The Illuminating Engineering Society Introduces Horticultural Lighting Standard

January 28, 2022 (New York, NY): The Illuminating Engineering Society (IES) recently introduced ANSI/IES RP-45-21 Recommended Practice: Horticultural Lighting. This standard describes the differences between architectural and horticultural lighting design, so that lighting professionals will have the necessary information to translate their architectural lighting know-how into horticultural lighting practice.

“Horticultural lighting is a science in its own right, bridging horticulture, botany, and illumination engineering,” explains Ian Ashdown, Horticultural Lighting Committee Chair. “We wrote this document with one purpose in mind: to provide a framework for discussions between horticulturalists and lighting professionals.”

Included in the Lighting Applications Standards Collection and published in consensus by the IES Horticultural Lighting Committee, this document is essential for lighting professionals interested in horticultural lighting for greenhouses, indoor farms, and building atria.


Established in 1906, the Illuminating Engineering Society is the recognized technical and educational authority on illumination. Our mission is to improve the lighted environment by bringing together those with lighting knowledge and by translating that knowledge into actions that benefit the public. We provide a variety of professional development, publications, networking and educational opportunities to our membership of engineers, architects, designers, educators, students, contractors, distributors, utility personnel, manufacturers and scientists in nearly 60 countries. Through our American National Standards Institute (ANSI) accredited process, we publish and maintain the Lighting Library®️, with over 100 standards written by subject matter experts in our technical committees. In all our efforts, we strive to improve life through quality of light. To learn more about us, visit