2025 TITLE 24, PART 6 · ECC / HERS GLOSSARY
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Plain-English reference

Title 24, ECC & HERS glossary.

Understand the forms, people, processes, abbreviations, and field-verification measures you may see on a California Energy Code project. Blue terms are navigational links; official CEC documents are provided inside the entries.

Essential terminology

Forms, roles, and processes explained.

Open any term for a short explanation. The exact required forms depend on the building type, project scope, code cycle, approved design, and enforcement agency.

Compliance-document families

CF1R — Certificate of Compliance

Single-family design-stage compliance documents. They describe the proposed building or alteration and the energy features the project is required to install and, when applicable, verify. Generally prepared for permit review by the responsible designer, energy consultant, or documentation author. Single-family CEC forms ↗

CF2R — Certificate of Installation

Single-family installation documents completed by the person responsible for the installed work. They document that the installed features match the approved compliance requirements and provide information used by the ECC rater.

CF3R — Certificate of Verification

Single-family verification documents completed by a certified ECC rater after required field verification or diagnostic testing. A sample PDF is informational; registered project forms are handled through the approved ECC Provider registry.

LMCC — Low-Rise Multifamily Certificate of Compliance

Design-stage compliance documents for low-rise multifamily projects under the 2025 form structure. When the project includes ECC measures, applicable forms must follow CEC registration requirements. Low-rise multifamily CEC forms ↗

LMCI — Low-Rise Multifamily Certificate of Installation

Documents installed low-rise multifamily systems and features. Registration depends on the form: the CEC notes that numbered LMCI forms and forms ending in “-H” have specific registration requirements.

LMCV — Low-Rise Multifamily Certificate of Verification

Documents ECC-rater verification for low-rise multifamily measures. LMCV forms must be registered through an approved ECC Provider.

NRCC — Nonresidential Certificate of Compliance

Design-stage compliance documents for nonresidential, hotel/motel, and applicable high-rise multifamily projects. They show how the proposed design complies with the Energy Code. Nonresidential CEC forms ↗

NRCI — Nonresidential Certificate of Installation

Documents that applicable nonresidential systems, equipment, and features were installed in accordance with the approved compliance documents and Energy Code requirements.

NRCA — Nonresidential Certificate of Acceptance

Documents required acceptance testing. Lighting-controls and mechanical NRCA forms generally require a qualified field technician or Certified Acceptance Test Technician working through an approved ATTCP; this is different from ordinary ECC-rater verification.

NRCV — Nonresidential Certificate of Verification

Documents applicable ECC field verification for nonresidential, hotel/motel, or high-rise multifamily measures. NRCV forms must be registered with an approved ECC Provider.

Certificate of Compliance

The design-side record describing how the proposed project will comply. It is normally part of the permit submittal and controls which installation and verification documents are later required.

Certificate of Installation

The installer-side record confirming what was actually installed and accepting responsibility for the installation information.

Certificate of Verification

The ECC-rater record of required field observations and diagnostic test results.

Certificate of Acceptance

The record of required nonresidential acceptance testing by an appropriately qualified acceptance-test technician or field technician.

People & organizations

CEC — California Energy Commission

The state agency responsible for adopting and supporting California’s Building Energy Efficiency Standards and approving ECC Providers.

ECC Program — Energy Code Compliance Program

The 2025 program for field verification and diagnostic testing used to demonstrate Energy Code compliance. It replaces the former HERS compliance-demonstration structure for the 2025 code cycle.

ECC Provider

A CEC-approved organization that trains and oversees ECC raters and operates an approved residential data registry. CEC provider information ↗

ECC Rater

An independent, certified field professional who performs required observations and diagnostic testing and completes applicable certificates of verification through an approved provider.

HERS / HERS Rater

HERS is the familiar legacy term still widely used for this work. For 2025 Energy Code compliance, the current program and professional terminology is ECC Program and ECC Rater.

CHEERS

California Home Energy Efficiency Rating Services, a CEC-approved ECC Provider whose registry can support applicable 2025 projects, raters, and compliance-document workflows.

AHJ — Authority Having Jurisdiction

The building department or other enforcement agency that issues permits, reviews plans, performs inspections, and controls permit approval and closure.

Responsible Person

The qualified individual who accepts responsibility for design, construction, installation, or documentation within their authorized scope. The exact signer depends on the document and work.

Documentation Author

The person who prepares a compliance document and certifies that the document is accurate and complete. This may be different from the installer, rater, or building owner.

ATT / CATT — Acceptance Test Technician

A technician qualified to perform applicable nonresidential acceptance testing. A CATT is a certified acceptance test technician working within the relevant acceptance-test program.

ATTCP — Acceptance Test Technician Certification Provider

A CEC-approved provider that trains, certifies, and oversees acceptance-test technicians for applicable nonresidential systems.

Compliance & field process

FV&DT — Field Verification & Diagnostic Testing

On-site observation, measurement, and testing used to verify that specified systems and features comply with the approved Energy Code documents.

Registration

The process by which applicable compliance documents are submitted to and recorded by an approved registry, producing a controlled project record and registration information.

Residential Data Registry

The approved electronic system operated by an ECC Provider for registered project documents, signatures, rater activity, status, and verification records.

Prescriptive Compliance

A compliance path that follows specified measures and requirements directly rather than demonstrating the project through whole-building performance modeling.

Performance Compliance

A compliance path using CEC-approved software to compare the proposed building’s calculated energy performance with the applicable standard design or energy budget.

ACM — Alternative Calculation Method

The approved rules and procedures used by compliance software and other approved calculation methods to demonstrate performance compliance.

QII — Quality Insulation Installation

A verified installation-quality measure involving air sealing and insulation observation at specific construction stages. Required areas must remain visible until the applicable inspection is complete.

Sampling

A registry-controlled verification approach allowed only under applicable CEC rules where a defined group of dwelling units or systems is represented by required testing and selection procedures. It is not simply choosing fewer jobs to inspect.

Correction / Retest

When a required measure does not pass, the responsible installer corrects the condition and the applicable measure is tested or verified again.

Permit Closeout

The local enforcement agency’s completion process. ECC documents may be required for closeout, but passing ECC testing does not by itself close the permit.

2025 Energy Code

The 2025 edition of California’s Building Energy Efficiency Standards, effective January 1, 2026 for applicable permit applications. Project requirements depend on the permit date and governing code cycle.

Title 24, Part 6

The Energy Code portion of California’s building standards. Part 1 contains applicable administrative provisions; Part 6 contains building-energy requirements.

Climate Zone

One of California’s 16 building climate zones. The project location’s climate zone affects applicable envelope, HVAC, water-heating, and performance requirements; it is not the same as a USDA plant-hardiness zone.

Compliance Manual

CEC guidance explaining how to apply and document the Energy Code. Separate manuals cover single-family residential, multifamily, and nonresidential projects.

Energy Code Ace

A California utility-supported education and resource program offering forms, tools, training, and code guidance. It is a helpful resource, but the CEC remains the official state authority.

VCA — Virtual Compliance Assistant

An Energy Code Ace tool used to explore code requirements by project type and scope. Final requirements must still be confirmed against the approved project documents and governing code.

ADU — Accessory Dwelling Unit

A secondary dwelling unit subject to the Energy Code based on its project type, scope, systems, and permit. An ADU may require its own compliance and installation documents and applicable field verification.

Approved Plans / Approved Set

The plans and compliance documents accepted by the permitting authority. Field verification should be coordinated against the approved set, not an outdated design draft.

As-Built

Documentation reflecting what was actually installed. When field conditions differ from approved compliance documents, revised or as-built documentation may be required before verification can be completed.

Form identifiers & technical references

MCH — Mechanical

Form-family code for HVAC, ducts, airflow, refrigerant charge, equipment, ventilation, exhaust, and related mechanical measures.

ENV — Envelope

Form-family code for building-envelope measures such as enclosure air leakage, air sealing, and insulation installation.

PLB — Plumbing / Water Heating

Form-family code for domestic hot-water systems, verified distribution, and related plumbing energy measures.

LTG / LTI / LTO / LTS — Lighting

Codes used for residential lighting or for nonresidential/multifamily indoor, outdoor, and sign-lighting document families.

ELC — Electrical

Form-family code for electrical-power-distribution and electric-ready requirements.

SAB / PVB / SRA / STH

Codes commonly used for solar and battery, photovoltaic/battery, solar readiness, and solar thermal or solar water-heating documents.

CXR — Commissioning

Form-family code associated with applicable building commissioning requirements.

PRC — Covered Process

Form-family code for covered process systems such as certain commercial kitchen, compressed-air, refrigeration, or process requirements.

CFM — Cubic Feet per Minute

A common airflow unit used for HVAC, ventilation, exhaust, and whole-house-fan measurements.

HVAC — Heating, Ventilation & Air Conditioning

The equipment and distribution systems that heat, cool, ventilate, and move air through a building.

IAQ — Indoor Air Quality

Indoor environmental conditions affected by ventilation, filtration, moisture, pollutants, and local exhaust. Title 24 measures may require verification of whole-building ventilation and local exhaust.

AHU — Air-Handling Unit

Indoor equipment that moves and conditions air. It may include a blower, coil, filter, and controls and must be accessible for applicable inspection or testing.

VCHP — Variable-Capacity Heat Pump

A heat pump capable of modulating output rather than operating only at a single capacity. Certain compliance credits require specific equipment and field verification.

WHF — Whole-House Fan

A ventilation-cooling fan that draws outdoor air through the home and exhausts warmer air toward the attic or outdoors. Applicable projects may require airflow and efficacy verification.

Kitchen Range Hood

A local mechanical exhaust appliance above cooking equipment. Applicable verification can include airflow, controls, ducting, capture area, sound or listed-product data under the project’s required measure.

Sone

A unit used to rate perceived fan noise. Some residential local-exhaust requirements use airflow and sound ratings from approved or listed product information.

Blower Door

Calibrated fan-and-pressure equipment used to measure building or dwelling-unit enclosure air leakage.

Duct Blaster

A common name for calibrated equipment used to pressurize a duct system and measure duct leakage.

Pa — Pascal

A pressure unit used in duct-leakage and building-envelope diagnostic testing, such as testing at a specified pressure difference.

ACH50 — Air Changes per Hour at 50 Pascals

A normalized building-envelope leakage result based on measured airflow, building volume, and a 50-pascal pressure difference.

R-value

A measure of resistance to heat flow used for insulation and insulated assemblies. Higher values generally indicate greater resistance, subject to the installed assembly and applicable code rules.

U-factor

A measure of heat transfer through an assembly such as a window, door, or wall. Lower values generally indicate less heat transfer.

SHGC — Solar Heat Gain Coefficient

The fraction of incident solar heat admitted through fenestration. Lower values admit less solar heat.

SEER2 / EER2 / HSPF2

Standard efficiency metrics for cooling and heat-pump equipment. The project’s approved documents identify the required equipment performance.

HVI / AHAM

Organizations associated with product performance certification or directories for ventilation products and appliances. Applicable range-hood or exhaust verification may rely on listed manufacturer data.

CSLB — Contractors State License Board

California’s contractor-licensing agency. A CSLB license number helps identify the contractor responsible for an installation but is separate from CEC registry credentials.

RA — Residential Appendix

Reference Residential Appendices contain detailed procedures and technical requirements for residential measures and diagnostic testing.

JA — Joint Appendix

Reference Joint Appendices contain definitions and requirements used across building types. JA1 is a major definitions source. 2025 Reference Appendices ↗

NA — Nonresidential Appendix

Reference Nonresidential Appendices contain technical procedures and requirements applicable to nonresidential compliance and testing.

-H / -E / -F — Form suffixes

Suffixes are part of the official CEC form identifier and distinguish document types and applicable workflows. “-H” is commonly associated with measures requiring field verification and diagnostic testing; always use the official form title and CEC library to determine registration and responsibility.

Field verification

Measure-code glossary

Open a measure below for a plain-English overview, inspection readiness notes, and the direct official CEC form.

MCH-20

Duct leakage diagnostic testing

Measures air escaping from an applicable duct system with calibrated equipment. The project documents determine the test method and allowable leakage.

Be ready: Ducts, air handler, plenums, boots, grilles, and registers must be installed to the required test stage and accessible.

MCH-21

Duct location

Confirms duct location and applicable conditioned-space or compliance-credit conditions shown in the approved documents.

Be ready: Duct routes and surrounding assemblies must remain visible where the verification requires observation before concealment.

MCH-22

Space-conditioning fan efficacy

Measures fan electrical power in relation to delivered airflow to verify the installed system meets the applicable efficacy requirement.

Be ready: The system, filters, grilles, controls, and all equipment must be installed, powered, and operating normally.

MCH-23

System airflow rate

Measures airflow through the space-conditioning system using an approved diagnostic procedure.

Be ready: Equipment must be commissioned, filters installed, registers open, and the system accessible for measurement.

MCH-24

Building enclosure air-leakage worksheet

Documents applicable building or dwelling-unit enclosure air-leakage diagnostic results associated with the mechanical compliance workflow.

Be ready: The building envelope must be complete enough for testing, with windows, exterior doors, penetrations, and applicable seals in place.

MCH-25

Refrigerant charge verification

Verifies eligible cooling equipment refrigerant charge using the applicable procedure and required operating conditions.

Be ready: The system must be fully operational with access to indoor and outdoor equipment. Weather and operating conditions may affect the test procedure.

MCH-26

Rated equipment verification

Confirms installed space-conditioning equipment matches the manufacturer and model information in the approved compliance documents.

Be ready: Manufacturer labels and model numbers on indoor and outdoor equipment must be accessible and readable.

MCH-27

Indoor air quality & mechanical ventilation

Verifies required whole-building ventilation equipment, controls, operation, and delivered airflow.

Be ready: Ventilation fans, outside-air connections, controls, grilles, filters, and occupant controls must be installed and operational.

MCH-28

Return duct & filter-device sizing

Verifies return-duct design and air-filter device sizing under the applicable Title 24 tables.

Be ready: Return ducts, filter grilles or cabinets, filters, and system design information must be accessible.

MCH-29

Duct surface area, R-value & buried ducts

Verifies conditions used for applicable duct-surface-area reduction, insulation R-value, or buried-duct compliance credits.

Be ready: Schedule before ducts or insulation are concealed; relevant duct dimensions, insulation, burial, and locations must remain observable.

MCH-30

Central fan ventilation cooling system

Verifies applicable central fan ventilation cooling system components, controls, airflow, and performance.

Be ready: Fans, dampers, outside-air paths, controls, and related HVAC components must be installed and operating.

MCH-32

Local mechanical exhaust

Covers applicable kitchen range hoods, bathroom exhaust, and other local exhaust requirements, including airflow and applicable sound or listed-product information.

Be ready: Fans and hoods must be installed, ducted, powered, accessible, and operational; manufacturer and model labels should be available.

MCH-33

Variable-capacity heat-pump credit

Verifies eligible variable-capacity heat-pump equipment and applicable compliance-credit conditions.

Be ready: Indoor and outdoor equipment, controls, labels, commissioning information, and required system settings must be available.

ENV-20

Building enclosure air leakage

Uses calibrated blower-door equipment to measure air leakage through the building or dwelling-unit enclosure.

Be ready: Exterior envelope, windows, doors, penetrations, and applicable seals must be complete; the building must be configurable for testing.

ENV-21

QII air-infiltration sealing — framing stage

Verifies required air sealing at framing stage before insulation and finishes conceal the inspection areas.

Schedule early: This is stage-sensitive. Do not cover framing, penetrations, joints, or sealing details before required observation.

ENV-22

QII insulation installation

Verifies insulation installation quality, including alignment and conditions involving gaps, voids, compression, and obstructions.

Schedule before covering: Insulation must be installed but remain visible before drywall or other assemblies conceal it.

EXC-20

Existing conditions for alterations

Verifies applicable existing building features used in an alteration compliance approach.

Be ready: Existing features claimed by the compliance documents must be safely accessible and observable.

PLB-22

Verified hot-water distribution

Verifies eligible single-dwelling-unit hot-water distribution measures specified by the approved compliance documents.

Be ready: Water-heating equipment, distribution piping, controls, insulation, and relevant fixtures must be accessible as required.

PROJECT SUPPORT

Registry, transfer, permit closeout & retesting support

These are service categories rather than a single CEC measure code. We review the project information, identify the relevant verification path within our scope, coordinate scheduling, and help organize next steps.

Not sure which code applies?

Send the project. We’ll help identify the next step.

The approved compliance documents determine the actual measures required for each job.

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