Farming is undergoing dramatic changes today. Though many crops will continue to be raised outdoors, an abundance of agricultural products are being grown in climate-­controlled environments powered by electricity. These grow environments include everything from small greenhouses to sophisticated vertical farming operations measuring 100,000 square feet.

Several factors have accelerated demand for controlled environment agriculture (CEA)—population growth, climate, a need to increase crop reliability and reduce transportation costs, a desire to extend growing seasons and the legalization of cannabis.

Because CEA consumes lots of electricity, demand for energy-efficient horticultural LED lighting is on the rise. The global market for horticulture lighting (estimated at $3.2 billion in 2019) is predicted to grow to $20.3 billion by 2030, according to market research firm Prescient & Strategic Intelligence Market Research. The United States currently leads all other nations with 16.9% of the market.

“I think there is a significant cultural shift to growing sustainable crops locally, especially after the supply chain issues people encountered with the pandemic,” said Kasey Holland, technical manager of the Horticultural Lighting Program run by the DesignLights Consortium (DLC).

DLC, a nonprofit, develops technical requirements for quality, safety and efficiency, which lighting manufacturers must meet for their products to be included on the DLC’s Qualified Products List (QPL). In doing so, it collaborates with utilities, state energy-­efficiency programs, manufacturers, lighting designers, building owners and government entities to create rigorous criteria for lighting performance and development.

LEDs curb energy, emissions and offer more control

“There’s a lot more support these days for horticulture lighting, and LED lighting is really being emphasized in this area,” Holland said.

That’s because LED lighting curbs energy use and carbon emissions, while allowing greater control over color and light quality, which can dramatically enhance plant characteristics and crop yields.

In 2018, DLC created an LED-based horticultural lighting QPL, making listed products eligible for incentives and rebates from utility companies in states with energy-efficiency programs. Those programs authorize utility companies to collect monthly percentage fees paid by their customers based on energy use. Funds are set aside to cover incentives and rebates given back to customers for purchasing energy-efficient lighting products such as those on DLC’s QPL. Participating customers enjoy significant energy savings.

“Because our list imposes standardized testing and reporting processes to validate performance, including energy efficiency and UL safety standards, it saves a lot of time with administering the incentive application process,” Holland said. “The utility knows their customers have selected products that are efficient and safe.”

DLC’s third iteration of its horticultural lighting technical requirements increased the photosynthetic photon efficacy threshold for LED horticulture lighting by 21%, which results in qualified luminaires being 35% more efficient than the best non-LED option, Holland said.

The Horticultural Technical Requirements Version 3.0 also introduced product-level controllability requirements such as dimming, and requirements for lighting manufacturers to more accurately report the intended use of products on applications. Member manufacturers also are now required to submit dimensions and schematics of products and photos or photorealistic illustrations for online viewing by prospective customers or installers.

Developing and tightening these technical requirements has involved reviewing the collective performances of horticulture LED products on DLC’s QPL list roughly every two years, Holland said. Each review was followed by a draft technical requirement revision proposal and a six-week open comment period for stakeholders, who include states and utilities committed to curbing energy usage and safety-related risks. DLC requires listed lighting manufacturers to keep their products in step as new performance standards are introduced.

“We basically look at the lower-performing 15% of listed manufacturers and insist they raise the bar on their performance,” Holland said. As standards ratchet up, one might assume manufacturers would drop off the QPL list, but the opposite has occurred.

DLC’s first version of performance standards for LED horticulture lighting took effect in 2018. 

“We started with a target of about 50 manufacturers,” Holland said. “Now we have a little over 200 listed manufacturers, representing almost 1,500 LED horticulture products.”

DLC is readying Version 4.0 for release in 2025. Controls are expected to command the biggest area of development for this new round of standards and products, Holland said.

All products on DLC’s QPL list must be electromagnetic ­radiation­-generating devices analogous to luminaires (or fixtures) or LED lamps (integrated or nonintegrated) as defined by ANSI/IES LS-1-22. They must also meet UL 1598 standard requirements for standard luminaires and UL 8800, which addresses safety issues applicable to horticulture luminaires and grow systems installed in horticulture environments in accordance with the National Electrical Code.

“These requirements involve far more rigorous testing and standards than just for regular LED lighting,” Holland said.

UL 8800 includes safety requirements and precautions corresponding to photobiological hazards to human eyes and skin consistent with IEC 62471, a regulation that aims to protect workers from injuries and blindness caused by exposure to ultraviolet (UV), visible and infrared/thermal electromagnetic radiation.

UL 8800 also allows for specialized wiring and connection methods that support flexible and frequent light repositioning, including daisy chains. It considers product suitability for damp and wet environments, as well as areas with elevated temperatures. It also considers ingress protection, because horticulture lighting is subject to greater risk of penetration by moisture and dust.

Last, UL 8800 sets forth equipment standards to discourage breakdown of polymeric materials by UV exposure within greenhouse environments.

“This isn’t your typical warehouse lighting,” Holland said of the products, which generate radiation programmable at varying photon lengths to enhance plant production. “It’s very important that growers and installers understand that not just any light can get the same results.”

Controllable horticulture LED lighting interacts with other systems such as heating and cooling, watering, dehumidifying and security. That interconnectivity requires systems integration.

Controllable horticulture LED lighting interacts with other systems such as heating and cooling, watering, dehumidifying and security. That interconnectivity requires systems integration, which also can make related lighting and climate controls vulnerable to cyberattack.

DLC wants to “accelerate” implementation and use of newer, higher-performing products to bring about optimized production practices with greater energy efficiencies and higher safety standards, Holland said. One way is to make it easier for installers to make recommendations for their customers by using a DLC website application showing fixtures in 3D for use in different settings.

Cannabis cultivation

Cannabis cultivation is just one setting requiring precision lighting equipment and environmental controls. As of September 2023, 23 states had fully legalized medical and recreational use and cultivation, according to DISA Global Solutions Inc., a drug testing company.

“The cultivation of cannabis, which consumes lots of energy, is a significant factor driving applications for rebates and incentives for LED horticulture lighting in many states,” Holland said, adding that two states—Massachusetts and Illinois—have codified DLC listing as a pathway to regulatory compliance for cannabis facilities.

Utilities and grow operations

Bearing that out, Ameren Illinois, a utility serving customers in the middle and lower portions of Illinois, encourages grow operations to apply for incentives for lighting fixtures on DLC’s QPL list. The utility may limit incentives beyond $500,000, depending on available program funding.

“Horticulture facilities have a large energy savings opportunity by transitioning from traditional HID lighting to LED fixtures due to the increased fixture efficiency and significant annual operating hours of the industry,” said Babette Washington, Ameren Illinois senior manager for energy efficiency operations. “LED horticulture lighting is a high-cost fixture, and the Ameren Illinois Energy Efficiency Program provides incentives for LED grow lighting fixtures to help commercial growers save energy and save money.”

Since 2018, Ameren Illinois has granted more than $2 million in incentives for LED horticultural lighting from DLC’s QPL list. It also has achieved more than 17 million kilowatt-hours (kWh) in savings to date, enough to power around 1,600 homes for one year. That calculation is based on 2021 U.S. Energy Information Administration data suggesting the average U.S. household uses 10,632 kWh annually.

Likewise, ComEd, which serves customers in northern Illinois, has granted or reserved more than $2 million in incentives for horticulture lighting products on DLC’s QPL list over the last few years. The resulting energy savings from completed and in-progress projects is estimated at 11.6 million kWh annually, enough to power 1,300 homes for one year.

“Indoor growers of all types can and have taken advantage of the beneficial incentives offered through the ComEd Energy Efficiency Program,” said Cordell Murphy, a representative for the program. “Grow lighting and controls measures offer significant energy savings for these types of customers.”

Horticulture lighting is a small portion of the number of commercial and industrial lighting applications submitted to ComEd’s Energy Efficiency Program. The same goes for Ameren Illinois at less than 1%. Yet the related installation work is significant.

CEA operations in smaller states also are taking advantage of incentives for installing horticultural lighting products.

Vermont has a population equal to a small or mid-size city—643,500—yet it enjoys a robust energy-efficiency program offering generous incentives for LED horticulture lighting on DLC’s QPL list.

“There’s a high percentage of gardeners and horticulturists here. The number-one driving factor for controlled environment agriculture is the climate. It’s cold here,” said Jill O’Connor, energy consultant for public utility Efficiency Vermont.

Efficiency Vermont does not generate or distribute electricity, but as an energy-­efficiency utility it administers incentives, discounts and rebates for LED lighting through the state’s energy-­efficiency program. 

Its mission is to make residents and businesses aware of lighting rebates and incentives, having organized energy-­efficiency fairs and encouraged networking among engineering firms and ECs.

Joining Efficiency Vermont’s Energy Efficiency Network requires filling out a form and having an electrical contractor’s license with the Vermont secretary of state.

Utilities in other states encourage electrical contractors to apply as agents and representatives for LED lighting incentive programs as well.

stock.adobe.com / KeronnArt / DesignLights Consortium