Controlled environment horticulture report exposes lack of standardized energy data

Oct. 26, 2022
With support from PG&E, researchers reviewed literature on energy and water use in CEH and found values varied widely due to estimated models and “operational assumptions.”

The California Public Utilities Commission and utility Pacific Gas and Electric Company (PG&E) completed a report this past summer studying the published literature on energy and water resource usage in controlled environment horticulture (CEH — also called controlled environment agriculture). The objectives were to quantify resource consumption by CEH operations in the state of California and identify areas for energy savings that can be addressed in future iterations of the California Energy Code.

Project management firm 2050 Partners and HVAC and engineering consultancy Dr. Greenhouse, Inc. collaborated on the research under the sponsorship of PG&E, with oversight from PG&E’s Emerging Technology team.

With the increase in California greenhouse and indoor farming facilities designed to address food production and legalized cannabis cultivation, questions have arisen as to the practical efficiency of modern growing facilities and how to ensure that they meet benchmarks for energy and water consumption — which have yet to be outlined in policy, said Dr. Greenhouse president and founder Dr. Nadia Sabeh, a primary author on the CEH study. LEDs Magazine focused mainly on the discussion of energy with Sabeh in a recent call, during which she summarized how the research is being executed and what collaborators have learned thus far.

“Controlled environment horticulture has the potential to make a big impact on energy use in the state and on decarbonization goals that the state has, trying to hit 1990 levels [of greenhouse gases] by 2030,” Sabeh explained. “As the utility administrator for all the agricultural projects in the state, [PG&E] found a project manager and coordinator, who then hired [Dr. Greenhouse] as their sub-consultant to do the work.”

That information gathering continues beyond the initial 100-plus-page report released in July. After reviewing the published studies on CEH practices and initiating a phase of online surveys of CEH operators, Sabeh said, “We actually visited operating facilities to document the type of technologies and practices they were using and to get their thoughts on different energy efficiency measures.”

The initiative should result in multiple reports: the first on the state of data in this burgeoning industry, and others with recommendations for establishing metrics — standardized terminology and methods for how facilities quantify energy use — and benchmarking practices for resources, which will be used to direct regulatory policy that helps meet California energy and GHG goals.

Discussion with Sabeh uncovered the key challenge with analyzing CEH energy usage. “Most of the reported energy use data is not actual data collected from operating farms. The majority of it is based on computer models trying to simulate how energy is going to be used, and then estimate the annual energy usage,” which Sabeh said was “a huge disappointment.”

Given speculation about the energy usage of greenhouse and indoor farming, she noted, and questions about why indoor growing is needed in favorable climate conditions like those of California, the frustration is warranted. “Nobody has collected data right from these operating farms… [In some cases] data was based on assumptions about how they’re operating…or [operating equipment] under the most extreme conditions in the hottest climate in the world, then adding different efficiencies to get the energy use down,” which Sabeh said was not reflective of practical operating conditions.

A range of CEH practices is to be expected due to differences in cultivars, size of operation, building envelope, supplemental lighting, and more. Still, Sabeh said, in order to develop recommendations for improved efficiencies, those ranges still need to be monitored and recorded consistently and transparently. And there lies the roadblock: “Nobody is recording energy use metrics the same way,” Sabeh revealed.

“Of those 150 [review] references, we counted 15 different ways that growers, researchers, utilities, were reporting energy,” she explained. “Some are reporting an EUI — an energy use intensity based off square footage of building area. Others care about product, so you’ll see energy use per pound or energy use per gram; or you’ll see power use per gram because growers are thinking in terms of light, not necessarily HVAC and the cumulative energy. You might see kilowatts per gram” or even further variants among the reported metrics, which confounds the process of normalizing data, she added.

“One of the things I’m going to advocate for is to have our own energy use metric for this industry, kind of like what data centers have — something more relevant to the building and process type than an office building,” which Sabeh said influences current energy code.

Other key findings of the report include:

  • Best practices and performance targets are lacking for newer cultivars and indoor grows without natural daylight
  • Evaluation of HVAC and dehumidification equipment energy usage is insufficient due to current testing standards that do not represent CEH conditions and use
  • Data is lacking in terms of how recirculation equipment impacts water and energy usage, as they are tied together

Next steps for horticultural industry stakeholders involve discussing cross-cutting metrics and perhaps even crop-specific metrics in order to address the differences in yields or usable product across food production, floriculture, and cannabis. “Do we need to have specific metrics for each horticultural product?” Sabeh asked. “I’m not the one to answer that question, but I can hopefully facilitate that conversation through these kinds of reports.”

The metrics will play a large role in developing the benchmarks that set minimum efficiency standards according to regulators. Further to that, policies would also consider what financial incentives could be supported or certifications could be made available for facilities that meet or exceed the standards.

Sabeh will participate in an energy-management roundtable at the upcoming Resilient Harvests Conference, alongside policy makers, programs representatives, equipment providers, and CEH/CEA researchers who will explore the state of the market and the path forward to a more sustainable and economically fruitful industry.

CARRIE MEADOWS is managing editor of LEDs Magazine, with 20+ years’ experience in business-to-business publishing across technology markets including solid-state technology manufacturing, fiberoptic communications, machine vision, lasers and photonics, and LEDs and lighting.

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