What Title 24 is, what it requires, what changed in the 2025 code, and who is responsible for it. Written for owners, developers, and builders who need a clear answer before they pull a permit.
Written by Frank Sylvester, P.E., licensed Electrical Professional Engineer. Updated June 2026.
A guide from a licensed California engineer
Title 24 is the part of California law that decides whether a building is energy-code compliant. If you are building, adding on, or remodeling in California, the building department will check your project against it before issuing a permit. This guide explains what Title 24 covers, what the 2025 code changed, the documents a project has to produce, and who signs for the work. It is written by the engineer who prepares and stamps these plans, so the answers reflect how compliance actually works on a real permit, not just the letter of the code.
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Title 24 is the California Building Standards Code, a section of the California Code of Regulations that sets the minimum standards new buildings and major remodels have to meet. It is enforced by local building departments through the permit process. A project that cannot show Title 24 compliance does not get a permit, and a project that does not match its approved Title 24 documents at the end does not pass final inspection.
When most people say Title 24, they mean one specific part of it: Part 6, the Building Energy Efficiency Standards, usually called the Energy Code. Part 6 governs how a building uses energy, including insulation, windows, heating and cooling, water heating, lighting, and on-site solar and battery storage. The California Energy Commission writes and updates Part 6.
The full code is broader than energy alone. Title 24 also contains the building, electrical, mechanical, plumbing, fire, and green-building codes that a California project answers to. The energy piece is the part that catches the most projects off guard, because it requires calculations and signed documents that a standard set of drawings does not include.
Title 24 is divided into 13 parts. Most projects deal directly with only a few of them. The two that drive energy compliance are Part 6 and Part 11.
Part 6 is the Energy Code. Part 11, CALGreen, is the green-building code, covering water efficiency, materials, indoor air quality, and construction-waste measures. A single project can have to satisfy both, plus the building and electrical parts. SLC handles the electrical, lighting, and energy scope across these parts on one coordinated set of plans.
A building permit triggers Title 24. New construction, additions, and many alterations to both homes and commercial buildings have to demonstrate energy-code compliance before the local building department issues the permit. Some smaller repairs and like-for-like replacements are exempt, but the moment a project changes the building envelope, the heating and cooling, the water heating, or the lighting in a way that needs a permit, Title 24 is usually in play.
One detail decides which version of the code applies: the date the building permit application is filed. A project that files its application before a new code takes effect follows the previous edition, even if construction runs well into the new cycle. This is why timing a permit application around a code change can matter to a project's scope and budget.
Common triggers include new residential and nonresidential buildings, room additions, accessory dwelling units (ADUs), tenant improvements, re-roofs that touch insulation, HVAC changeouts, water-heater replacements, lighting retrofits, and the addition of solar or battery storage.
The current edition is the 2025 Building Energy Efficiency Standards. It applies to projects whose building permit application is filed on or after January 1, 2026. Projects that applied before that date follow the 2022 Energy Code. California updates the standards on a three-year cycle, so the next edition will follow in the 2028 code.
The 2025 update continues California's move toward electrification and lower building emissions. The headline changes include expanded heat-pump requirements for space and water heating in new residential construction, stronger electric-readiness provisions, enhanced battery-storage standards, and tighter ventilation and indoor-air-quality requirements. For many commercial and multifamily projects, the practical effect shows up in the electrical and mechanical design: more capacity planned for heat pumps and storage, and earlier coordination on the service.
If a project straddles the January 1, 2026 line, the cleanest answer comes from the permit application date. The engineer of record can confirm which edition governs and design to it from the first drawing, so the energy scope does not get reworked at plan check.
Title 24 sets different paths for different building types. The Energy Code is split into residential and nonresidential standards, and each has its own compliance documents and approaches.
New homes, ADUs, additions, and alterations follow the residential standards. Compliance can be shown by a prescriptive path (meeting a checklist of minimums) or a performance path (modeling the whole building with approved software to hit an energy budget). The performance path gives more design flexibility, which is why most projects beyond the simplest additions use it.
Offices, retail, warehouses, schools, and other commercial buildings follow the nonresidential standards. These projects carry more electrical and lighting scope: lighting power limits, lighting controls, mechanical systems, and, on many buildings, acceptance testing to prove the installed systems actually perform as designed.
Remodels and tenant improvements only have to bring the changed portion of the building up to code, but the line between what is changed and what is existing is where projects get tripped up. An early read on which systems the work triggers keeps a remodel from discovering a compliance requirement after the budget is set.
Title 24 compliance is proven on signed, registered forms, not just on the drawings. There are three stages, and the form names differ between residential and nonresidential work.
Residential projects use three certificates. The CF1R, the Certificate of Compliance, shows the design meets the code and is submitted at permit. The CF2R, the Certificate of Installation, is completed by the installing contractor to confirm the work was built as designed. The CF3R, the Certificate of Verification, is completed by an independent HERS Rater who field-verifies specific measures.
Nonresidential projects use the NRCC (Certificate of Compliance) at permit, the NRCI (Certificate of Installation) during construction, the NRCA (Acceptance test) for systems that require functional testing, and the NRCV (Certificate of Verification) where independent verification is required. The right set has to be completed, signed, and registered with an approved registry before final inspection.
A common surprise is that the design-stage certificate is only the first of the set. The installation and verification documents have to follow during construction, which is why naming who owns each form at the start of a project prevents a scramble at closeout.
Lighting is one of the most heavily regulated parts of the Energy Code, especially for commercial buildings. Title 24 limits how much power a building's lighting can draw, the lighting power density, and requires controls that reduce energy when light is not needed.
For nonresidential interiors, that usually means a combination of occupancy sensing, automatic daylight response near windows and skylights, multi-level or dimming controls, and automatic shutoff. Outdoor lighting carries its own power allowances and control rules by lighting zone. Getting the photometric layout and the controls right at design time keeps a project from failing the lighting portion of plan check or acceptance testing.
The electrical side increasingly overlaps with the Energy Code as well. Electric-readiness, EV-capable parking, and battery-storage provisions all live at the intersection of the Electrical Code and the Energy Code, which is where a licensed electrical engineer adds the most value. SLC handles photometric and lighting design and the electrical scope on the same coordinated plans.
It depends on the project, but the owner is ultimately responsible for the permit set, and the question of who prepares the energy calculations is a practical one. On many residential jobs, the architect or a dedicated Title 24 energy consultant runs the calculations and produces the CF1R. On nonresidential and complex projects, the electrical, mechanical, and lighting scope is engineered and signed by a licensed Professional Engineer, and the energy compliance is part of that engineered design.
The risk in splitting the work is coordination. When the energy calculations are produced by one party and the electrical and lighting design by another, the two can disagree at plan check, and the owner is left reconciling them. Having the energy compliance engineered alongside the rest of the design, under one signature, closes that gap.
At SLC, Title 24 compliance is engineered and signed by Frank Sylvester, a licensed Electrical Professional Engineer, as part of the permit set, so the calculations and the drawings carry one accountable signature from design through final inspection. That is the difference between a compliance report handed off in isolation and compliance built into the engineering. See SLC's Title 24 compliance services for how that works on a real project.
Title 24 runs alongside a project from design to closeout, in four stages.
The projects that go smoothly are the ones that treat Title 24 as part of the engineering from day one, not a report bolted on right before submittal.
Title 24 affects a project most when it is handled late. Caught early, it is a set of design decisions made alongside everything else. Caught at plan check, it can mean redesigning systems, re-running calculations, and resubmitting, which costs time the schedule did not budget for.
The most common mistakes are predictable. Designing to the wrong code edition because the permit timing was not checked. Treating the design-stage certificate as the end of compliance and forgetting the installation and verification documents. Splitting the energy calculations from the electrical and lighting design so the two disagree at review. And underestimating lighting controls and acceptance testing on commercial work.
Each of these is avoidable with an early, engineered read on the compliance scope. That early read is usually the cheapest decision on the project.
No. Title 24 is California law and applies only to projects in California. Other states set their own energy codes. Many are based on the International Energy Conservation Code (IECC), with state-specific amendments. A project in Oregon, Nevada, or Washington follows that state's adopted code, not Title 24.
SLC engineers projects across California, Oregon, Nevada, and Washington, and designs to the code that governs each site. The principle is the same in every state: get the energy and electrical compliance engineered into the permit set early, under one licensed signature, so it holds up at plan check.
Who wrote this
Frank is a licensed Electrical Professional Engineer who designs and signs permit sets across California, Oregon, Nevada, and Washington, with Title 24 energy compliance built into the engineering. This guide reflects how compliance works on real projects, from the first load study to the stamped permit set.
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Related services
California energy code compliance engineered into the permit set, signed by the engineer of record.
Lighting layouts and controls designed to meet Title 24 power limits and acceptance testing.
Storage engineering tied to the energy code's expanding battery and electric-readiness provisions.
