NRCC-MCH Title 24 — Commercial Mechanical Compliance Reports
Title 24 Calcs prepares NRCC-MCH nonresidential mechanical compliance reports for commercial buildings throughout California. We cover new commercial construction, tenant improvements with HVAC work, and commercial HVAC replacement. Additionally, we serve building additions across all 16 California climate zones. See our cities service area for your location.
What Is the NRCC-MCH?
The NRCC-MCH is the Nonresidential Certificate of Compliance for mechanical systems. Specifically, it covers HVAC equipment, ventilation, heating, cooling, and duct systems in commercial buildings. Furthermore, the NRCC-MCH works alongside the NRCC-ENV and NRCC-LTI to form the complete commercial Title 24 package.
The 2025 California Building Energy Efficiency Standards introduced significant changes to commercial mechanical requirements. Notably, heat pump systems now score much better than gas systems under the new Long-Term System Cost compliance metric. Additionally, expanded demand control ventilation requirements and tighter duct insulation standards apply to most new commercial buildings. Read our 2025 Title 24 code changes guide for the full summary. New to Title 24? Start with our What Is Title 24 guide.
NRCC-MCH Report — key facts:
• Code: 2025 California Building Energy Efficiency Standards — effective January 1, 2026
• Project types: New construction, tenant improvement, HVAC replacement, addition
• Building types: Office, retail, medical, warehouse, hotel, restaurant, industrial
• Climate zones: All 16 California climate zones covered
• Turnaround: 2 to 3 business days for most projects
What the NRCC-MCH Covers
Specifically, the NRCC-MCH covers seven key elements of commercial mechanical systems. Each element must meet the minimum performance standards for the applicable California climate zone. Furthermore, the requirements differ by building type, occupancy, and system size.
| System Element | What the NRCC-MCH Documents | Key 2025 Requirement |
|---|---|---|
| HVAC equipment | Equipment efficiency ratings, model numbers, capacity | Minimum EER2, SEER2, IEER ratings by zone |
| Economizers | Economizer type, high-limit shutoff, controls | Required above capacity threshold by climate zone |
| Ventilation | Outdoor air rates, demand control ventilation | DCV required for high-occupancy spaces |
| Duct systems | Duct insulation R-value, leakage, sealing | R-8 duct insulation, acceptance testing required |
| Controls | Thermostat setback, scheduling, BAS provisions | Setback controls mandatory for most systems |
| Exhaust systems | Kitchen exhaust, lab exhaust, parking garage fans | Energy recovery and demand controls may apply |
| Water heating | Commercial water heating equipment and distribution | Heat pump water heater baseline for many building types |
How the 2025 Code Changed Commercial Mechanical Compliance
The 2025 code replaced the Time Dependent Valuation compliance metric with Long-Term System Cost. Consequently, all-electric and heat pump systems score significantly better than gas systems under the new metric. In practice, heat pump HVAC systems now score much better than gas under the performance approach.
However, the prescriptive path still allows gas heating in many commercial applications. However, the performance path makes all-electric designs much easier to pass than under the 2022 code. Therefore, Title 24 Calcs determines the best compliance path for your mechanical system before starting your report. See our prescriptive vs performance guide for more detail.
Which Commercial Projects Need an NRCC-MCH?
Specifically, any California commercial project that installs or replaces HVAC systems requires an NRCC-MCH report. Specifically, these project types commonly trigger the requirement:
- New commercial construction — every new office, retail, medical, warehouse, hotel, or restaurant building requires a full NRCC-MCH covering all mechanical systems
- Tenant improvements with HVAC — any TI that installs new HVAC equipment, replaces existing units, or modifies ductwork triggers an NRCC-MCH
- Commercial HVAC replacement — replacing a rooftop unit, split system, or package unit in an existing commercial building requires an NRCC-MCH when a permit applies
- Commercial additions — any addition that includes new conditioned floor area and new mechanical systems requires NRCC-MCH compliance for the new scope
- Exhaust system changes — commercial kitchen exhaust, laboratory exhaust, or parking garage ventilation changes may trigger NRCC-MCH requirements
When a TI Does Not Need an NRCC-MCH
A TI covering only interior finishes or plumbing — without touching HVAC — typically does not need an NRCC-MCH. However, any TI that adds, replaces, or modifies mechanical systems triggers the requirement. In practice, confirm with your building department before starting design. Title 24 Calcs confirms whether your TI scope requires mechanical compliance before starting any report.
Economizer Requirements for Commercial HVAC
Notably, economizers are one of the most important and commonly misunderstood elements of commercial mechanical compliance. Specifically, California requires economizers on most commercial HVAC units above a cooling capacity threshold. An economizer uses cooler outdoor air for free cooling when outside conditions allow. Consequently, it reduces mechanical cooling energy use and lowers operating costs.
How Economizers Work
Specifically, a commercial economizer monitors outdoor air temperature and humidity. When outdoor conditions fall below the high-limit setpoint, the economizer opens dampers. It then uses outdoor air instead of mechanical cooling. This we call free cooling. In coastal zones like Zone 6 and Zone 7, economizers deliver substantial savings. Outdoor temperatures stay cool much of the year in these zones. In hot desert zones like Zone 15, free cooling opportunities stay limited but still required when conditions allow.
Economizer Capacity Thresholds
The 2025 code requires economizers on commercial HVAC units above a capacity threshold. This threshold varies by climate zone. Title 24 Calcs confirms the applicable threshold for your project during report preparation. If your unit falls below the threshold, we document the exception in the NRCC-MCH.
Demand Control Ventilation — NRCC-MCH Requirement
Moreover, demand control ventilation (DCV) is a significant energy-saving requirement under the 2025 commercial mechanical code. Specifically, DCV uses CO2 sensors to modulate outdoor air supply based on actual occupancy rather than design maximum. Consequently, this reduces ventilation energy in spaces that are not always at full occupancy.
When DCV Is Required
DCV applies to commercial spaces with 40 or more occupants per 1,000 square feet. It also covers spaces designed for 25 or more people. Common spaces that typically require DCV include conference rooms, classrooms, assembly areas, and retail sales floors. In practice, DCV is one of the most commonly overlooked mechanical compliance requirements. Missing DCV documentation is a frequent cause of commercial plan check corrections.
DCV Sensor Requirements
Specifically, CO2 sensors must go in the occupied zone of each space requiring DCV. The sensors must connect to the HVAC controls and modulate outdoor air dampers based on CO2 concentration levels. Title 24 Calcs documents the DCV sensor locations, setpoints, and control sequences in the NRCC-MCH for each applicable space.
Acceptance Testing for Commercial Mechanical Systems
Furthermore, commercial mechanical compliance requires field verification by an Acceptance Test Technician after installation. Commercial acceptance testing differs from residential HERS testing. Both confirm that installed systems perform as specified. Specifically, the ATT signs the NRCA-MCH Certificate of Acceptance forms after field verification. Furthermore, these must register before the building department issues a certificate of occupancy.
What Acceptance Testing Verifies
- Economizer operation — confirms the economizer opens and closes correctly and the high-limit shutoff functions properly
- DCV controls — confirms CO2 sensors respond correctly and modulate outdoor air as specified
- Thermostat setback — confirms setback controls operate on the correct schedule
- Airflow rates — confirms supply and exhaust airflow meets design specifications
- Duct leakage — confirms duct systems meet leakage limits for the project scope
Therefore, your NRCC-MCH identifies which acceptance tests apply to your project. Read our Title 24 nonresidential commissioning guide for more on commercial acceptance testing requirements. The California Energy Commission publishes the official NRCA-MCH acceptance test forms.
Commercial Mechanical Requirements by Climate Zone
Notably, HVAC efficiency requirements, economizer rules, and ventilation standards all vary by California climate zone. Title 24 Calcs confirms your exact zone by project address before starting any NRCC-MCH report. Furthermore, using the wrong climate zone is one of the most common causes of commercial plan check corrections.
Specifically, Title 24 Calcs operates from Corona, CA in the Inland Empire. This gives us direct Zone 10 experience — one of California’s most demanding inland zones for cooling efficiency. We also serve Zone 15 markets including Palm Springs and Palm Desert. These zones have the highest cooling efficiency requirements.
We serve commercial mechanical projects across all California climate zones. Key cities we cover include Irvine, Anaheim, Corona, and Temecula. Additionally, we serve Murrieta, Fontana, Rancho Cucamonga, and Ontario. We also cover San Bernardino, Sacramento, Fresno, Chula Vista, and Carlsbad. See our climate zones guide and cities service area for all locations.
Frequently Asked Questions — NRCC-MCH
What is the NRCC-MCH form?
Specifically, the NRCC-MCH is the Nonresidential Certificate of Compliance for mechanical systems. It covers HVAC equipment, ventilation, economizers, duct systems, and controls in commercial buildings. California building departments require it at permit submittal for all new nonresidential construction and mechanical system modifications.
Does commercial HVAC replacement need an NRCC-MCH?
Yes when a permit applies. Replacing a commercial rooftop unit, split system, or package unit triggers an NRCC-MCH. Furthermore, acceptance testing by an ATT applies to verify economizer and control function. Title 24 Calcs confirms the full scope of requirements before starting your report.
What are economizer requirements for commercial HVAC?
Economizers apply to commercial HVAC units above a cooling capacity threshold that varies by climate zone. The economizer must include a high-limit shutoff strategy appropriate for your zone. Acceptance testing confirms the economizer operates correctly after installation.
What is demand control ventilation and when is it required?
DCV uses CO2 sensors to adjust outdoor air based on actual occupancy. It applies to spaces with 40 or more people per 1,000 square feet. This covers conference rooms, classrooms, and retail sales floors. Notably, missing DCV documentation is one of the most common causes of commercial plan check corrections.
How long does an NRCC-MCH report take?
Most projects are ready within 2 to 3 business days after we receive complete mechanical plans and equipment schedules. Furthermore, rush options are available for urgent submittals.
Do I need NRCC-ENV, NRCC-MCH, and NRCC-LTI together?
Most new commercial construction requires all three. The NRCC-ENV covers the building envelope. Mechanical systems fall under the NRCC-MCH. Lighting compliance goes in the NRCC-LTI. Tenant improvements may need only one or two forms depending on scope. Title 24 Calcs confirms which forms apply to your project. For residential projects see our ADU, new construction, addition, and alteration service pages.
What information do I need to provide?
Provide mechanical plans with HVAC schedules, model numbers, efficiency ratings, duct layout, and ventilation schedules. Also include exhaust and controls information. Also provide the project address. In practice, more complete plans mean faster delivery and fewer revision requests at plan check. See our Title 24 FAQ for more common questions.