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- EXTRA EDITION
Commissioning starts by preventing errors in the most critical, early stages: planning and design. After the ground is broken, the process checks for correct installation and start-up. Only the next two stages, functional and performance testing, check for incorrect operation. The last two stages include training and first year occupancy services, and pave the way for a sustainable building.
Because commissioning is integrated into the entire construction process, it is termed integrated commissioning. This represents the state-of-the-art in building quality assurance. It is the combined process of setting realistic and well-defined goals for the modern functional workplace and confirming the goals have been met during design and construction. This closes the circle on quality and assures that actual building performance meets expectations (see Figure 1).
A Definition, Please?There are several; let's try this one: Commissioning is the planned, collaborative, systematic, and documented process of confirming that a structure and its sub-systems perform as expected by the building occupants.
Let's take a closer look at that definition.
Commissioning is planned. This means that commissioning is part of the project from the start and is integrated into programming, design, construction, training, and maintenance.
Commissioning is collaborative. It is a team process from the beginning. The commissioning professional causes quality to be built into the project by creating respect for quality within the team. To be sure, there is error identification, both in design and construction. But in the main, quality is built in, not added on.
Commissioning is systematic. Commissioning follows a strategy wherein all items are tested in all modes of operation. They are first inspected in a static condition to assure they are installed correctly. Equipment is then started up for the first time under controlled conditions. After start-up, systems are tested as a group to prove that they operate as planned
Commissioning is documented. The value of commissioning remains after the building is turned over to the operating staff. Key parameters of the systems tested are documented, organized and preserved in the commissioning report as well as the operations and maintenance (O&M) manuals.
To gain a better understanding of the commissioning process, let's divide the conception and birth of a new building into eight stages and look at how commissioning affects each stage.
The Eight Stages Of CommissioningThe eight stages of commissioning are:
4. Early construction;
5. Acceptance - static inspection and start-up;
6. Acceptance - functional testing;
7. O&M staff training and documentation; and
8. Warranty period monitoring.
Usually, an independent individual or firm is contracted to see the commissioning process through these eight stages. This person or firm is called the commissioning authority (CA). The CA is an independent third party that is contracted directly to the owner. Alternatively, the CA may work for the design team, the general contractor, or the construction manager.
Contracting directly with the CA provides the best quality assurance for the owner. Many contractors have started their own in-house commissioning service because they have observed that the commissioning process reduces their callbacks by 25 percent to 95 percent. This benefits the owner as well as the contractor, but does not provide the same degree of protection as when the owner deals directly with an independent third party.
Many design firms are also providing commissioning services for their own projects and for projects designed by others. If the design firm commissions its own project, the rigor of the process can be questioned. Finding the right CA is no less important than hiring the right design team or contractor. Interview several potential candidates before the final selection is made. As a starting point in identifying qualified commissioning service providers, check with the Building Commissioning Association (BCA) (www.bcxa.org) and the annual National Conference on Building Commissioning (NCBC) (www.peci.org).
Quality Before Design?Building quality into a facility before it is designed may seem impossible. But, in fact, this is the best time (and maybe the last time) that occupants will get to tell the designers what they want. Changes thereafter are more expensive and less productive. The most important deliverable of the predesign phase is the Design Intent (DI) document.
The DI is the document recording how the building is expected to work, and is only as good as the work that goes into it. It is the CA's job to ask the right questions as the DI is being developed. The document is performance based and concentrates on what the occupants need and expect rather than on how the design team will provide it.
Designing The Quality ProjectDuring the design stage the architect/engineer team selects the most appropriate engineering and architectural approaches for satisfying the requirements described by the DI. These approaches constitute the basis of design (BoD). The designers then proceed to quantify the BoD in producing the actual bid documents.
For example, the design intent might describe an assembly area that will house 100 people for two hours, be empty for an hour after that, provide comfort and operate at maximum energy efficiency. The basis of design would specify a variable air volume system controlled with occupancy sensors and a DDC control system. The actual design in the bid documents would specify components, air volumes, and the required 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 design intent and basis of design, the CA continues to build in quality by checking the design documents for:
In addition to checking the drawings and specifications, the CA writes the commissioning portion of the specs. Frequently a "Division 17" is added to the standard specification format to include commissioning details for the bidders. Other details should be added to divisions 1, 15, and 16.
Team Building During BiddingThe call for bids is the first opportunity to bring the construction contractor(s) into the commissioning process. As the bidders prepare their bids there will be questions about their role in commissioning. The CA needs to address these questions accurately and promptly in order to engender the support of the construction team.
It is vital that the 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 is performed by contractor personnel and takes time and money. It also saves the contractor time and money through reduced callbacks, and the early and fair resolution of problems. (They are frequently not the contractor's fault.) Most contractors readily accept commissioning once they understand it, but it's a mistake to blind-side the construction workforce by adding commissioning during construction.
Early Construction CommissioningAfter the notice to proceed, a pre-construction meeting is usually held to establish the ground rules for construction. At this time the CA assists in getting commissioning milestones on the construction schedule. Having commissioning included in the schedule is a good way to confirm that everyone is "with the program." Coordinate with the (owner's) construction manager (CM) to assure this scheduling is done prior to processing the first request for payment. And also make sure that the CM has met with the CA before the pre-construction meeting to coordinate their tasks.
As the contractor makes equipment submittals to the design team, the construction manager should route copies of the approved submittals to the CA. The CA needs the submittals to develop commissioning procedures including static inspection, start-up, and functional test descriptions. The CA writes and assembles these procedures as equipment information is available from submittals. As the documents are completed, they should be submitted to the owner for approval and then to the contractor for scheduling.
Fastened, Sealed, And ConnectedPiping and ductwork should be inspected for correct installation, and then pressure tested. Testing domestic water and sanitary sewer piping is frequently a requirement of local building authorities, and if they witness the tests, that is one less thing for the CA to do. Nonetheless, the CA needs to collect copies of all such tests for the commissioning report. Roof drains and under-foundation drains should be pressure tested. All air-handling units (AHUs) and other moving equipment should be inspected for lubrication, rotation, case drains, filter sealing, maintenance access, air tightness, and vibration isolation.
But Does It Work?After equipment has been started up, functional performance tests (FPTs) are conducted to confirm that everything works together. For example, functional tests would be conducted on AHUs to confirm:
Actuator tests include:
Tests for the building automation system include:
Also, a sample of items included in the subcontractor's test and balance report should be checked for accuracy. If a substantial failure rate is encountered, all should be corrected and a different sample chosen for a repeat test at the contractor's expense.
O&M Staff, Take It AwayAs 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, attending all training sessions to assure that important issues are raised.
At the completion of training, the contractor is granted substantial completion and the building is occupied. The CA will return in several months for "off-season" testing, to test equipment in the best outdoor conditions (for example, testing boilers in the winter and chillers in the summer). Continued monitoring of the mechanical and electrical systems will identify some items during the early months of occupancy. But if the CA process has been followed, these will be minor and a trained O&M staff will be able to readily handle them before they impact the quality of the workplace.
Ron Wilkinson is vice president of operations for Dome-Tech Commissioning Services located in Edison, N.J. For more information, visit www.dome-tech.com.
Publication date: 04/05/2004
For more information on the Building Commissioning Association, visit www.bcxa.org or call 425-774-6909.
Portland Energy Conservation Inc. (PECI) sponsors the annual National Conference on Building Commissioning. More information is available at www.peci.org or call 503-248-4636.
Wilkinson, Ronald, "The Commissioning Design Intent Narrative," ASHRAE Journal, April, 1999.