Why commission the building enclosure?

by Mickey D. Parker, PE

Photo © BigStockPhoto.com

For many years, designers, contractors, and owners have understood the value of a systematic approach to ensure the mechanical and electrical systems in buildings meet the owner’s needs. This approach is known as the commissioning (Cx) process. As a result of implementing the Cx process into the design and construction of buildings, defect claims and litigation related to these commissioned systems are relatively low. The building enclosure (sometimes referred to as the building envelope), however, has often been excluded in the Cx process. Unlike mechanical and electrical systems, poorly performing building enclosures are the most common causes for construction claims and/or construction defect litigation.1

Applying the Cx process to the building enclosure has been discussed as a concept within the construction industry for at least 10 to 15 years, but in the author’s experience, it has not yet been widely adopted. This article explores the commissioning process and how it can be used to improve the performance of a building enclosure. For the purposes of this article, the building enclosure commissioning process will be referred to as BECx.

What does it mean to commission a building? The commissioning process is a structured, quality assurance (QA) process intended to ensure a completed building meets or exceeds the owner’s requirements. There are three keys points to this definition.

First, commissioning is a structured process. The American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) publication Guideline 0 provides the framework for the commissioning process. Other publications available from ASHRAE and ASTM International provide guidance on how the commissioning process can be applied to ensure the satisfactory performance of the building enclosure.2 Consistently following these published guidelines can ensure the commissioned building has been carefully planned and constructed in a way that meets the needs and expectations of the owner.

Second, it is critical to understand BECx is a QA process, focused on achieving the owner’s required level of quality. Quality control (QC), on the other hand, is monitoring work as it occurs, ensuring the work satisfies the project requirements, and enforcing corrective actions as needed. The commissioning process is a supplement to the contractor’s QC program, rather than a replacement for it.

Third, the end goal of a BECx program is to ensure the completed building meets the stated performance and quality goals of the owner. Commissioning professionals focus on the word “ensure” (to make certain, verify) as opposed to guarantee (a formal promise that certain conditions will be fulfilled). The BECx process strives to make certain a building performs as intended, but BECx offers no guarantees. Guarantees are the purview of the various product manufacturers and the contractors who install those products. Just as commissioning the mechanical and electrical systems has improved the performance and reduced the litigation related to those systems, the intent of the BECx program is to improve the performance of the building enclosure and to reduce the litigation (risks) associated with the failures of the enclosure systems.

For the BECx process to be effective, it needs a written plan. This plan is developed and modified throughout the project by the BECx professional, and it becomes the roadmap for the BECx throughout the remainder of the project. In the ideal situation, the BECx team is involved with the owner and the design team from the outset of the project. This allows for collaboration on the project from the development of the owner’s project requirements (OPR) through the schematic design, design development, and final construction documents.

The BECx plan should establish:

  • each BECx action;
  • who will be responsible for coordinating and performing each action; and
  • when each action should be completed.
Finding window leaks with a spray rack, following the protocols of ASTM 2128.
Photo courtesy of Rimkus

Without an adequate plan, it is very probable BECx actions will be overlooked during design and construction. For many BECx actions, if they are not completed at the appropriate time, there will not be another opportunity to do so without complications, significant costs, and project delays. For example, consider a situation where the OPR indicates a maximum air leakage (infiltration and/or exfiltration) rate for the building, but the leakage rate is only tested after the building is substantially complete, and the measured leakage is found to exceed the maximum allowed by the owner. With the finish materials all installed, it would be extremely difficult to find and correct the deficiencies in the building’s air barrier assembly. Another example is testing the windows
on a building after the finish materials have been installed and finding out the windows leak. If tested at the appropriate times, necessary corrective actions can be generally limited to the failed item. When the defects are found later in the project, some trades may be forced to remove their completed work and then reinstall it when the identified deficiencies have been corrected.

The role of a BECx provider
Just as it is important to select a designer and contractors with experience in designing and constructing buildings similar in use, size, and geography to the project being considered, it is also important to select properly qualified professionals for building enclosure commissioning (BECx). The University of Wisconsin currently offers courses and exams for the certification of BECx providers (BECx-P) and BECx authorities (BECx-A). BECx-P are individuals who have demonstrated knowledge of how to perform various BECx activities. BECx-A are professionals who lead a commissioning team and are knowledgeable in the design, construction, and operation of systems. Although there are limited programs for certifying BECx professionals at this time, it is anticipated more opportunities for education and certification will become available as more designers specify, and owners request, certified commissioning professionals. Until then, building owners and project specifiers should take care to thoroughly vet prospective commissioning providers.

A common question is “Who retains the BECx professionals?” Ideally, the BECx team is retained by the owner/developer of the proposed project. In this situation, the owner is in a position to require the designers and contractors to cooperate with, and accommodate, the activities of the BECx professionals.

Although retained by the owner/developer, the BECx professionals do not normally serve as the owner’s agent. An owner’s agent typically has the authority to direct the designers and the contractor. Rather than this authoritative role, the BECx team strives to advise the designers and contractors on ways to ensure improved performance and to verify the installed components will meet the owner’s project requirements. The BECx team provides recommendations, not requirements.

In this author’s experience, the BECx team is most often retained by the contractor as a result of requirements written into the project specifications.  A common way to manage the commissioning teams is to have them retained by the contractor but reporting to the owner/developer.

Given the above described role of the BECx team, it is not surprising there can be some “push back” from designers and contractors. It has been this writer’s experience that by carefully handling the situation, BECx professionals can demonstrate they are acting to ensure the project is successful.

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