Efficacy at a glance

摘要

One measure of lighting efficiency is efficacy. Efficacy is expressed as lumens per watt (Im/w)— the amount of light produced for each unit of electricity consumed. Incandescent lights have efficacies between 10 and 20 Im/w, and fluo-rescents range from 60 to 100 Im/w. LED products tested last year by the U.S. Department of Energy's Solid-State Lighting program were in the 70 to 80 Im/w range. However, LEDs are expected to surpass fluorescents in the next year and exceed 150 Im/w by 2015. The chart shows representative examples.