A commercial unit of electric energy. One kilowatt year represents the amount of energy delivered at a rate of 1000 watts over a period of one year. This equals 8760 kilowatt hours for an ordinary (365 day) year or 8784 kilowatt hours for a leap year. For greater accuracy, it's best to use 365.25 days per year; with this definition, the kilowatt year is exactly 8766 kilowatt hours or 31.5576 gigajoules; this is about 1.2463 million Btu or 969.8 million foot-pounds