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Nonresidential Controlled Environment Horticulture

Measure Description

The Statewide CASE Team proposes to categorize CEH operations as a covered process, and to provide definitions of several terms directly related to CEH, to clarify appropriate application of proposed submeasures. The term “photosynthetic photon efficacy (PPE)”, an industry-accepted metric for horticultural lighting efficacy would be defined as part the 2022 Title 24, Part 6 rulemaking. To address the marked increase in energy demand by the CEH sector, the Statewide CASE Team proposes three submeasures related to CEH facilities:

  • Horticultural lighting minimum efficacy,
  • Efficient dehumidification, and
  • Greenhouse envelope standards.

These proposed submeasures apply to new construction, additions to facilities with CEH operations, alterations that change the occupancy classification of a building (for example, a warehouse converted to a CEH facility), and alterations that involve lighting systems or installing new dehumidification or HVAC systems in CEH facilities.

Horticultural Lighting Minimum Efficacy

The horticultural lighting minimum efficacy submeasure proposes a mandatory requirement for minimum PPE of up to 2.1 micromoles per joule (µMol/J) for luminaires used for plant growth and maintenance in indoor growing facilities with more than 40 kW of total connected horticultural lighting load and a minimum PPE of 1.7 µMol/J in greenhouses with more than 40 kW of total connected horticultural lighting load. The submeasure requires time-switch controls and multilevel lighting controls in both types of CEH facilities. Additionally, this submeasure requires the designing of the electrical power system serving CEH spaces so horticultural lighting loads are separated from other lighting loads.

The submeasure applies to new construction, additions to CEH facilities, alterations that change the occupancy classification of a building (for example, a warehouse converted to a CEH facility), and alterations that involve replacing 10 percent or more of the luminaires serving an enclosed space.

Efficient Dehumidification

The efficient dehumidification proposed submeasure applies to newly constructed facilities and newly installed HVAC and dehumidification systems in existing facilities.

The submeasure mandates the use of one of the following dehumidification systems in indoor growing facilities:

  • Stand-alone dehumidifiers that meet the following minimum integrated energy factors as measured by the test conditions in the Code of Federal Regulation (CFR) Title 10, Appendix X1 to Subpart B of Part 430:
    1. Minimum integrated energy factor of 1.77 L/kWh for product case volumes of 8.0 cubic feet or less
    2. Minimum integrated energy factor of 2.41 L/kWh for product case volumes greater than 8.0 cubic feet
  • Integrated HVAC system with on-site heat recovery for reheating dehumidified air; or
  • Chilled water system with on-site heat recovery for reheating dehumidified air; or
  • Solid or liquid desiccant dehumidification system for system designs that require a 50°F dewpoint or less.

The submeasure requires the on-site heat recovery system to be designed to fulfill at least 75 percent of the facility’s annual reheat needs.

This submeasure also proposes to exempt CEH facilities from the prescriptive requirement to install an air-side economizer, when carbon dioxide (CO2) enrichment is used as a strategy to promote plant growth.

Greenhouse Envelope Standards

The greenhouse envelope standards submeasure focuses on clarifying existing code language as it relates to greenhouses. Code language that is difficult to interpret and apply in practice can impede the uptake of measures that were designed to reduce energy use and benefit the facility owner over the life of the installed technology. Confusing code language can also slow down the compliance process. Therefore, the Statewide CASE Team is proposing a path of compliance for greenhouses as well as clarifying which measures apply to greenhouses to “clean up” the language to reduce the opportunity for misapplication in practice. Specifically, this submeasure proposes the following envelope requirements specific to conditioned greenhouses:

  • Opaque walls and opaque roof assemblies must meet the existing mandatory insulation requirements in Section 120.7.
  • Non-opaque wall assemblies must have a combined U-factor of 0.7 or less; and
  • Non-opaque roof assemblies must have a combined U-factor of 0.7 or less.

The submeasure also exempts greenhouses from existing prescriptive building envelope requirements for window wall ratio, skylight roof ratio, and daylighting requirements for large enclosed spaces.

The proposed submeasure applies to newly constructed greenhouses and to greenhouses being converted from unconditioned to conditioned. Furthermore, this proposal applies to additions to conditioned greenhouses.

Since this submeasure is a code cleanup effort, there are no associated savings or incremental costs.

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

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Final CASE Report Now Available

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.