Ways the DesignLights Consortium Is Addressing Your Most Critical Lighting Questions

The DesignLights Consortium (DLC) is a non-profit organization whose mission is to achieve energy optimization in lighting by enabling controllability with a focus on quality, people, and the environment. It works with member companies and industry experts to establish performance thresholds and to create new programs that work for all of stakeholders.

Greenhouse Grower Senior Editor Brian Sparks recently caught up with Kasey Holland, Technical Manager of Horticulture at DLC, to learn more about how the organization works with growers to learn more about and address their most critical needs at a time when energy savings can make or break a company’s bottom line.

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Brian Sparks: In your conversations with growers, what are some of the most common concerns or challenges they mention?

Kasey Holland: Some of the biggest concerns that we hear from growers are incorporating a new lighting system will impact the overall process and change the quality of the crop being grown (i.e. a risk to their brand), as well as whether the capital expense of the new lighting equipment is too high for crops that are already produced with minimal profits. They also ask us, while controls can enable greater process efficiency, what can they do if the luminaire or lighting control manufacturer goes out of business and their products no longer operate as intended and aren’t serviceable?

Sparks: What steps are you taking to address these challenges?

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Holland: The DesignLights Consortium recognizes that a lighting change is a process change and that LED lights need to be reviewed to ensure they are evaluated appropriately and consistently. We rely on and are involved in the development of industry standards covering topics ranging from nomenclature to testing methodologies. This allows the DLC to develop Technical Requirements and a Qualified Products List specific to Horticultural Lighting, that QPL users can rely on, knowing that qualified products’ performance have been measured by appropriately accredited testing labs and reviewed to ensure that performance data is reported accurately.

Growers looking to identify suitable products can leverage the QPL to identify products that meet their application needs in terms of light output (photosynthetic photon flux), knowing that whether they want to match their current photosynthetic photon flux density (PPFD) and save energy, or match their current energy consumption and provide a higher PPFD, the product being selected meets baseline thresholds in terms of efficiency (photosynthetic photon efficacy), lifetime (flux maintenance, driver lifetime, fan lifetime, etc.), and much more.

We work with utilities and energy efficiency programs across North America to support the development of incentive and/or rebate programs, helping buy down the upfront cost of lighting equipment and savings growers money over time through improved energy efficiency. The DLC requirements set baseline thresholds for product lifetime to help ensure that installed products perform consistently over time. These requirements cover a few critical topics including:

  • Q90 >= 36,000 hours, which ensures PPF output does not decrease more than 10% over 36,000 hours,
  • Driver lifetime >= 50,000, which ensures that the power supply for each luminaire, lamp, or module has been tested and verified to provide consistent performance in the hottest, most energy intensive environment that product is rated for
  • A five-year warranty for all products, other than specific replacement lamp options which require at least a 3-year warranty, and more

Sparks: What are the factors growers should consider when making decisions on how and when to invest in lighting technology?

Holland: Growers should consider whether they want to match PPFD or match wattage when converting to an LED-based system. Matching PPFD will allow energy savings, while maintaining the status quo in terms of how much light (PPF) is being provided to the crop. Matching wattage will allow the grower to increase the amount of light being provided to crop (i.e. higher PPFDs), which translates to more output potential, but will require additional process changes. For example, increasing PPFD necessitates higher HVAC/D energy demands to maintain target humidity or relative humidity that would increase due to higher transpiration rates in the crop.

Sparks: What are the primary benefits that a modern, updated lighting system can provide?

Holland: The primary benefits are both energy savings and flexibility in lighting recipe. DLC-listed LED-based horticultural lighting products are at least 20% more efficient than the best incumbent technology (1000W DE HPS), with the average product being 45% more efficient. These energy savings let growers focus on spending money in other areas or increasing profits. Products with more advanced capabilities, such as spectral tuning, empower growers to dial in their lighting practice to consider target spectra to drive development of secondary metabolites and much more.

The DLC is still investigating the roadblocks and obstacles growers currently face in implementing new lighting technology by increasing outreach to growers. We would be happy to share more on this topic.

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I have some issues with the reliance solely on LEDs; particularly as regards the ongoing evolution of grow lighting.
a) Not all photons carry the same eVoltage charge. As a result, different luminaires can test out at the same PPF, yet have radically dissimilar Quantum Yields. 1kW worth of photons at 660nm is a LOT more photons than 1kW worth of photons distributed helio-mimetically.
b) Just as the numbers on the dial do not provide an accurate measurement of the decibels of Sound Pressure Level (SPL) the audio system is putting out, nor of the accuracy of reproduction of the original sounds, counting photons does NOT tell us how many of the Watts being drawn at the wall are ending up as Watts actually being used by our plants to trigger and/or energize beneficial phyto-chemical reactions.
c) This school of photo-biology disregards what we’ve learned from accoustics, radio/radar engineering and optonics about the role of harmonic frequencies in optimizing the availability of the energy at any given frequency in a wave.
c) Other than computer-modeling, using data that is still to be gathered, the most accurate way to compare dissimilar techniques and/or technologies is salable yield/ total area used in production/ unit of time. (It is my understanding that some academician in Canada has come up with a theoretical maximum yield, for cannabis, of 1 kilogram/ft.2/year.)

The very first deliberate Sea of Green grown cannabis (1982) yielded 6.5 pounds from 198 clones given 2000 Watts of lighting. This was done in 13 weeks from cutting to chopping down. It was grown under a HydroTech 6’10” umbrella style Alclad reflector running a Sylvania 3-K phosphor-coated metal halide lamp and four Hydro-tech horizontal-throw reflectors running 250-Watt Osram OptimArcs (the first lamp running the salt mix now found in 4K CMH luminaires.)

S-o-o-o…any standard enacted should be productive-efficacy driven (another way to say Quantum Yield-based), e.g. regardless of technology used the standard should be:
G grams/ F square feet/ per year, regardless of the technology that is used to accomplish it.