GC: n

CT: Electricity used at any moment is measured in watts. It only makes sense that a 100-watt bulb uses 100 watts of electricity. A desktop computer uses about 65 watts and a central air conditioner uses about 3,500 watts. Since all of the watts add up quickly, the term kilowatt is used to represent 1000 watts. To understand how much energy you’re using you also have to consider how long you run your appliances. When you use 1000 watts for an hour, that’s a kilowatt-hour. The key is to reduce the number of kilowatt hours you use each month in order to save money and our natural resources…

S: http://www.stevespanglerscience.com/lab/experiments/how-much-is-a-kilowatt (last access: 19 December 2014)

N: 1. kilowatt (n): 1884, from kilo- + watt. Kilowatt hour is from 1892.
hour (n): mid-13c., from Old French hore “one-twelfth of a day” (sunrise to sunset), from Latin hora “hour, time, season,” from Greek hora “any limited time,” from PIE yor-a-, from root yer- “year, season”. Greek hora was “a season; ‘the season;'” in classical times, sometimes, “a part of the day,” such as morning, evening, noon, night.
The Greek astronomers apparently borrowed the notion of dividing the day into twelve parts (mentioned in Herodotus) from the Babylonians (night continued to be divided into four watches), but as the amount of daylight changed throughout the year, the hours were not fixed or of equal length. Equinoctal hours did not become established in Europe until the 4c., and as late as 16c. distinction sometimes was made between temporary (unequal) hours and sidereal (equal) ones. The h- has persisted in this word despite not being pronounced since Roman times. Replaced Old English tid, literally “time” and stund “period of time, point of time, hour” (compare German Stunde “hour”), As a measure of distance (“the distance that can be covered in an hour”) it is recorded from 1785.
2. The watt-hour (symbol W·h or Wh) is a unit of energy. It is most commonly used on household electricity meters in the form of the kilowatt-hour (kW·h or kWh), which is 1,000 watt-hours. It is not used in the International System of Units (SI), despite being based on the watt, as the hour is not a SI unit. The SI unit of energy is the joule (J), equal to one watt-second. It is, however, a commonly used unit, especially for measuring electric energy. 1 watt-hour is equivalent to 3,600 joules (1 W x 3600 s), the joule being the canonical SI unit of energy. Thus a kilowatt-hour is 3,600,000 joules or 3.6 megajoules. … The kilowatt-hour is commonly used for electrical and natural gas energy. Many electric utility companies use the kilowatt-hour for billing.
3. Megawatt-hours are used for metering of larger amounts of electrical energy. For example, a power plant’s daily output is likely to be measured in megawatt-hours.
4. plural: kilowatt-hours or kilowatthours. Lots of variants can be found, but they should be avoided: kilowattshours, kilowatts hour, kilowatts hours, kilowatt hours, kilowatts-hour, kilowatts-hours, kilowatts/hour, kilowatts/hours, kilowatt/hours.

S: 1. OED – http://www.etymonline.com/index.php?allowed_in_frame=0&search=kilowatt&searchmode=none (last access: 19 December 2014). 2, 3 & 4. TERMIUMPLUS.

SYN: kilowatthour, kWh.

S: GDT

CR: electrical energy, electric substation, kilowatt, megawatt , [power station], watt, wind energy.