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Nonresidential Controlled Environment Horticulture

Measure Description

The Statewide CASE Team proposes to evaluate indoor horticulture measures for inclusion in the 2022 update cycle of the Title 24, Part 6, Building Energy Efficiency Standards. The proposed measures aim to reduce energy and water use, while maintaining product quality and production volume for crops grown in non-stacked and stacked indoor farms and greenhouses. The Statewide CASE Team considered the plant growth requirements for the following crops in the evaluation of the proposed measures: cannabis, microgreens, vegetable transplants, basil (representing herbs), lettuce (representing leafy greens), tomatoes (representing vine plants), and roses. 

Controlled environment horticulture (CEH) is best categorized as a covered process. The primary sections of Title 24, Part 6 for the proposed measures include:  

  • 120.6 Mandatory Requirements for Covered Processes and 
  • 141.1 Requirements for Covered Processes in Additions, Alterations to Existing Nonresidential, High-Rise Residential, and Hotel/Motel Buildings. 

Greenhouse Envelope 

Greenhouses with heating that has capacity greater than 10 Btu/hr-ft2 or mechanical cooling that has capacity greater than 5 Btu/hr-ft2 are currently defined by Title 24, Part 6 as “conditioned space.” As such, they must meet nonresidential building envelope requirements, which were never intended for greenhouses. This submeasure proposes envelope requirements specific to greenhouses: either non-opaque walls and roof assemblies must have a U-value of 0.71 or less, or a shade curtain system must be installed. These requirements would apply to conditioned greenhouses. 

Lighting Efficacy 

The proposed Lighting Minimum Efficacy submeasure requires a minimum photosynthetic photon efficacy (PPE) of 2.1 micromole per joule for luminaires used for plant growth and maintenance in indoor growing facilities and a minimum PPE of 1.4 for greenhouses. The submeasure applies to new construction and lighting alterations of at least 10% of existing luminaires serving an enclosed space in CEH facilities with at least 1,000 ft2 of canopy. 

Efficient Dehumidification and Reuse of Transpired Water 

The Efficient Dehumidification and Reuse of Transpired Water submeasure requires using one of the following dehumidification equipment in indoor growing facilities: 

  • Free-standing dehumidification units with a minimum energy factor of 1.9 L/kWh.  
  • Chilled water system with heat recovery for reheating dehumidified air. 
  • Integrated HVAC system with heat recovery for reheating dehumidified air. 

Under this measure, indoor growing facilities with more than 1,000 ft2 of canopy and with stand-alone dehumidification system(s) would be required to reuse transpired water for irrigation. 

Furthermore, the measure requires CEH facilities – greenhouses and indoor growing facilities – to have integrated thermostatic and humidity controls. This measure also exempts CEH facilities from the prescriptive requirement to install an air-side economizer when CO2 enrichment as a strategy to promote plant growth is used. 

Submeasures Moved to Future Code Cycles

The Statewide CASE Team is no longer pursuing the proposed changes listed below.

  • Environmental and Irrigation Controls
  • Circulation Fan Minimum Performance Specifications

Relevant Documents

Measure proposals, supporting documents, and other outside references will be made public as they become available.

Round Two Utility-Sponsored Stakeholder Meeting Materials

Round One Utility-Sponsored Stakeholder Meeting Materials

Provide Feedback

Click here to register for the April 16 Controlled Environment Horticulture Utility-Sponsored Stakeholder Meeting.

This measure description will be updated as research is developed to support the 2022 code cycle. For questions or suggestions, email info@title24stakeholders.com. Include the measure name in the subject line.

Give Us Your Feedback

The Statewide CASE Team values input from all stakeholders engaged in the Title 24, Part 6 code change process. We encourage the open exchange of code change comments and concerns.

  • Use the form above to provide feedback on this measure.