Introduction
California's energy code uses several professional roles that often confuse builders, contractors, and developers — especially those newer to working in the state. Two of the most commonly confused are the ECC writer (also called a Title 24 energy consultant or Title 24 analyst) and the HERS Rater.
Both are required on most new residential construction projects in California. But they perform completely different functions at completely different stages of the project. Hiring the wrong one — or assuming one covers what the other does — leads to delays, failed inspections, and missed permit deadlines.
This post explains exactly what each role does, when each is required, and how the 2022 Title 24 Standards (now in effect for projects permitted on or after January 1, 2023) affect what you need on your project.
What Is an ECC Writer?
ECC stands for Energy Compliance Certificate — though in everyday practice, the terms "ECC writer," "Title 24 energy consultant," and "Title 24 analyst" are used interchangeably to describe the same role.
An ECC writer is the professional who prepares the Title 24 compliance calculations for a project. They use CEC-approved energy modeling software (such as EnergyPro, CBECC-Res, or CBECC-Com, depending on the project type) to model the building and demonstrate that it meets California's Building Energy Efficiency Standards.
The primary output of the ECC writer's work is the CF1R — the Certificate of Compliance. This document is submitted with the building permit application and serves as the compliance roadmap for the entire project. It specifies every energy measure the building is designed to include, which of those measures require HERS field verification, and the overall energy budget compliance margin.
The CF1R is a design-stage document. The ECC writer works from architectural and mechanical drawings, and their job at the design phase is complete once the CF1R is finalized and submitted.
You need an ECC writer on virtually every permitted construction project in California, including new single-family residential construction, new multifamily construction, commercial new construction, residential additions over a certain conditioned floor area threshold, HVAC system replacements and alterations that require a Title 24 compliance calculation, and major renovations that affect the building envelope or mechanical systems.
What Is a HERS Rater?
A HERS Rater (Home Energy Rating System Rater) is a CEC-certified, independent field professional who performs on-site verification and diagnostic testing after systems are installed. Their job is to confirm that what was designed and specified on the CF1R was actually installed correctly and performs as required.
The HERS Rater's work takes place in the field, during and after construction — not at the design stage. They visit the job site, run tests, take measurements, and enter their findings into the HERS Registry. The registry generates the CF3R — the Certificate of Verification — which is the field counterpart to the design-stage CF1R.
Common HERS verification tasks include duct leakage testing (measuring actual duct system leakage using a duct blaster), refrigerant charge verification (measuring superheat or subcooling to confirm the HVAC system is properly charged), airflow measurement, window verification (confirming installed windows match the U-factor and SHGC on the CF1R), insulation verification (visual confirmation of insulation type, location, and R-value before close-up), mechanical ventilation verification, and solar and battery system verification (under the 2022 standards, newly required for many residential projects).
A HERS Rater is required whenever a project's CF1R specifies HERS-verified measures — which means almost all new single-family residential construction in California, low-rise multifamily new construction, HVAC replacements in existing homes when duct leakage testing is triggered, and residential additions when new HVAC equipment or duct work is included.
ECC Writer vs. HERS Rater: Key Differences
The ECC writer handles design-stage compliance calculations, is involved before and during permit application, and produces the CF1R. They work from architectural and mechanical drawings.
The HERS Rater handles field verification and diagnostic testing, is involved during and after construction, and produces the CF3R. They work from installed systems on the job site.
Both are required on most new residential projects in California.
In most cases, one person cannot fill both roles. The HERS verification system is built on third-party independence — the HERS Rater must be independent from the contractor and from the design team. Treat these as two separate hires for two separate scopes of work.
What Changes for 2025+ Projects Under the 2022 Standards
The 2022 Title 24 Standards, which took effect January 1, 2023, introduced several changes that affect both roles. New single-family homes must include both a solar PV system and a battery storage system with a minimum usable capacity of 7.5 kWh — California was the first state to mandate both solar and storage for new residential construction. ECC writers must account for both in the compliance calculation; HERS Raters must verify both are installed.
Heat pump water heaters are now effectively the standard path to compliance for most new homes under the 2022 standards. New requirements for electrical panel capacity and conduit for future EV charging infrastructure also affect the compliance calculation. Updated whole-building and spot ventilation requirements affect both design compliance and HERS field verification.
Which Do You Need — and When?
For most new residential construction projects in California, you need both. The ECC writer comes first — before or during permit application. The HERS Rater comes second — during and after construction, before permit final.
A practical timeline: during the design phase, engage your ECC writer to prepare the CF1R and submit it with your permit application. Before construction begins, review the CF1R to understand which HERS measures are required and engage a HERS Rater, scheduling their site visits in advance. During construction, contractors install systems and complete CF2R certificates, and you coordinate with your HERS Rater to ensure insulation and other pre-close-up verifications happen at the right time. Near completion, the HERS Rater performs duct testing, equipment verification, and any remaining field tests to generate CF3R certificates. At permit final, submit the complete compliance document set to the building department.
Conclusion
The ECC writer and the HERS Rater are both essential to Title 24 compliance in California — but they do entirely different jobs. The ECC writer works at the design stage to produce the compliance roadmap (the CF1R). The HERS Rater works in the field to verify that the roadmap was followed (producing the CF3R). For 2025 and beyond projects operating under the 2022 standards, both roles carry expanded scope due to new solar, battery, and heat pump requirements.
Engage both early, keep your compliance document chain organized, and you'll be well-positioned to move smoothly through permit final.