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Commissioning: Core & Shell and Tenant Fit-Out Projects, Part 2

Missing terminal units offer no easy solutions.

Last month this column addressed special considerations for developing the Owner’s Project Requirements/Design Intent documentation (DID) for projects that are designed and constructed as a Core & Shell (C&S) by the developer with customized Tenant Fit-Out (TFO) of occupied spaces as they are leased. Documenting Owner’s Project Requirements/Design Intent is valuable for any project and is imperative for commissioned projects.

Defining the Scope

If the new building is to be commissioned, the developer will need to assign a commissioning professional for the C&S portion of the project. A number of questions will surface very quickly when defining a scope of services for the commissioning professional and, eventually, the commissioning plan for the C&S project.

First and foremost will be the issue of whether commissioning will be limited to the C&S project or extend into the subsequent TFO projects. In most situations, it seems that the developer will not be in a position to compel the TFO tenants and/or their design and construction teams to incorporate commissioning into the TFO process. Putting that type of stipulation on potential tenants could be a deal stopper, depending on the sophistication of the tenants. This assumes, which is often the case, that the individual TFO projects may be performed by separate teams from the C&S project team.

The next question is the crux of the C&S/TFO commissioning issue. Can the C&S systems be satisfactorily commissioned without also commissioning at least a portion of the TFO systems? Probably the best example of this conundrum is where the C&S project includes the central air handling equipment and common area terminal units but no terminal units serving tenant spaces. Can a central air handling system be proven to meet the Owner’s Project Requirements/Design Intent without the majority of terminal units connected to it?

A Creative Approach

I propose that it is possible to develop a functional performance testing process for an “unloaded” air handling system, if that is what is required for the C&S project. This takes extra creativity in defining acceptance criteria, analysis, special devices, and test preparation. However, it should be possible to simulate a fully loaded condition, even with only a few permanent terminal units connected to the distribution system. This approach may not be ideal, but it may be deemed the most contractually manageable one. Any commissioning professional considered by the project developer should be able to present options for C&S-only systems commissioning.

What about something better? Is it practical to consider extending the C&S commissioning process, and thus the entire C&S project acceptance process, until the TFO projects are completed? Air handling systems these days, especially in high performance buildings which aspire to provide ASHRAE standard levels of ventilation and environmental control as energy efficiently as possible, integrate the terminal unit controls with the central system. The central air handling unit devices respond to load conditions as communicated by the terminal units. For this feature to be effective with all TFO terminal units, how can commissioning of the central air handlers not wait until TFO terminal units are installed, programmed, and integrated?

Similarly, even with non-integrated air handling systems, how can the real estate developer confidently commit to all future tenants that the central system performance will meet the Owner’s Project Requirements/Design Intent goals in all tenant spaces without confirming that all TFO systems are functioning within their individual TFO project guidelines? For example, do the terminal units installed and balanced as part of each TFO project have capacities (CFM/square foot, square foot/ton, etc.) less than or equal to the Owner’s Project Requirements/Design Intent criteria?

Broadening the Scope

Without some type of commissioning oversight for the TFO projects, how can the developer know that the C&S central systems can serve all TFO needs? If the first few TFO projects over-tax the central air and/or hydronic systems, what will be left for the last tenants? Commissioning of the TFO projects would be one method by which the developer/property manager can objectively manage demands on the central systems.

This brings us back to the initial questions. Is commissioning of the C&S systems enough? Can the developer compel the tenants to commission their TFO projects? Perhaps the developer needs to offer to provide commissioning services to the TFO projects, limited to the extent necessary to protect the integrity of the central systems. If presented in the right way, TFO project commissioning could be seen as a benefit offered by the developer to potential tenants, not as an onerous contractual stipulation.

This approach would necessitate a new cost for the developer, but the magnitude of that cost could be minimized through standardization and the use of the same commissioning professional engaged for the C&S systems. The benefit for the developer would be a confidence level with respect to each tenant and their demands on the central system. In addition, the quantitative data collected as part of the C&S and TFO commissioning processes can be very helpful in documenting the developer’s due diligence in meeting his/her obligations to each tenant.

 

Commissioning: Getting It Right

Engineered Systems, June, 2007

by
Rebecca Ellis, PE, LEED AP, CCP, CxA
President
Questions & Solutions Engineering
1079 Falls Curve
Chaska, MN  55318
rteesmag@QSEng.com