Title 24 2025 Horticultural Lighting Rules for Permits After Jan 1, 2026

Effective date and scope

The 2025 California Energy Code (Title 24, Part 6) applies to projects permitted on or after January 1, 2026 [cec-ceh-faq-2025]. Controlled environment horticulture (CEH) spaces include indoor cannabis cultivation and conditioned greenhouses [cec-ceh-faq-2025].

CEH must meet mandatory lighting, dehumidification, and envelope rules that cannot be traded off against other measures [cec-ceh-faq-2025].

2.3 µmol/J minimum efficacy

For buildings with CEH spaces or greenhouses with more than 40 kW aggregate horticultural lighting load, electric lighting for plant growth must meet [cec-ceh-faq-2025]:

Photosynthetic photon efficacy (PPE) rated per ANSI/ASABE S640 for 400-700 nm wavelengths.

Integrated luminaires: minimum 2.3 µmol/J.

Removable lamp luminaires: lamps at least 2.3 µmol/J.

The 2025 cycle raised indoor minimums from 1.9 to 2.3 µmol/J [title24-case-ceh]. Greenhouse horticultural lighting rose from 1.7 to 2.3 µmol/J [title24-case-ceh].

Double-ended HPS generally cannot meet 2.3 µmol/J [title24-case-ceh]. Practical compliance paths use LED on DLC Hort QPL.

Alterations and retrofits

Section 141.1(c) triggers compliance when alterations [upcodes-ceh]:

Increase lighting wattage, or

Add, replace, or alter 10% or more of horticultural luminaires in an enclosed space.

Exception: alterations limited to controls only or lamp/ballast/driver swaps without crossing the 10% luminaire threshold [upcodes-ceh].

A phased LED retrofit crossing 10% in one permit pulls entire altered scope to 2.3 µmol/J fixtures.

Controls and acceptance testing

2025 code continues mandatory lighting controls (time switches, multilevel operation where applicable) [cec-ceh-faq-2025]. Acceptance testing by certified technicians is part of nonresidential compliance.

Cannabis operators accustomed to bypassing residential-style rules face third-party verification on commercial permits.

Document:

Control sequences tied to photoperiod.

Manual override limits for maintenance.

Commissioning reports for inspection folders.

Interaction with DCC rules

DCC dropped renewal electricity reporting July 1, 2026, but building code still governs permitted construction [dcc-2025-01-r]. Local building departments enforce Title 24, not DCC.

Permitted indoor rooms must comply regardless of DCC renewal simplification.

Utility rebates and Title 24

Utilities often require DLC Hort V4.0 listing at 2.5 µmol/J for rebates [dlc-hort-v4], stricter than Title 24's 2.3 minimum [cec-ceh-faq-2025]. Spec 2.5+ µmol/J fixtures to satisfy both code and LED rebate programs.

Apply for pre-approval before purchase where required.

HVAC and dehumidification coupling

CEH spaces must meet HVAC and dehumidification requirements in Section 120.6(h)1-2 [cec-ceh-faq-2025]. Higher efficacy LEDs reduce heat load but may shift dehumidification needs dehumidification load.

Engineering plans should resize HVAC when lighting watts per square foot drop.

Worked compliance example (illustrative)

10,000 sq ft flower room, 35 W/sq ft proposed horticultural load:

Aggregate load = 350 kW (> 40 kW threshold) [cec-ceh-faq-2025].

All specified fixtures must be ≥ 2.3 µmol/J.

At 800 µmol/m²/s target intensity, 2.3 µmol/J implies roughly 35 W/sq ft at typical optical efficiency (order-of-magnitude check, not substitute for photometric plan).

Contractor submits CF1R and acceptance tests with permit package.

Greenhouse note

Greenhouses with >40 kW horticultural load face same 2.3 µmol/J rule [title24-case-ceh]. Single-layer glazing rules from prior cycles still apply separately [cec-ceh-faq-2025].

Mixed-light cannabis tiers should map canopy area to aggregate kW early in design.

Cost planning

Title 24 compliance is CapEx, not operating expense, but lowers kWh afterward. Use LED retrofit ROI calculator with:

Fixture cost at 2.3+ µmol/J.

Rebate if pre-approved.

kWh savings vs legacy HPS.

HVAC downsizing if engineered.

Permitting timeline tips

Submit permit applications with cut sheets showing ANSI/ASABE S640 PPE.

Coordinate electrical load letter with utility service upgrade lead times California cultivation energy.

Schedule acceptance tester before drywall closes access to drivers.

CF1R and acceptance test package for CEH permits

Title 24 compliance for controlled environment horticulture rides on the CF1R energy compliance report and acceptance tests signed by certified technicians [cec-ceh-faq-2025]. For cannabis remodels, the AHJ typically wants:

Document	Content
CF1R-PRF-01-E	Project scope, climate zone, CEH square footage
Fixture cut sheets	ANSI/ASABE S640 PPE ≥ 2.3 µmol/J per luminaire [cec-ceh-faq-2025]
Control narrative	Photoperiod schedules, override limits
NRCA-LTI-E	Lighting controls acceptance
NRCA-LTO-E	Horticultural lighting operational testing

A 350 kW flower room permit applied for February 12, 2026 falls under the 2025 code [cec-ceh-faq-2025]. If your contractor priced fixtures in November 2025 under 2022 assumptions at 1.9 µmol/J, the submittal fails plan check. Re-spec before PO, not after drywall [title24-case-ceh].

Schedule acceptance testers before drivers are concealed. Failed LTO tests force reopening finished ceilings and push harvest slots by weeks.

Permit date election: 2022 vs 2025 code

Projects with applications on or after January 1, 2026 use the 2025 Energy Code [cec-ceh-faq-2025]. Applications in December 2025 may remain on 2022 requirements depending on local enforcement and how long the permit stays valid without lapse [cec-ceh-faq-2025].

Operators sometimes split a retrofit across two permits to stay under the 10% luminaire alteration threshold [upcodes-ceh]. That strategy backfires when Phase 2 crosses 10% in a later year and pulls the entire room to 2.3 µmol/J anyway. Model total CapEx for a single compliant phase rather than two staggered noncompliant ones [upcodes-ceh].

DCC dropped renewal electricity uploads July 1, 2026 [dcc-2025-01-r], but the building department—not DCC—signs off on CEH lighting. Plan check timelines in cannabis-hostile jurisdictions can exceed eight weeks; pad procurement accordingly.

Enforcement risk

Failed acceptance tests delay occupancy and harvest schedules. Budget rework time if spec sheets do not match installed drivers.

Resources

CEC 2025 CEH FAQ [cec-ceh-faq-2025].

CASE report economics and code language [title24-case-ceh].

Local AHJ interpretations may add scrutiny for cannabis land uses; confirm with jurisdiction.

Title 24 sets the floor. Competitive cultivation economics favor exceeding minimums for yield and rebate eligibility while meeting code on permit date [cec-ceh-faq-2025].

Failed plan check scenarios and how to avoid them

Building departments enforce CEH rules on permit date, not on DCC renewal status [cec-ceh-faq-2025] [dcc-2025-01-r]. Common failures on cannabis remodels:

Cut sheets show 2.1 µmol/J on a permit applied for March 2026. Code requires 2.3 µmol/J for aggregate horticultural load above 40 kW [cec-ceh-faq-2025].

Alteration crosses 10% luminaire threshold without upgrading full scope to compliant fixtures [upcodes-ceh].

Controls narrative missing photoperiod override limits required for acceptance testing [cec-ceh-faq-2025].

CF1R lists 2022 code on a January 2026 application. Projects on or after January 1, 2026 use the 2025 Energy Code [cec-ceh-faq-2025].

Budget eight to twelve weeks for plan check in jurisdictions that scrutinize cannabis land use, then two weeks for acceptance testing before occupancy [title24-case-ceh]. Failed NRCA-LTO-E horticultural operational tests force ceiling rework and delay harvest slots [cec-ceh-faq-2025].

Spec 2.5 µmol/J or higher DLC Hort V4.0 fixtures when you also want utility rebates above the 2.3 code minimum [dlc-hort-v4] [cec-ceh-faq-2025]. Coordinate HVAC resize when wattage per square foot drops; dehumidification load may rise even as sensible load falls [title24-case-ceh].

Greenhouse and mixed-light tiers

Greenhouses with more than 40 kW aggregate horticultural load face the same 2.3 µmol/J minimum as indoor CEH spaces [title24-case-ceh]. Mixed-light cannabis tiers should map canopy area to aggregate kW early in design so you know whether Section 120.6(h) triggers [cec-ceh-faq-2025]. Single-layer glazing rules from prior cycles still apply separately from lighting efficacy [cec-ceh-faq-2025].

Outdoor operators permitting only processing or packaging rooms may still hit CEH definitions if conditioned spaces exceed thresholds [upcodes-ceh]. Confirm scope with the AHJ before you assume outdoor cultivation exempts all horticultural lighting rules [cec-ceh-faq-2025] [title24-case-ceh].

Use the LED retrofit ROI calculator with 2.3+ µmol/J fixture costs, rebate pre-approval if available, kWh savings versus HPS, and HVAC downsizing if engineered [cec-ceh-faq-2025]. DCC dropped renewal electricity uploads July 1, 2026, but building departments still enforce CEH on permit date [dcc-2025-01-r] [cec-ceh-faq-2025].

Coordinate electrical load letter with utility service upgrade lead times when aggregate horticultural load exceeds 40 kW [cec-ceh-faq-2025]. Local AHJs in cannabis-hostile jurisdictions may add scrutiny beyond minimum code [title24-case-ceh] [upcodes-ceh].

Section 141.1(c) triggers compliance when alterations add, replace, or alter 10% or more of horticultural luminaires [upcodes-ceh]. Exception: controls-only or lamp/ballast swaps without crossing the threshold [upcodes-ceh]. A phased retrofit that crosses 10% in one permit pulls the entire altered scope to 2.3 µmol/J fixtures [cec-ceh-faq-2025].

The 2025 cycle raised indoor minimums from 1.9 to 2.3 µmol/J and greenhouse horticultural lighting from 1.7 to 2.3 µmol/J [title24-case-ceh]. Double-ended HPS generally cannot meet 2.3 µmol/J [title24-case-ceh]. Practical compliance paths use LED on DLC Hort QPL [dlc-hort-v4].

Greenhouse vs indoor CEH paths

Greenhouses with more than 40 kW aggregate horticultural load face the same 2.3 µmol/J minimum as indoor CEH spaces under the 2025 code [cec-ceh-faq-2025] [title24-case-ceh]. Mixed-light cannabis tiers should calculate aggregate kW early: a 30,000 sq ft greenhouse at 1.5 W/sq ft horticultural load clears 45 kW and triggers full Section 120.6(h) rules [cec-ceh-faq-2025].

Single-layer glazing and envelope requirements from prior cycles still apply separately from lighting efficacy [cec-ceh-faq-2025]. A greenhouse permit applied for February 2026 must use 2025 code fixtures even if a November 2025 application could remain on 2022 requirements until lapse [cec-ceh-faq-2025]. DCC dropped renewal electricity uploads July 1, 2026, but AHJs enforce CEH on permit date [dcc-2025-01-r] [cec-ceh-faq-2025].

Use the LED retrofit ROI calculator with 2.3 µmol/J baseline fixture cost, not legacy HPS, when comparing phased retrofit phases [title24-case-ceh] [dlc-hort-v4].