Publications and Articles

HVAC Commissioning Important to the Satisfactory Installation, Operation, and Performance of Systems  by Wayne T. Bonhag, P.E., P.P.  (First appeared in DH In Design, 1997)   One of the consulting services that we as mechanical engineers can and do provide to owners is assistance with HVAC system commissioning. Commissioning is the process through which final system operation is evaluated and verified with respect to its original design intent. This activity includes documenting HVAC tests and inspections, scheduling training programs, and verifying the application of the O and M manuals, as-built drawings, spare parts and special tools listing, and other items as may be specified for proper support of the HVAC systems and equipment. Commissioning is accomplished during completion of final project tasks including electrical control wiring, equipment "bumping," system testing and balancing, ATC control setup, and punch list troubleshooting. By combining these tasks at the end of the project the owner gets maximum value from the dollars spent on both engineering and contracting. At this point, the engineer and contractors know more about the details of the project than anyone and are in the best position to pass that information on to the owner to ensure proper operation of the HVAC system. If an owner elects not to undertake the commissioning process there is increased likelihood of dissatisfaction due to the perception of a malfunctioning project. Additional staff time on the owner's part may be needed after the project has been closed out to sort out any concerns that arise. HVAC systems in building projects are among the few dynamic systems that exist and should be treated accordingly. Many factors that affect HVAC system operation, for example, are subject to change. These factors include weather conditions, directional exposure, load status and time of day, to name a few. In accommodating these changes, HVAC systems must respond reasonably quickly to maintain the comfort level of the occupants and optimum process levels. Therefore, the actual cost of commissioning may not be nearly what an owner initially perceives. The time to decide whether or not to perform commissioning for HVAC systems is at the beginning of the project when budgets are being established. This allows the owner to carry a line item for commissioning throughout the project until it is needed. Except in extraordinary circumstances, human nature and budgetary belt tightening preclude adding a cost at the end of a project. Typical costs for commissioning range from a quarter percent of the HVAC construction cost to four percent, depending on the complexity of the systems. The process is strongly advised for more complicated, sophisticated and sensitive projects. As HVAC systems and subsystems become more expensive, they comprise a larger percentage of project cost and are driven by requirements for increased comfort or demand for production standards, it becomes increasingly more important for owners to evaluate the need for commissioning their projects.

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