PAR for plants, Lumen for people.

  Added by: Mr.Zog  Last edited by: administrator  Viewed: 568 times  Rated by 16 users: 7.83/10
While the lumens measurement is based on the sensitivity of the human eye to light, PAR Watts objectively measure the total watts of Photosynthetically Active Radiation (PAR) emitted by the lamp. It accounts for the nutritional value and is a direct measure of light energy available for all-important plant photosynthesis.
  Last modified: 13:13 - Dec 03, 2000 

faq:589 "PAR for plants, Lumen for people."