The current California energy code (Title 24 Nonresidential) requires luminaires or lamps that are used for plant growth to have a photosynthetic photon efficacy (PPE) of at least 1.9 micromoles per joule (µmol/J) for indoor grow facilities with more than 40 kW of horticultural lighting load. Luminaires or lamps used for plant growth in greenhouses with more than 40 kW of horticultural lighting load must have a PPE of at least 1.7 µmol/J. Both the indoor and greenhouse requirements can be met by double-ended high-pressure sodium (HPS) technology, a legacy product that has been in the CEH market for over a decade.
For the 2025 cycle, the Statewide CASE Team is analyzing the potential for increasing the PPE levels for both indoor and greenhouse facilities. The Statewide CASE Team is comprised of five California utilities: PG&E, SCE, SDG&E, LADWP, and SMUD. Specifically, the Statewide CASE Team is proposing to increase the minimum PPE for luminaires and lamps used to grow plants in indoor facilities from 1.9 to an LED-based efficacy of at least 2.3 µmol/J. This change would mandate the use of LEDs whereas HPS lamps can meet the existing requirements. The Statewide CASE Team will investigate the potential for requiring controls that operate indoor lighting systems based on Photosynthetic Photon Flux Density (PPFD) and Daily Light Integral (DLI).
For greenhouses, the Statewide CASE Team is looking into increasing the minimum PPE for luminaires and lamps used to grow plants from 1.7 to 1.9 µmol/J. Double-ended HPS lamps and LED luminaires would be able to meet this proposed level while ceramic metal halides would likely not.
The full Statewide CASE Team proposal is available here.