<P> An electric heater rated at 1000 watts (1 kilowatt), operating for one hour uses one kilowatt hour (equivalent to 3.6 megajoules) of energy . A television rated at 100 watts operating for 10 hours continuously uses one kilowatt hour . A 40 - watt electric appliance operating continuously for 25 hours uses one kilowatt hour . In terms of human power, a healthy adult male manual laborer will perform work equal to about half a kilowatt hour over an eight hour day . </P> <P> Electrical energy is often sold in kilowatt hours . The cost of running an electric device is calculated by multiplying the device's power in kilowatts, by the running time in hours, by the price per kilowatt hour . The unit price of electricity may depend upon the rate of consumption and the time of day . Industrial users may also have extra charges according to their peak usage and the power factor . </P> <P> Whereas individual homes only pay for the kilowatt hours consumed, commercial buildings and institutions also pay for peak power consumption, the greatest power recorded in a fairly short time, such as 15 minutes . This compensates the power company for maintaining the infrastructure needed to provide peak power . These charges are billed as demand charges . </P> <P> Major energy production or consumption is often expressed as terawatt hours (TW ⋅ h) for a given period that is often a calendar year or financial year . A 365 - day year equals to 8,760 hours, therefore over a period of one year, a power of one gigawatt equates to 8.76 terawatt hours of energy . Conversely, one terawatt hour is equal to a sustained power of approximately 114 megawatts for a period of one year . </P>

What is a kilowatt hour in real time