Decoding Building Enclosure Commissioning

by Stacy Rinella | March 31, 2025 7:03 am

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Since they were first introduced in the 1970s, building energy codes and standards have primarily focused on prescriptive efficiency requirements for HVAC and lighting, as well as R-values for insulation and U-values for fenestration. Over time, compliance through projected performance design modeling was introduced, and later performance verification of building systems (HVAC and lighting) through post-construction commissioning. Until recently, the compliance of building enclosure was still based on prescriptive requirements, but this is changing. Codes and standards now recognize that leaky building enclosures undermine the benefits of insulation and significantly impact building energy performance, as well as comfort and air quality.

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Building enclosure codes and standards

Some states, such as Washington, have had more stringent requirements in place for several code cycles that require whole building air barrier testing (WBAT), commonly referred to as blower door testing. Many others have only recently adopted (or will soon adopt) the International Energy Conservation Code (IECC) 2021. This code introduces new requirements to address building enclosure performance, offering two options:

1. Engage a qualified third-party air barrier inspector to conduct field observations of the air barrier installation and generate inspection reports, or
2. Conduct WBAT per ASTM E779 and demonstrate that air leakage is below 0.40 cfm/sf (cubic feet per minute of air per square foot of building enclosure area). If a building fails the 0.40 cfm/sf threshold, but is below 0.60, code compliance is still possible but will require documented remedial work.

For comparison, the Washington State Energy Code (WSEC) sets the maximum air leakage at 0.25 cfm/sf @ 75 pa, which is significantly better than the baseline in the IECC. Some states adopting IECC – 2021 may similarly set more stringent leakage requirements. Federal agencies (GSA, USACE, NAVFAC, etc.) require a WBAT and the more stringent air leakage requirements (0.25 cfm/sf) regardless of location.

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Some voluntary standards also set air leakage requirements. For example, Passive House (PHIUS) has its own requirement (0.08 or 0.11 cfm/sf @ 75 pa depending on height and building construction). While it has not set performance thresholds, the U.S. Green Building Code (USGBC) has proposed new building enclosure commissioning requirements in LEED version 5, including field testing. Previous versions had not articulated specific testing requirements. LEED v5 Fundamental Commissioning prerequisite will require building system and building enclosure commissioning per ANSI/ASHRAE/IES Standard 90.1 – 2019, including a requirement for testing. The building enclosure option within the Enhanced Commissioning credit (Option1, Path 2) requires completing the tasks and deliverables from ASTM E2947-21a Standard Guide for Building Enclosure Commissioning (except Section 7.2.4 and 7.4.3) and complying with the field-testing requirements for building air leakage testing, water penetration testing, and infrared imaging.

 

What does this mean for projects?

In areas that had not previously required verification of air leakage, there will be a learning curve for architects, builders, and owners in material selection, detailing, and execution of effective air barriers. Even in locations like Washington with stricter requirements, project teams are often still opting for mechanically attached water resistive barriers (WRBs) such as traditional building wraps, probably due to familiarity and cost. However, unless these are meticulously detailed as air barriers (not just water barriers) mechanically attached WRBs will most likely not achieve the more stringent performance requirements in the 2021 WSEC and similar codes, potentially requiring costly corrective actions. Given this, careful detailing and specification, installer education, and construction inspection is required to achieve effective performance from mechanically attached WRBs. Alternative WRB options that tend to support superior air barrier performance include self-adhered membranes, fluid applied membranes, insulated metal panels, and sheathing panels with integrated factory-applied barriers. Each of these solutions has pros and cons and may require installer training.

 

What is the role of the building enclosure commissioning professional?

Regardless of the system used, proper detailing, specification, and installation of code and standard compliant air barriers is critical, so quality assurance is the key. This is where the building enclosure commissioning professional (BECxP) comes in. The BECxP will review building enclosure details early in the design phase to evaluate trade-offs, identify areas of concern, and propose solutions. They will also back-check details and review specifications in the construction document phase to confirm the continuity of control layers for air, water, water vapor, and thermal resistance, and the compatibility of specified products, especially at transitions from one system to another (e.g. wall to roof).

During construction, the BECxP will conduct site visits to review installations, troubleshoot unanticipated conditions, and catch deficiencies in workmanship before they are covered up. Unlike commissioning of mechanical, electrical, and plumbing systems, once the building enclosure is complete, it is costly or nearly impossible to make corrections. They will also observe building enclosure testing including water penetration testing and air leakage testing. The BECxP will typically provide guidance for on-going maintenance, seasonal inspections, and/or periodic testing to help building owners to maintain performance and durability for the full useful service life. Warranties can be hard to enforce and even harder to collect on.

 

How is building enclosure
testing performed?

During construction, building enclosure testing provides assurance that the various systems that make up a complete building enclosure are performing as required. The primary tests include:

• Water Penetration Testing methods include ASTM E1105 (chamber test) and AAMA 501.2 (nozzle test). These tests are a quality check for water and air tightness of installed fenestration systems (windows, storefront, curtain wall, skylights, etc.).

The test confirms that the factory assemblies have not been damaged in shipping and that the entire installation of the fenestration system, flashings, perimeter sealants, etc. is functioning properly. Testing is often performed on a mock-up, and on a random sampling of installed fenestration on the building. AAMA 501.2 nozzle testing can be adapted to test joints in metal panel systems and expansion joint assemblies too

• Whole building air barrier testing (ASTM E779) is typically performed using one of more blower doors to test the finished enclosure for air tightness. The test will determine if the building passes or fails the air tightness required by a code or standard, but not why it is failing. This is why air barrier testing is often combined with thermography or smoke tracer testing to help identify specific areas of leakage that are not plainly visible.
• Infrared thermographic testing (ASTM C1153 or ASTM C1060) is used to help detect moisture within a roof assembly (C1153) or gaps in insulation/thermal bridging (C1060) in a wall assembly. These can be helpful non-destructive diagnostic tools.

Verified building enclosure performance is now understood to be an integral part of energy efficiency, and this is increasingly reflected in building energy codes and other high-performance building standards. Developers, building owners, architects, and general contractors need to be aware of these increasingly stringent requirements and the building enclosure commissioning processes and testing procedures that proactively assure performance.

 

David Jaffe, AIA, is an architect and building enclosure commissioning professional with Intertek Building Science Solutions in Kent, WA.

 

Alan Scott, FAIA, LEED Fellow, LEED AP BD+C, O+M, WELL AP, CEM, is an architect and consultant with over 36 years of experience in sustainable building design. He is Director of Sustainability with Intertek Building Science Solutions in Portland, OR. To learn more, follow Alan on LinkedIn at linkedin.com/in/alanscottfaia/.

Source URL: https://www.metalarchitecture.com/articles/decoding-building-enclosure-commissioning/

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