Energy efficiency

For energy efficiency in relation to economics, see energy conservation

In physics and engineering, including mechanical and electrical engineering, energy efficiency is a dimensionless number, with a value between 0 and 1 or, when multiplied by 100, is given as a percentage. The energy efficiency of a process, denoted by eta, is defined as

$\mathrm {efficiency} \ \eta =\mathrm {{power\ output} \over \mathrm {power\ input} } \ (={\frac {{\text{work}}\ W}{{\text{energy}}\ E}})\,$

where W is the amount of useful work done by the process (in joules), and "energy" E is the quantity of energy (again, in joules) used to run the process.

Due to the principle of conservation of energy, energy efficiency within a closed system can never exceed 100%.

See also

• Energy conversion efficiency
• Fuel efficiency
• Thermal efficiency
• Sensitivity (electronics)
• Figure of merit
• Exergy efficiency

External links

• Conversion of sensitivity in dB per Watt and meter to energy efficiency in percent for passive loudspeakers