QII, California ECC Compliance, and the RESNET HERS Index

California construction teams often use “HERS” as shorthand for state-required field verification. A national RESNET HERS Index rating is a different product. Both can involve insulation and building-envelope observations, but completing California Quality Insulation Installation (QII) verification does not, by itself, create or guarantee a particular RESNET HERS Index score.

For 2025-code projects, the CEC’s Reference Residential Appendix RA3.5 defines the California QII installation and ECC-rater verification procedure. It does not define a national RESNET rating score.

California QII and ECC Field Verification

In California, QII is a field-verification procedure tied to the Building Energy Efficiency Standards and the project’s approved compliance documents. The inspection evaluates whether insulation and related air-barrier details meet the applicable California verification criteria before they are concealed.

Whether QII is required depends on the project. It may be called for by a performance compliance model or by an applicable prescriptive package, while some additions and alterations follow different provisions. The approved energy documents determine the required California Energy Code Compliance (ECC) field verifications; QII is not universally mandatory or universally voluntary.

What a RESNET HERS Index Rating Does

A RESNET HERS Index is a national whole-home energy rating produced under RESNET standards. It uses a software model and required field data to compare the rated home with a reference home. Envelope assemblies are part of that model, along with mechanical systems, water heating, ventilation, and other inputs required by the rating standard.

The resulting Index is not the same as a California compliance margin, a CF1R/CF2R/CF3R document, or confirmation that a specific state field-verification measure passed. A project can need California ECC verification without commissioning a RESNET rating, and a RESNET-rated home still must satisfy any separate California permit and compliance requirements.

Where the Concepts Overlap

Both processes care about the installed building envelope because gaps, compression, missing insulation, and incomplete air barriers can change heat flow and building loads. Good installation also gives designers and contractors a sounder basis for load calculations and equipment selection.

For a home that is receiving both services, observations or documentation may support each workflow when the applicable rules allow it. However, the RESNET rating provider must enter and verify the insulation condition under the national rating standard, and the California rater must complete the state forms and registry workflow required by the approved compliance documents. One label should not be substituted for the other.

Insulation quality can affect modeled energy use, but no fixed Index-point improvement can be promised from QII alone. The result depends on the rating standard, the software inputs, the building geometry, the assembly details, the climate, and the rest of the home’s systems. Project-specific modeling is the appropriate way to evaluate any potential change.

Which Service Do You Need?

• If the permit set or compliance report lists QII or another California field-verified measure, coordinate the required ECC inspection and documentation.
• If a program, lender, buyer, or project goal asks for a RESNET HERS Index, confirm that a national rating is included in the scope.
• If both are required, identify both deliverables at the start so modeling, site visits, and documentation can be coordinated without assuming they are interchangeable.

For California inspection scope, scheduling, and preparation guidance, visit Poppy Energy’s Quality Insulation Inspection service hub. For a national rating, ask specifically whether the proposed scope includes a RESNET HERS Index and its required modeling and field data.

For the installation-quality intent behind California QII without rating-score claims, read QII vs. non-QII homes.