LM-79

LM-79 is the IES-approved method for photometric and electrical testing of complete SSL (LED) products: total luminous flux, efficacy, intensity distribution, chromaticity, CRI, and power quality measured on the whole luminaire in an integrating sphere or goniophotometer. Its defining principle is absolute photometry — the fixture is tested as sold, so results already include driver, thermal, and optical losses, leaving no room for the chip-lumen inflation common in marketing. Buyers and rebate programs (such as DLC listings) request LM-79 reports as the evidentiary basis for datasheet lumens; the companion IES file from goniophotometer testing is what lighting-design software consumes.