Building enclosure commissioning—BECx—is intended to assure building quality by establishing an explicit process to verify that a building enclosure is designed and constructed to meet the owner’s objectives. The concept of building enclosure commissioning has been around for several decades, but it has not been well defined, understood, or utilized.
With the advent of new building performance standards such as LEED, the Green Building Initiative’s Green Globes, and the Living Building Challenge, building enclosure commissioning is gaining popularity. In fact, the new version of LEED, LEED v4, includes a prerequisite for a fundamental level of building enclosure commissioning.
The design and construction industry needs to understand the intent and scope of building enclosure commissioning so that BECx can be implemented effectively to assure building quality and performance, manage risk, and reduce costly changes and delays.
The governing standard for the commissioning process within the building construction industry is ASHRAE Guideline 0-2013, The Commissioning Process. According to this standard, commissioning is “a quality-focused process for enhancing the delivery of a project. The process focuses upon verifying and documenting that the facility and all of its systems and assemblies are planned, designed, installed, tested, operated, and maintained to meet the Owner’s Project Requirements.”
After reading this article, you should be able to:
• Define the concept of building enclosure commissioning (BECx) and its impact on meeting the owner’s project requirements (OPR).
• Discuss the key areas of concern that the owner’s project requirements (OPR) should establish.
• List at least three important duties of the building enclosure commissioning authority (BECxA).
• Describe the value to the project of using off-structure and on-structure mockups of building envelope components in advance of construction.
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ASTM E2813-12, Standard Practice for Building Enclosure Commissioning, was developed more recently to focus specifically on building enclosure commissioning. This standard practice defines building enclosure commissioning as a “…process that begins with the establishment of the Owner’s Project Requirements [OPR] and endeavors to ensure that the exterior enclosure and those elements intended to provide environmental separation within a building or structure meet or exceed the expectations of the Owner as identified in the OPR.” ASTM E2813 also outlines different levels of building enclosure-commissioning scope (fundamental and enhanced commissioning), which are discussed in more detail below.
Another helpful industry guide is the National Institute of Building Sciences Guideline 3-2012, Building Enclosure Commissioning Process BECx.
These definitions may seem relatively straightforward, but that can be deceiving. For Building Teams that are unfamiliar with building enclosure commissioning, it can be a confusing and at times overwhelming process. Building Teams may find its many tasks vague, not readily understood, and sometimes difficult to implement. Moreover, since commissioning has traditionally addressed the building’s mechanical systems, many requirements in the BECx process tend to be more suitable for documenting and verifying standard mechanical equipment and systems, rather than documenting and verifying project-specific enclosure designs.
The following eight strategies will help Building Teams sort through the various building enclosure commissioning guidelines and use BECx in a logical and cost-effective way.
1. Make building enclosure commissioning a process.
The industry definitions of building enclosure commissioning all put forth the notion that commissioning is a process. This is important. Building enclosure commissioning cannot be effective if it is implemented as a series of isolated activities or evaluations; it must be an ongoing and continuous review to verify that the owner’s project requirements are being accounted for throughout the entire design and construction cycle.
To be truly effective, building enclosure commissioning should begin in the predesign phase and continue through the design, preconstruction, and construction phases of the project. ASTM E2813 requires that BECx activities commence during design development (DD) for fundamental commissioning and during schematic design (SD) for enhanced commissioning.
Since commissioning guidelines originate with ASHRAE, they tend to approach commissioning of other building systems much as they would those for mechanical and HVAC systems commissioning. However, there is a significant difference between how mechanical systems are constructed and tested as compared to building enclosures. Even though mechanical systems can be very complex, the key pieces of equipment—furnaces, air-handling units, chillers, etc.—can usually be accessed, tested, and adjusted as needed to function properly after installation.
Conversely, many of the materials and systems that perform the most critical functions of the building enclosure, such as waterproofing, air- and vapor-control membranes, and insulation, are concealed behind cladding and finish materials. Once the finishes are installed, it is difficult and costly to access these materials and systems to make repairs. Moreover, these components of the building enclosure—wall assemblies, cladding, curtain walls, windows, roofs, etc.—must be carefully integrated in order to obtain optimal performance of the whole building envelope. If these detailing conditions are not properly designed and installed at the outset, they can be difficult to access and repair at some future date.
To reduce the risk of encountering such obstacles in the future, it is important to apply building enclosure commissioning through all the design and construction phases of a project. Starting commissioning tasks late in the design or during construction limits your ability to make needed changes easily and cost-effectively.
2. Retain an independent third party as BECx authority.
Industry guidelines define a building enclosure commissioning authority (BECxA) as an independent third party retained by the owner. It is not uncommon for a Building Team to bring in a consultant to offer technical advice on the building enclosure, but that does not make such a consultant a building enclosure commissioning authority. The consultant is working for the Building Team, not the owner, as would be the case for a BECxA.
A building enclosure commissioning authority provides the owner with broad, independent advice to help the owner understand complex enclosure issues and thereby manage risk more effectively. The owner can decide which problems or concerns to seek the BECxA’s advice on, with the understanding that any such advice would be provided solely with the owner’s interests and project requirements in mind.
LEED v4 allows a qualified member of the design or construction team who is not directly responsible for the design of the building enclosure to perform the function of the BECxA. In our opinion, this model is inconsistent with the intent of the building enclosure commissioning process and detracts from the objectivity and value the owner should receive from having an independent third-party review. If the goal of the BECx process is to assure the anticipated quality of the building enclosure, it must be collaborative and inclusive, but the BECxA should be independent of the entire Building Team.
Meaningful involvement requires that the building enclosure commissioning authority staff be qualified and experienced. The owner must vet the prospective building enclosure commissioning authority candidates to determine that they are sufficiently competent and experienced in the design and construction of similar building enclosures. As outlined in ASTM E2813, the BECxA must have basic core competencies, including knowledge of:
• Exterior façade design
• Building and material science
• Procurement and project delivery
• Contract documents and construction administration
• Performance test standards and methodology
Previous experience with similar enclosure systems will enable the building enclosure commissioning authority to provide advice and guidance to the entire Building Team, thereby helping to improve the quality and performance of the building enclosure.
The depth of involvement of the building enclosure commissioning authority in each of the project phases is not as important as the having the BECx authority provide continuous review throughout the entire process, provided key tasks (such as design reviews, mockup testing, etc.) are included.
3. Define the owner’s project requirements (OPR).
The building enclosure commissioning process should always start with a clear definition of the owner’s project requirements. The OPR is a written document that outlines the owner’s goals for the building enclosure, with particular attention to energy, environment, safety, security, durability, sustainability, and operation.
Developing a written OPR will confirm that the Building Team shares an accurate understanding of the project’s enclosure requirements and sets the stage for an efficient design process. Even in a case where the owner and the design team believe they have a general understanding of the OPR for the building enclosure, creating a written document that outlines all the goals is still recommended.
The building enclosure commissioning authority can guide the discussion about the OPR for the enclosure and help define performance objectives. Conducting a thorough discussion of enclosure goals and requirements early in the design process will improve the future alignment of the design with the owner’s expectations.
A field-constructed off-structure mockup of a building enclosure system. Performance assessment and testing of building enclosure systems via off-structure mockups can establish quality standards and verify that designed systems are capable of meeting required performance metrics well in advance of construction. This gives the Building Team the time to integrate any necessary changes before wholesale construction begins. Photo: courtesy Simpson Gumpertz & Heger Inc.
The written OPR can take many forms, such as a statement of objectives or a table of requirements. It should be tailored to the particular owner’s needs and goals and to the general type of building that is planned. At a minimum, the OPR should establish:
• Interior and exterior temperature, humidity, and pressurization conditions
• Desired service life and construction type
• Energy use and sustainability requirements
Some typical building enclosure requirements—limiting interior leakage, minimizing maintenance, improving occupant comfort, and so on—are subjective and qualitative. Nonetheless, it is important to define these requirements as clearly as possible so that the performance metrics for the building enclosure can be adopted into the design appropriately. Once the OPR is clearly defined, the building enclosure commissioning authority will be better able to recommend an appropriate scope for its BECx activities.
4. Align the building envelope commissioning scope with the OPR and the project’s complexity.
The various building enclosure commissioning industry standards cited above describe many possible tasks that could be accomplished throughout the process; not all these tasks may be necessary or even desirable, depending on the overall project scope, schedule, and budget. After establishing the owner’s project requirements, the next step in selecting the scope of the BECx process is to undertake an analysis of:
1) the building enclosure’s potential complexity
2) the amount of risk the owner is willing to undertake
3) the roles and responsibilities of the architects, engineers, contractors, and specialty consultants that make up the Building Team
As noted above, both the ASTM standard for building enclosure commissioning and the LEED v4 requirements include two levels of building enclosure commissioning: fundamental commissioning and enhanced commissioning. The selected scope will depend on the owner’s expectations for building quality, the level of risk the owner is willing to accept, and the building type, size, and complexity. In general, the scope defined by LEED is relatively limited for both fundamental and enhanced commissioning. LEED does not stipulate a particular time in the project schedule that the BECx authority must be engaged and requires only minimal assistance with the OPR and the basis of design (BOD).
Neither fundamental nor enhanced LEED v4 commissioning requires design reviews, and only enhanced commissioning requires oversight during the construction phase. Such a limited scope of building enclosure commissioning services, while better than not performing commissioning at all, does not address some of the more systemic issues—incompatibility of materials, unconstructable details, discontinuities in the exterior barriers, and so on—that could arise from inadequate design or construction; in that regard, LEED v4 is equally limited in its ability to assure and control building enclosure quality.
ASTM E2813 requires a more extensive, but still manageable, scope of work for building enclosure commissioning. The ASTM standard requires that the commissioning authority be engaged early in the design process—in the design development (DD) phase for fundamental commissioning, in the schematic design (SD) phase for enhanced commissioning. Under ASTM E2813, the BECx authority must also:
1) Provide assistance with the owner’s performance requirements and the basis of design
2) Perform design reviews—one design review for fundamental commissioning, three design reviews for enhanced commissioning
3) Participate in preconstruction activities
4) Monitor ongoing construction work
This more detailed and more integrated scope enables the BECx authority to provide more meaningful advice and have a more beneficial impact on the overall quality of the building enclosure. The level of building complexity and the owner’s tolerance for risk can be accounted for in the project scope by adjusting the number and depth of design reviews, the frequency of construction site visits, participation in Building Team meetings, etc.
5. Produce a written BECx plan.
After you have defined the level and scope of building enclosure commissioning for your project, the BECx authority should prepare a written plan that 1) provides an overview of the commissioning process, 2) defines the roles and responsibilities of the Building Team members, 3) outlines the planned commissioning activities, and 4) documents the expectations for communication during the commissioning process. The written BECx plan should be revised over the course of the project as requirements change, but that does not diminish its value in keeping the project on track and making sure that all Building Team members understand their roles and the owner’s expectations for the project.
In some cases, the BECx authority may prepare a specification that documents the various commissioning tasks, performance metrics, and testing requirements for inclusion in the contract documents. Such a specification can be helpful, but may not always be necessary, provided the performance tests are included in the enclosure technical specifications and the written commissioning plan offers a clear summary of the process and expectations.
6. Plan design reviews for optimum impact.
It is important that the building enclosure commissioning authority review the design team’s work to verify that the basis of design aligns with the established owner’s project requirements. The enclosure systems selected for the project must be able to meet the criteria established by the owner as important. The BECxA is responsible for reporting basis-of-design items that are inconsistent with the owner’s project requirements to the owner, who can then decide to either modify the project requirements to accept the design change, or ask for adjustments in the basis of design.
The BECxA’s reviews of the building enclosure design documents must determine that the details and selected materials align with the agreed-upon OPR and BOD and that the performance tests and criteria are properly integrated into the project specifications. It is difficult—and sometimes impossible—to make major changes to a design once adjacent systems have been developed, construction pricing is under way, and aesthetic reviews have been completed, particularly with today’s ultra-fast construction schedules.
ASTM E2813 includes a nearly exhaustive list of possible performance testing options, including water testing (shown here) and air-infiltration testing. Such tests help verify performance for important building enclosure components, such as windows and flashing. Photo: courtesy Simpson Gumpertz & Heger Inc.
Design reviews should be scheduled so that changes needed to align with the OPR can be implemented early in the design process. A review by the building enclosure commissioning authority late in the schematic design or early in the design development phase can help identify fundamental issues that can still be resolved before detailing begins. A subsequent review in the early stages of the construction documents further would further allow the BECx authority to comment on typical detailing of the enclosure systems and provide recommendations for system integration details. Yet a third review later in the construction documents phase can be helpful to make sure that all previous comments have been incorporated and all necessary details and requirements have been provided.
Design reviews typically include markups of the drawings and specifications and development of an issues log. The issues log tracks all identified deviations of the design from the OPR. The envelope commissioning process is not complete until each item in the issues log is resolved to the owner’s satisfaction. The owner should work closely with the BECx authority during the design review process because it is the owner’s responsibility to enforce the BECx authority’s recommendations with the project design team or determine if changes to the OPR are acceptable.
Caution: Even though its name may imply otherwise, the building enclosure commissioning authority does not have the authority to make changes to the design. The design team maintains control over the design throughout the entire process.
7. Establish enclosure system performance metrics during the design phase.
During the design phase, the BECx authority should help the owner and the Building Team develop appropriate performance assessment and testing requirements for the various enclosure systems. Performance assessment and testing typically include:
• Preconstruction laboratory mockups
• Field-constructed mockups, both off-structure and on-structure
• Field testing at milestone intervals
• Post-occupancy evaluation
The performance metrics must relate directly to the established owner’s project requirements.
ASTM E2813 includes a nearly exhaustive list of possible performance testing options. The Building Team should determine which tests will be performed and their required test values or performance measures. The BECxA can either prepare an enclosure commissioning specification that includes all these performance metrics, or confirm that the metrics have been integrated into other design documents.
Requiring off-structure mockup testing of the component building enclosure systems can be effective in establishing quality standards and verifying that the designed systems are capable of meeting the required performance metrics. Off-structure mockups can be completed well in advance of building construction, allowing time to integrate any changes that may be needed for the tested system to meet the established metrics. On-structure mockups are less expensive and less labor-intensive than off-structure mockups; they can also be effective, provided that necessary changes can still be incorporated in the manufacturing/fabrication process or during erection. On-structure mockups completed too late in the process can result in changes that cannot easily be accommodated without significant implications to schedule and budget, so they are sometimes not as viable as off-structure mockups.
After mockup testing is complete and installation begins, the initial installation should be tested. This will help confirm that the materials and systems delivered to the site and their installation on the building match the quality and performance of the mockup. Testing the initial installation gives you a chance to make needed changes or adjustments before the bulk of the construction is completed. Periodic testing thereafter can serve to verify that the installation quality remains consistent throughout the life of the project. All testing must be coordinated with the construction schedule to make sure that necessary testing is not abandoned in an effort to maintain completion deadlines.
8. Monitor construction early and regularly.
The BECxA should be an active participant in the construction phase of the project to verify that the owner’s project requirements are being met and the project is constructed as designed. This responsibility starts with the BECxA acting as a second reviewer for building enclosure submittals and shop drawings. Items that do not align with the OPR must be brought to the owner’s attention for resolution with the design and construction components of the Building Team. These reviews should confirm that all items related to the building enclosure are properly documented and that they comply with the established OPR. The owner should evaluate the authority’s comments and recommendations and decide how to direct the project design team to address these concerns. Identifying items in the submittals and shop drawings that do not align with the OPR and design can avoid costly and frustrating problems down the line.
In our experience, it’s a good idea to have the building enclosure commissioning authority meet with the relevant trades before construction or installation of the building enclosure begins. This gives the BECxA the opportunity to review and clarify the required performance testing and quality control/quality assurance tasks face to face with the skilled trades who will be doing the actual work.
The BECxA should perform periodic site visits as the building enclosure is being constructed. During these visits, the authority should review the installed work to verify that the construction meets the intent of the contract documents and therefore the intent of the OPR. During these site visits, the BECx authority should keep a construction issues log for items that require further attention or adjustment to comply with the contract documents. The construction issues log will help the owner understand the items that need to be addressed and resolved. The construction issues log keeps track of nonconforming issues, which must be closed out prior to the completion of the enclosure construction.
Caution: As noted above, the building enclosure commissioning authority does not have authority to change the design or direct construction work. It is up to the owner to discuss such concerns with the authority and promptly relay required changes to the Building Team.
During construction site visits, the BECx authority should witness the performance testing required in the design documents. The BECxA should verify that the proper performance tests have been performed, that the test procedures were correctly followed, and that the test results indicate conformance with the OPR. The owner may elect to have the BECx authority conduct performance testing itself (assuming the individual has the appropriate qualifications) to further assure proper testing methods.
Building enclosure commissioning can't be half-hearted
The building enclosure commissioning process must be implemented thoughtfully to be a reliable and effective way of assuring quality in the building enclosure, without becoming cumbersome and adversarial. Building enclosure commissioning should never be thought of as a replacement for good design and construction workmanship. The commissioning process helps reassure the building owner that the design has been properly evaluated and implemented; but even properly commissioned buildings can have problems if the basis of design is misguided and the design is flawed.
Building enclosure commissioning must be executed as a process from predesign through construction to be most valuable. Implementing only isolated portions of the process, such as limited performance testing or construction checklists, will be ineffective if the original basis for the design is not appropriate and the construction is not consistently reviewed for conformance.
About the Authors
Emily Hopps is a Senior Project Manager specializing in building enclosure design and building enclosure commissioning at engineering firm Simpson Gumpertz & Heger, Waltham, Mass. Peter Babaian, Associate Principal, is the Building Technology Division Head of SGH’s Chicago office and leads the firm’s Building Enclosure Commissioning group.