COMcheck vs. Title 24

The Two Things You’re Complying With

There's a whole category of plan-check comments that has nothing to do with whether your systems are designed well. The equipment can be right-sized, the ductwork clean, the panel schedules tight — and the set still bounces, because the energy-code compliance document is missing, wrong for the jurisdiction, or doesn't match the drawings.

Before the paperwork, the standard. Outside California, commercial energy-code compliance in the U.S. traces back to one of two documents:

• The IECC (International Energy Conservation Code), published by the ICC, adopted by most states.
• ASHRAE Standard 90.1, published by ASHRAE, which most jurisdictions accept as an alternative compliance path to the IECC.

The catch: jurisdictions adopt a specific edition — one edition today, a newer one next cycle — and they adopt on their own timelines. The energy code in force for your project depends on where and when you're permitting, not on the newest book on the shelf. Step one on any project is always the same: confirm the adopted code and edition for that jurisdiction.

Prescriptive vs. Performance (and the Trade-Off Path)

Every energy code offers more than one road to "compliant," and choosing the road is real engineering:

• Prescriptive path. Meet a checklist of minimum requirements component by component — insulation values, window U-factors/SHGC, lighting power density, equipment efficiencies. Simple and fast, but rigid: every element has to meet its own minimum, with no credit for over-performing elsewhere.
• Trade-off path. A middle route that lets one component's shortfall be offset by another's over-performance within a category (common on the envelope) — more flexibility without a full model.
• Performance path. Model the whole building's energy use and show it meets a code-defined performance target, with the mandatory requirements still met. The most flexible — it rewards good design holistically and enables aggressive glazing or unusual systems — but it takes an energy model and more documentation.

The right path depends on the project: prescriptive when the design is conventional and you want speed; performance when the architecture pushes past prescriptive limits and you need the trade-offs. Picking the wrong path is a common source of avoidable rework.

Inside COMcheck: Envelope, Lighting, Mechanical

A COMcheck submission is really three compliance checks bundled together, and each is often searched on its own:

• Envelope. Insulation, fenestration U-factor and SHGC, and the assemblies — checked against the adopted code for the project's climate zone.
• Lighting. Interior (and sometimes exterior) lighting power density (LPD) — total watts against an allowance — plus required controls (occupancy sensors, daylighting, time controls). This is the piece our electrical design team owns.
• Mechanical. HVAC and service-water equipment efficiencies, economizers, and control requirements — coordinated with HVAC / mechanical design.

The critical thing — and the whole point of this article — is that all three have to agree with the drawings. The COMcheck lighting page has to match the lighting schedule; the mechanical page has to match the equipment schedule; the envelope inputs have to match the architectural assemblies. A COMcheck that's internally valid but disagrees with the set can trigger a plan-review comment.

Getting the climate zone wrong is its own common miss — it drives insulation and glazing minimums across the whole envelope check, not just one line item, so it's worth confirming before any of the other inputs get run.

COMcheck’s Two Codes: IECC vs. ASHRAE 90.1

COMcheck can demonstrate compliance with either the IECC (International Energy Conservation Code) or ASHRAE 90.1 — and many jurisdictions accept 90.1 as an alternative compliance path to the IECC. They're closely related but not identical: they differ in some prescriptive requirements, how certain trade-offs work, and the exact efficiency and LPD numbers. The adopted code (and which edition) is set by the jurisdiction, and on some projects choosing 90.1 vs. the IECC path within COMcheck can make a marginal design comply that wouldn't under the other. The practical move is to confirm, up front, which code and edition the AHJ has adopted — because designing to the wrong one is invisible until plan check rejects it.

ASHRAE 90.1 isn't the only ASHRAE standard on the set, either — ventilation rates are governed separately, by ASHRAE 62.1 or the mechanical code the jurisdiction adopts (in California, Title 24 Part 6 Sections 120.1 and 160.2), and the two get confirmed together at the same kickoff conversation. If the performance path is in play, the cooling-load methods behind the energy model matter too.

The Other Exceptions You Have to Know

California is the big one, but it isn't the only state that goes its own way. Several states adopt the IECC or 90.1 but require their own forms or amended versions. Practically, that means for jurisdictions like Washington, Oregon, Florida, and New York City, you should confirm the required format — not just assume a national COMcheck will be accepted.

The takeaway isn't "memorize fifty states." It's "never assume." The energy-compliance format is a jurisdiction question you answer at project kickoff, every time.

For firms running a multi-state pipeline, this becomes an every-project checklist item rather than a one-time lookup — the jurisdiction, code edition, and accepted format get re-confirmed for each site, even within the same portfolio, because two projects five miles apart can sit in different jurisdictions with different requirements.

Which Path Applies Where — and the Workflow

The document you prepare is decided before any modeling starts, by the jurisdiction's adopted code:

(Confirm the specific jurisdiction and adopted edition — states amend and update on their own schedules.)

The workflow, either way: confirm jurisdiction → identify the adopted code and edition → choose the compliance path (prescriptive / envelope trade-off / whole-building performance) → run the tool that matches it: COMcheck for prescriptive and envelope trade-off documentation, CBECC or another CEC-approved tool for Title 24, or an approved whole-building simulation for the IECC C407 or ASHRAE 90.1 performance path (Appendix G or the Energy Cost Budget method) → reconcile the report against the drawings → submit for permit → satisfy plan review → verify at inspection. The same sequencing applies whether it's a restaurant build-out or a multifamily project — only the systems being checked change. COMcheck documents prescriptive and trade-off compliance; it is not a whole-building energy model.

The energy-compliance comments that bounce sets: the COMcheck (or NRCC) built to the wrong code edition; the wrong climate zone; a lighting schedule that doesn't match the compliance lighting page; HVAC efficiencies that don't match the equipment schedule; and envelope assumptions that don't match the architectural drawings. Every one is a coordination failure between the compliance document and the set — which is exactly why the compliance report can't be an afterthought produced in isolation, and why we treat it as part of MEP coordination rather than a separate task. It's also just one entry on a longer list — see our broader look at common MEP plan-check comments for the patterns that show up beyond energy code.

A Five-Question Decision Flow

When a new project lands, run it through this before you pick a compliance path:

1. What jurisdiction and what adopted code edition? Confirm it; don't assume the newest.
2. Is it California? If yes → Title 24 (NRCC forms for nonresidential and high-rise multifamily work), full stop.
3. Does the state or city require its own form or amended code? WA, OR, FL, NYC and others — check.
4. Commercial or low-rise residential? COMcheck vs REScheck.
5. Prescriptive or trade-off/performance? Pick the path, then make sure the drawings match the assumptions you used.

Documentation That Survives Review

Once the code, edition, climate zone and format are right, a reviewer approving your energy package checks that the compliance document passes, agrees with the drawings, and covers the applicable mandatory requirements.

• Match every value. Fixture wattages on the compliance form match the lighting schedule. Equipment efficiencies match the mechanical schedule.
• Use the right form for the jurisdiction, at the correct code edition.
• Put the signed report in the set, not in a separate email nobody can find at review.
• If you ran a trade-off, say so and make sure the drawings carry the same assumptions.
• Confirm who owns it. On some teams it's unclear whether the MEP engineer or the architect is confirming the code edition and compiling the report — that's a scope question worth settling at kickoff, not at submittal.

We treat the energy-compliance package as part of the design, not a box we check at the end. The jurisdiction and code edition get confirmed at kickoff — during the same early MEP design phases (SD/DD/CD) conversation where the rest of the scope gets set — the right compliance path gets chosen before we're deep into the drawings, and the compliance document is cross-checked against every schedule before the set goes out.

One miss we look for: a set designed to the wrong energy-code edition because the team assumed the newest one applied. Confirmed at kickoff, it's a non-issue; discovered at plan check, it's a resubmittal.

See how we work, or schedule a scope call.

Related: Cooling-Load Methods (Heat Balance / RTS / CLTD) · ASHRAE 62.1 Ventilation · MEP Coordination Best Practices

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