What’s the difference between efficiency and efficacy?
2011-8-19 Efficacy is a term normally used in cases where the input and output units differ. In lighting, we are concerned with the amount of light (in lumens) produced by a certain amount of electricity (in watts).On the other hand, efficiency is a term that is typically dimensionless. For example, lighting fixture efficiency is the ratio of the total lumens exiting the fixture to the total lumens initially produced by the light source.
