How do MEP Plans connect with Title 24?

MEP plans and the Title 24 energy report are two halves of the same compliance story, and they must agree with each other exactly. The Title 24 report (the CF1R) sets the minimum efficiency requirements — for HVAC, water heating, and lighting — and the MEP plans must specify equipment that meets or exceeds those minimums. When they don't match, the plan checker issues corrections.

What Title 24 actually controls

Title 24, Part 6 is California's Building Energy Efficiency Standards. For an ADU, the CF1R (Certificate of Compliance) establishes the targets your MEP equipment has to hit:

• HVAC efficiency — the heating and cooling equipment shown on the mechanical plans must meet the efficiency thresholds in the CF1R. Under the 2025 code (effective January 1, 2026), heat pumps are the prescriptive baseline.
• Water heater efficiency — the type and efficiency of the water heater on the plumbing plans must align with the CF1R, which strongly favors heat pump water heaters.
• Lighting power density and controls — lighting shown on the electrical plans must meet Title 24 efficiency requirements.
• Ventilation — the whole-building ventilation on the mechanical plans must satisfy ASHRAE 62.2 as reflected in the energy model.

The CF1R, CF2R, and CF3R

The energy report isn't a single document — it spans the life of the project. The CF1R is prepared and registered before permit submittal. The CF2R is completed by the installing contractors during construction, certifying the install matches the CF1R. The CF3R is completed by a HERS rater after field verification (such as refrigerant charge and ventilation airflow). The building department won't issue a certificate of occupancy until the required CF3Rs are registered.

Why coordination prevents corrections

The most common Title 24-related plan check correction is a mismatch: the HVAC unit or water heater listed on the MEP equipment schedule doesn't meet the efficiency value modeled in the CF1R. When two different companies prepare the energy report and the plans independently, these mismatches are easy to miss. When the same team produces both, the documents are reconciled from the start.

How the compliance path affects your MEP plans

Title 24 offers two routes to compliance, and which one applies shapes what your MEP equipment has to do. Under the prescriptive method, each component must individually meet a fixed minimum — so the HVAC, water heater, and lighting on your plans each have to clear their own threshold. Under the more flexible performance method, CEC-approved software (CBECC-Res or EnergyPro) models the whole ADU as a system, allowing a strong showing in one area to offset another. The performance path is the most common for ADUs, and a well-insulated all-electric design with a heat pump and heat pump water heater typically compiles easily — which is also why those system choices show up so often on California ADU mechanical and plumbing plans.

Climate zone ties it all together

The CF1R is calculated for your project's specific California climate zone — one of 16, determined by parcel address, not city or ZIP. That zone drives the insulation, window, and HVAC efficiency targets the MEP plans must reflect. A CF1R built on the wrong climate zone produces invalid results and is a frequent cause of plan check rejection, so the address-level zone has to be confirmed before either the energy report or the plans are finalized.

Bundling Title 24 with your MEP plans is the cleanest way to eliminate the single most common source of energy-code corrections — and our CF1R add-on is +$240, below the typical standalone fee from most energy code compliance providers.

Learn more on our Title 24 Reports page, or add the report to a coordinated Full MEP Package. Requirements vary by jurisdiction and code cycle — confirm specifics with your local building department.