01Key facts / TL;DR
It depends on the project and supported design inputs: prescriptive compliance follows applicable component/system provisions, while performance compliance evaluates a defined design against an edition-specific energy budget.
Yes, both approaches must address applicable mandatory requirements; performance is not permission to trade away every code obligation.
No, a preliminary model or favorable option study is not the final permit package and does not guarantee approval.
Yes, confirm building classification, AHJ-recorded application date and permit scope before choosing software, forms or a modeling boundary.
Decision checklist
Four decision steps before choosing a compliance path
1.Confirm edition, classification and project boundary
Record the AHJ application date, building classification and retained-versus-proposed scope. Establish whether the question concerns new construction, an addition, an alteration or a nonresidential package.
2.Check the prescriptive fit and mandatory provisions
Compare supported assemblies, fenestration and equipment with the applicable prescriptive provisions. Identify missing inputs and mandatory measures rather than assuming a model can trade away any requirement.
3.Evaluate permitted performance options if useful
Ask whether eligible design choices and the confirmed modeling boundary justify an edition-matched option study. Keep preliminary assumptions separate from final selections and do not present illustrative results as proof of compliance.
4.Coordinate the final package and separate handoffs
Align the selected method, software, CF1R or NRCC documents and drawings. Confirm required registration and separate installation, ECC verification or nonresidential acceptance responsibilities with the project team and AHJ, then upload the coordinated inputs for a scoped quote.
Educational guidance, not legal advice. Verify the application date and requirements with your AHJ.
Upload plans / Get a Quote02Compare the decision, not just the report label
A compliance method answers how the design demonstrates the applicable Energy Code requirements. It is not a quality ranking and does not decide whether the project needs a permit. The prescriptive route can be practical when the planned assemblies and systems already satisfy its applicable provisions. Performance analysis can be useful when the team needs to evaluate allowable design options rather than accept one straightforward component-by-component arrangement.
| Decision | Prescriptive approach | Performance approach |
|---|---|---|
| Starting evidence | Supported assemblies, schedules and systems matched to the applicable project provisions. | The same supported design inputs plus the geometry, boundary and modeling information required for the selected scope. |
| Design flexibility | Meet the applicable prescribed provisions and mandatory requirements. | Evaluate only trade-offs permitted by the applicable software and code rules; mandatory provisions still apply. |
| Typical document question | Which eligible NCB, ADD, ALT or applicable nonresidential component records fit? | Which software-generated CF1R-PRF or applicable NRCC performance output fits the defined scope? |
| Change control | Recheck the affected provisions and documents when the specification changes. | Review the changed assumptions and rerun the affected model/package as needed. |
03Start with five decisions the project team can actually resolve
First establish the AHJ and recorded application date. The 2025 California Energy Code applies to building-permit applications on or after January 1, 2026; confirm earlier or revised applications with the reviewing authority. Then identify the building classification and permitted work. A single-family addition, multifamily alteration and commercial lighting TI cannot be treated as one interchangeable analysis.
Next ask whether the proposed design can use an applicable prescriptive path without unwanted revisions. If it can, a performance model is not automatically a better purchase. If important options need comparison, define the question before modeling: which assembly, system or boundary is being tested, which inputs are supported, and which features remain provisional?
- +Confirm application date, code edition and the reviewing AHJ.
- +Classify the building and distinguish existing, altered and new scope.
- +Define the relevant prescriptive option and any unresolved design choices.
- +Confirm whether performance analysis can evaluate those choices within the permitted scope.
- +Assign drawing coordination, final document preparation and later installation/verification responsibilities.
Application-date guideWhich Title 24 forms?Project-specific modeling help
04Inputs that matter in either method
Begin with plans that distinguish conditioned area, existing conditions and proposed work. Support insulation and assembly descriptions rather than supplying only an unexplained R-value. Fenestration inputs need sizes and product/schedule information such as U-factor and SHGC; performance analysis may also need orientation and shading details. An attractive rendering is not a substitute for coordinated dimensions and schedules.
Describe HVAC, water heating and relevant lighting or controls within the actual scope. Identify which equipment is selected and which is provisional. Explain the proposed PV, battery or readiness measures where relevant to the project rather than assuming they create unrestricted compliance credit. Electrical and CALGreen obligations remain separate questions, even when coordinated on the same drawings.
Existing-building evidence can affect the appropriate analysis. Unknown insulation, undocumented equipment or an unclear addition boundary should be flagged, not guessed into a favorable model. Ask what evidence is needed and whether the relevant component or existing-plus-addition pathway can use it. The appropriate climate zone must come from the actual project location and reliable tools, not a county-wide assumption.
05What performance modeling can—and cannot—trade
Performance compares a proposed design with a code-defined standard design using approved software and the applicable edition’s rules. It is not an unrestricted offset bank. A favorable result depends on the recorded input set and all required checks, not a verbal promise that one upgraded product will compensate for any other change.
The CEC’s 2025 overview describes long-term system cost, or LSC, and source-energy budgets and distinguishes new-construction checks from addition/alteration checks. Ask the preparer which checks apply to this building and scope. Do not compare old-cycle TDV/EDR results with a current run as though they were the same measurement, or infer a complete compliance result from one summary number.
Mandatory measures, required installation details and applicable verification remain obligations. Neither adding a battery to a sketch nor selecting a high-efficiency appliance establishes that an otherwise unsupported design complies. Code modeling uses standardized assumptions and is educational, not legal advice. It is not mechanical sizing, a utility-bill prediction or a comfort guarantee.
06Illustrative comparison: settle the question before producing the package
ILLUSTRATIVE ONLY. A detached ADU design has a settled floor plan, but the designer is comparing two roof assemblies and has not finalized water heating. One option may fit the applicable prescriptive provisions without further modeling. Another may warrant performance analysis because the team wants to evaluate the combined design choices. Neither result can be declared from the product names or the ADU label alone.
The useful option-study deliverable identifies the tested assumptions, the compliance method and unresolved selections. If the team chooses a performance option, the final run must reflect the selected roof, water heating and other coordinated inputs. If it chooses the eligible prescriptive route, the applicable certificates still need complete supporting information. Both outcomes require an agreed final drawing revision rather than a preliminary option screenshot.
An attached addition or garage conversion needs its own classification and project boundary. Do not transfer a detached-new-dwelling analysis to an existing-building conversion. Ask whether addition-alone, existing-plus-addition or an altered-component pathway is appropriate, then use the corresponding records and evidence. The AHJ confirms project-specific requirements.
Do I need Title 24 for an ADU?ADU and garage-conversion serviceAddition modeling boundaries
07Residential versus commercial: method is not the form family
Single-family design documentation can use applicable prescriptive CF1R families or software-generated performance CF1R records. Multifamily projects need their classification-specific catalog; do not assume that every dwelling uses single-family CF1R. Commercial/TI work commonly uses NRCC design certificates for the applicable systems, with performance documentation when that method is used.
A lighting-only TI should begin with its affected lighting and controls scope, not automatically a whole-building model. NRCI installation records, applicable NRCV verification and NRCA acceptance documents belong to their separate stages. Similarly, residential CF2R and CF3R responsibilities are not included merely because a CF1R package was prepared. Current-cycle field-verification language is ECC; HERS may remain in older-cycle records or legacy searches.
Nonresidential form familiesCF1R documentation and handoffsCommercial energy-document scope
08Order the right scope, then control the final handoff
Upload plans, schedules, project data and the specific decision you need help resolving. Ask whether the request is an early option study or a permit-ready package, and identify who will confirm final selections. Published pricing remains residential by scoped conditioned area and dwelling units, or commercial by scoped area—not separate menus for each compliance-method abbreviation.
Review the report against the final drawings before submittal. Keep the agreed inputs and identify which changes require review later. Field testing, acceptance testing, registry/document-registration fees, CALGreen documentation and AHJ fees remain excluded. Production and AHJ review are separate; neither method promises permit approval.
Report-cost scope explainedPublished pricingOrder / upload preparationUpload plans / Get a Quote
09Six questions about performance and prescriptive compliance
Is performance always better than prescriptive compliance?
No. If the proposed design fits an applicable prescriptive route, a performance study may not answer an additional useful question. Performance is valuable when permitted design comparisons or trade-offs matter. Confirm classification, scope and the actual decision before commissioning analysis.
Can a performance model waive mandatory measures?
No. Both methods must address applicable mandatory requirements. A passing budget result is not a waiver of required installation details, controls or verification. Ask which obligations must appear on drawings and carry through construction, rather than treating the report as a general exemption.
Can solar or a battery compensate for any inefficient design?
No unrestricted credit is promised. The applicable code, software and project-specific checks control how measures are evaluated. Confirm the relevant energy, electrical and readiness requirements; adding equipment to a plan does not automatically establish compliance or replace separate code documentation.
Does an ADU always need performance modeling?
No universal method follows from the ADU name. A detached new dwelling, attached addition and conversion need their actual classifications and eligible pathways checked. Either method requires supported inputs and matching documents. Confirm project-specific requirements and application date with the AHJ.
Is an option-study result enough for the permit submittal?
No. Preliminary studies test provisional assumptions. A final permit package must match the selected design and drawing revision, include applicable certificates and address signatures/registration where required. Keep unresolved selections visible until the responsible team confirms them.
Does the report include field testing, CALGreen or permit fees?
No. Our scoped deliverable is design-phase Part 6 documentation. Field verification/testing, nonresidential acceptance testing, registry fees, CALGreen documentation and AHJ fees are separate. Upload the plan set and scope question so we can identify the appropriate energy-document request.
Sources
- CEC: 2025 Energy Code and January 1, 2026 effective date
- CEC: 2025 single-family manual, including performance and existing-building chapters
- CEC: 2025 Energy Code overview — LSC/source-energy performance budgets and ECC roles
- CEC: 2025 single-family CF1R, CF2R and CF3R forms
- CEC: 2025 NRCC, NRCI, NRCV and NRCA forms
- CEC Energy Code Support Center: edition-specific forms, software and registration guidance
- CEC: Energy Code Compliance (ECC) Program and transition questions