- Building commissioning is an independent quality verification process that confirms building systems are designed, installed, and operating as intended to meet the owner’s project requirements.
- The Commissioning Authority (CxA) is independent of the design and construction team — providing unbiased verification that what was specified was actually built and works correctly.
- Functional performance testing goes beyond startup verification to test system intelligence — verifying that controls, sequences of operation, and failure responses match the design intent.
- California Title 24 acceptance testing is a mandatory code requirement distinct from (but often coordinated with) the broader commissioning process.
- LEED Fundamental Commissioning is a prerequisite for all LEED certifications — requiring an independent CxA and compliance with ASHRAE Guideline 0 or equivalent.
- Budlong provides commissioning authority services for new construction, LEED projects, healthcare facilities, and retro-commissioning of existing buildings throughout California.
- What Is Building Commissioning?
- The Commissioning Authority (CxA) Role
- Phase 1: Pre-Design Commissioning
- Phase 2: Design Phase Commissioning
- Phase 3: Construction Phase Commissioning
- Phase 4: Functional Performance Testing
- Phase 5: Post-Occupancy and Ongoing Commissioning
- California Title 24 Acceptance Testing
- LEED Commissioning Requirements
- Who Uses Commissioning Services?
- Related Reading
- Frequently Asked Questions
Every building is commissioned — the question is whether that commissioning is systematic and documented, or informal and inadequate. Buildings that proceed from construction to occupancy without formal commissioning consistently underperform their design intent: HVAC systems run in the wrong modes, lighting controls fail to execute their programmed sequences, variable speed drives operate at constant speed, and sensors are mounted in locations where they cannot measure what they were intended to measure. The consequences accumulate in wasted energy, occupant complaints, and premature equipment failures that cost building owners far more than commissioning would have.
At Budlong, our commissioning services team provides Commissioning Authority (CxA) services for commercial, healthcare, educational, and government projects throughout California. This guide explains the complete building commissioning process from pre-design through post-occupancy — what commissioning involves at each phase, what the CxA delivers, and why systematic commissioning is one of the best investments an owner can make in their building.
1. What Is Building Commissioning?
Building commissioning (Cx) is a quality-focused process that verifies and documents that a building’s systems are designed, installed, and operating as intended to meet the Owner’s Project Requirements (OPR). It is performed by an independent Commissioning Authority who provides third-party verification — separate from the contractor’s own startup and testing — that systems perform correctly under all required operating conditions.
The scope of building commissioning typically encompasses HVAC and mechanical systems, electrical systems including emergency power, lighting controls, domestic hot water systems, plumbing systems, building automation and controls, and fire and life safety systems. On larger or more complex projects, building envelope commissioning (air and water tightness testing) is also included. The specific scope is defined in the Commissioning Plan and the Owner’s Project Requirements, which are the foundational documents of the commissioning process. Commissioning services for building performance at Budlong begin with a thorough OPR development process that establishes clear performance expectations before design begins.
2. The Commissioning Authority (CxA) Role
The Commissioning Authority is the professional who leads and manages the commissioning process on behalf of the building owner. The CxA’s fundamental characteristic is independence — they do not design the systems being commissioned and do not perform the construction or installation. This independence allows the CxA to objectively evaluate whether the design and installation meet the owner’s requirements without the inherent conflicts of interest that would arise if the designer or contractor performed their own final acceptance testing.
CxA Responsibilities Across Project Phases
The CxA’s responsibilities span the full project lifecycle: developing the OPR and Commissioning Plan in pre-design; reviewing design documents for commissionability in the design phase; developing installation verification checklists and functional performance test procedures during the construction documents phase; witnessing equipment startup and documenting installation verification during construction; performing functional performance testing; documenting deficiencies and tracking their resolution; producing the Final Commissioning Report; and — on LEED Enhanced Commissioning projects — conducting seasonal testing and reviewing the building’s operational performance during the first year of occupancy.
CxA Qualifications
In California, building commissioning providers are not formally licensed by the state, but industry certifications from the Building Commissioning Association (BCxA) and ASHRAE provide recognized credential frameworks. The Certified Commissioning Professional (CCP) from BCxA and ASHRAE’s Building Energy Assessment Professional (BEAP) are the primary credentials in the field. For LEED Fundamental Commissioning, the USGBC requires that the CxA have documented commissioning authority experience — not merely a certification — and that the CxA be independent of the project design and construction team.
3. Phase 1: Pre-Design Commissioning
The commissioning process begins at pre-design — ideally before the architect has established the building massing and before the MEP engineering team has selected system types. Early CxA engagement ensures that the Owner’s Project Requirements are clearly defined and that the design team understands the performance standards against which their design will be evaluated.
Owner’s Project Requirements (OPR)
The OPR is the foundational commissioning document that defines what the owner requires the building and its systems to do. It captures the owner’s performance objectives (comfort parameters, energy performance targets, system reliability requirements), functional requirements (operational schedules, special occupancy needs, maintenance capabilities), and sustainability goals (LEED certification target, Title 24 compliance requirements). The OPR is developed collaboratively between the CxA and the owner and serves as the reference standard for all subsequent commissioning activities. A well-developed OPR prevents the most common commissioning failure mode: systems that work as designed but don’t meet what the owner actually needed.
Commissioning Plan
The Commissioning Plan documents the CxA’s approach to achieving the OPR — which systems will be commissioned, what testing protocols will be used, what the team structure and communication protocols are, and what the schedule and deliverable milestones are. The Commissioning Plan is a living document updated throughout the project as scope, schedule, and team composition evolve. It is the central reference for all commissioning activities and becomes part of the project record at closeout.
4. Phase 2: Design Phase Commissioning
During the design phase, the CxA reviews the MEP engineering team’s design documents at each milestone to verify that the design addresses the OPR and that the systems will be commissionable once constructed.
Basis of Design Review
The CxA reviews the Basis of Design (BOD) document — the MEP engineer’s technical narrative describing the system types selected and the design criteria used — for consistency with the OPR. Discrepancies between the OPR and BOD identified at this stage are far less expensive to resolve than discrepancies discovered during construction or after occupancy. Integrated MEP services from Budlong simplify this review because the mechanical, electrical, and plumbing disciplines share a common design intent within the same firm.
Construction Document Reviews
The CxA reviews the completed construction documents — typically at 50 percent and 100 percent CD milestones — for commissionability. This review checks that: control sequences of operation are clearly specified, test and balance requirements are documented, access for commissioning activities is provided, controls system points lists are complete, and commissioning-specific items such as test ports, isolation valves, and sensor access are shown. The CxA’s design review comments are provided to the design team for resolution before permit submission, reducing the likelihood of constructability or testability issues discovered in the field.
5. Phase 3: Construction Phase Commissioning
During construction, the CxA shifts from a review role to an active field verification role, confirming that what was specified is being installed correctly and that systems are ready for formal functional performance testing.
Pre-Functional Checklists
Pre-functional checklists (PFCs) are installation verification forms that document the as-installed status of each commissioned system component before startup. They confirm that equipment is correctly installed (correct model, correct location, correct connections), that controls wiring is complete, that sensors are correctly located and secured, and that contractors have completed their own startup and verification procedures. The CxA develops the PFCs from the construction documents and distributes them to the relevant contractors for completion. The CxA reviews and signs off on completed PFCs as a prerequisite for functional performance testing of each system.
Equipment Startup Witnessing
The CxA attends and documents critical equipment startup events — particularly for major HVAC equipment, emergency generators, UPS systems, and fire alarm systems. The CxA verifies that startup is performed by qualified factory-trained personnel, that the startup checklist is completed, and that the initial operating parameters are consistent with the design intent. Budlong’s commissioning services include systematic startup witnessing with documented verification records for all major equipment on every project.
Issues Log
The Issues and Deficiencies Log is maintained by the CxA throughout the construction phase to document every non-conformance identified during installation verification and functional testing. Each issue is documented with a description, the responsible contractor, the required corrective action, and the resolution status. The Issues Log is reviewed at regular commissioning meetings with the project team, ensuring that deficiencies are tracked through resolution rather than forgotten. A complete, closed Issues Log is one of the primary quality documentation artifacts produced by the commissioning process.
The most common commissioning finding in commercial HVAC systems is incorrect controls programming — sequences of operation that do not match the specified design or that were programmed for a different building type entirely. On one in three commercial construction projects, the BAS contractor delivers a controls system with sequences copied from a previous project that are inconsistent with the current project’s mechanical design. Functional performance testing by an independent CxA catches and requires correction of these systematic controls errors before the owner occupies the building.
6. Phase 4: Functional Performance Testing
Functional performance testing (FPT) is the core technical activity of the commissioning process — the systematic verification that each system and its controls operate correctly through all required modes and respond appropriately to simulated conditions and failure scenarios.
FPT Scope and Methods
For HVAC systems, FPT typically includes: verification of design airflow rates at all air handling units and terminal units; verification of supply air temperature control sequences; testing of economizer operation; verification of occupied and unoccupied setback sequences; testing of night setback and morning warm-up modes; verification of refrigeration shutdown on freezestat or high-limit conditions; and verification of Building Automation System (BAS) alarm responses. For electrical systems, FPT includes: automatic transfer switch operation (simulated utility failure), emergency generator start sequence and load transfer, UPS battery operation and bypass switching, and lighting controls occupancy and daylight response verification.
Test and Balance Integration
Test and balance (TAB) verification — confirming that air and water flow rates match the design values throughout the HVAC distribution system — is a prerequisite for functional performance testing. TAB reports are reviewed by the CxA to confirm that design flow rates are achieved before the controls sequences that depend on those flows are tested. Discrepancies between TAB reports and design values that would affect system performance are documented as commissioning deficiencies and resolved before the Final Commissioning Report is issued. Building commissioning services from Budlong include TAB report review and integration with functional testing as a standard scope element.
Seasonal Testing
HVAC systems are often commissioned during a construction season that does not allow testing of all operating modes. A system commissioned in summer cannot be tested for heating season performance; a system commissioned in winter cannot be fully tested for cooling. LEED Enhanced Commissioning and ASHRAE Guideline 0 require seasonal testing to verify system performance under heating and cooling season conditions. The CxA coordinates seasonal testing visits to fill these gaps and confirm complete system performance across the full climate range. LEED certified building MEP engineering from Budlong incorporates seasonal testing planning from the earliest project phases.
7. Phase 5: Post-Occupancy and Ongoing Commissioning
Commissioning does not end at occupancy. The period after occupants move in reveals system performance issues that cannot be detected during construction-phase testing — tenant-driven occupancy pattern variations, actual versus assumed internal load profiles, and real-world extreme weather conditions that were not present during construction-season testing.
10-Month Warranty Review
The standard commissioning scope includes a 10-month post-occupancy warranty review — a site visit and operational data review conducted approximately 10 months after occupancy, before the building’s 1-year contractor warranties expire. This review evaluates whether systems are performing as tested during construction, identifies any drift from original setpoints, and generates a deficiency list for warranty correction before the 1-year warranty period closes. Issues identified at 10 months — such as failing actuators, drifted sensor calibrations, or inappropriately modified controls programming — are still within the contractor’s warranty obligation, making this review financially valuable to the owner.
Ongoing and Continuous Commissioning
Ongoing commissioning (OCx) and continuous commissioning leverage the building automation system’s data stream to continuously monitor building performance against benchmarks and identify developing issues before they become significant energy wastes or comfort problems. Fault detection and diagnostics (FDD) algorithms compare actual system behavior to expected behavior and generate automated alerts when deviations are detected. This capability transforms the BAS from a passive monitoring tool into an active performance management system that supports the building operations team with prioritized maintenance guidance. Smart building technology implementation at Budlong incorporates FDD and continuous commissioning as components of the integrated building intelligence strategy for sophisticated clients.
Commissioning Authority Services from Budlong
Budlong provides independent Commissioning Authority services for new construction, LEED projects, healthcare facilities, and existing building retro-commissioning throughout California — with ASHRAE Guideline 0 compliant processes and complete documentation.
8. California Title 24 Acceptance Testing
California Title 24 Part 6 requires acceptance testing for specific building systems and controls as a condition of receiving the certificate of occupancy. Acceptance testing is a code-mandated subset of the broader commissioning process — it verifies compliance with specific energy efficiency measures rather than overall system performance and design intent.
Systems Requiring Title 24 Acceptance Testing
California Title 24 acceptance testing requirements apply to: HVAC systems and controls (demand-controlled ventilation, economizers, VAV terminal units, supply air temperature reset, and other controls features); lighting controls (occupancy sensors, daylighting controls, manual dimming, and demand response capability); domestic hot water systems; and high-efficacy lighting. The CEC publishes standardized Acceptance Test Procedures (ATPs) for each required test, and acceptance testing must be performed by a Certified Acceptance Test Technician (CATT) or a Certified Acceptance Test Employer (CATE) using these standardized procedures.
Coordination with Commissioning
Title 24 acceptance testing is most efficiently coordinated with the broader commissioning process rather than treated as a separate activity. The CxA can coordinate with the CATT to conduct acceptance tests and functional performance tests on the same site visits, reducing contractor mobilization cost and schedule impact. The commissioning specifications should explicitly identify which acceptance tests will be coordinated with commissioning activities to ensure that both the commissioning and acceptance testing requirements are satisfied efficiently. Commissioning services in Fremont, Los Angeles, and other California locations from Budlong include Title 24 acceptance test coordination as a standard scope element.
9. LEED Commissioning Requirements
LEED v4.1 addresses commissioning in the Energy and Atmosphere category with two tiers: Fundamental Commissioning (a prerequisite required for all certifications) and Enhanced Commissioning (an optional credit worth additional points).
Fundamental Commissioning Prerequisite
LEED Fundamental Commissioning requires: an independent CxA who is not employed by the design or construction team, Owner’s Project Requirements documentation, Basis of Design review, a Commissioning Plan, verification testing of all energy-related systems (HVAC, lighting controls, renewable energy), and a Final Commissioning Report. The CxA must document all work performed and findings in the commissioning report, which is submitted as part of the LEED documentation package. Beyond LEED — operational sustainability metrics driven by MEP systems highlights that commissioning quality directly determines whether LEED-targeted energy performance is actually achieved in operation.
Enhanced Commissioning Credit
LEED Enhanced Commissioning adds additional activities beyond the Fundamental prerequisite: design review by the CxA (identifying issues before design is finalized), enclosure commissioning (building envelope air and water tightness testing), monitoring-based commissioning (implementing automated performance monitoring tools), and a detailed ongoing commissioning plan for the first year of operation. Enhanced Commissioning credits are worth 3 to 6 points in LEED v4.1, making them a significant contribution to the total LEED score for projects pursuing higher certification levels.
10. Who Uses Commissioning Services?
- Commercial Office Buildings — Commissioning ensures HVAC controls, lighting controls, and building automation perform as specified for tenant comfort and energy performance
- Healthcare Facilities — Hospital commissioning is mandatory for OSHPD-regulated facilities, verifying infection control pressurization, emergency power, and medical gas systems
- LEED Projects — LEED Fundamental Commissioning is a prerequisite for all LEED certifications; Enhanced Commissioning adds valuable points
- Educational Facilities — School and university commissioning verifies DSA-compliant fire alarm, HVAC, and life safety systems
- Existing Buildings — Retro-commissioning delivers median 16 percent energy savings with payback under 2 years in most California commercial buildings
11. Related Reading
- Building commissioning is independent quality verification that building systems are designed, installed, and operating as intended — not the contractor’s own startup procedures.
- The CxA leads the process from pre-design through post-occupancy, providing documentation at every phase that creates a complete performance record for the building owner.
- Functional performance testing verifies system intelligence — controls sequences, failure responses, and all operating modes — not just mechanical startup.
- California Title 24 acceptance testing is mandatory for HVAC controls, lighting controls, and DHW systems — most efficiently coordinated with the broader commissioning process.
- LEED Fundamental Commissioning is a prerequisite for all LEED certifications; Enhanced Commissioning adds 3 to 6 additional credit points.
- Retro-commissioning existing buildings delivers median 16 percent energy savings with a typical payback of 1.1 years — one of the most cost-effective energy investments available.
- 10-month warranty reviews identify drifted systems and controls changes while warranty obligations are still in effect, protecting the owner’s investment in commissioning.
For technical reference, consult ASHRAE Guideline 0 — The Commissioning Process, Building Commissioning Association technical resources, the California Energy Commission Title 24 acceptance testing procedures, the USGBC LEED v4.1 Energy and Atmosphere — Commissioning credit requirements, and Lawrence Berkeley National Laboratory commissioning cost-effectiveness research.
12. Frequently Asked Questions
What is building commissioning?
Building commissioning is an independent quality verification process that confirms building systems are designed, installed, and operating as intended to meet the Owner’s Project Requirements. It is performed by a Commissioning Authority (CxA) who provides third-party verification — separate from the contractor’s startup procedures — that HVAC, lighting, electrical, plumbing, and controls systems perform correctly under all required conditions. Commissioning services for building performance from Budlong cover the full process from pre-design through post-occupancy.
What is the role of the Commissioning Authority (CxA)?
The CxA is the independent professional who manages and oversees the commissioning process on the owner’s behalf. They develop the OPR and Commissioning Plan, review design documents for commissionability, develop functional test procedures, witness equipment startup, perform functional performance testing, document deficiencies, track their resolution, and produce the Final Commissioning Report. For LEED, the CxA must be independent of the design and construction team.
What building systems are typically commissioned?
Commissioned systems typically include HVAC (air handlers, terminal units, pumps, fans, controls), domestic hot water, electrical systems (emergency power, transfer switches, UPS), lighting controls and daylighting systems, fire and life safety systems, and building automation system programming. Healthcare facilities add medical gas, infection control pressurization, and specialized clinical systems to the commissioning scope.
What is functional performance testing in commissioning?
Functional performance testing (FPT) verifies that systems and controls operate correctly through all required modes — occupied and unoccupied, heating and cooling, normal operation and failure scenarios. The CxA observes and documents system responses to simulated conditions (setpoint overrides, simulated sensor failures) and verifies that responses match the specified sequences of operation. FPT catches incorrect controls programming — found in approximately one-third of commercial projects — before occupancy.
What is California Title 24 acceptance testing and how is it different from commissioning?
Title 24 acceptance testing is a mandatory code requirement that uses standardized CEC procedures to verify that specific energy efficiency controls are installed and operating correctly. It is narrower than full commissioning — verifying code compliance rather than overall performance and design intent. It is most efficiently coordinated with the broader commissioning process rather than treated as a separate activity. Budlong includes Title 24 acceptance test coordination in its commissioning services scope.
What is LEED Fundamental Commissioning?
LEED Fundamental Commissioning is a prerequisite for all LEED certifications — it must be achieved to qualify for any certification level. It requires an independent CxA, OPR documentation, BOD review, a Commissioning Plan, installation verification, functional testing of all energy-related systems, and a Final Commissioning Report. LEED Enhanced Commissioning adds design review, enclosure commissioning, monitoring-based commissioning, and seasonal testing for 3 to 6 additional credit points.
What is retro-commissioning (RCx) and when is it appropriate?
Retro-commissioning applies the commissioning process to existing buildings — reviewing current performance against original design intent, identifying deficiencies (incorrect setpoints, failed sensors, drifted calibrations), and implementing corrections. LBNL research shows median energy savings of 16 percent with a 1.1-year simple payback — making RCx one of the most cost-effective energy investments for California commercial building owners. RCx is appropriate for any building over 5 years old that has not been recently commissioned.
What deliverables does the Commissioning Authority produce?
CxA deliverables include: Owner’s Project Requirements documentation, Basis of Design review comments, Commissioning Plan, Commissioning Specifications, Pre-Functional Installation Verification Checklists, Functional Performance Test procedures and results, Issues and Deficiencies Log, 10-month warranty review report, and the Final Commissioning Report. For LEED Enhanced Commissioning, additional deliverables include an ongoing commissioning plan and seasonal testing documentation.
