Building commissioning is an owner-directed quality process that verifies a new building or major renovation is designed, installed, tested, documented and handed over to meet the Owner’s Project Requirements. It begins before design decisions are fixed and continues through construction and initial operation. Commissioning coordinates evidence and accountability; it does not replace design, construction, code inspection, balancing, maintenance or the owner’s acceptance authority.
How is building commissioning different from retro-commissioning?
Commissioning terms describe when and why a process is performed. Defining the term in the contract prevents scope confusion.
| Process | Typical application | Primary emphasis |
|---|---|---|
| New construction commissioning | New building or major renovation | Verify requirements through design, construction, testing and initial operation |
| Retro-commissioning | Existing building that was not commissioned originally | Investigate and correct current operational problems |
| Recommissioning | Previously commissioned building | Revisit performance after time, change or drift |
| Ongoing commissioning | Building with a continuing performance program | Use monitoring, testing and corrective action to sustain requirements |
For the existing-building process, read The Tustin Group’s separate commercial building retro-commissioning guide. Keeping the scopes separate avoids using an existing-building investigation as a substitute for early design review on a new project.
Why should commissioning begin before design?
Early commissioning gives the owner time to define measurable requirements before major decisions are embedded in drawings and contracts. The commissioning provider, or CxP, can help the owner translate business needs into the Owner’s Project Requirements, commonly called the OPR. The design team then explains its technical response in the Basis of Design.
An OPR should address more than target room temperatures. It can define occupancy, operating schedules, critical functions, resilience, maintainability, energy and water objectives, indoor environmental conditions, controls, metering, staff training, documentation and testing expectations. Requirements should be prioritized when budget, schedule or technical constraints create tradeoffs.
What happens during each commissioning phase?
| Phase | Owner-focused activities | Key evidence |
|---|---|---|
| Predesign | Set goals, select the CxP, define systems and assign responsibilities | OPR and initial commissioning plan |
| Design | Review the Basis of Design, drawings, sequences and testability | Design-review comments and commissioning specifications |
| Construction | Track submittals, observe installation, complete checklists and manage issues | Approved submittals, installation records and issues log |
| Acceptance | Execute functional tests, retest corrections and review training | Test results, deficiency disposition and training records |
| Occupancy | Complete seasonal tests, update documents and verify handoff | Final report, systems manual and ongoing plan |
Which building systems should be commissioned?
Scope should follow owner risk, code requirements, project complexity and budget. Common candidates include HVAC, building automation, electrical distribution, emergency power, lighting controls, domestic hot water, renewable energy, envelope assemblies and selected plumbing systems. Fire and life-safety systems have specialized testing and authority requirements; commissioning must coordinate with—not replace—required inspections and acceptance.
Interfaces deserve particular attention. A generator may start correctly while a cooling unit fails to reconnect. An air handler may operate in normal mode but not respond as required during an alarm or occupancy change. Meter data may exist but use inconsistent units or names. Commissioning tests the defined interactions and records exceptions.
Coordinate equipment and sequence questions with qualified commercial mechanical services and building automation and energy specialists. The project team must still define design authority, commissioning responsibility and acceptance criteria.
What should owners include in the OPR?
- Facility mission, occupancy and critical operating scenarios
- Indoor temperature, humidity, ventilation and pressure requirements
- Required operating schedules, setbacks and after-hours modes
- Resilience, redundancy, recovery and alarm-notification expectations
- Energy, water, metering and reporting requirements
- System-access, maintainability and replacement-clearance needs
- Controls sequences, trend data, naming and integration expectations
- Operator staffing, training and systems-manual requirements
- Functional test conditions and owner acceptance process
- Warranty review, seasonal testing and post-occupancy follow-up
Make requirements measurable where practical. “Easy to operate” is difficult to test. “Operators can identify alarm priority, affected equipment and required response from the interface” creates a clearer acceptance condition. Update the OPR when the owner approves a change instead of allowing design drift to remain undocumented.
How does functional performance testing work?
Functional tests demonstrate how a system responds to defined inputs, modes and failures. A test may change a simulated condition, command an operating mode, verify a sequence step, observe an alarm or confirm recovery. Procedures should state prerequisites, responsible parties, expected results, safety limits, restoration steps and required data.
Testing should be coordinated with contractors, controls personnel, operators and occupants. Do not create unsafe conditions or disrupt critical operations merely to complete a script. Some tests must be deferred until weather or load conditions are appropriate; list them as open seasonal tests with owners and dates.
A failed test is useful evidence, not an administrative inconvenience. Record the expected result, observed result, responsible party, correction and retest. Do not mark an item closed solely because work was promised.
What does commissioning not prove?
Commissioning does not certify perfection, guarantee a universal energy-savings percentage or eliminate future maintenance. It verifies the defined scope against documented requirements using agreed procedures. Outcomes depend on the quality of the OPR, design, installation, testing, issue resolution and operation.
It also does not replace preventive maintenance. After handoff, operators need service records, recurring tasks, alarm review and periodic verification. A commercial HVAC service agreement may support equipment care, but its task list should be coordinated with commissioning findings and warranty obligations.
How should owners evaluate a commissioning proposal?
Compare proposals against the same system list, phases and deliverables. Confirm when the CxP joins the project, how many design reviews and site observations are included, who writes and executes tests, which seasonal tests are deferred and how retesting is priced. Identify exclusions for envelope, electrical, controls integration or specialized systems.
Review independence and qualifications in relation to the project. Ask for sample plans, issues logs, functional tests and final reports with confidential information removed. Determine how the CxP communicates urgent risks and who has authority to accept unresolved items.
What should the owner receive at handoff?
Useful closeout is organized for operation, not merely archived. The owner should receive an updated OPR and Basis of Design, final issues log, test records, training documentation, sequences, setpoints, controls backups, equipment information, warranties, as-built records and a systems manual appropriate to the scope.
Assign every unresolved item. Seasonal tests, warranty issues and approved exceptions need a responsible party and target date. The owner should also define how performance will be reviewed after occupancy. The Tustin Group’s commercial building case studies illustrate documented project work, but each commissioning plan must establish its own requirements and evidence.
When should a commercial owner start?
Start while project goals and procurement strategy are still flexible. Identify an internal owner representative, involve operations staff and decide how the CxP will be contracted. For a renovation, collect existing sequences, trend data, service history and known complaints so the new OPR reflects actual operating needs.
To discuss mechanical, controls or building-performance scope for a specific property, use The Tustin Group’s commercial service contact page. Commissioning-provider roles, design responsibility, testing authority and local service availability should be confirmed in the project contracts.
What do commercial owners ask about building commissioning?
Is commissioning the same as an inspection?
No. Inspections generally evaluate defined code or installation requirements. Commissioning is a broader process that tracks owner requirements, system interactions, testing, documentation, training and handoff.
Who accepts the commissioning results?
The owner or designated representative retains acceptance authority under the contracts. The CxP documents observations and verification; designers, contractors and authorities keep their respective responsibilities.
Does commissioning end at substantial completion?
Not necessarily. Training, seasonal tests, warranty review, unresolved issues and initial-operation verification often extend beyond substantial completion. Define the endpoint and deliverables in the plan.
Can an existing occupied building be commissioned?
Yes. Existing-building commissioning may take the form of retro-commissioning, recommissioning or ongoing commissioning, depending on history and objectives.
Which primary sources informed this guide?
- Whole Building Design Guide, Building Commissioning: The Process.
- Whole Building Design Guide, Commissioning Documents: Process, Contents and Acceptance.
- U.S. Department of Energy FEMP, Commissioning Process for Federal Facilities.
- ASHRAE, Standards and Guidelines Titles, Purposes and Scopes, including the commissioning-process standard.
- U.S. Department of Energy FEMP, Existing Building Commissioning Decision Tool.
This article provides general planning information. Commissioning scope, professional roles, code obligations, testing, safety procedures and acceptance authority should be established for the specific project.