Converting an office from rooftop to VRF or multi-zone ductless is generally treated as an alteration under California Title 24, Part 6, so the new work must meet the code edition in effect at permit application. Expect plan check, inspections, acceptance testing and certificates of installation. Utility and manufacturer incentive programs may exist but change often, so verify eligibility before design and before purchase.
- A conversion is rarely exempt from energy code. Plan on current Title 24 requirements applying to the altered system, and confirm with the local building department and the project's designer.
- Permit timing is the most common source of schedule slippage, not construction. Start the permit package early and expect at least one round of plan check comments.
- Acceptance testing and signed certificates are required deliverables, not paperwork you can finish after tenants move in.
- Incentive programs are real but conditional. Check eligibility, pre-approval rules and documentation requirements before equipment is ordered.
- Refrigerant rules, including A2L refrigerants in newer equipment, affect design and documentation. Confirm current requirements with the designer.
How Title 24 generally treats an office conversion
California's energy code for nonresidential buildings is Title 24, Part 6. When mechanical systems in an existing building are replaced or substantially altered, the code usually treats that work as an alteration, and the altered systems must comply with the edition in effect when the permit is applied for. A rooftop-to-VRF conversion changes the equipment, the distribution and the controls at once, so it touches several parts of the code rather than one.
Because the rules are detailed and revised periodically, this page describes what to expect rather than what to cite. The designer of record, or the mechanical contractor in a design-build arrangement, should confirm the exact requirements for your building type, size and climate zone. The broader walk-through of triggers is in the Title 24, permits and acceptance testing guide.
Areas the code commonly touches in a conversion
- Equipment efficiency and listing. New equipment must meet applicable minimum efficiency standards and be certified for sale in the state.
- Controls. Thermostat capability, setpoint limits, scheduling and shutoff behavior are all addressed. Central controllers and BAS connections are part of this conversation.
- Ventilation. Removing a rooftop unit that supplied outside air means the new design must still deliver required ventilation. A dedicated outdoor air unit or ventilation-capable indoor units are part of many VRF designs.
- Ductwork. If ducts are altered, sealing and insulation requirements may apply. Where ducts are abandoned, the scope should say so.
- Fault detection and economizer questions. These are tied to rooftop packaged equipment. When that equipment goes away, confirm what the code expects of the replacement design.
Climate zone matters for several of these items. Coastal Orange County, the Inland Empire and San Diego County sit in different zones, and the same conversion can have different requirements in each. The designer should confirm the zone for the specific address.
Permits and plan check, step by step
Permits are issued by the building department of the city or county where the building sits. Each jurisdiction has its own submission format, counter or online portal, and review times. Treat the steps below as the typical flow, not a guarantee of how any one city operates.
- Scope definition. The conversion is defined well enough to draw: equipment locations, line routes, indoor unit layout, ventilation approach, controls and electrical requirements.
- Drawings and calculations. Mechanical plans, load calculations and equipment schedules, plus the energy compliance forms the jurisdiction expects. Structural and electrical drawings accompany them where the work requires.
- Submittal. The package goes to the building department, along with applications for any related permits the city requires (for example, for a crane staging area or street closure).
- Plan check. The reviewer may return comments. Plan on responding, revising and resubmitting at least once.
- Permit issuance. Work starts only after issuance. Jobsite copies of approved plans are usually required.
- Inspections. Typically include rough-in or concealed work, final mechanical, and electrical inspections as applicable.
- Acceptance testing and certificates. Completed before final sign-off.
- Final approval. The building department closes the permit.
Responsibilities matter here. Davinci's mechanical, refrigeration and controls work is performed by its own UA Local 250 crew with no subcontractors, but a conversion also involves electrical service, structural review of roof loads, and sometimes fire-alarm or roofing work. The permit package and scope should name who performs and signs off each of those trades, and the owner or GC should confirm each responsible licensed party.
Contractor will prepare and submit mechanical permit documents, respond to plan check comments, and schedule mechanical inspections. Owner or Owner's representative will identify the parties responsible for electrical, structural and any other trades required by the permit. Schedule dates are estimates and depend on the building department's review and inspection availability.
Acceptance testing and certificates of installation
Acceptance testing is how the code confirms that the installed system works the way the design says it does. For a conversion, expect testing on the controls, ventilation, and any distribution components that fall under the code. The exact list depends on what was installed. Certain tests must be performed by certified acceptance test technicians, and the forms are signed and submitted to the building department and kept with the project records.
Where a third-party test-and-balance agency is part of the project, it is a separate party. Davinci does not claim third-party test-and-balance work. The testing, balancing and commissioning scope explains how that line is usually drawn.
| Document or step | Why it exists | Who usually supplies it |
|---|---|---|
| Certificates of installation | Record that equipment and controls were installed per the compliance documentation | Installing contractor, as applicable to their scope |
| Acceptance test forms | Show that required functional tests were performed and passed | Certified acceptance test technician working with the installing contractor |
| Startup and commissioning records | Show refrigerant circuit readings, communication status and zone verification | Mechanical contractor |
| Final inspection sign-offs | Closes the permit | Building department |
| As-built layout and asset records | Support maintenance and later audits | Mechanical contractor; stored in the DaVinci Portal with service history |
Treat these as schedule items, not afterthoughts. A conversion that is physically finished but waiting on a test, a signature or an inspection slot cannot be fully handed to the tenant. Tenants notice, and so do lenders and insurers if the building is financed.
Incentives: how to approach them without relying on them
Electric utilities, regional energy programs and equipment manufacturers have offered incentives for efficient HVAC equipment, including VRF and heat-pump systems. These programs are not permanent. Their eligibility rules, application windows, funding levels, qualifying equipment lists and documentation requirements change, sometimes during a project. Do not budget on a number you have not confirmed in writing.
Davinci does not quote incentive amounts, and neither should a designer or sales representative until the program is confirmed for your specific equipment, building and service territory. What you can do is build the process to be ready for whichever programs apply.
- Identify your utility. Southern California buildings are served by different electric providers, including SCE, LADWP and SDG&E, and their programs are separate. Gas utility programs, where they exist, are separate again.
- Ask about pre-approval. Some programs require an application before equipment is ordered or work begins. Buying first can disqualify the project.
- Confirm the paperwork. Typical needs include equipment model and certification information, invoices, commissioning or startup records, and sometimes pre- and post-installation documentation. Ask the contractor whether they can supply those records.
- Check who applies. Some programs let the contractor apply, others require the owner. Decide this before the contract is signed.
- Treat incentives as upside. A conversion that makes sense on comfort, reliability, tenant needs and operations should not depend on an incentive that might change or run out.
Tenant-funded or landlord-funded structure also matters. In a leased building, ask who is entitled to the incentive and how that interacts with the lease. This is a question for your lease counsel, not the mechanical contractor.
Refrigerant rules that shape the design
The HFC transition is changing which refrigerants new commercial equipment can use. Many current VRF and multi-zone products use lower-global-warming-potential refrigerants such as R-32 or R-454B, which are classed as A2L, meaning mildly flammable. That affects design, ventilation and leak response in occupied spaces, and standards such as ASHRAE 15 address refrigerant safety. Confirm the current CARB and EPA requirements, and ask the manufacturer and designer how the specific system complies.
Handling refrigerant during demolition of the old system falls under EPA Section 608 and California rules. Recovery, tracking and record keeping should be part of the scope. For the detail, read the refrigerant compliance guide.
Timing risks that surprise owners
Conversions rarely slip because of construction. They slip on process. These are the risks worth putting on the first schedule review.
- Plan check cycles. Each round of comments adds days or weeks. Complete drawings the first time, and respond to comments fully.
- Equipment lead times. VRF outdoor units, branch controllers and controllers are specified products. Lead times vary, and a program or code change can alter which models are available.
- Electrical and structural work. These are not Davinci trades. If the electrician or structural engineer is not on the schedule, the mechanical work will wait.
- Inspection availability. Rough and final inspections depend on the city's calendar.
- Acceptance testing scheduling. Certified testers have their own calendars. Book them while construction is still in progress.
- Edition changes. If a permit application is made close to a code edition changeover, confirm which edition applies before the drawings are completed.
- Incentive deadlines. An application window that closes can force a decision before design is ready. Do not let it.
Large projects, particularly public or institutional ones, add further layers. The bid projects page and the project delivery and bidding guide cover how those schedules are built. For the VRF-specific installation scope, see the VRF installation scope of work.