Horticultural Lighting Resources
The resources below are supplemental guides for particular areas of interest in horticultural lighting. These guides introduce and summarize the topic, explain how it relates to DLC policy, and point the way to additional resources for further reading.
Please note that several of these resources address topics that do not appear in the current Horticultural Lighting Technical Requirements, but that the DLC may consider in the future. For more detail on the DLC’s horticultural lighting revision and update cycle, please visit the Horticultural Lighting QPL Revision Cycle page.
If you would like to contribute to future revisions of the DLC Horticultural Lighting Technical Requirements through the DLC's stakeholder input process, please sign up for our mailing list here.
Limitations of Predicting Far-Red's Effect on Photosynthesis
This resource explains the limitations of metric development around far-red light and clarifies some assumptions regarding far-red spectra.
Terms and Definitions
This guide explains the common units of measure one might encounter in the general illumination world, and emphasizes that plant-specific units should be used when working on horticultural applications.
This guide explains the challenges with attenuated reflection in currently-used whole-fixture measurement methods for horticultural lighting.
The application design guide walks the reader through the interrelated considerations of energy flowing through a growing facility.
The active cooling guide explains the background of current test procedures, and how questions need to be answered to test actively cooled fixtures in the same way.
Massachusetts State Regulations
Section 500,120 (11)(b)
"Lighting used for Cannabis Cultivation must meet one of the following compliance requirements:
1. Horticulture Lighting Power Density must not exceed 36 watts per square foot, except for Tier 1 and Tier 2 which must not exceed 50 watts per square foot; or
2. All horticultural lighting used in a facility is listed on the current DesignLights Consortium Solid-state Horticultural Lighting Qualified Products List ("Horticultural QPL") or other similar list approved by the Commission as of the date of license application, and lighting Photosynthetic Photon Efficacy (PPE) is at least 15% above the minimum Horticultural QPL threshold rounded up to the nearest 0.1 :mol/J (micromoles per joule).
3. A facility seeking to use horticultural lighting not included on the Horticultural QPL or other similar list approved by the Commission shall seek a waiver pursuant to 935 CMR 500.850 and provide documentation of third-party certification of the energy efficiency features of the proposed lighting. All facilities, regardless of compliance path, shall provide third-party safety certification by an OSHA NRTL or SCC-recognized body, which shall certify that products meet a set of safety requirements and standards deemed applicable to horticultural lighting products by that safety organization."
Illinois State Regulations
Section 410 ILCS 705/30-10(21)(b)
"Lighting. The Lighting Power Densities (LPD) for cultivation space commits to not exceed an average of 36 watts per gross square foot of active and growing space canopy, or all installed lighting technology shall meet a photosynthetic photon efficacy (PPE) of no less than 2.2 micromoles per joule fixture and shall be featured on the DesignLights Consortium (DLC) Horticultural Specification Qualified Products List (QPL). In the event that DLC requirement for minimum efficacy exceeds 2.2 micromoles per joule fixture, that PPE shall become the new standard."
Resource Innovation Institute Cannabis PowerScore