Energy code
California Title 24 Energy Code: Commercial Metering and Circuit Separation
California is the largest commercial construction market in the United States and the one most often got wrong by teams working from an IECC playbook. The state does not adopt the International Energy Conservation Code. It writes and enforces its own Building Energy Efficiency Standards — Title 24, Part 6 of the California Code of Regulations — on a three-year cycle. The governing edition is the 2025 California Energy Code, Title 24 Part 6, incorporating the January 2026 errata.
The trigger is kVA, not square feet
IECC Section C405.12 and C405.13 trigger on gross conditioned floor area — 25,000 square feet in the 2021 edition, 10,000 square feet in 2024. Title 24 does not work that way. Section 130.5 scales with the size of the electrical service, measured in kVA. A 9,000 square foot building with a large service can carry more metering obligation than a 40,000 square foot building with a small one. Every square-footage rule of thumb imported from an IECC state gives the wrong answer in California.
Section 130.5(a) — Service electrical metering
Applies to nonresidential, high-rise residential, and hotel/motel buildings.
| Electrical service | Meter must measure |
|---|---|
| Any size | Instantaneous kW demand and kWh over a user-defined period |
| Over 250 kVA | The above, plus historical peak demand in kW |
| Over 1,000 kVA | The above, plus kWh by rate period |
A utility-provided meter that already meets these requirements is acceptable. Metering at either the service or the feeder level satisfies the requirement, provided all loads are captured.
Section 130.5(b) — Separation of electrical circuits
Requirements scale with service size under Table 130.5-B. In outline:
- Under 50 kVA — renewable power sources and EV charging separated from other loads
- 50 to 250 kVA — separate risers for lighting, receptacles and equipment, and HVAC
- Over 250 kVA — lighting and plug loads separated by floor, type or area
Four compliance methods are permitted: disaggregated equipment by load type; equipment serving multiple load types where the values can be separated arithmetically; branch circuits serving a single load type with provisions for future monitoring; or a complete metering system measuring each load type.
Tolerance, quoted from the CEC compliance manual: “for each separate load type, up to 10 percent of the connected load may be of any other load type.”
Exemption: healthcare facilities overseen by California's Office of Statewide Health Planning and Development are exempt from the separation requirement.
Title 24 compared with the IECC
| California Title 24 §130.5 | 2021 IECC C405.12 | 2024 IECC C405.13 | |
|---|---|---|---|
| Trigger metric | Electrical service size (kVA) | Gross conditioned floor area | Gross conditioned floor area |
| Threshold | Scales from under 50 kVA | 25,000 sq ft | 10,000 sq ft |
| Approach | Separation of circuits by load type | Separate metering of electrical end uses | Separate metering of electrical end uses |
| Non-electric end uses | Not covered by §130.5 | Not required | Required under C405.13.8 |
| EV charging | Separated at any service size | Not addressed | Addressed in the 2024 cycle |
For how the IECC editions are landing state by state, see the IECC submetering state adoption tracker.
Specifying the equipment
Circuit separation is a distribution design decision; metering is what makes it measurable and what a plan checker can see evidence of. Typical equipment for a Title 24 project:
- Split-core current transformers for retrofitting existing branch circuits without taking the panel down
- Wireless self-powered sensors where running CT leads back to a meter is impractical
- Multi-circuit branch-circuit monitors where a single panel carries many separated load types
- Revenue-grade meters at the service entrance to satisfy §130.5(a) where the utility meter alone does not
- Gateways and data acquisition hardware to aggregate readings for reporting
Emergent Metering supplies the metering hardware — current transformers, meters, sensors, gateways and enclosures — for Title 24 projects across California.