Is Building Envelope Commissioning Required in LEED v5?

What does LEED v5 BD+C actually say about BECx and fundamental commissioning?

Under the LEED v5 BD+C prerequisite EAp3 Fundamental Commissioning, there are five specific requirements regarding building envelop commissioning (BECx):

1. By referencing newer editions of Standard 90.1, LEED introduces minimum BECx requirements: The fundamental commissioning prerequisite pulls in BECx requirements by way of referencing Standard 90.1-2019/2022. The prerequisite states:

Comply with ANSI/ASHRAE/IES Standard 90.1 commissioning requirements for building systems, controls, and the building envelope, with the following additional provisions:

• All projects shall provide fundamental commissioning. Section 4.2.5.2 exceptions shall not apply.
• The referenced version of Standard 90.1 with errata shall be: 
• 2019 or later for projects registered before January 1, 2028
• 2022 or later for projects registered on or after January 1, 2028.

Section 4.2.5.2 outlines building commissioning requirements, qualifications of the commissioning provider (CxP), activities prior to building permit issuance, and activities prior to building occupancy. This section also contains a subsection clarifying that project commissioning documents shall comply with ASHRAE/IES Standard 202: The Commissioning Process Requirements for New Buildings and New Systems (or another standard approved by the local jurisdiction). 

In addition to the requirements of the applicable version of ASHRAE 90.1, the commissioning provider (CxP) shall also ensure:

2. The Owner addresses the building envelope in the OPR: The prerequisite goes on to clarify that the owner's project requirements (OPR) must include HVAC, service water heating, power, lighting, other equipment (include on-site renewable energy), and envelope. 

3. The design team addresses the building envelope in BOD and meets at least once on the matter: Pursuant to review of the basis of design (BOD) for compliance with the OPR, the project team must convenes during design to hold at least one meeting focused on the review of the envelope. 

4. During construction, the CxP must review submittals related to the envelope for QA/QC: The intent is to identify submittals and substitutions for design deviations that impact the OPR. Additionally, the CxP must attend milestone meetings at 50% and 100% completion, and perform a sample review (minimum 10%) of completed contractor documentation for quality assurance/quality control (QA/QC).

5. Include testing in commissioning documents and witness a sample of tests: Standard 90.1-2019/2022 requires verification and testing (V&T) of the building envelope to ensure a continuous air barrier outperforms the minimum whole-building air leakage rate.

What are the minimum qualifications of the BECx and can the duties be performed by someone other than the CxP?

Yes. The LEED v5 Reference Guide for Building Design and Construction notes the following qualification:

The CxP must have direct commissioning experience from the design phase through the construction phase for at least two projects with equal or larger scope and complexity. The previous experience should address buildings of similar types and size range, similar types and capacities of HVAC and service water heating equipment, and controls with similar complexity, and the building envelope unless this scope of work is completed independently by a Building Envelope Commissioning Provider (BECxP).

What are the requirements in Standard 90.1?

Standard 90.1-2019 establishes the following:

Section 5.4.3.1.1 Whole-Building Air Leakage

Whole-building pressurization testing shall be conducted in accordance with ASTM E779 or ASTM E1827 by an independent third party. The measured air leakage rate of the building envelope shall not exceed 0.40 cfm/ft² under a pressure differential of 0.3 in. of water, with this air leakage rate normalized by the sum of the above-grade and below-grade building envelope areas of the conditioned space and semiheated space.

Alternately, a continuous air barrier design and installation verification program conducted by an independent third party must meet the requirements when using Section 5.4.3.1.1, Exception 3. 

Additionally, Section 5.9.1.2, requires verification and testing, including a design review, periodic field inspection, and reporting.

The commissioning requirements for the 2019 and 2022 versions of Standard 90.1 are similar. One notable addition to Standard 90.1-2022 that influences the commissioning scope is the requirement for whole-building air-leakage testing for buildings less than 25,000 square feet (2,320 square meters).

Again, this is only the prerequisite.

It is critically important to note that all of the above is required as part of fundamental commissioning under LEED v5 BD+C and primarily addressed air leakage per the commissioning requirements defined in Standard 90.1-2019/2022.

Conversely, the EAc5 Enhanced Commissioning credit requires projects to follow a much more expansive and comprehensive process for BECx that includes all tasks referenced in ASTM E2947-21a: Standard Guide for Building Enclosure Commissioning, except Section 7.2.4 and 7.4.3.

The enhanced commissioning credit also expands the scope of BECx field testing to encompass air leakage testing, water penetration testing, and infrared imaging—referencing ASTM and ANSI standards.