According to Testing and Reporting Requirements for LED-based Horticultural Lighting, Version 1.2, which was effective on October 21, 2019 from DLC ^a, this is a technical standard based on UL 8800 and The American Society of Agricultural and Biological Engineers (ASABE), the standard for horticultural lighting equipment and systems.

 

Eligibility

For photosynthesis, which identify Quantities and units of electromagnetic radiation for plants, represents the bulk of energy consumption for the plant, photosynthetically active radiation(PAR) ranges from 400-700 nm (as defined by ANSI/ASABE S640).

 

The measured result of PAR can be reported in unit of Photosynthetic Photon Flux (PPF), Photosynthetic Photon Flux Density (PPFD), or Photosynthetic Photon Intensity Distribution (PPID). ^b

 

Photosynthetic Photon Flux Density (PPFD), unit of μmol/㎡s, or μmol/ft² s, describe the density of light on the work area of interest, is often the end goal of the design process, in general terms, answer the question “how bright will it be?”

 

 

a. DLC: The DesignLights Consortium, a non-profit organization

Official website: http://www.designlights.org/

b. Quotes from DLC Horticultural Lighting Resources: Terms and Definitions, paragraph 3.