Efficacy is also known as “Luminous efficacy”, it is luminous flux of a lamp in relation to its power consumption and that is why it is expressed by lumen per watt (lm/W).
Source: The 2017 Lighting Terms Glossary, Regency Lighting.
Efficacy is also known as “Luminous efficacy”, it is luminous flux of a lamp in relation to its power consumption and that is why it is expressed by lumen per watt (lm/W).