Commissioning: A Quality Assurance Process
Commissioning is not primarily a process of error identification. It is a quality-assurance program-undertaken while the workforce is still on the site and before the damage is done. When the commissioning process begins in the planning and design phase, it can be the ounce of prevention that eliminates the...
Commissioning is not primarily a process of error identification. It is a quality-assurance program undertaken while the workforce is still on the site and before the damage is done. When the commissioning process begins in the planning and design phase, it can be the ounce of prevention that eliminates the pound of cure required in the final project stages.
Commissioning is the process of confirming that a structure and its subsystems perform to the occupants' expectations.
Commissioning is planned, which means that it should be part of the project from the very start and integrated into programming, design, construction, training and maintenance.
It is collaborative, indicating that it should be a team process. The commissioning professional brings quality to the project by creating respect for quality within the team.
It is systematic. All items should be tested in all modes of operation. Systems are first inspected in a static condition to assure they are installed correctly. Equipment is started up for the first time under controlled conditions, and systems are then tested as a group to prove they operate as planned.
It is documented, assuring that the commissioning results remain after the building is turned over to the operating staff. Systems parameters are documented in the commissioning report and the operations and maintenance (O & M) manuals.
The eight stages
Commissioning is a vital part of all project stages: predesign, design, bidding, early construction, acceptance (static inspection and start-up), acceptance (functional testing), O & M staff training, and warranty-period monitoring.
Usually, an independent individual or firm a commissioning authority (CA) is contracted to see the commissioning process through these eight stages. The CA may be an independent third party who is contracted directly to the owner, or alternatively, the CA may work for the design team, general contractor or construction manager. Many design firms are providing commissioning services for their own projects and for those designed by others. However, when a design firm serves as its own CA, impartiality might be questioned.
Quality before design
Building quality into a facility before it is designed may seem impossible, but this is the best time maybe the last time for occupants to tell the designers what they want. The most important deliverable of the predesign phase is the design-intent (DI) document, which is performance-based and concentrates on what occupants need and expect.
During the design stage, the architect/engineer team selects the most appropriate approaches for satisfying the DI requirements. The designers then proceed to quantify this basis of design (BoD) by producing the actual bid documents.
For example, the DI might describe an assembly area that will house 100 persons for two hours, be empty for an hour after that, and provide comfort and operate at maximum energy efficiency. The BoD might then specify a variable-air-volume system integrated with occupancy sensors and a direct-digital control system. The actual design in the bid documents would specify components, air volumes and control sequence.
Commissioning assures that the equipment has been supplied and installed correctly, the air volumes and control sequence are correct and that the overall system works at each occupancy level. After confirming and documenting the DI and BoD, the CA checks the design documents for consistency with the design intent; inspection and testing of accessories; verifiable equipment parameters; equipment layout; and a fully described commissioning process for the bidders. In addition to checking the drawings and specifications, the CA writes the commissioning portion of the specifications.
The CA needs to address questions about the contractor's role in commissioning in order to engender the support of the construction team. It is vital that contractors cooperate in the commissioning process if the team is to reach the goal of a quality building. The inspection and testing required by the CA are often performed by contractor personnel so the CA must make sure that it is part of the bid documents.
After the notice to proceed, a preconstruction meeting is generally convened to establish the ground rules for construction. At this time, the CA assists in getting commissioning milestones on the construction schedule. The CA must coordinate with an owner's construction manager (CM) to assure this scheduling is done prior to processing the first requests for payment; the CA must also make sure to meet with the CM before the preconstruction meeting to coordinate tasks.
As the contractor makes equipment submittals to the design team, the construction manager should route copies of approved submittals to the CA for use in drafting procedures for the commissioning plan. The procedures are submitted to the owner for approval and to the contractor for scheduling.
Does it work?
Testing is frequently a requirement of local building authorities. If local inspectors conduct a test, the CA needs to collect copies of all such tests for the commissioning report.
After equipment has been started up, functional performance tests (FPTs) are conducted to confirm that everything works together. For example, FPTs would be conducted on air-handling units to confirm that the units shut down upon smoke detection, the economizer cycle operates and the discharge-air temperature is stable. Actuator tests would confirm that operators travel full stroke, dampers seal closed and control air is dry. A sample of items included in a subcontractor's test-and-balance report should be checked for accuracy. If a substantial failure rate is encountered, all items should be corrected and a different sample chosen for a repeat test at the contractor's expense.
Training the staff
As the systems are confirmed to work correctly, O & M staff training begins. The CA takes the lead in reviewing and approving the O & M manual for content and organization and confirms approval by the operating staff and the design team. The CA then coordinates training sessions with the staff and subcontractors and attends all sessions to assure that important issues are raised.
At the completion of training, the contractor is granted substantial completion and the building is occupied. Continued monitoring of building systems may identify some items during the early months of occupancy, but if the CA process has been followed, these should be minor.
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