Commissioning is a systematic process of ensuring that all building components and systems are expertly designed and perform according to the contract documents, owner’s objectives and operational needs. Ideally, this is achieved by developing and documenting owner project requirements beginning in the pre-design phase; continuing through design, with reviews of design and contract documents; and continuing through construction and the warranty period with actual verification through review, testing and documentation of performance, including ensuring that operations personnel receive adequate training and system documentation.
Building commissioning has grown in the last five years. Institutional owners, particularly universities and hospitals, are broadly adopting commissioning in new construction projects. Government bodies are also adopting commissioning policies.
The reasons for the growth in commissioning can be traced in part to the increasing complexity of buildings over the last 20 years. Over the same period, designers, suppliers and technicians have become more specialized. This increase in specialization and complexity calls for greater integration in the design and construction process. But just the opposite has occurred. Cost pressures and liability concerns have led designers, suppliers and contractors to divide responsibilities. As a result of changes in their compensation, designers have less time to spend on designs and have reduced the amount of construction oversight. On top of that contractors and subcontractors are pressured by low-bid policies.
The result is that things fall through the cracks. Systems don’t work because of design flaws or poor set-up, or they cannot be operated easily or are difficult to troubleshoot because of poor or non-existent design and operations documentation.
Most owners who have incorporated commissioning use it again, usually starting even earlier in the process. Commissioning reduces the owner’s total cost of ownership. The cost of commissioning will more than be paid back by energy savings and fewer change orders, time delays and callbacks.
Because the scope of what is commissioned varies from owner to owner, and the rigor of the process varies from one practitioner to the next, it isn’t possible to provide tight costing guidelines. Design-phase commissioning for the process described below may range from 0.2 to 0.6 percent of the total construction cost for a typical office building. Commissioning during the construction phase for a typical office building will cost from 2 to 3 percent of the total mechanical cost for commissioning the HVAC and control systems, and 1 to 2 percent of total electrical cost for commissioning the electrical system, according to an estimate in the ASHRAE Journal (February 2000). Looked at another way, the cost of commissioning the HVAC and controls systems and primary electrical systems will range from 0.5 to 1.5 percent of total construction cost. Commissioning buildings with significant floor area in complex systems like laboratories may cost more.
The commissioning process begins in pre-design with selection of a commissioning authority who manages the process. During pre-design, the owner’s project requirements or design intent is developed. These project requirements are similar to programming report information, but are more discrete and list requirements the owner explicitly wants tracked and verified.
During design, a commissioning plan is developed to set the scope of commissioning and guide the entire process. The commissioning authority verifies that designers submit clear narratives and rationales of their designs that meet project requirements.
Peer reviews of plans and specifications during early and late design stages verify that submissions follow design narratives and owner requirements. These reviews also identify issues that are likely to cause change orders, construction delays, or inefficient commissioning, operations or maintenance. The commissioning authority should provide specification language listing commissioning requirements of the contractor, which are incorporated into bid documents, and should ensure that solid training and O&M manual requirements are included.
At the beginning of the construction phase, the commissioning plan is updated. The commissioning authority reviews construction submittals of commissioned equipment and observes installations. The commissioning authority normally provides — and spot-checks the completion of — checklists that contractors use to document their own installations and startup. The commissioning authority also witnesses elements of contractor startup and other tests such as duct pressure testing and piping system cleaning and flushing.
During construction, periodic meetings are held and progress reports provided by the commissioning authority. The commissioning authority develops detailed functional testing procedures and, with the contractor, executes and documents the tests just prior to substantial completion. Deficiencies are corrected and systems retested. An issues log is issued to track all findings needing to be addressed until they are resolved. The commissioning authority ensures that training is conducted according to the specifications and reviews O&M manuals for completeness and clarity. A commissioning report is generated at the completion of commissioning.
The commissioning authority usually compiles the systems manual — a compilation of documentation providing the information needed to understand and optimally operate systems and assemblies. The manual focuses more on operations than traditional O&M manuals, which are geared to maintenance. The systems manual includes the owner’s project requirements, the design rationale and narratives, space and use descriptions, single line drawings and schematics for major systems, control drawings, sequences of control, table of all setpoints and implications when changing them, and instructions for operation of each piece of equipment.
During the occupied one-year warranty period, the commissioning authority normally analyzes building automation system trend logs of system performance, conducts opposite-season testing for HVAC systems and assists the owner with outstanding performance problems. The commissioning authority may assist in optimizing system operation and performance or in developing preventive maintenance and operations plans or electronic facilities manuals.
Generally the owner hires the commissioning authority that offers the highest objectivity. The commissioning authority is the owner’s advocate in managing the commissioning process and recommends acceptance of system performance to the owner.
In another approach to commissioning, some or all of the tasks are assigned to a qualified party on the construction team, with the commissioning authority reviewing test procedure forms before execution, spot-witnessing execution and reviewing completed test reports.
The owner’s operations staff can be valuable contributors in the development of the owner’s project requirements and in performing design and specification reviews. They can also play a valuable role in making construction observations and in verifying the contractor's checklist activities. During functional testing, facility staff can assist the commissioning authority or contractor. These activities not only improve the commissioning outcomes, but provide valuable information on system configuration and operation for the staff.
The owner can obtain the most from commissioning by starting early. Engage a qualified commissioning authority during pre-design. If that is not possible, start as early in design as possible, still documenting the owner’s project requirements.
Another key to effective commissioning is to select a qualified commissioning authority. Select firms and individuals that can provide the breadth and depth of commissioning services needed for the project. Technical expertise in design, operations and troubleshooting must be matched with management and communication expertise on projects of similar size and complexity.
It’s also important to be clear about the scope of work. The owner should know precisely who is doing each task, such as writing test procedures and documenting their results. This is particularly needed for non-HVAC tests like electrical and life-safety testing that has been done by contractors in the past.
Along the same lines, be sure to develop good owner’s project requirements. Take the time to bring representatives from building-occupant, construction and facilities groups together in a workshop to define the project objectives. The commissioning authority can assist in providing formats and examples of good documentation.
One easily overlooked stumbling block is inadequate compensation for designers. The designers will likely need additional fees to provide detailed design narratives and rationale, and to consider and respond to design review comments from the commissioning authority. They may also have to attend some commissioning meetings during construction and may be responsible for facility staff training and elements of the systems manual.
Another personnel issue involves the facility staff. Supervisors often want staff to be part of the commissioning process, but the staff is unable to participate due to other pressing responsibilities. Make sure that there is sufficient back-up coverage.
Finally, it’s crucial that the building owner support the commissioning authority. Contractors often don’t take the commissioning authority’s role seriously and delay responding until the project manager gets involved. The owner must let the contractor know that the commissioning authority has the owner’s support.
The complex interrelated building systems of today and the emphasis on indoor air quality and energy conservation, combined with owners not receiving buildings that work well, warrant an enhancement to the building delivery process. Commissioning offers just such an enhancement, one that can be integrated into current design and construction delivery process. The result is systems that completely work when turned over to the owner. The process reduces the total cost of ownership over the life of the facility.
Karl Stum is a senior commissioning and sustainable design manager for CH2M HILL’s facilities services design and construction division.
