The California Energy Commission (CEC) has published the 2025 Building Energy Efficiency Standards (document CEC-400-2025-010-F), the latest triennial update to Title 24, Part 6. The standards apply based on the project’s permit-application date and CEC effective-date rules. For builders, ECC raters (formerly HERS raters), insulation contractors, and energy consultants, understanding where Quality Insulation Installation (QII) fits into the approved compliance path is essential.

This article provides an overview of major 2025-code changes and key places QII is referenced in the official standards document. You can download the full 2025 Building Energy Efficiency Standards PDF here.

What Are the 2025 Building Energy Efficiency Standards?

California’s Building Energy Efficiency Standards (Title 24, Part 6) are updated every three years by the CEC to progressively reduce energy consumption in new construction and major renovations. Each code cycle builds on the last, raising baseline performance requirements for building envelopes, HVAC systems, water heating, lighting, and solar-electric systems. The 2025 standards continue this trajectory with a clear focus on electrification, decarbonization, and grid harmonization — reflecting the state’s broader climate goals under SB 100 and the California Air Resources Board’s scoping plan.

The 2025 code restructures several compliance pathways, updates prescriptive component packages across California climate zones, refines performance-modeling assumptions, and introduces revised multifamily provisions. A design prepared for an earlier code cycle needs to be reevaluated, and QII may be one project-specific compliance measure when it appears in the applicable path or model.

Major Changes in the 2025 Energy Code

Electrification and Heat Pump Baselines

The 2025 code accelerates California’s transition away from natural gas in new residential construction. Heat pump space heating and heat pump water heating are now the baseline assumptions in the standard reference design for most climate zones. This means that builders who specify gas furnaces or gas water heaters must demonstrate equivalent or better overall performance through other efficiency measures — a significantly harder bar to clear. QII becomes more valuable in this context because a high-performing building envelope reduces the heating and cooling loads that heat pump systems must handle, directly improving their efficiency and the home’s overall compliance margin.

Enhanced Envelope Performance Requirements

Insulation R-value requirements and air-sealing expectations have been updated for several climate zones. The prescriptive component packages in Table 150.1-A (single-family) and Table 170.2-A (multifamily) now include updated insulation specifications and explicit QII requirements that vary by climate zone. Builders using the prescriptive path must meet these component packages exactly, including QII where specified. Builders using the performance path benefit from QII credits that provide additional compliance headroom.

The code also tightens requirements around continuous insulation, thermal bridging, and air barrier continuity — areas where QII verification plays a direct role in confirming that the installed insulation matches the design intent.

Updated HVAC Efficiency Baselines

Heating, cooling, and ventilation provisions have been revised for the 2025 code. Builders should have the energy consultant evaluate the combined project measures rather than assume a fixed compliance value for QII.

Multifamily Provisions Strengthened

The 2025 standards contain distinct multifamily envelope and ECC field-verification provisions. QII is not a blanket requirement for every multifamily project: applicability depends on factors including building height, climate zone, the selected compliance path, and the approved compliance documents. Developers and builders of apartments, condominiums, townhomes, and mixed-use residential projects should confirm those inputs before carrying QII into the construction scope.

Updated Prescriptive Component Packages

The prescriptive component packages — the pre-defined sets of building specifications that satisfy the code without performance modeling — have been revised for 2025. Table 150.1-A (single-family) and Table 170.2-A (multifamily) organize requirements by climate zone and identify where QII applies. Builders following a prescriptive path must use the table and provisions applicable to their building type and scope, including QII where specified.

Where QII Appears in the 2025 Standards: A Section-by-Section Breakdown

The 2025 Building Energy Efficiency Standards reference QII in multiple places. Below is a topic-based guide to key provisions; use the official standards and Reference Appendices for the controlling text. Page numbers refer to document CEC-400-2025-010-F.

Administrative and Audit Requirements

Section 10-103.3(d)5 — Exemplary Designation and Quality-Assurance Audits

The 2025 standards maintain and clarify the administrative framework for QII inspections performed by certified ECC raters. Under Section 10-103.3(d)5 of the official 2025 standards, an ECC rater becomes eligible for the Exemplary ECC-Rater designation after at least five years of continuous certification and after passing all required quality-assurance audits within a 12-month period, including at least one annual QII shadow audit and one desk audit (PDF p. 62).

A shadow audit is a supervised field observation where an ECC-Provider auditor watches an ECC rater perform a QII verification under Reference Residential Appendix RA3.5. The standards set an annual QII shadow-audit minimum for ECC raters generally, but reduce the minimum for an ECC rater who already holds exemplary status to once per triennial code cycle; the Commission may request additional audits, and the ECC-Provider retains discretion to perform them (PDF pp. 64–65).

The code specifies that shadow audits are limited to QII verifications. If an audit shows that the ECC rater did not accurately perform the verification or collect or report the data, the ECC-Provider must initiate the disciplinary process described by the standards.

Single-Family Residential Requirements

Section 150.0(j)1 Exception 3 — Pipe Insulation in Walls (p. 408)

This exception allows builders to omit pipe insulation for hot water distribution piping located within exterior walls, provided the wall assembly meets QII compliance under RA3.5. The rationale is that a wall with QII-verified insulation installation provides sufficient thermal protection for the piping without requiring separate pipe insulation. This exception can simplify plumbing installations and reduce material costs in walls where QII is already being verified.

Section 150.1(b)2(ix) — Performance Approach Field Verification (p. 436)

Under the performance compliance approach for single-family homes, the code requires field verification of QII when the compliance analysis (CBECC-Res model) calls for it. This means that if the energy model includes QII credits to demonstrate compliance, the builder must obtain QII verification through an ECC rater inspection. QII cannot be claimed in the model without being verified in the field — a provision that prevents builders from taking credit for installation quality that has not been confirmed.

Section 150.1(c)1(E) — Prescriptive Path QII Requirement (p. 437)

For builders following the prescriptive compliance path, the code requires QII per Table 150.1-A and RA3.5 when applicable for the home’s climate zone. Under the prescriptive path, there is no energy model and no trade-offs — the builder must meet every specification in the component package, including QII where the table requires it.

Table 150.1-A — Single-Family Component Package (p. 446)

This is one of the most important tables in the residential energy code. It defines the prescriptive component packages for single-family homes across all 16 California climate zones. The 2025 version of this table includes a QII requirement column that specifies whether QII is required for each climate zone. Builders using the prescriptive path should review this table carefully to determine whether QII is a mandatory part of their compliance package.

Section 150.2(a)1 — Additions and Alterations (p. 451)

The code provides relaxations and exemptions for certain types of additions and alterations. Some additions and conversions relax specific parts of the QII requirement — for example, the air-sealing component of QII may be relaxed for certain small additions. Some small-addition pathways exempt QII entirely. Builders working on addition or remodel projects should review this section carefully to understand which QII provisions apply and which are waived.

Multifamily Residential Requirements

Section 160.4(e) Exception 2 — Multifamily Water-Heating Piping (p. 519)

Parallel to the single-family pipe insulation exception, this provision allows multifamily buildings to omit pipe insulation for water-heating piping located within walls, provided the wall assembly meets QII compliance under RA3.5. This exception applies specifically to multifamily water-heating distribution systems and offers the same cost and installation simplification benefits as the single-family equivalent.

Section 170.1(G) — Multifamily Performance Approach (p. 547)

For multifamily buildings using the performance compliance approach, the code requires field verification of QII when the compliance model includes QII. This mirrors the single-family requirement in §150.1(b)2(ix); a modeled QII measure must be supported by the applicable field verification.

Section 170.2(a)6 — Multifamily Prescriptive Requirements (p. 552)

For the multifamily prescriptive path, Section 170.2(a)6 of the official 2025 standards directs buildings up to three habitable stories to the QII requirements shown in Table 170.2-A; where the table requires QII for the applicable climate zone, installation must meet RA3.5. This provision should not be read as a universal QII requirement for every multifamily building or compliance path.

Table 170.2-A — Multifamily Component Package (p. 554)

Table 170.2-A defines prescriptive component requirements for multifamily buildings by climate zone, including its QII entries. Builders should use the table together with the building-height limitation in §170.2(a)6 and the project’s approved compliance documents rather than assuming the table governs every multifamily project.

Section 180.1(a)1(B) — Multifamily Additions (p. 615)

Similar to the single-family additions provision in §150.2, this section provides relaxations for certain multifamily additions. The air-sealing portion of QII may be relaxed for specific addition types, and some small-addition pathways exempt QII altogether. This is relevant for developers working on building expansions or conversions of existing multifamily structures.

Back-of-Book Index (p. 697)

The standards document index lists the principal QII references across the code: §150.1, §150.2, §160.4, §170.1, §170.2, and §180.1. This provides a quick cross-reference for anyone looking up QII-related provisions.

The Role of Reference Appendix RA3.5

Many QII references in the 2025 standards point to Reference Residential Appendix RA3.5 as the defining procedure for QII verification. RA3.5 provides technical criteria for an ECC rater’s evaluation, including:

Criteria for acceptable insulation installation (no gaps, voids, compression, or misalignment)
Air-barrier alignment and contact criteria for the approved assembly
Procedures for inspecting different insulation types (batts, blown-in, spray foam)
Documentation and reporting requirements
Pass/fail criteria

It is important to note that the full RA3.5 procedure text is published separately from the main standards document. The 2025 standards PDF (CEC-400-2025-010-F) references RA3.5 repeatedly but does not include the complete appendix text. Builders and ECC raters should use the CEC’s official 2025 Reference Appendices for the detailed inspection procedures.

QII in Single-Family vs. Multifamily: What’s Different?

The 2025 code addresses QII in both single-family and multifamily provisions, with structural differences worth noting:

Single-family QII requirements are defined in §150.1 (new construction) and §150.2 (additions/alterations), with the prescriptive component package in Table 150.1-A.
Multifamily QII requirements are defined in §170.1 and §170.2 (new construction) and §180.1 (additions/alterations), with the prescriptive component package in Table 170.2-A.
Both building types use the QII verification procedures in RA3.5 when QII applies.
Both building types allow the pipe insulation exception (§150.0(j)1 Exception 3 for single-family; §160.4(e) Exception 2 for multifamily) when walls meet QII compliance.
The climate zone requirements in Tables 150.1-A and 170.2-A may differ between single-family and multifamily for the same zone, so builders should reference the table and provisions applicable to their project type.

The key takeaway for multifamily builders is that QII can apply, but not through one universal rule. For prescriptive projects, §170.2(a)6 points buildings up to three habitable stories to the climate-zone entries in Table 170.2-A. Performance projects require field verification when QII is included in the compliance model, while additions and alterations have separate provisions. Building height, climate zone, compliance path, and the approved compliance documents must all be checked before treating QII as a project requirement.

The Administrative Side: Shadow Audits and Rater Accountability

The 2025 standards maintain a quality-assurance framework around QII. In summary:

Qualifying for exemplary status — An ECC rater must meet the experience requirement and pass all required audits during the qualifying 12-month period, including the annual QII shadow audit and a desk audit.
Reduced minimum frequency after designation — Under §10-103.3(d)5, the minimum onsite, QII shadow, and desk audit frequencies for an Exemplary ECC-Rater are each reduced from annual to once per triennial code cycle. Commission-requested or ECC-Provider-discretionary audits can still occur.
Discipline for failures — An audit failure triggers the applicable disciplinary process and revocation rules in §10-103.3.
Separation of audit types — Onsite, QII shadow, and desk audits are distinct quality-assurance reviews with different procedures.

This administrative framework is designed to maintain the integrity of QII verification statewide. For builders, it means that ECC raters work within an oversight system administered by an ECC-Provider under CEC rules.

Exceptions and Relaxations for Additions and Alterations

Not every project requires full QII compliance. The 2025 code recognizes that additions, alterations, and conversions present different challenges than new construction, and it provides targeted relaxations:

Single-family additions (§150.2(a)1): Certain additions and conversions relax the air-sealing component of QII. Some small-addition pathways exempt QII entirely, recognizing that connecting new insulation to existing construction may not achieve the same air-barrier continuity as new construction.
Multifamily additions (§180.1(a)1(B)): Similar relaxations apply to multifamily additions. The air-sealing portion of QII may be relaxed, and some small-scope projects are exempt.

Builders working on remodels or additions should carefully review these sections with their energy consultant and ECC rater to determine exactly which QII provisions apply to their specific project scope. Even when full QII is not required, following QII installation practices voluntarily can improve the energy performance and comfort of the finished space.

What This Means for Builders in 2026 and Beyond

The 2025 Building Energy Efficiency Standards send a clear message: insulation installation quality matters more than ever. Here are the key takeaways for builders:

Tighter Compliance Margins Make QII More Valuable

QII can affect a project’s compliance calculation when it is included in the approved path or performance model and verified in the field. Its modeled value and cost relative to other measures are project-specific and should be evaluated by the energy consultant.

Prescriptive Packages Now Include QII by Climate Zone

Builders following the prescriptive path must check Table 150.1-A (single-family) or, for multifamily buildings within the scope of §170.2(a)6, Table 170.2-A to determine whether QII is part of the applicable component package for the project’s climate zone.

Multifamily Builders Must Check the Applicable QII Path

Multifamily projects have their own prescriptive tables, performance-model inputs, and provisions for additions and alterations. Developers of apartments, condos, and townhomes should confirm whether the approved compliance path calls for QII and, when it does, budget for inspections and prepare insulation contractors to meet RA3.5 standards.

Early Planning Is Essential

The time to plan for QII under the 2025 code is before permit application — not during construction. Builders should work with their energy consultants to model QII’s impact on their standard floor plans, train insulation contractors on QII criteria, and build ECC rater inspections into their construction schedules from day one.

Administrative Oversight Protects Quality

The shadow-audit and exemplary-designation rules place QII verification within the CEC’s ECC-Provider oversight framework. Builders should confirm that the rater is certified for the applicable 2025 ECC work and that required verification documents are registered for the project.

Builder Preparation Checklist for the 2025 Code

Use the approved energy documents—not a blanket rule—to determine whether QII applies to a particular project. QII may be specified as a field-verified measure in a performance model or required by the applicable prescriptive package; additions and alterations can follow different provisions. Before construction begins:

Confirm the project type, climate zone, compliance path, and QII requirement with the energy consultant.
Carry the approved QII measure into scopes, specifications, trade contracts, and the construction schedule.
Review details at tub and shower surrounds, kneewalls, cantilevers, dropped soffits, and other locations that need backing or a continuous air barrier before insulation.
Train insulation crews on complete cavity fill, fitting around penetrations, avoiding gaps and compression, and maintaining required contact with the air barrier.
Coordinate the QII inspection before drywall or other finishes conceal the insulation and air-barrier details.
Allow time for corrections and reinspection instead of placing QII at the end of a critical-path schedule.
Keep the rater’s verification records aligned with the permit and compliance documentation required for project closeout.

Early coordination is especially important on repeat plans and production work: resolving a recurring framing or air-barrier detail once can prevent the same correction across multiple homes. The QII inspection process guide shows how those decisions carry into scheduling, rough-in, corrections, and closeout.

How Poppy Energy Can Help

At Poppy Energy, our certified ECC raters are trained on the 2025 Building Energy Efficiency Standards and ready to help builders navigate the new code. We provide:

QII inspections for single-family and multifamily projects under RA3.5 procedures
Compliance consulting to model the impact of QII on your specific floor plans and climate zone
Insulation contractor training to improve first-time QII pass rates and reduce correction costs
Required ECC field verifications identified by the approved compliance documents, including duct testing, fan efficacy, refrigerant charge, and envelope leakage
Quality-assurance readiness for the audit and continuing-education requirements that apply to our raters

Builders, developers, and energy consultants can contact Poppy Energy to coordinate the ECC field-verification stages identified in the project’s approved 2025-code compliance documents.

Inside the 2025 California Building Energy Efficiency Standards: What Changed and Where QII Fits In