Energy efficiency may refer to: *

Energy efficiency (physics) 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 (radi ...

, the ratio between the useful output and input of an energy conversion process **

Electrical efficiency The efficiency of a system in electronics and electrical engineering is defined as useful power output divided by the total electrical power consumed (a vulgar fraction, fractional Expression (mathematics), expression), typically denoted by the G ...

, useful power output per electrical power consumed **

Mechanical efficiency In mechanical engineering, mechanical efficiency is a dimensionless ratio that measures the efficiency of a mechanism or machine in transforming the power input to the device to power output. A machine is a mechanical linkage in which force ...

, a ratio of the measured performance to the performance of an ideal machine **

Thermal efficiency In thermodynamics, the thermal efficiency (\eta_) is a dimensionless performance measure of a device that uses thermal energy, such as an internal combustion engine, steam turbine, steam engine, boiler, furnace, refrigerator, ACs etc. For ...

, the extent to which the energy added by heat is converted to net work output or vice versa ** Luminous efficiency, a measure of how well a light source produces visible light **

Fuel efficiency Fuel efficiency (or fuel economy) is a form of thermal efficiency, meaning the ratio of effort to result of a process that converts chemical energy, chemical potential energy contained in a carrier (fuel) into kinetic energy or Mechanical work, w ...

, the efficiency of converting potential energy in a fuel into kinetic energy **

Energy efficiency in transportation The energy efficiency in transport is the useful travelled distance, of passengers, goods or any type of load; divided by the total energy put into the transport propulsion means. The energy input might be rendered in several different types depe ...

, the fuel economy of various modes of transportation ** Energy-efficient landscaping, a type of landscaping designed for the purpose of conserving energy *

Efficient energy use 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. For ...

, minimizing the amount of energy used for a given, constant energy service *

Energy conservation Energy conservation is the effort to reduce wasteful energy consumption by using fewer energy services. This can be done by using energy more effectively (using less and better sources of energy for continuous service) or changing one's behavi ...

, reducing energy consumption by using less of an energy service

See also