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 mandatory photosynthetic photon efficacy (PPE) requirements for indoor growing and greenhouse lighting. In indoor growing facilities, all horticultural luminaires shall be rated with PPE of at least 1.9 micromoles per joule, and all horticultural luminaires with removable lamps shall contain lamps with rated PPE of at least 1.9 micromoles per joule. In greenhouses, all horticultural luminaires shall be rated with PPE of at least 1.7 micromoles per joule, and all horticultural luminaires with removable lamps shall contain lamps with rated PPE of at least 1.7 micromoles per joule. These requirements would apply to luminaires used for plant growth and maintenance in facilities with more than 40 kW of total connected horticultural lighting load.

The submeasure requires time-switch and multilevel lighting controls in both indoor growing facilities and greenhouses. Additionally, this submeasure requires designing electrical power distribution system serving controlled environment horticulture (CEH) spaces in a way that allows energy use monitoring of aggregate horticultural lighting load.

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 lighting alterations that involve replacing 10 percent or more of the horticultural luminaires serving an enclosed space. For lighting alterations involving replacement of 10 percent or more of luminaires serving an enclosed space, only the newly installed lighting would be subject to the proposed code. Lighting alterations involving replacing lamps only, ballasts only, or drivers only would not be subject to the proposed code.

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.

• CASE Study Results Report – Controlled Environment Horticulture
• Final CASE Report – Controlled Environment Horticulture (updated 3/3/2021 to include Appendix M)
• Draft CASE Report – Controlled Environment Horticulture

Round Two Utility-Sponsored Stakeholder Meeting Materials

• Presentation – April 16 – Controlled Environment Horticulture
• Controlled Environment Horticulture Submeasure Summary (Updated 4/15/2020)
• Notes – April 16 – Controlled Environment Horticulture

Round One Utility-Sponsored Stakeholder Meeting Materials

• Controlled Environment Horticulture – Sept 10 – Submeasure Summaries
• Presentation – Sept 19 – Controlled Environment Horticulture
• Notes – Sept 19 – Controlled Environment Horticulture