Title 24 Requirements for Cannabis Cultivation Facilities
Cannabis cultivation is regulated as controlled environment horticulture, a covered process under Section 120.6(h). The rules do not depend on the crop. They follow the grow lights, the dehumidification and, in a greenhouse, the glazing.
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The space is regulated, not the crop
A controlled environment horticulture (CEH) space is building space dedicated to plant production by manipulating indoor conditions — electric lighting, irrigation, mechanical heating or cooling, dehumidification. The Compliance Manual says the requirements apply whatever is grown, and that the state's cultivation licence categories are not relevant to Energy Code compliance.
What the code does distinguish is indoor growing from a greenhouse, and it decides that by the share of roof that is glazed: under 50 per cent is indoor growing, 50 per cent or more is a greenhouse. Installed electric light does not change which it is.
Grow lights: 2.3 micromoles per joule
Section 120.6(h)5 applies "in a building with CEH spaces or a greenhouse with more than 40 kW of aggregate horticultural lighting load". The plant-growth lighting must then reach a photosynthetic photon efficacy of at least 2.3 micromoles per joule, rated to ANSI/ASABE S640 over 400 to 700 nanometres — measured on the lamp where lamps are removable, on the luminaire where they are not. The Compliance Manual notes that only high-efficacy LEDs reach it; high pressure sodium does not.
The same lighting needs time-switch controls, which are acceptance tested, and multilevel controls. In return it is excluded from the indoor lighting power calculation.
Indoor rooms: dehumidification and metering
Dehumidification for indoor growing takes one of four routes: a dehumidifier meeting the federal appliance standard; an integrated HVAC system, or a chilled water system, with on-site heat recovery designed to supply at least 75 per cent of the annual reheat energy; or a desiccant system where the design dewpoint is 50°F or lower. The electrical distribution must let a measurement device monitor the aggregate horticultural lighting load. Where outdoor air would upset carbon dioxide enrichment, the economizer requirement gives way.
Greenhouses bring the envelope back
A greenhouse becomes a conditioned greenhouse once it has mechanical heating above 10 Btu/hr per square foot, cooling above 5, or wood heating. Its opaque walls and roof then meet Section 120.7, its glazing must be at least two layers separated by air or gas, and the space-conditioning serving plant production meets every applicable requirement.
Retrofits and conversions
Under Section 141.1(c), an alteration that raises horticultural lighting wattage, or adds, replaces or alters 10 per cent or more of the luminaires serving an enclosed space, brings the new luminaires up to the efficacy requirement. Lamp, ballast, driver or controls-only changes do not. Converting a warehouse into a grow facility is a change of occupancy, which the Compliance Manual confirms triggers the CEH requirements.
Where to go deeper
Horticulture sits beside the other covered processes, and its lighting efficacy is documented on the NRCC-PRC process-systems certificate rather than in the indoor lighting set.