New energy requirements for Greenhouses and Indoor Controlled Environment Horticulture in ASHRAE 90.1 Model Code Updates

Industry News

What: ANSI/ASHRAE/IES Standard 90.1 (90.1) is poised to establish energy efficiency requirements related to greenhouses and indoor controlled environment agriculture (CEA) facilities. These model codes can then be adopted by state building commissions. A public draft for these requirements is available for public review starting Friday, September 24, 2021.

Why: The intent of this media alert is to inform the horticulture industry of the 90.1 standard draft addendum “AR” and its public review period where stakeholders can provide their feedback on the draft requirements.

Who: Growers, lighting manufacturers, distributors, energy efficiency consultants, research groups, industry trade groups, developers and facility designers, facility managers, and state officials should be aware of the proposed changes. 

Where/When/How: Draft 90.1 Standard addendum “AR” for CEA will be in public comment review until October 31, 2021 after which the comments will go to the 90.1 committee for consideration before adoption. The state of California has recently adopted similar CEA lighting requirements as a part of its broader suite of mandatory energy efficiency requirements that will go into effect in California on January 1, 2023. 

At their own discretion, individual states review the 90.1 standard with addendum updates to determine whether to adopt the model standard into their state’s building code. Once this occurs, the code takes effect in the state and growers will need to comply.

Proposed language will be posted at and public comments will be accepted until October 24, 2021.

If you are interested in following the code adoption proceedings, you can monitor the ASHRAE 90.1 website. 


In June 2021, the ASHRAE Standard 90.1 lighting subcommittee passed a standards addendum that proposing aligning Controlled Environment Agriculture (CEA) lighting efficacy requirements similar to those that were recently adopted in the 2022 California Energy Code. Visit the ASHRAE 90.1 website to see more information about the general ASHRAE model code development process. 

The proposed model code updates will apply to greenhouse lighting and indoor CEA lighting. If the requirements are adopted by ASHRAE 90.1, they will only apply to new construction. Comments regarding whether or not to expand to major alterations are welcome. The proposed model code does not apply to existing buildings unless those buildings are being significantly altered through permitted alterations. 

Here is a full list of applicability:

  • Newly constructed greenhouses or CEA facilities
  • Additions to greenhouses or CEA facilities
  • Lighting alterations that involve replacing 10 percent or more of the horticultural luminaires serving an enclosed space; only the newly installed luminaires need to meet the requirements and lamp replacements do not count as an alteration.

Each proposed model code update is described below. 

Horticultural Lighting Minimum Efficacy (indoor CEA lighting): 

  • For indoor CEA operations, luminaires with removable lamps will be required to use lamps with a photosynthetic photon efficacy (PPE) of at least 1.9 micromoles per joule.
  • Luminaires without removeable lamps shall meet a minimum luminaire PPE of 1.9 micromoles per joule.
  • This will allow the use of efficient double-ended HPS lamps; most LED luminaires will qualify. The minimum efficacy requirements only apply to CEH spaces with more than
    40 kW of aggregate horticultural lighting load. This equates to approximately (36) 1000W HPS luminaires.
  • Time switch controls will be required for indoor horticultural lighting systems.

Horticultural Lighting Minimum Efficacy (greenhouse lighting): 

  • For greenhouses, luminaires with removable lamps will be required to use lamps with a PPE of at least 1.7 micromoles per joule. 
  • Luminaires without removeable lamps will also need to meet a minimum luminaire PPE of 1.7 micromoles per joule. 
  • The minimum efficacy requirements only apply to greenhouse lighting with more than
    40 kW of aggregate horticultural lighting load.
  • Time switch and daylight availability controls will be required for greenhouse horticultural lighting systems.

Visit ASHRAE’s public review website ( more details on this and other potential updates. ASHRAE may modify the proposed changes in advance of adoption.  

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