New standard for LED-based hort. lighting

The American Society of Agricultural and Biological Engineers (ASABE) has announced publication of the ANSI/ASABE S640 standard entitled “Quantities and Units of Electromagnetic Radiation for Plants (Photosynthetic Organisms).”

The work is the first in an expected three-prong effort of standards development by ASABE that can forward the proliferation of LED-based horticultural lighting. Solid-state lighting (SSL) is increasingly important to horticulture in both vertical farms and as supplemental under-cover applications in greenhouses, and the standards effort is intended to provide a common language for characterizing LED-based systems relative to plants.

The standards effort for characterizing LED-based lighting for humans has been underway for a decade or more now. But basic metrics such as efficacy (lm/W) that are directly applicable to humans, since the lumen is based on human visual sensitivity, have little applicability to the effectiveness of light for plant growth.

Last November, LEDs Magazine published a detailed article about the work of the ASABE that had begun back in 2015 and that by last year had become a three-part proactive effort on standards development. As the article described, the first priority was definition of metrics and a new plant biologically active radiation (PBAR) radiometric band that spans 280–800 nm — covering the ultraviolet (UV) region below human visual sensitivity and the far-red region above.

The horticultural sector has for some time used de facto metrics such as photosynthetic photon flux (PPF) and photosynthetic photon flux density (PPFD) that are based on the photosynthetically active radiation (PAR) band from 400–700 nm. Those metrics remain useful. But UV light is now known to impact plant morphology. And the far-red region can impact seed germination, flower induction, plant height, and leaf expansion. The new standard will add new metrics in those regions.

The ASABE announcement said the S640 standard would be available for purchase in six weeks. But the standard appears to already exist in the ASABE Technical Library. Visit that library (http://elibrary.asabe.org/) and search for S640 and an offer to purchase the standard will be displayed. The non-member price is $61.

The new standard, as well as the continued development of the next two standards in the pipeline, will certainly be detailed at the upcoming Horticultural Lighting Conference. Make plans to join on Oct. 17 in Denver, CO.

Click here to read the original article at LEDs Magazine.

08/09/2017 - LEDs Magazine

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