One of the worst-case examples is when design changes are made to a system by the design team after functional performance testing of that system. This is sometimes because the system in question is unable to achieve its OPR performance criteria even though the system performed as originally designed and documented in the construction contract. In a few cases, a perfectly fine system needs to change in order to accommodate modifications made to another system that did not pass its commissioning tests. In other cases, the owner realizes that the original OPR criteria are not really acceptable.

The purpose of this month’s column is not to dwell on the causes of the late-in-the-game design changes, but I list a few possibilities here.

• The owner changed the OPR.

• The design team disregarded previous commissioning design review comments.

• The design and/or construction team disregarded previous commissioning submittal review comments.

• The root cause of the system’s inability to achieve the OPR was so unique, complex, or subtle that no one on the project team identified it ahead of time.

The purpose of this column is to outline the additional effort required by the commissioning professional in order for the commissioning process not to be derailed and/or compromised by significant design modifications after functional performance testing. Some of this commissioning rework is associated with verifying that the systems perform according to the new design and/or OPR, and the other rework is associated with modifying the systems documentation and training to ensure that the O&M staff receive the most up-to-date and accurate information.

Systems Operation Verification

1. Modify customized functional performance test procedures to reflect the new design. This typically includes revised test steps and new acceptance criteria.
2. Retest each affected system to confirm new design performance is achieved without negatively affecting unchanged system elements or systems integration.
3. Document any deficiencies discovered during new testing.
4. Track resolution of any new deficiencies.
5. Retest to confirm successful resolution of any new deficiencies.

O&M Documentation & Training

1. Revise systems manual to reflect design changes. This may include OPR documentation, basis of design documentation, sequences of operation, schematic diagrams, systems integration descriptions, preventive maintenance schedule, and recommissioning test procedures.
2. Conduct a supplemental training session to explain design modifications, any related operational strategy changes, and the reasoning behind them.

In conclusion, I offer a couple words of advice. For commissioning professionals — do not give up and do not let schedule pressures force you to compromise the results of the commissioning process after coming so far. For owners — do not be surprised if commissioning costs increase if the design changes after construction is complete.