The kilowatt hour, or kilowatt-hour, (symbol kW·h, kW h or kWh) is a unit of energy equal to 1000 watt hours or 3.6 megajoules. For constant power, energy in watt hours is the product of power in watts and time in hours. The kilowatt hour is most commonly known as a billing unit for energy delivered to consumers by electric utilities.

The kilowatt-hour (symbolized kWh) is a unit of energy equivalent to one kilowatt (1 kW) of power expended for one hour (1 h) of time.

Inversely, one watt is equal to 1 J/s. One kilowatt hour is 3.6 megajoules, which is the amount of energy converted if work is done at an average rate of one thousand watts for one hour.

A heater rated at 1000 watts (1 kilowatt), operating for one hour uses one kilowatt hour (equivalent to 3.6 megajoules) of energy.

Using a 60-watt light bulb for one hour consumes 0.06 kilowatt hours of energy. Using a 60-watt light bulb for 1000 hours consumes 60 kilowatt hours of energy.

Using a 100-watt light bulb for one hour consumes 0.10 kilowatt hours (100 W / 1000 W/kW) × 1 h = 0.10 kW·h. If the rate being charged for electricity is 10 cents per kilowatt hour, then running the 100-watt bulb for one hour would cost 0.10 kW·h × $0.10/kW·h = $0.01, or one cent. Running a typical space heater rated at 1500 watts would cost 15 cents per hour (1.5 kW × 1 h x $0.10/kW·h = $0.15). Indeed one can determine how much any electrical device will cost to run by multiplying the amount of kilowatts consumed by the device by the rate per kilowatt hour by the time it will be run for (kilowatts × hours × rate-per-kilowatt-hour = cost-to-run), being mindful of the fact that different rates may exist even within one tariff.

Stephan Mathieu (born 11 October 1967) is a German musician and sound artist whose work is based on digital and analog processing techniques. He lives and works in Saarbrücken, Germany.

Stephan Mathieu is a self taught composer and performer of his own music, working in the fields of electroacoustics and abstract digitala. His sound is largely based on early instruments, environmental sound and obsolete media, which are recorded and transformed by means of experimental microphony, re-editing techniques and software processes involving spectral analysis and convolution; it has been compared to the landscape paintings of Caspar David Friedrich, the work of Painters Mark Rothko, Barnett Newman and Ellsworth Kelly.

During the last decade Stephan’s music has been released on 30 CDs and vinyl records, both solo and in collaboration with Akira Rabelais, Douglas Benford, Ekkehard Ehlers, Janek Schaefer, John Hudak and Taylor Deupree on electronic music labels worldwide.

Since 1992 he performed his music live in solo shows and on festivals all over Europe, Scandinavia, North- and Southamerica and created various audio installations for galleries and museums, a glass-blowing factory, a 17th century garden, Berlin Mitte, a 19th century steel plant, parks, an arrangement of 30 Peugeots, a late antique throne hall and various other places.

David Sylvian (born David Alan Batt, 23 February 1958) is an English singer-songwriter and musician who came to prominence in the late 1970s as the lead vocalist and main songwriter in the group Japan. His subsequent solo work is described by critic Jason Ankeny as "a far-ranging and esoteric career that encompassed not only solo projects but also a series of fascinating collaborative efforts." Sylvian's solo work has been influenced by a variety of musical styles and genres, including jazz, avant-garde, ambient, electronic, and progressive rock.

Sylvian was born in Beckenham, Kent, the son of a plasterer and a housewife. He was educated at Catford Boys' School, Catford, South East London leaving at 16. As a youth, he listened to glam rock artists such as David Bowie and Roxy Music.^{[citation needed]}

The band Japan, whose other members included bassist Mick Karn, guitarist Rob Dean, keyboardist Richard Barbieri and Sylvian's brother Steve Jansen as drummer, began as a group of friends. As youngsters they played music as a means of escape, playing Sylvian's two-chord numbers – sometimes with Karn as the front man, sometimes with Sylvian at the fore.