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Is Commissioning Undermining Quality Control?

My December, 1999 Getting it Right column explored the differences between commissioning and quality control. In summary, I suggested that quality control is about confirming static equipment and component installation and commissioning is about confirming dynamic system performance and preparing operations and maintenance (O&M) staff to operate those systems. With two more years of commissioning experience behind us, it seems imperative to re-visit the relationship between quality control and Cx.

Commissioning is a process intended to supplement “normal” project delivery processes and, for the most part, is not intended to duplicate successful efforts being provided in other aspects of a normal program. As such, the success of commissioning is dependent on the proper execution of all normal project delivery tasks such as design engineering, team communication, construction scheduling, equipment installation and startup, testing and balancing, and, of course, quality control. These are all prerequisites to one of the key milestones in the commissioning process: functional performance testing.

If any team member fails in their responsibilities, it could very well result in a failure of the system to perform as intended and this will become apparent during functional testing. For example, if a space temperature sensor is not terminated at the appropriate control panel, its associated variable air volume unit will not respond to changes in space temperature. Similarly, if the test and balance contractor doesn’t adjust exhaust fan speed to achieve design air flows to all spaces served, some individual space pressure controls will be unable to achieve their setpoints.

In theory, the approach of first completing all normal quality control checks and then proceeding into functional testing is quite logical. I’ve always viewed the functional testing process as an opportunity for the installation contractors to “show off” their good work and receive credit for it. However, as time goes on and some contractors (particularly in a low-bid environment) learn about how commissioning is performed, they are using commissioning as an excuse to lighten up on their quality control responsibilities. The feedback I have heard goes something like this, “If commissioning is going to test everything at the end, why should I bother checking things out ahead of time? Let the commissioning process find my mistakes and then I’ll fix them.”

I was shocked and demoralized to hear this attitude in more than one instance, as it seemed to represent the opposite effect on quality than what was originally intended by commissioning. So, what can be done? Short of doing away with the low bid, price-based, schedule-focused project delivery process altogether, the following is one idea.

It has been suggested to me that a random sample commissioning checkout and testing approach be adopted for as many systems as possible. Although it has been the opinion of many building owners that more testing equals better quality, a less-is-more theory may apply in this case. If 100% prefunctional checkout and functional performance testing is specified, the contractors know they will have to test everything regardless of how successful the test results are. A random sampling strategy could motivate the contractors to do everything in their power to be sure the small sample passes, if the penalty would be for them to be required to test all the remaining systems if the initial sample fails. In this scenario, the commissioning consultant would randomly choose the initial systems for testing, unknown to the contractors prior to the test day. Therefore, the contractors would want to make sure all systems were installed, started, and fully operational in order to avoid having to spend many more hours (and dollars) supporting a full test schedule.

This approach could work for a low bid environment where the contractors want to include a minimal amount of time in their bids for testing activities in order to stay competitive. It could also work in negotiated contracts where the contractor may budget for a certain level of testing and actually successfully complete the testing in less time. That should translate into additional profit on the bottom line.

It is time to revisit the old adage that you can not “test in” quality. This is true, and we are realizing it on projects where the contractors are doing less quality control because the commissioning process is seen as doing it for them. That is not the intent of the commissioning, so the commissioning plan needs to include features to discourage that response from installation contractors.



Engineered Systems, March, 2002

Rebecca Ellis, PE, LEED AP, CCP, CxA
Questions & Solutions Engineering
1079 Falls Curve
Chaska, MN  55318