Commissioning Engineered Building Systems: All In The Timing

By George Bourassa, P.E., LEED AP, Senior Vice President and National Director of Commissioning, Facilities Division, Carter & Burgess, Inc., Chicago June 24, 2005

In my last column , I looked at the concept of “breadth of scope” as it applies to building system commissioning and discussed the diversity of scope.

And just as there is diversity in the scope of commissioning, there is also diversity in timing. So, when should you start the commissioning process and when, if ever, do you end it?

Most clients are now realizing that commissioning should start early in the process, typically at the programming stage or at the conceptual design stage, of overall project development. In my experience, it should start in the programming phase, but should commence no later than the beginning or mid-point of schematic design.

Yet, there are still some owners and facility managers who believe that commissioning occurs at the end of construction. From time to time, we are contacted when a project is 50% or more complete in construction to come in and initiate a commissioning program.

At that point, in my view, there will be very minimal, if any, benefit to the owner because essentially the building systems are already “cast in stone” and any opportunity to contribute to change is history.

In contrast, by being involved earlier in project development, the commissioning provider can fulfill many roles and make the commissioning and building processes smoother; can begin to form partnerships with the design team to make sure the process is understood and how the designers will be affected; and is also able to initiate the overall commissioning plan that details everyone’s roles and responsibilities in the process.

It also allows the commissioning provider to start developing commissioning documents and specifications that can be issued to contractors in the bidding process. The commissioning provider can carry out reviews at milestone junctures of the design phase. These are not peer reviews or second guessing, but are focused on how the project will be commissioned, ensuring all of the appropriate instrumentation, sensors, controls and valves are in place and look at the sequence of operations of all of equipment components and systems, to ensure that these are compatible in preparation for the commissioning process.

Early involvement also helps to create clearly defined Owner Project Requirements (sometimes referred to as Basis of Design or Design Intent) that set out the performance requirements of systems. This document facilitates a clear understanding for all project team members of expectations related to building system performance, by defining in quantitative terms the criteria that will be the benchmarks against which the functional verification testing will be measured.

By defining the criteria in quantitative rather than qualitative terms, the potential for subjectivity in assessing whether system performance is in compliance with the criteria is eliminated. In other words, a measured airflow that is “satisfactory” does not meet the rigorous compliance standard of the commissioning process. If the required air flow is 5,000 cfm, for example, an air flow level of 4,800 cfm would result in a failed functional performance verification test. The system must produce 5,000 cfm or is deemed not to be in compliance with the performance criteria.

This may seem fairly straightforward, but the designer’s vision and the owner’s expectations are often at variance. This, in combination with normal turnover of personnel in the often lengthy time for development and delivery of projects can lead to confusion regarding expectations. With clearly defined Owner Project Requirements, maintained and updated by the commissioning provider, the project’s performance requirements are consistent throughout and can be readily measured in the functional performance verification testing phase of the project.

The commissioning provider has a “30,000-foot” view of the project and can act to circumvent system integration and design problems that may be precipitated through changes in design or value engineering choices. Especially with respect to the latter, owners often do not recognize the direct and indirect impact of value engineering revisions. We can alert an owner that if they should accept a value engineering suggestion, there may be an impact on system performance, so that they are aware of the ramifications. If they accept changes to the basis of design or design intent, then the commissioning provider revises the Project Requirements documents to reflect the ongoing evolution of the design.

After the building is occupied and following substantial completion, the commissioning provider is still involved during the warranty period. Involvement with the project team during this period allows the commissioning provider to ensure that the level of system performance is maintained and, frequently, this monitoring will evolve into permanent facility management. In this regard, the commissioning process can logically extend through the life of a building, when it is appropriately structured and has real value.

It’s pretty easy to see that the performance criteria established and tested can be used to establish procedures and standards for computerized maintenance management programs or other ongoing maintenance, which leads to intrinsic involvement in permanent asset management.

Commissioning provides a “snapshot” of building performance that can be used as a benchmark against future performance assessments of building systems. It provides the roadmap for the designers’ and owners’ expectations and can offer a benchmark for the performance of a building throughout its life.

The information gathered during commissioning makes the process repeatable and after a few years of operation, when systems may drift or degrade, the commissioning provider can return to help ensure the building is operating at the performance levels designed into and expected from its systems.

In a nutshell, the commissioning process should extend throughout the lifetime of the building, because of the quantity and quality of data collected during the commissioning process.