Introduction
If you're building or renovating in California, there's a good chance you'll need to work with a HERS Rater before you can get final sign-off. But for most builders, contractors, and homeowners, the term is unfamiliar — and the role is often confused with other compliance professionals.
This post explains exactly what a HERS Rater is, what they do on a project, when California's Title 24 energy code requires one, and how to find a certified rater in your area.
What Is a HERS Rater?
HERS stands for Home Energy Rating System. A HERS Rater is a certified professional who conducts field verification and diagnostic testing to confirm that energy-related systems in a building were installed correctly and perform as designed.
In California, HERS Raters are certified through California Energy Commission (CEC)-approved rating organizations called HERS Providers. As of September 2024, CHEERS (California Home Energy Efficiency Rating Services) is the sole active CEC-approved HERS Provider operating in California. CalCERTS, the other major provider, permanently closed its registry on September 1, 2024. New projects must be registered through CHEERS.
HERS Raters are third-party verifiers — they are independent from the contractor or installer and are required to have no financial interest in the outcome of the project they are testing. This independence is a core requirement of the role.
What Does a HERS Rater Actually Do?
A HERS Rater performs field verification and diagnostic testing on specific building components and systems. The tests and verifications required on a given project depend on what features were claimed on the building's Title 24 compliance documentation (the CF1R).
Common tasks a HERS Rater may perform include duct leakage testing (measuring how much air is lost through the HVAC duct system), refrigerant charge verification (confirming HVAC systems are properly charged), airflow measurement (verifying air is distributed correctly throughout the building), window and glazing verification (confirming installed windows match compliance document specifications), insulation verification (checking that insulation type, location, and R-value match the design), indoor air quality system verification (confirming mechanical ventilation systems are installed and functioning), and solar and battery storage verification (increasingly required under the 2022 Title 24 standards).
The rater records their findings and submits results to the HERS registry, which generates the CF3R — the verified certificate that confirms compliance was achieved in the field.
When Is a HERS Rater Required in California?
Under California's Title 24 Part 6 (the Building Energy Efficiency Standards), a HERS Rater is required whenever a project uses measures that require HERS verification. This is determined by the compliance documentation prepared by the energy consultant or Title 24 analyst.
Common project types that trigger HERS verification requirements include new single-family residential construction (almost universally requires HERS verification for duct systems, HVAC, and other components), new multifamily construction, HVAC replacements or alterations (replacing a furnace, air conditioner, or heat pump in an existing home often requires duct leakage testing), additions and alterations, and newly installed or replaced duct systems.
If a project does not claim any HERS-verified measures on its compliance documentation, a HERS Rater may not be required. However, this is uncommon for new construction in California.
The specific HERS measures required on your project are listed on the CF1R (the compliance certificate prepared by your Title 24 analyst). Review this document early — it tells you exactly what will need to be verified.
HERS Rater vs. Other Title 24 Compliance Roles
It's common to confuse HERS Raters with other professionals involved in Title 24 compliance. A Title 24 Energy Consultant or ECC Writer prepares the compliance calculations and generates the CF1R. They work at the design stage and do not perform field testing. A HERS Rater performs field testing and verification after installation and generates the CF3R, confirming what was actually installed. An Acceptance Tester is a separate certified role required for nonresidential and some multifamily projects — they verify that lighting controls, HVAC controls, and other systems function correctly.
Some professionals hold multiple certifications and can fill more than one role, but each role has distinct requirements and responsibilities.
How to Find a Certified HERS Rater in California
HERS Raters in California must be certified through a CEC-approved rating organization. To find a certified rater, use the CHEERS rater directory (CHEERS is now the sole active CEC-approved HERS Provider in California), check the CEC's HERS Provider page at energy.ca.gov, use Title 24 Directory (our directory lists verified HERS Raters across California, searchable by location and specialty), or ask your Title 24 energy consultant (many analysts work regularly with raters and can refer you to someone familiar with your project type).
When selecting a HERS Rater, confirm they are currently certified, have experience with your project type (residential vs. multifamily vs. commercial), and are familiar with the specific measures on your CF1R.
Conclusion
A HERS Rater is a certified, independent field professional who verifies that the energy features in your building were actually installed and perform correctly. They are required on most new construction and many alteration projects in California, and their work is what produces the CF3R — the document that closes out your Title 24 compliance in the field.
If you're planning a project in California and aren't sure whether a HERS Rater is required, start by reviewing your CF1R compliance document or consult with your Title 24 energy analyst early in the process.