California’s New Energy Code Regulates Controlled Environment Horticulture

Effective January 1, 2023, California’s new energy code (2022 Title 24, Part 6) includes requirements aimed at reducing the energy use of controlled environment horticulture (CEH) operations (1). This new code section (Section 120.6(h)) covers both indoor and greenhouse growing of all crops (not just cannabis), and includes measures around lighting, HVAC, envelope, and power monitoring. There is also a lot that this code does NOT include, either because energy savings couldn’t be proven or because industry stakeholders pushed back against measures they argued would be unattainable or uneconomical. The following article summarizes what is and isn’t in the new energy code and how stakeholders, like you, can influence the 2025 energy code, already in the works.

What’s in the New Energy Code

1.     CEH is a Covered Process, Not a Building

It may seem counterintuitive to those of us who have been inside a greenhouse, warehouse, or other structure used to commercially grow crops, but this energy code does not consider CEH to be a building. Instead CEH is defined as a “Covered Process”, which is an activity or treatment of a building that is NOT related to human occupancy. Some other covered processes include computer rooms, refrigerated warehouses (cold storage), commercial kitchens, and elevators. Yes, we need to condition, illuminate, and otherwise treat those rooms, but not necessarily for people to occupy them, other than temporarily. With this definition in mind, classifying CEH space as a process, rather than a human-occupied building, is a good thing for indoor ag.

2.     New Construction Projects Only

The energy code only applies to new CEH facilities that are not currently operating. That includes building a new greenhouse, constructing a new concrete or steel building, or retrofitting an existing warehouse into a CEH operation.

3.     The Measures are Mandatory

All the energy efficiency measures included in Section 120.6(h) are mandatory. There is no getting around them, even if you plan to implement an alternative technology or practice that would reduce energy use more than the requirement. It might be possible to get an exception, but it’s unlikely.

California Energy Code, Controlled Environment Horticulture Mandatory Measures (Title 24, Part 6, Section 120.6(h), Effective Jan 1, 2023)
Indoor Growing	Greenhouses
Horticultural Lighting - PPE ≥ 1.9 mmol/Joule	Horticultural Lighting - PPE ≥ 1.7 mmol/Joule
Electrical Power Distribution - Design electrical panels such that electrical energy use of horticultural lighting systems can be monitored and measured	Building Envelope (Air-Conditioned Greenhouses) - Opaque walls and roof: comply w/Section 120.7 - Transparent covers: glazings must have two or more layers separated by air, argon, or other gas
Dehumidification - Standalone dehumidifiers: comply with federal appliance standards - Integrated HVAC system: meet 75% of dehumidification reheat needs w/heat recovery - Chilled water system: meet 75% of dehumidification reheat needs w/heat recovery - Desiccant system: Only allowed when target dewpoint ≤ 50F	Space-Conditioning Systems - Air conditioners, chillers, heaters, fans: comply with all applicable requirements (eg. mechanical, plumbing, and electrical codes associated with HVAC systems)
All New CEH Operations
Time-switch lighting controls: - Install automatic or astronomical time-switch controls that can be programmed to operate lights at a minimum of two levels (Section 110.9(b)1) - Install controls that can automatically shut off lights (Section 130.4(a)4) - Inspect and test the functionality of time-switch controls (applicable sections of NA7.6.2)
Multilevel lighting controls: Horticultural lighting levels must be adjustable up and down (Section 130.1(b).

What’s NOT in the New Energy Code

1.     Existing CEH Facilities Need Not Comply

If you are currently operating a greenhouse or indoor grow facility, this energy code does NOT pertain you. However, if you are planning an expansion within the existing building or perform a major renovation of your existing space (like changing out all the HVAC equipment), you will likely need to comply.

2.     Trade-Offs with Other Energy Efficiency Measures

Unfortunately, growers won’t be able to trade one of these required measures with a different measure that also reduces energy use. We call these “Prescriptive Measures”. The reason this option isn’t available to CEH is because there simply isn’t enough research or data to demonstrate the savings of various alternative measures. Therefore, it’s impossible to know how much energy will be used or saved by different technologies and practices.

3.     A Performance Approach

For many building projects, engineers and energy professionals can develop a model that simulate the energy use of a building and its systems and then compare it to a baseline to demonstrate savings. However, in the case of CEH, we don’t have uniform or accepted methodologies for calculating thermal loads, simulating HVAC operation, or practicing the art and science of indoor cultivation. We also don’t have baseline buildings or systems defined to compare against. The Resource Innovation Institute (RII) is attempting to gather data from various grow operations around the country to help establish these baselines, but they need a lot more participation to develop those baseline standards.

Get Involved

California is already eyeing changes and additions to the 2025 Energy Code. The researchers hired to analyze and propose new measures, the Statewide CASE Team, has begun their process to evaluate new potential energy efficiency measures for CEH. Whether you are a grower, researcher, engineer, lighting vendor, HVAC manufacturer, greenhouse supplier from the Midwest, cannabis advocate in New York, regulator in Ohio, farm bureau member in San Diego, or have any interest whatsoever in the success of Controlled Environment Agriculture (Ahem! Horticulture), they want (and need) to hear from you. The first stakeholder meeting is February 9, 2023 starting at 10:45am PST and is a great opportunity to voice your support or concerns.

We also need data and research to support alternative compliance paths, including tradeoffs between measures (prescriptive path) and standardized calculation and data collection methods to demonstrate savings compared to baseline systems and facilities (performance path). That means we need greater transparency and collaboration from growers to establish those standards and benchmarks. We are grateful to the growers in and out of California who participated in our recent energy survey study, which found that CEH may not actually use as much energy as all the models have been predicting. That’s amazing news for the industry, so let’s keep sharing!

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If you want to learn more or have questions about how the energy code might affect your upcoming CEH project, contact us at energy@doctorgreenhouse.com.

(1)   In case you’re wondering why California chose Controlled Environment Horticulture (CEH) rather than Controlled Environment Agriculture (CEA), it’s because the acronym “CEA” was already taken by the California Energy Alliance, a non-profit organization, advocating for energy productivity through research, policy, and outreach.