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Taking the Guesswork out of Horticultural Lighting

By Leora Radetsky
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With 33 states and the District of Columbia having passed laws legalizing marijuana in some form, cannabis cultivation is quickly becoming a booming new business across much of the US. From an energy standpoint, unfortunately, it’s not easy being “green”.

New Frontier Data’s 2018 Cannabis Energy Report found that legal cannabis cultivation in the US consumes approximately 1.1 million megawatt hours of electricity annually – enough to power 92,500 homes or a community the size of Newark, NJ, and accounts for carbon emissions equivalent to that of 92,600 cars. And that consumption is forecasted to increase 162 percent from 2017 to 2022. The report recommended that the industry “evaluate energy-efficient and renewable energy technologies” to nip this challenge in the bud.

Growers seeking to reduce their electricity usage through more efficient lighting face a confusing landscape of options, however. It can be difficult to know what will save electricity and work well for their operations. Technology is advancing quickly and questions abound, from how long a fixture will last and whether a manufacturer’s claims about efficacy are accurate to the effectiveness of various wavelengths for growing a particular plant.

Here’s the good news: there are reliable, third-party lighting and safety standards to help indoor growers make the leap from old-school lighting to state-of-the-art light-emitting diodes (LEDs) that use a fraction of the electricity and are increasingly effective for growing crops from cannabis to tomatoes. Here’s a closer look:

Most lighting fixtures in the North American market go through rigorous inspection by certified third-party testing labs. The first part of the check is for safety – an official UL safety standard tailored for the unique challenges of the greenhouse environment was recently released (UL 8800, the Standard for Horticultural Lighting Equipment and Systems). This standard and similar safety certifications at other major labs address wiring, environmental conditions, ingress protection and worker safety related to prolonged photobiological exposure to the eyes and skin. Growers should always ask a fixture manufacturer about safety certification specifically targeted for horticultural environments.

Next on the standards checklist for horticultural fixtures is performance testing. This often happens at the same labs that do safety testing, but is designed to verify efficacy, output, spectrum and other important performance variables. Commercial labs are certified for specific standards, so that a test on a fixture is repeatable at any other lab certified to the same standard. This performance testing results in a report summarizing items like photosynthetic photon flux (PPF), input power (watts), photosynthetic flux efficacy (PPE, measured in μmol/J or micromoles of photosynthetic photons per joule of electrical input power), and spectral content (flux per nanometer (nm) between 400 and 700 nm).

Then, there are flux maintenance standards (such as IES LM-80 and IES TM-21) that help make sure the photosynthetic light output of LED products degrades at an acceptable rate to make a grower’s investment worthwhile. The testing and calculation methods that go into these standards were painstakingly developed through a consensus of knowledgeable lighting stakeholders. A key difference between general lighting and plant lighting, however, is how flux maintenance is measured and benchmarked – the bar is significantly higher for plants compared to people since their metabolism and growth are dependent on the light spectrum and amount.

A plant in flowering under an LED fixture

What’s described above just scratches the surface of the detailed testing used to determine and communicate performance features for commercial horticultural lighting fixtures. There’s a lot of important information to know, but it takes an informed reader to analyze this information and use it to select appropriate horticultural lighting. Our organization, the DesignLights Consortium (DLC), strives to make the vetting process easier for everyone, freeing up growers to focus on their core business.

In the early days of LED lighting, electric utilities had to compare these different lighting factors and reports to inform their energy efficiency rebate/incentive programs. The DLC was founded to fill this need, serving as a central clearinghouse for setting energy efficiency and other product performance minimum standards, and to evaluate products against those standards. Then and now, lighting products that pass review qualify for an online qualified products list (QPL) that utilities use to quickly and accurately incentivize high-performing products.

Credit: ProGrowTech

With its new minimum performance standards for horticultural light fixtures, the DLC seeks to accelerate the adoption of new energy-saving LED fixtures in controlled agriculture environments. To be on the new DLC Horticultural QPL, an LED fixture must be at least 10 percent more efficacious than the best non-LED alternative – a 1,000-watt double-ended high-pressure sodium (HPS) fixture. It also must have a Q90 of 36,000 hours (the number of hours before the photon flux output depreciates to 90 percent), and its driver and fan (if included) must have a rated life of at least 50,000 hours.

Most importantly, every product is listed online in a searchable, filterable database to help growers and facility designers quickly narrow their options. For example, in a retrofit, a grower might know what PPF is needed from each fixture but might also need to stay within a power budget to avoid rewiring circuits. The DLC’s Horticultural QPL can be filtered to quickly find and compare conforming products.

When a new technology is introduced, there is always uncertainty about how to optimally apply it. The horticultural world is no different. We look forward to research supporting additional predictive metrics that allow us to take advantage of the full benefits of high-performance LED and controls technologies. In the meantime, the established standards described here allow for energy efficient and safe cultivation facilities where growers can confidently produce more with less.

Building or Converting to a Greenhouse? Four Considerations for Commercial Growers

By Taylor Engert
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Successful cannabis cultivation practices leverage commercial agricultural industry practices for the most efficient and cost-effective production of the crop. Since the 1990s, the cannabis industry has cultivated primarily in indoor warehouses and outdoor farms, however the industry is experiencing a significant shift toward greenhouses.

Shelly Peterson, vice president of light product solutions at urban-gro, joined a recent panel of industry experts including Shivawn Brady, chief executive officer and founder of Seva Crop Consulting, and Karl Keich, executive director at Canna Consulting Group, at the Marijuana Business Conference in Orlando, Florida, to discuss how to transition from an indoor or outdoor grow to a greenhouse facility.

What are the considerations when deciding between a warehouse and greenhouse? The panel shares four factors around the costs and operational challenges, and the benefits of a greenhouse.

panel
The panel at the Marijuana Business Conference.

Maximize Efficiency in Every Process

Why are cannabis cultivators looking toward greenhouses? Peterson says it is all about efficiency. “In a warehouse, electricity costs can run up to 50 percent of the total cost of goods sold, which is a tremendous amount that can be decreased by switching to a greenhouse,” says Peterson. “In a greenhouse, you can add supplemental lighting to augment what the plant is receiving from the sun.”

For cultivators, Peterson noted that it is critical to ensure growers have experienced vendors and advisors on the team to help maximize the efficiency of the greenhouse. “As the cost of this product comes down, the efficient growers will be the ones in it for the long haul,” added Peterson.

Construction vs. Operating Costs

A greenhouse facility that urban-gro helped bring to operation.
A greenhouse facility that urban-gro helped bring to operation.

The panel identified upfront cost as one of the biggest challenges faced when building out a greenhouse. “The cost of retrofitting a warehouse and building a greenhouse are similar, but where you will save is in the operational costs,” says Peterson. “Lighting can be up to one third of your total cost in indoor facilities, when you switch to a greenhouse that cost can be reduced by 50 to 70 percent.”

Brady acknowledged that some traditional greenhouses have challenges in controlling the environment, but automated greenhouses offer retractable roofs and siding. “If you have the resources to invest in your greenhouse system upfront, that is generally a better way to save money in the long run,” says Brady. “Managing pests in greenhouses can also become very challenging if you don’t have the proper climate regulations.”

Lighting for Your Greenhouse

One of the greatest benefits of growing in a greenhouse is the ability to source natural light. But what about the required light levels? Peterson pointed out that light levels change throughout the year and the plants have different light needs in different stage. Supplement with a lighting system that can read the natural light levels received over any given period of time and be adjusted accordingly. “Greenhouse facilities also need to be outfitted to meet the needs of the cannabis plant, which differ in some ways from other agricultural crops,” says Peterson.

Peterson explained that every light is designed with a different purpose in mind. “There are different lights for indoor warehouse facilities where the lighting system provides 100 percent of the available light for cannabis growth versus supplemental lighting for greenhouses,” Peterson adds. “The key is to measure how much light is actually delivered by the sun on a daily basis, which changes throughout the year; at urban-gro, we supplement the facility with light fixtures that will not create shadowing during hours of sunlight and adjust to reach the optimal collective light levels.”

With LED lighting a hot button topic, Peterson explained that the most important consideration for any light fixture, whether LED or HPS, is it’s efficiency capacity. “It all depends on the budget and payback period and a lot of numbers need to be crunched,” says Peterson. “Yield is directly correlated to light; planning properly, sealing your environment, making sure you have the right target DLI, and buying good light meters, are all key.”

Make a Positive Impact and Quality Product

Brady noted that industry leaders are conscious of positive impact towards human health and environmental stewardship when moving to a greenhouse. Cultivators may find the process challenging initially, however the facilities are quite easy to operate and manage, and allow stress-free cultivation of commercial-scale crops.

Keich added that the cannabis industry is becoming more like commercial agriculture. By utilizing the correct technologies and regulators, greenhouse cultivation makes the crop smell, taste and look that much better. “Let’s use natural sunlight to minimize costs and be environmentally friendly to produce a superior product,” says Keich.

Peterson wrapped up by stressing that cultivators should evaluate the greenhouse environment and lighting to improve their bottom line. “Look at the most efficient way to lower your cost of goods sold. Lighting is a very big component to that,” she continued. “Make sure you evaluate the efficiency of the fixture and ask the questions: Why are we targeting this light level? Is the color spectrum correct? Are you measuring in micromoles per watt? These are all different questions, however figure out how much light is coming out of the fixture and verify it for yourself, and you will be successful,” says Peterson.