Microwave ovens cook or heat food and beverages by converting electricity to microwave radiation to heat water molecules within the substance.
DOE established the first efficiency standards for microwave ovens in 2013, and they took effect in 2016. The new standards specify a maximum standby power of 1 watt for microwave-only ovens and countertop combination microwave ovens and 2.2 watts for built-in and over-the-range combination microwave ovens.
More than 95% of US households own a microwave. DOE identified several technology options that could reduce power consumption in standby mode including lower-power display options; cooking sensors with no standby power requirement; improved power supply and control board options; and automatic power-down. Adding an automatic power-down element, which turns off most power-consuming components after a period of inactivity, can allow for achieving standby power levels of less than 1 watt.