Jun 11 2014
Answer:
Efficacy is a term that is generally used when the input units and output units are different. For lighting, we are focused on the conversion of electrical energy (watts) into light (lumens.) The efficacy of a lighting fixture is a measure of the amount of light produced per unit of electricity and will take into account for energy lost by the power supply (AC/DC conversion), energy lost converting the DC energy into light (LED) and the energy lost into directing the light to where it is needed. It is measured in lumens per watt.