Building Enclosure Performance and the approach to Building Enclosure Commissioning
Evolving trends in sustainable building design and ever-increasing requirements of building energy codes (see: Toronto Green Standard, BC Energy Step Code, etc.) are placing greater emphasis on the performance of the building envelope.
In addition to more stringent requirements for overall thermal performance, which has long been included in energy codes, new criteria for the building enclosure include defined levels of airtightness and thermal energy demand associated directly with heat loss through the envelope.
To satisfy some voluntary green building rating systems, owners are required to demonstrate enclosure performance with certainty both early in the design process (through modelling) and at completion (through post-construction verification, such as mandated whole-building air-tightness testing).
Additionally, architectural and product innovation have added significant complexity to the typical enclosure elements and, with it, added cost and risk. Enclosure systems can represent a sizeable portion of construction cost (sometimes up to 20%), and their failure, commonly in the form of water intrusion, has been found to result in the largest share of insurance claims in the industry. Accordingly, it has become more important than ever that the performance of the building envelope be carefully considered at all stages of the project lifecycle. Enter, the Building Enclosure Commissioning process.
At a high level, the Enclosure Commissioning process offers rigorous documentation of the intended performance for the building enclosure and tracks the development of the design and construction of the project to meet these targets.
The Importance of Selecting the Right Commissioning Team
When selecting a BECx team, it’s important to ensure that design, installation, and testing experience are represented. This should not be a checkbox activity, but one that balances performance with constructability to make sure the owner is getting value.
Although BECx could be considered a process of simple checks and balances, we feel there is added value in the Building Envelope Commissioning Agent (BECxA) being a building envelope specialist, because they will bring with them the technical expertise to actually fact check the envelope design, installation, and testing. The Entuitive Building Enclosure Commissioning Team is comprised of building enclosure specialists who are systematically engaged in consulting work and therefore have an extensive knowledge of the building enclosure systems on any project, and, when paired with our internal network of subject matter experts, can efficiently leverage the knowledge and experience of the broader group. On our projects, our team acts as the BECxA with regard to the exterior enclosure, which would typically consist of Exterior Wall Assemblies, Exterior Glazing Systems, Roofing Assemblies, and Exterior Waterproofing Systems.
“When we act as the Building Envelope Commissioning Agent it is important to understand the needs of the Owner. Our aim is to verify that the building meets all objectives in terms of building envelope durability and efficiency,” said Senior Associate Heather Elliot from our Calgary office. “The first step to that verification is to confirm the project’s overall requirements. We focus first on being a collaborative member of the Commissioning team, so that our first conversations with the Owner and the design team begin to provide a clear path for testing those expectations.”
As a third party, or a disinterested member of the design team, the BECxA executes the necessary services to fulfill the Fundamental and/or Enhanced Commissioning process (CxP) activities for the building’s enclosure in accordance with ASHRAE Guideline 0–2005 and the National Institute of Building Sciences (NIBS) Guideline 3–2012, Exterior Enclosure Technical Requirements for the Commissioning Process, as they relate to energy, water, indoor environmental quality, and design service life.
In fact, the BECx process really holds the entire industry to a higher standard. Says Associate Timothy Wong from our Vancouver office, “The BECx process continues to be a driver of change in the building envelope industry by enabling and validating on projects what is typically considered best practice to a certified industry standard.”
We work according to the Building Envelope Commissioning Plan, which is essentially a project road map and, in some cases, incorporated into contract documents and upheld by the contractor. Our services can be provided in relation to the pursuit of LEED V4 Enhanced Commissioning credits, or outside of LEED, where simple verification and documentation of the performance of the building enclosure is required to meet the owner’s objectives.
Further validation in the form of review of the design documents, field review, and field testing ensure the performance targets are met for the entirety of the project.
Including a warranty review and training on the building enclosure with operation and maintenance staff can assure the owner that their new building is performing as intended. It also provides them with the knowledge to run and operate their building and maintain the building enclosure.
Defining the Role of the Commissioning Agent Ensures Effective Collaboration Throughout the Project Lifecycle
Traditionally, this service is engaged with prescriptive requirements provided by the owner based on their experience with other or similar projects often in the form of an OPR (Owner’s Project Requirements) or SOR (Statement of Requirements) document. In various instances the requirements may far exceed what would be recommended to the specific project or provide insufficient scope, such as testing to effectively document the performance of the building enclosure. Alternatively, the service is engaged with no specific requirements, which can leave the owner exposed to a wider range in fee and scope structure. The process is recommended to form a collaborative engagement between the owner and the BECxA, who will ultimately be documenting and testing the building enclosure on the owner’s behalf.
There is Little Point Commissioning an Envelope That Was Inadequately Designed to Meet Performance Requirements.
A focus on commissioning throughout the design phase ensures that the initial objectives are not lost and that the construction phase verification is indeed confirming the performance as originally intended.
Principal Mike Lembke of our Vancouver office agrees: “The building envelope is an intricate and complex collection of products and systems, holistically tasked with providing front line protection between the exterior and interior environments. Errors in envelope design or installation can have cascading effects on occupant comfort, operating costs, maintenance activities, and capital costs in the short term, and over the life of the building. The BECx process provides a formal platform to engage all parties in the goal of achieving, and proving, the intended envelope performance, from schematic design through to the end of the first year of service.”
Our experience in both envelope design and energy analysis allow us to identify those elements that are critical to the overall building performance at the design phase and specifically define performance criteria and quality assurance methods for these.
Once the owner’s project requirements (OPR) are clear, and the basis of design (BOD) is confirmed, our team provides objective engagement with the design and construction team throughout the design, tender, construction, and post-construction phases to ensure OPR and BOD requirements for the building enclosure are fulfilled and verified.
Our role includes the day-to-day and milestone BECxA oversight and plan that is core to building enclosure commissioning, as well as other services that are deemed relevant based on the project type, scale, and complexity, such as the breadth of on-site and off-site testing, plant review for off-site manufactured materials/systems, and post-occupancy training and field reporting.
BECx Requires a Keen Understanding of Where and Why Failures Occur
Our experience in whole building (envelope) design allows us to foresee and identify those areas which are at greatest risk of failures.
When a building enclosure is left undocumented, it does not necessarily indicate a poor performing building enclosure. Rather, it represents an uncertainty of the performance.
Should any components or assemblies be installed in a manner that falls below the intended project standards, these may only become known post-occupancy or post-warranty period. Such issues leave the building owner exposed to premature repairs or replacements depending on the severity of the issue(s) experienced and the time period for which the issue(s) has persisted.
The Entuitive Building Enclosure Commissioning Team has vast experience both on building typology and in region/climate and can help address failures and prevent them happening in the future.
Get in Touch
Any one of our regional building envelope leaders would be happy to discuss your project. Reach out to them here.