The total electrical energy consumed by a device when it is operating, usually for a given period of time. The usual unit of power consumption is the kilowatt hour (kWh), which corresponds to the energy consumed by an appliance with a power rating of 1kW over a period of one hour. So a 2kW appliance running for three hours consumes 6kWh of electricity. The term ‘power consumption’ is a misnomer, as it actually refers to energy consumed (strictly speaking, power is the rate at which energy is consumed).