Most of the energy used by dishwashers is actually the
energy required for heating the water they consume. So the most efficient
dishwashers use less water to do the job.
Most dishwashers available today use booster heaters to add
heat to the water that is supplied by the water heater. This helps get your
dishes cleaner, and it may kill more germs. But it also allows you to lower the
temperature setting on your water heater. With this type of booster, you can
lower your current water-heater water temperature to about 120° F and still
have clean and sanitary dishes.
Newer dishwashers also use significantly less water than
hand washing – as much as one-half less. Like clothes washers, dishwashers conserve energy and water when using
their low and medium cycles. Water usage varies from a low of 7 gallons, for the
light wash, to a high of 14 gallons for the heavy-duty cycle.
Many of the most efficient dishwashers incorporate
soil-sensors to adjust water use depending on how dirty the dishes are in each
load washed. An improved dishwasher test procedure, used to provide the
information on the EnergyGuide labels, gives a more realistic estimate of the
energy consumption of soil-sensing dishwasher models. Be sure to read the
EnergyGuide labels whenever you buy a new dishwasher or other appliance.
Recent studies have shown that most new dishwashers do a
great job cleaning even the dirtiest dishes without pre-rinsing. In a recent
study, dishwashers were compared to doing the job by hand. The dishwasher was
more efficient and got the dishes cleaner than its human counterparts.