Luminous Efficacy (lm/W)

Luminous efficacy is the ratio of luminous flux delivered to electrical power consumed, expressed in lumens per watt. It is the headline efficiency metric for LED lighting: modern industrial fixtures typically achieve 120–160 lm/W at the luminaire level, versus roughly 80–100 lm/W for metal halide systems once ballast losses and optical losses are counted. Two cautions when comparing figures: chip-level efficacy (measured on a bare LED at 25 °C) always exceeds real luminaire efficacy, and efficacy varies with CCT and CRI — warmer color temperatures and higher color rendering typically cost a few percent. Regulatory schemes such as the EU Ecodesign regulation set minimum efficacy thresholds for general lighting.