The California Energy Commission (CEC) has published the 2025 Building Energy Efficiency Standards (document CEC-400-2025-010-F), marking the latest triennial update to Title 24, Part 6. These standards apply to all buildings with permit applications submitted on or after January 1, 2026, and they represent the most significant tightening of California’s residential energy code in recent memory. For builders, HERS Raters, insulation contractors, and energy consultants, understanding exactly what changed — and where Quality Insulation Installation (QII) fits into the new requirements — is essential for staying compliant and competitive.

This article provides an in-depth look at the major changes in the 2025 code and a section-by-section breakdown of every place 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 does not simply tweak a few numbers. It restructures several compliance pathways, updates prescriptive component packages across all 16 California climate zones, refines the performance modeling assumptions in CBECC-Res, and introduces new provisions for multifamily buildings that bring their requirements closer to parity with single-family residential standards. For builders, these changes mean that designs that barely passed under the 2022 code may no longer comply — and QII becomes one of the most cost-effective tools for closing the gap.

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

Minimum efficiency requirements for heating, cooling, and ventilation equipment have been revised upward. Higher-efficiency heat pumps, updated fan efficacy requirements, and refined duct-sealing standards all contribute to a tighter compliance margin. For builders, this means there is less room for trade-offs in the performance model, making every available compliance credit — including QII — more important.

Multifamily Provisions Strengthened

One of the most notable changes in the 2025 code is the alignment of multifamily residential requirements with single-family standards. Previous code cycles treated low-rise multifamily buildings somewhat differently, but the 2025 standards bring multifamily requirements much closer to single-family in terms of envelope performance, QII verification, and HERS field testing. This affects developers and builders of apartments, condominiums, townhomes, and mixed-use residential projects.

Grid Harmonization and Demand Flexibility

The 2025 code introduces new provisions for demand flexibility, including requirements and incentives for battery storage, load-shifting controls, and grid-responsive equipment. While these provisions do not directly reference QII, they create additional compliance pathways where a well-insulated, QII-verified envelope can reduce the size and cost of battery and demand-response systems needed to comply.

Updated Prescriptive Component Packages

The prescriptive component packages — the pre-defined sets of building specifications that automatically satisfy the code without performance modeling — have been revised for 2025. Both Table 150.1-A (single-family) and Table 170.2-A (multifamily) now include updated QII requirements organized by climate zone. Builders who follow the prescriptive path must meet these QII requirements as part of the package. The inclusion of QII in these tables underscores the CEC’s recognition that insulation installation quality is a critical factor in real-world building performance.

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

The 2025 Building Energy Efficiency Standards reference QII in multiple places throughout the document. Below is a comprehensive breakdown of every QII reference, organized by topic area. All page numbers refer to the PDF page numbers of document CEC-400-2025-010-F.

Administrative and Audit Requirements

Pages 63, 65–66 — Exemplary Designation and Shadow Audits

The 2025 standards maintain and clarify the administrative framework that ensures QII inspections are performed accurately and consistently by certified HERS Raters. The code establishes an exemplary designation program that requires annual QII shadow audits and at least one desk audit for raters seeking this higher certification level (p. 63).

A shadow audit is a supervised field observation where an experienced evaluator watches a HERS Rater perform a QII verification under the procedures defined in Reference Residential Appendix RA3.5 (p. 65). These shadow audits are required annually for all HERS Raters who perform QII inspections — not just those seeking exemplary designation. The audits ensure that raters are applying the QII criteria consistently and accurately in the field.

The code specifies that QII shadow audits are limited to QII verifications — they are distinct from other types of HERS shadow audits (p. 66). If a rater fails a QII shadow audit, the standards allow for disciplinary action, including potential suspension of the rater’s ability to perform QII inspections. This enforcement mechanism protects builders and homeowners by ensuring that QII certifications are meaningful and reliable.

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 is legally obligated to obtain QII certification through a HERS 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 credits. This mirrors the single-family requirement in §150.1(b)2(ix) and ensures that multifamily builders cannot claim QII benefits in their energy model without obtaining actual field verification from a certified HERS Rater.

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

Buildings up to three habitable stories must meet QII requirements under Table 170.2-A and RA3.5 when required by the prescriptive path. This section establishes the QII obligation for low-rise multifamily construction and ensures that apartment buildings, townhomes, and similar structures receive the same insulation quality verification as single-family homes.

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

The multifamily equivalent of Table 150.1-A, this table defines prescriptive component packages for multifamily buildings across all climate zones. Like its single-family counterpart, the 2025 version includes QII requirements that vary by climate zone. Multifamily builders and developers should review this table to determine whether QII is required for their specific project and location.

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

Nearly every QII reference in the 2025 standards points to Reference Residential Appendix RA3.5 as the defining procedure for QII verification. RA3.5 is the detailed technical appendix that specifies exactly how a HERS Rater must evaluate insulation installation quality, including:

Criteria for acceptable insulation installation (no gaps, voids, compression, or misalignment)
Air barrier contact requirements on all six sides of each insulated cavity
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 uploaded 2025 standards PDF (CEC-400-2025-010-F) references RA3.5 repeatedly but does not include the complete appendix text. Builders and HERS Raters should obtain the full Reference Appendices document from the CEC for the detailed inspection procedures.

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

The 2025 code treats QII consistently across single-family and multifamily buildings, but there are 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 share the same QII verification procedures under RA3.5.
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 always reference the correct table for their project type.

The key takeaway for multifamily builders is that QII is no longer just a single-family concern. The 2025 code makes clear that multifamily buildings must meet QII requirements with the same rigor as single-family homes, and the administrative oversight (shadow audits, rater accountability) applies equally to both.

The Administrative Side: Shadow Audits and Rater Accountability

The 2025 standards strengthen the quality assurance framework around QII by maintaining strict shadow audit requirements. Here is how the system works:

Annual shadow audits — Every HERS Rater who performs QII inspections must undergo at least one shadow audit per year, where an experienced evaluator observes them performing a QII verification under RA3.5 procedures.
Exemplary designation — Raters seeking the higher “exemplary” certification must undergo additional QII shadow audits and at least one desk audit annually.
Discipline for failures — A rater who fails a QII shadow audit may face disciplinary action, including restrictions on their ability to perform QII inspections.
Separation of audit types — QII shadow audits are conducted separately from other types of HERS audits, ensuring focused evaluation of insulation inspection skills.

This administrative framework is designed to maintain the integrity of QII certifications statewide. For builders, it means that QII certifications issued by properly audited HERS Raters carry real weight — they represent verified, quality-controlled inspections that the CEC actively oversees.

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 HERS 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

With higher baseline efficiency requirements, electrification mandates, and updated HVAC standards, the compliance margins under the 2025 code are thinner than under previous cycles. QII provides one of the most cost-effective ways to gain compliance headroom because it does not require changing materials or specifications — it simply ensures the insulation already being installed receives full credit in the energy model.

Prescriptive Packages Now Include QII by Climate Zone

Builders following the prescriptive path must check Table 150.1-A (single-family) or Table 170.2-A (multifamily) to determine whether QII is a mandatory component of their prescriptive package. In many climate zones, QII is no longer optional under the prescriptive path — it is a required element of the component package.

Multifamily Builders Need QII

The 2025 code makes it unambiguous: QII applies to multifamily buildings with the same force as single-family homes. Developers of apartments, condos, and townhomes should budget for QII inspections and ensure their insulation contractors are prepared 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 HERS Rater inspections into their construction schedules from day one.

Administrative Oversight Protects Quality

The shadow audit and exemplary designation requirements mean that QII certifications are backed by active CEC oversight. Builders can have confidence that a QII certification from a properly credentialed HERS Rater represents genuine verification of insulation quality — not just a rubber stamp.

How Poppy Energy Can Help

At Poppy Energy, our certified HERS Raters are fully 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
All required HERS verifications under the 2025 code, including duct testing, fan efficacy, refrigerant charge, and envelope leakage
Shadow audit readiness — our raters maintain exemplary standing through regular audits and continuing education

Whether you are building single-family production homes, custom residences, or multifamily developments, Poppy Energy has the experience and expertise to keep your projects compliant, on schedule, and on budget under the 2025 Energy Code.

Contact Poppy Energy today to discuss your 2025 code compliance strategy and schedule QII inspections for your upcoming projects.

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