California Title 24 energy requirements for HVAC are mandatory efficiency and construction standards that apply to heating, ventilation, and air conditioning systems in newly built or significantly altered buildings across the state. Here is the short version of what they cover:
- Equipment efficiency minimums – systems must meet ratings such as 15.2 SEER2 / 12.0 EER2 for central air conditioners and the federal minimum AFUE for gas furnaces (80% today, rising to 95% for furnaces made from late 2028 under the DOE rule)
- Duct sealing and insulation – ducts in unconditioned spaces must be insulated to at least R-6 and sealed to limit leakage
- Proper sizing – HVAC systems must be sized with an ACCA Manual J load calculation, not a rule of thumb
- Ventilation – a minimum of 15 cubic feet per minute (CFM) of mechanical ventilation per occupant
- Smart controls – thermostats must offer setback scheduling and be demand-response ready
- HERS verification – an independent Home Energy Rating System rater must field-verify key measures before the permit is finaled
- Two compliance paths – prescriptive (meet every table minimum) or performance (whole-house energy modeling)
These standards live in Title 24, Part 6 of the California Code of Regulations, also called the California Energy Code. The code is updated every three years. The 2025 Energy Code took effect on January 1, 2026; projects permitted before that date follow the 2022 code. If you own or manage a home in the Sacramento area, these rules touch every permitted HVAC installation, replacement, or significant alteration.
The good news: compliance is very achievable once you know what is actually required. The sections below break it down.
Understanding California Title 24 Energy Requirements for HVAC
Title 24 is a large set of building standards written to make California buildings safe, healthy, and efficient. For homeowners in Roseville, Rocklin, Folsom, and Sacramento, the HVAC portions are not just red tape; they are the reason a code-compliant system costs less to run and keeps the house more comfortable through a 105-degree July.
The HVAC requirements are maintained by the California Energy Commission (CEC). Recent code cycles have pushed hard toward electrification and high-efficiency heat pumps, which is why so many replacement conversations now start with “should this be a heat pump?”
Compliance pathways: prescriptive vs. performance
- Prescriptive approach. The checklist method. Every component, from the air conditioner’s efficiency rating to the duct insulation thickness, must meet or beat a specific value in the code tables. Simple, but inflexible.
- Performance approach. Approved energy-modeling software (such as CBECC-Res) builds a virtual version of the house and allows trade-offs. Better windows and extra wall insulation, for example, can offset a different HVAC configuration because the whole house already performs well.
The performance path scores energy with Time-Dependent Valuation (TDV), which counts energy saved during peak hours, such as a hot weekday afternoon in Citrus Heights, more heavily than energy saved at 3 a.m. The point is to reduce strain on the grid when it matters most.
Mandatory Requirements for Sizing and Ducts
Oversized systems short-cycle, waste energy, and never run long enough to pull humidity out of the air. Title 24 ended the era of guessing.
ACCA Manual J load calculations
The code requires ACCA Manual J (or an approved equivalent) for sizing. The calculation accounts for the home’s orientation, insulation levels, window types, and occupancy. Whether it is a new install or a replacement, the contractor must show the system is sized for that specific house.
Duct sealing and insulation
Ductwork is the circulatory system of the home. If it leaks, you are paying to condition the attic.
- Sealing: joints sealed with mastic or metal-backed tape
- Leakage limits: new construction ducts must test at 6% leakage or less; altered or replaced systems in existing homes are held to 10% total leakage, or 7% leakage to outside (6% when the air handler sits in a garage)
- Insulation: ducts in unconditioned spaces, which means most attics in Fair Oaks, Orangevale, and Carmichael, need a minimum R-6 so the cooled air does not pick up attic heat before it reaches the registers
Ventilation and Controls
Modern homes are built tight enough that stale air can get trapped inside, so Title 24 pairs efficiency with indoor air quality rules.
Mechanical ventilation
The code generally requires at least 15 CFM of fresh air per occupant. In many newer homes that means a balanced ventilation system or a heat-recovery ventilator that swaps stale air for fresh air without giving up the indoor temperature.
Smart thermostats and demand response
Thermostats must support setback scheduling and be demand-response ready, meaning they can receive utility signals during grid emergencies and, with the homeowner’s permission, nudge the setpoint to help prevent outages. Programmed properly, these controls routinely trim a meaningful share of a home’s HVAC energy use.
Electric-ready requirements
Even when a gas furnace is installed today, new homes must include the electrical infrastructure (a dedicated 240V circuit and panel space) to switch to a heat pump or electric water heater later. Homeowners planning ahead often ask us to confirm this during a maintenance visit.
Efficiency Standards and Equipment Metrics
Efficiency ratings read like alphabet soup. The current standards use “Version 2” metrics (SEER2, EER2, HSPF2), which are measured under more realistic test conditions than the older ratings.
| Equipment type | 2019 minimum | Current minimum |
|---|---|---|
| Central air conditioner (<65k Btu/h) | 14.0 SEER | 15.2 SEER2 / 12.0 EER2 |
| Gas furnace | 80% AFUE | 80% AFUE (federal minimum; 95% for units manufactured after December 2028) |
| Air-source heat pump | 8.2 HSPF | 7.5 HSPF2 |
| Mechanical ventilation | 15 CFM/occupant | 15 CFM/occupant |
For the Sacramento Valley, choosing a 90%-plus AFUE furnace still matters: 90 cents of every dollar spent on gas goes into heating the house, with only a dime lost up the flue.
The state is also steering homeowners toward heat pumps. In many climate zones the prescriptive baseline is now a heat pump, so choosing a gas furnace may mean making up the energy difference elsewhere in the design under the performance path. We walk through those trade-offs on every replacement estimate.
Compliance Verification: HERS Testing
Who checks that the ducts are actually sealed and the refrigerant charge is right? A HERS rater: an independent, state-certified third party who is not the contractor. The rater is the referee. Typical tests include:
- Duct leakage test – pressurizing the duct system to measure exactly how much air escapes
- Refrigerant charge verification – confirming the system holds the correct charge for peak efficiency
- Fan efficacy – confirming the blower is not using excess electricity to move air
- Airflow – confirming at least 350 CFM per ton of cooling
The paperwork trail
- CF1R – the certificate of compliance created at design
- CF2R – the installation certificate the contractor signs
- CF3R – the verification certificate the HERS rater signs after field tests pass
Non-residential systems have a parallel process: since 2021 the state has required certified Acceptance Test Technicians to sign off on commercial mechanical systems before a Certificate of Occupancy is issued.
Climate Zones and What They Mean Here
California is divided into 16 climate zones so the code can fit local weather. Most of our service area sits in Climate Zone 12 (Sacramento, Carmichael, Citrus Heights, Fair Oaks, Rancho Cordova, Folsom, Rio Linda and El Dorado Hills), and Roseville and Rocklin sit in Climate Zone 11. Both zones have very hot, dry summers and chilly winters, and both carry the same duct leakage and refrigerant charge verification rules for HVAC changeouts. That is why cooling efficiency and attic insulation requirements here are strict.
- Orientation: large west-facing windows push a home toward higher-efficiency HVAC or lower solar-heat-gain glass to pass
- Fenestration: window U-factors are tightly regulated in this zone
- Local reach codes: some cities, including Sacramento and Davis, adopt reach codes stricter than the state minimum, such as all-electric requirements for new construction
Frequently Asked Questions
Does Title 24 apply to HVAC replacements or only new construction?
Both. New construction carries the most requirements, but alterations such as replacing a central air system or adding a room also trigger Title 24. A standard changeout in an existing home usually triggers duct testing and equipment efficiency minimums. Replacing a single part such as a blower motor or thermostat typically does not.
What is the difference between the prescriptive and performance paths?
Prescriptive is a fixed recipe: use every ingredient the code lists. Performance is an energy budget: as long as the whole house stays under its limit, you can spend it how you like, for example better insulation in exchange for more glass.
Is HERS verification required for every HVAC changeout?
In Climate Zones 11 and 12, most central HVAC changeouts require HERS verification for duct leakage and refrigerant charge. There are narrow exceptions for very small additions and certain repairs, but for a normal system replacement the HERS test is part of the permit.
Making Sure Your Project Complies
Title 24 can feel overwhelming, but it is designed to put money back in your pocket through lower energy use; the CEC has estimated that a home built to recent code saves its owner thousands of dollars in energy and maintenance over 30 years.
At Bronco Plumbing, Heating & Air we handle the process end to end: the load calculation, the permit, the installation paperwork, and coordinating the HERS test. Every system we install in Roseville, Sacramento, and the surrounding communities is permitted and code-compliant. If you are planning a replacement or a new system, call 916-675-1062 or request a free estimate, and see our HVAC installation and replacement page for what is included.