Title 24, explained

Guides to California’s energy code, written for the people who have to comply with it rather than the people who wrote it.

• ADUComplianceTitle 24 for ADUs: What California Homeowners Need to KnowDetached, attached or garage conversion: how the energy code treats each kind of ADU, when solar is required, and which HERS tests to expect.
• HERSCostHow Much Does a HERS Test Cost in California?What drives the price of HERS and ECC verification for a changeout, an ADU or a new home, and how to avoid paying for a retest.
• ComplianceECCCalifornia 2025 Energy Code: What Changed for HomesThe 2025 code took effect January 1, 2026. HERS became ECC, heat pumps moved further toward the baseline, and insulation and window minimums got tighter.
• HERSECCWhat Is a HERS Rater (Now Called an ECC Rater) and When Do You Need One?Learn what a HERS Rater does, how the role is transitioning to ECC Rater under the 2025 energy code, and how to find one for your California project.
• FormsCF2R vs CF3R: What's the Difference?Understanding the difference between CF2R installer certificates and CF3R verifier certificates for Title 24 compliance.
• ComplianceCalifornia Title 24 Compliance: A Builder's Complete GuideA complete guide to navigating California's Title 24 energy code for new construction and major renovations.
• ComplianceWhat Does an Acceptance Tester Do? Title 24 Acceptance Testing ExplainedTitle 24 acceptance testing explained: what it covers, when it's required, and how to find a certified tester.
• HERSECCHERS Rater or ECC Rater? Same Role, New NameHERS and ECC raters are the same certified field verifier under two names. Which term applies depends on your permit — and the ECC Writer is a different job.
• SolarComplianceTitle 24 Solar PV Requirements for New Construction in CaliforniaCalifornia requires solar PV on most new construction and battery storage on some building types. What Title 24 mandates, what's exempt, and who verifies it.
• FormsComplianceWhat Is a CF1R? California Title 24 Compliance Report ExplainedThe CF1R is the foundation of every Title 24 project. Learn what it contains, who prepares it, and how it connects to the CF2R and CF3R.
• HVACHERSDuct Leakage Testing in California: What to ExpectDuct leakage testing is one of the most common HERS requirements. Learn what it measures, when it's required, and how to prepare for a clean test.
• HVACComplianceHeat Pump Water Heater Requirements Under California Title 24The 2022 standards made heat pump water heaters the baseline for new single-family homes, and the 2025 code extends that to multifamily. What that means.
• ComplianceHVACThe Performance Path to Title 24 Compliance: How Heat Pumps, Mini Splits, and R-21 Work TogetherHow the Title 24 performance path lets you trade efficiency measures — heat pump water heaters, ductless mini splits, R-21 insulation — for design freedom.
• HVACHERSHVAC Replacement and Title 24: When Do You Need a HERS Rater?Replacing an HVAC system in California often triggers HERS verification. Learn when it applies and what tests are required.
• HVACHERSRefrigerant Charge Verification (RCV) in California: When It's Required and How It WorksUnder the 2025 code's prescriptive rules, refrigerant charge verification is required for heat pumps in every climate zone. Here is when RCV applies, how raters test it, and what the refrigerant transition means.
• InsulationHERSQuality Insulation Installation (QII): What It Is and How to Pass the InspectionQII is a multi-visit rater inspection of your insulation and air sealing before drywall. Learn when it is required, how the stages work, and the common fail points.
• FormsECCHow to Find Your CF2R and CF3R Documents in the California Data RegistryYour installation and verification certificates live in an ECC-Provider registry, not at the CEC. Here is how to get copies and fix missing paperwork at final inspection.
• HVACComplianceDo You Need a Permit to Replace an AC or Furnace in California?Replacing an AC or furnace in California needs a permit, and the job usually needs duct testing and often refrigerant charge verification. Here is how it works and what skipping it costs.

Looking for the compliance report rather than the verifier? Title 24 reports (CF1R) are prepared by T24 Studio.