Building Envelope Commissioning 101
By Kevin Zhu
Kevin Chris Zhu is Verdical Group’s Sustainability Intern. Kevin is a LEED AP BD+C accredited professional, holds a B.S. Civil and Environmental Engineering and is currently wrapping up a M.S. Civil and Environmental Engineering with an Atmosphere/Energy Program, Sustainability and Energy Focus at Stanford University.
What is the first thing that pops into your mind when you hear the word commissioning?
Most of us in the A/E/C industry would probably link the process of Commissioning (Cx) first to the active mechanical, electrical, and plumbing systems of a building. But what about “Envelope (or Enclosure) Commissioning (BECx)”? And what role does it play in building performance standards, such as LEED?
In this blog post, I will take you on a tour of the BECx process which can have just as much and even more of an impact on the building’s performance than MEP Cx.
The Aquarium Analogy
Before jumping into the details of BECx, let us first imagine a scenario:
Unfortunately, you had little experience in crafting a nice living environment for the fish. Fortunately, your neighbor Emma happens to work at a local pet shop with years of know-how on building a functioning, beautiful, and long-lasting aquarium. Additionally, Emma’s husband generously offered to help to put all the components together for you.
You brought Laura’s colorful sketch to them and voila! After just a couple of days, you now have a fully-constructed aquarium with all the features in Laura’s drawing, including a circulation pump, heater, filter, coral substrate, UV lighting, and a glass tank. Finally, just before filling the tank with water and fish, you referred to an online guideline to ensure that all the pumps and the heater function as intended, and you examined the tank for potential cracks and leaks.
All of this might sound familiar to you. In this analogy, you as a parent have already performed some key building envelope commissioning tasks by ensuring future owner’s (Laura’s) requirements get executed and by checking the integrity of the fish tank’s envelope against official guidelines.
The Background on BECx
In formal terms, BECx is a quality assurance process to meet an owner’s building performance requirements by following a project from its early design stage to the construction and operation phase.
Historically, static envelope systems were often overlooked and sometimes left completely unchecked. Many have overlooked the importance of envelope performance simply because there are no “moving parts” within a wall or slab.
As technology advances, today’s architects are starting to design increasingly complex envelopes, with challenging installation techniques, and new materials for better thermal performance. Implementing these innovative yet complex envelope systems made by different manufacturers and installed by multiple contractors introduces uncertainties about the final performance of the building’s envelope system.
To address such problems, more stringent envelope design requirements have been released through energy codes. Designers and contractors need to deliver an envelope with better air leakage control and thermal performance targets and check its performance based on any of three major guidelines:
- ASHRAE Guideline 0-2013, The Commissioning Process
- NIBS Guideline 3-2012, Exterior Enclosure Technical Requirements for the Commissioning Process
- ASTM E2813-12, Standard Practice for Building Enclosure Commissioning
BECx in LEED v4 BD+C: The What? Who? When? How?
Beyond the three major guidelines, there are new building performance standards such as LEED, the Green Building Initiative’s Green Globes, and the Living Building Challenge which address enclosure commissioning in their certification process. Of all the existing building performance standards that incorporate BECx, LEED is undoubtedly the most used guideline here in the United States.
|What?||There are two main components to the LEED Application that address BECx: |
1. Prerequisite: fundamental commissioning
2. Credit: enhanced commissioning
In the scope of the fundamental commissioning process, the LEED Handbook states clearly that, “requirements for exterior enclosures are limited to inclusion in the owner’s project requirements (OPR) and basis of design (BOD), as well as the review of the OPR, BOD and project design.”
The Enhanced Commissioning credit goes on to offer additional steps for the Commissioning process (CxP) for the building’s thermal envelope in accordance with ASHRAE Guideline 0–2013 and the NIBS Guideline 3–2012 as they relate to energy, water, indoor environmental quality, and durability.
|Who?||Going back to the fish tank scenario, every character plays an important role in the building enclosure commissioning process. Your imaginary daughter Laura is the owner/manager of the aquarium, who crafted her Owner’s Project Requirements (OPR) through a sketch. Your neighbor Emma is the architect who designs your aquarium (building), and Emma’s husband is the contractor who executes the final design into a product. Finally, you act as the BECx Agent who manages throughout the process and is responsible for checking for the final quality of the tank (building envelope).|
|When?||The entire BECx process should begin as early as possible. A BECx authority should engage with the owner and design team early in the design process, helping them incorporate clear envelope objectives into the OPR. The entire enclosure commissioning procedure should typically be completed before the commissioning of active mechanical, electrical, and plumbing systems.|
|How?||There are 4 main phases in the LEED requirement for BECx: |
1. Early Design
A. BECxA should be involved in reviewing OPR through a charrette to define envelope performance goals clearly early in the Design Phase (i.e. durability of materials, warranties, air infiltration, required maintenance, etc.)
2. Design Phase
A. Conduct schematic design meetings, assist in building envelope reviews of BOD documents, and make sure designs are compliant with OPR.
B. Prepare BECx Plan based on OPR and BOD entries.
3. Construction Phase
A. The BECxA will review submittals and inspect mock-ups and initial installations to identify potential issues before all installation is complete
B. Verify seasonal testing
4. Post-Occupancy Phase
A. Review envelope conditions 10 months after substantial building completion
B. Verify operator and occupant training delivery
C. Interview building facility managers
D. Develop an on-going commissioning plan
Why Should One Consider it?
Considering envelope commissioning at an early stage can help the building owner to better understand their goal, provide guidelines for careful material choices and design, and encourage collaboration between MEP and envelope designers. There are additional benefits such as improved building durability, improved building performance, and educated building operators — not to mention that pursuing enhanced commissioning can potentially earn a LEED project two additional points.
With many successful building commissioning projects under our belt, Verdical Group is here to help answer any questions you may have. We invite you to contact us to learn more about our services or simply to ask a quick question about how the process may impact your project.