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Commissioning: LEED® Commissioning Design Review 

As with so many things, the when is as important as the what or how.

I, as well as most commissioning professionals, have been facilitating commissioning for an increasing number of USGBC LEED registered projects. LEED includes a prerequisite for fundamental commissioning which focuses solely on systems installation and performance verification at the end of construction. The LEED rating system also offers a credit (one additional point) for implementing an enhanced commissioning process.

Enhanced commissioning, as defined by the LEED program, includes design-phase reviews, O&M training verification, the development of a systems manual for the commissioned systems, and an end-of-warranty period review meeting. This month, I would like to focus on the design review portion of the enhanced commissioning process.

The following is taken directly from the LEED for New Construction Version 2.2 Reference Manual:

The CxA shall conduct, at a minimum, one commissioning design review of the owner’s project requirements (OPR), basis of design (BOD), and design documents prior to mid-construction documents phase and back-check the review comments in the subsequent design submission.

The following comments are not meant to be criticisms of the LEED process or requirements, because the LEED program consciously allows for latitude in how its requirements are achieved. The USGBC recognizes the infinite variety of building types, project delivery processes, project team relationships, etc., and does not attempt to prescriptively define the details of how commissioning must be performed. My suggestions are for project teams to consider — particularly owners hiring commissioning professionals and commissioning professionals developing commissioning plans — in order to obtain the most value out of their LEED commissioning process and budget.

Obtaining Value

The requirement to “review design documents prior to mid-construction documents phase” is appropriate from the perspective of performing a commissioning review early enough that the design could reasonably be changed or redirected, if deemed necessary, prior to development of final construction documents. The commissioning feedback should be seen as helpful, but review comments received too late will be considered a hindrance if they result in the reworking of nearly complete design documents.

The challenge with the mid-construction documents phase is that many of the design elements most important to commissioning are often not started by then, much less ready for review. These elements include system flow diagrams and control system design (points list and control sequences). Meeting the minimum requirement for enhanced commissioning, therefore, could result in minimal value to the owner from the commissioning review process.

Back-checking the “subsequent design submission” does not address this issue, because a back-check — by definition — is simply confirming that the initial comments have been addressed. A back-check does not require reviewing new material that might be available in the subsequent submission.

The best approach to obtaining more value would be for the owner to require the design team to develop the systems-level design elements (schematics, control sequences, etc.) by the mid-construction documents phase. This is beneficial to the project as a whole, because when the system operations and integration planning is delayed until the last 95% of the design effort (or, worse, performed via addendum), opportunities for team coordination and quality control are limited.

The 50% to 70% Guideline

However, what I believe to be the best approach and what is realistic to influence in today’s design and construction business are two different things. In the majority of projects where neither the owner nor the commissioning professional are able or willing to influence the order in which the design team does their work, the LEED commissioning process can be implemented differently in response to that reality. In that case, I propose that the commissioning professional review individual aspects of the design at their respective “mid-construction documents” phases. For example, review the piping and ductwork drawings when they are 50% to 70% complete (that might be at design development); review the equipment schedules when they are 50% to 70% complete (that might be at 50% construction documents); review the specifications when they are 50% to 70% complete (that might be at 50% construction documents); and review the control system design when it is 50% to 70% complete (that might be at 95% construction documents). The subsequent design submission back-checks would similarly be staggered to confirm appropriate action was taken in response to the initial design review comments.

As with many things in the LEED rating program, meeting the minimum requirements for a prerequisite or credit does not necessarily mean that the project and owner realize a meaningful benefit from that work. The above-proposed approach to commissioning design review will meet the LEED enhanced commissioning requirements while also providing the owner with the best value from the commissioning design review process.

 

Commissioning: Getting It Right

Engineered Systems, July, 2008

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