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Test & Balance In The Commissioning Provider's Scope

In last month’s Getting it Right column, we discussed the importance coordinating the testing, adjusting, and balancing (TAB) work with the commissioning work on each project. Three options were presented for approaches most often taken by facility owners; (1) commissioning as separate from TAB, (2) commissioning that includes spot checking the TAB contractor’s work, and (3) commissioning that includes all TAB work as part of the commissioning consultant’s scope of services. This month I want to concentrate on some of the issues associated with the latter approach.

It is rare to have a facility owner request that the commissioning provider include TAB as part of their scope of services. However, some owners are looking for the commissioning process to solve a multitude of problems experienced on past construction projects, and sometimes these include TAB problems. Simply slipping the TAB work under the commissioning umbrella will not necessarily make some TAB issues go away, but it will make them the responsibility of a professional who has no interests other than delivering a quality project.

One of the common concerns of owners regarding TAB work subcontracted to either the mechanical or general contractor is the potential conflict of interest the installation contractors have with respect to a quality project. The mechanical and general contractors are also, understandably, concerned about schedule and budget. As such, they are sometimes suspected of negatively influencing the TAB contractor’s performance in order to either meet a deadline or save money.

I have not been privy to the details of contractor/subcontractor financial arrangements, but I have seen enough times when schedule pressures have limited the TAB contractor’s ability to do an excellent job. In these cases TAB is seen as a necessary project closeout requirement but isn’t seen as critical to meeting a deadline commitment. As an example, the absence of a TAB report is a recurring item on substantial completion punchlists. This is reflective of the culture that defines project completion as installation completion (something that can be observed during a walkthrough) and not functional completion (something that needs to be tested and demonstrated).

Performing TAB work after substantial completion, which typically means after building occupancy, is both inefficient (more costly for the TAB contractor) and too late to stem the flood of occupant comfort complaints inherent to unbalanced systems. These facts further limit the effectiveness of the TAB process because the TAB contractor will be tempted to cut corners and the occupants will be less inclined to be satisfied.

Incorporating TAB into the independent third party commissioning provider’s scope of services will give the TAB process the same level of scheduling attention and discipline as other commissioning activities. The commissioning provider will be able, on behalf of the owner, to push the contractors to schedule installation completion early enough to achieve both good balancing and good functional performance testing before substantial completion, because the installation contractors will have no power to influence the commissioning provider to back off.

I had the experience of having a construction manager’s mechanical, electrical, plumbing (MEP) coordinator explain that the TAB contractor being assigned to the commissioning provider would not work, because the TAB contractor would expect the systems to be ready for testing, adjusting, and balancing when he showed up to start TAB work. This was seen as a real stumbling block for that construction manager (CM), because, apparently, the CM relied on the TAB contractor to do his quality assurance checkout for him. If equipment and systems were not installed or operating properly, i.e., not ready for TAB due to improper installation, wiring problems, control problems, etc., the CM expected the TAB contractor to either correct minor problems on the spot or to report them to the CM and return to perform the balancing after corrections were made by the installing contractors.

Because I do not believe that commissioning is either quality control or quality assurance in the traditional construction industry definition of those terms (refer to Getting it Right column from March, 2002), this does create a challenge for the integration of TAB into the commissioning scope of services. I believe the solution needs to be for the CM or the general contractor to take responsibility for the quality control/quality assurance of the equipment and system installation. If they need to hire a separate TAB contractor to perform the system checkout on their behalf, they can do that. However, the intent should be that the system, when handed over to the commissioning provider to test, adjust, and balance, is installed properly and operates as intended. The TAB activities performed as part of commissioning are intended to take a properly installed system, document its performance, and distribute its flows per design requirements. After TAB is successfully completed, the commissioning process will move into functional performance testing as a final demonstration that the systems meet the owner’s design intent.



Engineered Systems, October, 2002

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