More than half of the energy used by a dishwasher goes towards heating the water. In fact, water heating accounts for approximately 60% of total energy use by dishwashers. Models that use less water also use less energy. Thanks to national efficiency standards, first effective in 1994, the energy and water consumed by dishwashers has dropped dramatically — energy use is now capped at 307 kWh/year and while older models typically used 8 to 14 gallons of water, new models can use no more than 5.0 gallons per cycle. ENERGY STAR models can use no more than 4.25 gallons; the best units use as little as 2.0 gallons per cycle. Even as dishwashers have become more miserly in their water use, they have made great strides in cleaning performance. ENERGY STAR has developed a method for testing cleaning performance; expect criteria for cleaning to become part of a future ENERGY STAR specification.