Browse Definitions :
Definition

kilowatt-hour (kWh)

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. The kilowatt-hour is not a standard unit in any formal system, but it is commonly used in electrical applications.

An energy expenditure of 1 kWh represents 3,600,000 joules (3.600 x 106 J). To obtain joules when kilowatt-hours are known, multiply by 3.600 x 106. To obtain kilowatt-hours when joules are known, multiply by 2.778 x 10-7.

In general, energy (E) is equivalent to power (P) multiplied by time (t). To determine E in kilowatt-hours, P must be expressed in kilowatts and t must be expressed in hours. Suppose a 1.5-kW electric heater runs for 3 h. Then P = 1.5 and t = 3, so the energy E in kilowatt-hours is:

E = Pt = 1.5 x 3 = 4.5 kWh

If P and t are not specified in kilowatts and hours respectively, then they must be converted to those units before determining E in kilowatt-hours.

The consumption of electrical energy by homes and small businesses is usually measured in kilowatt-hours. Larger businesses and institutions sometimes use the megawatt-hour (MWh), where 1 MWh = 1,000 kWh. The energy outputs of large power plants over long periods of time, or the energy consumption of states or nations, can be expressed in gigawatt hours (GWh), where 1 GWh = 1,000 MWh = 106 kWh.

The kilowatt-hour is rarely used to express energy in any form other than electrical. A quantity of gasoline, oil, or coal contains potential energy that is liberated when the fuel is burned. The heat energy resulting from combustion of such fuels is usually expressed in joules according to the International System of Units (SI) or in British thermal units (Btus) according to the foot-pound-second (fps) or English system. If this energy is used to operate an electric generator, the output of the generator over a certain period of time can be expressed in kilowatt-hours.

Compare watt-hour. Also see energy, joule, International System of Units (SI), and Table of Physical Units.

This was last updated in September 2006

SearchCompliance

  • information governance

    Information governance is a holistic approach to managing corporate information by implementing processes, roles, controls and ...

  • enterprise document management (EDM)

    Enterprise document management (EDM) is a strategy for overseeing an organization's paper and electronic documents so they can be...

  • risk assessment

    Risk assessment is the identification of hazards that could negatively impact an organization's ability to conduct business.

SearchSecurity

  • honeypot (computing)

    A honeypot is a network-attached system set up as a decoy to lure cyber attackers and detect, deflect and study hacking attempts ...

  • spam trap

    A spam trap is an email address that is used to identify and monitor spam email.

  • cracker

    A cracker is someone who breaks into someone else's computer system, often on a network; bypasses passwords or licenses in ...

SearchHealthIT

SearchDisasterRecovery

  • risk mitigation

    Risk mitigation is a strategy to prepare for and lessen the effects of threats faced by a business.

  • call tree

    A call tree is a layered hierarchical communication model that is used to notify specific individuals of an event and coordinate ...

  • Disaster Recovery as a Service (DRaaS)

    Disaster recovery as a service (DRaaS) is the replication and hosting of physical or virtual servers by a third party to provide ...

SearchStorage

  • cloud storage

    Cloud storage is a service model in which data is transmitted and stored on remote storage systems, where it is maintained, ...

  • cloud testing

    Cloud testing is the process of using the cloud computing resources of a third-party service provider to test software ...

  • storage virtualization

    Storage virtualization is the pooling of physical storage from multiple storage devices into what appears to be a single storage ...

Close