In recent years, a growing demand for high-performance building envelope solutions has been evidenced by the increased attention paid to this topic throughout the building design and construction industry.
Building Envelope Council (BEC) Initiative
Seeing this emerging priority, in 2004 the National Institute of Building Sciences (NIBS) Building Enclosure Technology and Environmental Council (BETEC) and the American Institute of Architects (AIA) signed an agreement to establish the Building Envelope Council (BEC) initiative. The initial goal of the initiative was to have local AIA components establish at least nine BECs by May of 2007. Since then, the program has founded 26 BEC Chapters, representing both cities and states. Today, more than 3,000 affiliated architects, engineers, contractors, manufacturers and others with an interest in building enclosures participate in BECs around the country. The Councils promote the exchange of information and facilitate discussion on topics pertaining to building enclosures and related science.
As a resource toward this effort, the NIBS, under guidance from the past Federal Envelope Advisory Committee, developed a comprehensive guide for building envelope design and construction for office and institutional building types. The Building Envelope Design Guide (BEDG) is continuously improved and updated by the BECs and can be accessed (for free) through the online Whole Building Design Guide (WBDG), a program of the NIBS.
ASHRAE Guideline 0 and NIBS Guideline 3
A development in the work of the BETEC is the creation of NIBS Guideline 3 Building Enclosure Commissioning Process BECx. The guideline, available for free through the WBDG, is intended to be used in concert with ASHRAE Guideline 0.
ASHRAE Guideline 0: The Commissioning Process describes the quality-oriented “Commissioning Process” (CxP) capable of achieving, evaluating, and documenting that a facility and its systems meet the Owner's Project Requirements (OPR). The procedures, methods, and requirements in Guideline 0 outline each phase of the project delivery and the associated commissioning processes from pre-design through occupancy and operation.
While ASHARE Guideline 0 outlines the commissioning process, NIBS Guideline 3 provides specific information related to commissioning the building enclosure. It is essential that a project’s commissioning authority (CxA) understand and comprehend the basic process provided in Guideline 0 as well as the specific BECx requirements of NIBS Guideline 3. The latter recognizes that, just like other critical elements of a building, an independent review of the commissioning process is an impartial way to see that the design and construction of facades, fenestrations, roofing, and other envelope components are all carried out and tested appropriately to perform as intended.
BECx Process in a Nutshell
The notion of “building enclosure commissioning” may conjure up thoughts of on-site performance testing. While such exercises constitute an important aspect of BECx, the process involves much more breadth of scope. BECx should begin at pre-design and continue through post-occupancy – in the same manner as the more common mechanical and electrical systems commissioning process. In fact, BECx goes hand-in-hand with the more familiar scope of mechanical systems commissioning.
In accordance with NIBS Guideline 3, the process basically looks like this:
During pre-design, the BECx team typically contributes to initial budget estimates and provides third-party expertise regarding the most appropriate building envelope materials and assemblies, what types of testing may be needed, and how project performance targets (e.g., energy or water efficiency) and/or enclosure longevity can be best achieved within project constraints and budget limitations.
Over the course of the design development process, drawing reviews are critical for ensuring the continuity of various barriers that address the damage functions – particularly moisture management. Some drawing sets exhibit problematic details; a meticulous BECx drawing review can identify potential issues before they manifest themselves in the field.
During construction, mock-ups and on-site inspections take place with regularity. Testing mock-ups serve many needs of the BECx commissioning process throughout construction. The mock-ups can identify weak points in assembly design, help a team establish the most efficient construction sequencing, and serve in training exercises. Through on-site inspections, the commissioning authority can verify that sequencing is being executed properly and better ensure that field conditions will perform in accordance with the OPR.
Field testing occurs during the pre-occupancy phase and is just as vital as mock-up testing. It is during this phase that the exercises most professionals associate with building enclosure commissioning take place. BECx protocol will ensure that an action plan is implemented to address insufficient field testing results. Ultimately, the building enclosure must meet the performance requirements specified by the owner.
During post-occupancy, BECx helps ensure that inspection and maintenance plans are in place for the building envelope and that critical documentation, such as warranties, are included the owner’s manual and delivered to the owner.
BECx in LEED
With LEED v4 for Building Design + Construction (BD+C), BECx has a vehicle for more expansive market uptake. While not mandatory, under EA Credit Enhanced Commissioning project teams have the option to pursue two points for building enclosure commissioning. Under the option for “Envelope Commissioning,” LEED asks project teams to first fulfill the requirements in EA Prerequisite Fundamental Commissioning and Verification as they apply to the building’s thermal envelope in addition to mechanical and electrical systems and assemblies. Next, teams are asked to complete the commissioning process activities for the building’s thermal envelope in accordance with ASHRAE Guideline 0–2005 and NIBS Guideline 3–2012 as they relate to energy, water, indoor environmental quality, and durability.
The Value Proposition
The case for BECx is the same any building commissioning effort: Whether during construction or occupancy, our buildings will fail in some regard. The purpose of commissioning is to assess and confirm that building systems are installed and operate as designed and intended in order to better ensure that facility owners gets what they think they are paying for.