Horticultural Technical Requirements V4.0

Summary

To be eligible for listing on the DLC Horticultural Lighting Qualified Products List (Hort QPL), Horticultural lighting products using LEDs must comply with the provisions of this document. Products eligible for DLC qualification must be complete LED light fixtures or modules. That is, they must be electromagnetic radiation-generating devices analogous to luminaires (or fixtures) as defined by ANSI/IES LS-1-22.

In North America, increasing demand for locally produced food combined with the legalization of medical and/or recreational cannabis and the desire for resilient supply chains are fueling the growth of controlled environment agriculture (CEA). Valued at $7.8 billion last year, the global CEA market is expanding at a compound annual growth rate of 12.2 percent and expected to reach $22 billion by 2033, according to a February 2025 market research report. With lighting being the largest operational expense, there are significant opportunities to increase energy efficiency and cost savings with the right lights.

The DLC Horticultural Lighting Technical Requirements are designed to help the industry achieve sustainable growth that facilitates decarbonization efforts. The US Department of Energy has encouraged this shift to LEDs and projected a 34% reduction in electricity consumption and $350 million in savings in a 2020 report. Horticultural lighting solutions include many options and variables to evaluate such as cooling methods, control features, and suitability for specific applications. The Hort QPL provides reliable information on product specifications to help growers and energy efficiency program administrators select the best lights for their application.

Relying on industry standard nomenclature, testing, and reporting methodologies, the DLC Technical Requirements establish minimum performance baselines for horticultural LED fixtures. The requirements support the successful adoption of energy efficient practices in CEA through the implementation of LED luminaires and controls. Since the implementation of Hort V1.0, the average efficacy of listed products has increased by 24.9%. Additionally, the Hort QPL has achieved an annual growth rate of over 102% since 2019 and, as of February 2025, it is comprised of over 1200 V3.0 listed products from over 130 manufacturers and is estimated to represent around 90% of the non-residential horticultural lighting market.

Key Revisions

Hort V4.0 is designed to further support and accelerate the adoption of energy efficient lighting and controls in CEA. This is accomplished through the following key revisions to the V3.0 technical requirements:

• Photosynthetic Photon Efficacy (PPE) threshold increase
  Hort V4.0 increases the PPE threshold to a minimum of 2.5 μmol × J^-1, which is an 8.7% increase over the Hort V3.0 PPE threshold. This increase will set the DLC efficacy threshold for LED-based horticultural lighting at more than 45% above the most efficacious non-LED option, the 1000W double-ended high pressure sodium luminaire. This increase will delist the least efficacious V3 listed products (~11% of the QPL).  

• Removal of lamp categories
  In 2021, Hort V2.1 introduced several new product qualification pathways for DC-powered products, liquid cooled products, and several lamp types. Since then, all new categories have seen participation and QPL listings have been actively growing, except for lamps. With the lack of uptake around lamps and no comments received on the draft proposal during the comment period to maintain lamp eligibility, Hort V4.0 removes the qualification pathway for lamps.

• Clarifications to various requirements
  To improve the clarity of the Horticultural Technical Requirements, a variety of updates have been made throughout the document. For example, clarifications to what the DLC considers “nominally distinct wavelength band” have been included in the LM-80 applicability section. Additionally, language has been added to clarify testing requirements for spectrally tunable products based on their spectral tunability and to better define what the PPE-tested qualifying state should be and other clarifications have been made to various requirement details.

Schedule of Revisions

Technical Requirements

Horticultural lighting products using LEDs must comply with the provisions of this document to be eligible for listing on the DLC Solid-State Horticultural Lighting Qualified Products List.

For Definitions, Eligibility, Testing Methods, etc., please download the full Technical Requirements document.

Horticultural Technical Requirements V4.0

Safety Certification

The DLC requires specific testing and reporting to ensure that all listed products have an appropriate safety certification. All products must be certified to the applicable safety standard by a safety certification organization relevant in the United States or Canada.

Specific Requirements for Safety Certification

Level 2 (formerly Family Grouping) Requirements

The DLC allows Level 2 (formerly Family Grouping) applications for horticultural lighting products. Level 2 applications are designed to reduce the total testing and application fees required to list groups of products that comply with the family grouping definition. Typically, parent products are based on tested data from worst-case models within a family group, and child products are based on reported data. Generally, limited testing can be provided if the worst-case models demonstrate compliance with the technical requirements.

Level 2 Requirements for Horticultural Lighting

Private Label Requirements

Private label applications allow manufacturers the option to list qualified products under multiple manufacturers and brands without having to conduct duplicate testing. Private label applications may only be submitted if the original equipment manufacturer’s (OEM) product is already DLC qualified. Private label products must be identical to the originally qualified versions.

Requirements for Horticultural Private Label Applications

Testing Lab Requirements

DLC applications require that product testing be conducted at an accredited laboratory appropriate for the performance being evaluated. These tests may include in situ measurement tests (ISTMT), ANSI/IES LM-79-19, ANSI/IES LM-80, ANSI/IES LM-84.

Testing Lab Requirements

Testing Constraints

The DLC understands that in some scenarios, products that are required to be tested may be unable to test in the necessary apparatus’ as stated in the Horticultural Technical Requirements, due to size or other restrictions.

Testing Constraints Policy