How is efficiency measured for SSL luminaires?
ENERGY STAR uses a metric called “luminaire efficacy” to measure the energy efficiency of an LED lighting product. Luminaire efficacy compares the useful light that comes out of a luminaire (measured in lumens) to the total power consumed (measured in watts), and is reported in lumens per watt. This metric measures how well the luminaire illuminates the desired surface, and is a more stringent method than simply reporting the efficiency of the light source alone.
