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Common energy efficiency label on appliances to indicate their energy efficiency in a clear manner. Efficient energy use, or energy efficiency, is the process of reducing the amount of energy required to provide products and services. There are many technologies and methods available that are more energy efficient than conventional systems.
Energy conversion efficiency (η) is the ratio between the useful output of an energy conversion machine and the input, in energy terms. The input, as well as the useful output may be chemical , electric power , mechanical work , light (radiation), or heat .
Energy efficiency may refer to: Energy efficiency (physics), the ratio between the useful output and input of an energy conversion process Electrical efficiency, useful power output per electrical power consumed; Mechanical efficiency, a ratio of the measured performance to the performance of an ideal machine
Electric kettle: more than 90% [citation needed] (comparatively little heat energy is lost during the 2 to 3 minutes a kettle takes to boil water). A premium efficiency electric motor: more than 90% (see Main Article: Premium efficiency). A large power transformer used in the electrical grid may have efficiency of more than 99%. Early 19th ...
Measurable energy conservation and efficiency gains in the 1980s led to the 1987 Energy Security Report to the President (DOE, 1987) that "the United States uses about 29 quads less energy in a year today than it would have if our economic growth since 1972 had been accompanied by the less- efficient trends in energy use we were following at ...
Energy efficiency gains can increase energy consumption by two means: by making energy appear effectively cheaper than other inputs; and by increasing economic growth, which pulls up energy use. … These results, while by no means proving the Khazzoom-Brookes postulate, call for prudent energy analysts and policy makers to pause a long moment ...
Energy (from Ancient Greek ἐνέργεια (enérgeia) 'activity') is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat and light.
For a heat engine, thermal efficiency is the ratio of the net work output to the heat input; in the case of a heat pump, thermal efficiency (known as the coefficient of performance or COP) is the ratio of net heat output (for heating), or the net heat removed (for cooling) to the energy input (external work). The efficiency of a heat engine is ...