations, and be confident that you were really getting an energy-efficient dishwasher? It would be nice, but it’s not the case. Due to a glitch in the DOE efficiency test procedure for dishwashers, models are being grossly mislabeled regarding their energy performance.

Here’s the problem: Years ago, DOE came up with a standardized procedure for measuring the efficiency of dishwashers—this test calls for filling the dishwasher with clean dishes and measuring water and energy consumption through a wash cycle. (Most of the energy consumption with dishwashing is associated with heating the water—either externally, through a water heater, or internally in the dishwasher.) That used to be fine because dishwashers used the same amount of water (and energy) whether the dishes were dirty or clean. But over the past few years, manufacturers have introduced advanced dishwashers with sensors that measure how dirty the dishes are and adjust the hot water use accordingly. These sensors have photoelectric eyes that sense the turbidity of the wash water. Roughly 40% of dishwashers manufactured today are equipped with this sensor technology, according to Consumers Union, publisher of

Consumer Reports.