The topic of aligning Commissioning with Testing Adjusting and Balancing (sometimes referenced unfavorably as Cx vs. TAB, or TAB =/≠ Cx) arises from time to time. In the interest of today’s critical need for accurately optimized air quality and overall building performance, we talked with three BCxA subject matter experts who have significant field experience in both Cx and TAB. Jim Magee, President, Facility Commissioning Group; Tom Bedford, Commissioning Specialist, MCW Hemisphere Ltd.; and Kris Pylate, ACP, Page Southerland Page, Inc.
We asked a dozen questions about who, what, why and how building commissioning should – or should not – be more aligned with TAB for efficient project delivery. The experts’ answers and varying opinions, below, end with a final section by Jim Magee, CxA, EMP, LEED AP BD+C, on “A Case for Benefits of Cx/TAB Teamwork.”
*After reading this article, please voice your opinion and discuss with other professionals on the BCxA LinkedIn.
Do you have to be TABB-, AABC-, or NEBB-certified to be a TAB contractor?
Technically no, but many specs require it. If you are approved by the owner or engineer on the job, you do not have to be certified. For a large design project, participation as a certified TAB contactor is typically a function of the particular project tasks added to a specification. Certification with a recognized agency may not be written into contract language. For smaller projects, there may be no balancing provided for in the design and/or budget.
If not, who else can be contracted to do TAB?
Tom: In my experience, sheet metal contractors will take on this role. In a large mechanical contractor’s shop, there may be an individual or two who take on the QA/QC aspect of an installation. All it really takes is someone who has the foresight (there may be a better word here!) to buy the equipment.
Kris: Anyone with experience, or even if they are good at selling themselves, unfortunately. I have been part of many TAB cleanups where a “Balance” was performed by unqualified contractors.
Who (what project entity) typically engages the TAB contractor?
Tom: It could be either the sheet metal contactor or the mechanical contactor. Sometimes the general contractor carries this cost.
Kris: For the most part it is the owner. That is also the best case for the Tab contractor. I have also worked multiple projects where we were contracted under the mechanical contractor.
When do TAB contractors engage in the design/construction process?
Tom: I seldom see a TAB contractor involved as early as design. Sometimes, they are tasked with several site visits during construction. Most of the time they are on site in the final weeks before substantial completion or occupancy.
Kris: That really depends on the firm. From my experience, it is typically early in the construction phase when we got hands on. As far as bidding the jobs, that was late in the design phase. The ideal time to get involved would be early in the design phase.
As building control systems become more complex, and new energy efficient equipment becomes standard, technicians will need more in-depth knowledge to balance HVAC systems.” UC Davis WCEC Technical Report, January 4, 2021, “Testing, Adjusting and Balancing HVAC Systems: An Overview of Certification Agencies,” examines the benefits of using a certified contractor for TAB.
What do TAB contractors do that CxPs don’t do … and vice versa?
Tom: This depends on the “trust but verify” slogan of any particular CxP. The TAB report should be reviewed thoroughly and “spot tested” to ensure that enough data has been captured for adequate troubleshooting if required at a later date. This varies extensively with the individual CxP and the same goes for the TAB tech. CxP tends to take a higher-level view of the installation, performance and operation of various systems. Typically, the CxP is on the project longer, sometimes as early as the design phase and could still be with the project at end of warranty or even longer if there is a measurement and verification program specified.
Kris: More hands on! We [TAB Techs] literally tested every piece of HVAC equipment and sometimes the domestic water as well. TAB also works hands on with the control’s software daily. A lot more time is spent in the field too. Also touching electrical and plumbing. Cx requires a bit of being a jack of all trades, but master of none. Most TAB firms do not do functional testing.
Jim: TAB is limited to HVAC and plumbing systems. Cx is the broadest thing encompassing all systems. Cx is a big picture overriding operability and interconnected systems perspective. TAB is technical fluid flow experts certifying or rejecting equipment and system performance. Both roles are important, but the mindsets are different. At a certain point the TAB professional will determine it is an equipment or installation issue and that’s the end for him. The Cx pro wants to know what is the issue, is it manufacturing, system effect, design selection, what?
What kind of testing and documentation results from TAB? Who gets the results?
Tom: TAB results are a very important part of the closeout documentation required during the life of a project. In fact, these are likely the most important documents the building owner or end-user may require when troubleshooting any issues he may encounter after occupancy.
Kris: TAB gives a full air/water balance profile of the entire building’s HVAC equipment. It can also include sound, vibration, and pressure testing documentation. Typically, a test and balance report would go to the owner. Even if we were contracted under the mechanical, at the end, the owner would also get a copy of the report. Not only did it verify that the installed equipment could perform to design intent, but it would also give the end user an easy guide for belts, filters, and other maintenance items they would need.
What systems are (and are not) included in TAB?
Tom: Systems included in TAB vary with the design professional and the experience level. Typically, a standard motor test sheet (AABC, NEBB or TABB) includes enough operational data for accurate troubleshooting of air or water systems.
Kris: TAB (for the most part) consists of all HVAC equipment. Mainly electrical and plumbing are not included. Occasionally, TAB would balance the domestic hot water system as well.
What codes and standards rule the implementation of TAB?
· I’m not aware of any codes for TAB. The main TAB certification agencies have their published standards and certification procedures approved through ANSI.
· NEBB and AABC are the standards. There are local codes that can apply as well
In a non-adversarial world, what would be the best reasons FOR and AGAINST combining TAB and Cx into one approach to validating building/systems performance for comfort, health, safety, resilience, sustainability, energy efficiency, benchmarking, etc.?
· TAB work is similar to Cx work and there should be an arm’s length relationship between the installer and the test technician.
· Although attention to detail varies with an individual, this level of operational understanding and high-level approach can be done by anyone.
· Adding TAB in Cx would provide more certainty and clarification of results for end-user/building owner.
· Efficiency gained during the Cx effort.
· Building function and performance validation is a “one stop shop”.
· Performance verification is completed at arm’s length by a third-party entity.
· Gain efficiencies in Cx.
· Expand control knowledge of the HVAC system.
· Being able to be on site longer.
· In my TAB business (Canada), I combined both functions and issued a report as “Performance Verification”.
· CxP already has a full plate. Soon, they may become [more like] a project manager.
· Most Cx firms do not have the knowledge or background to perform test and balance work. For example, it is easy to review programming, but difficult to create the program yourself.
· From experience it is better to have commissioning be a third-party check for the TAB contractors. Trust but verify.
· For some CxPs it may dilute their attention to a project.
· While for some CxPs it may open a door of opportunity, for others it could drag them down a rocky road if they do not pay attention to what they are doing or try to complete TAB without correct tools and/or experience.
· Lose third party TAB verification.
· TAB included in Cx: the TAB technician doesn’t have enough knowledge for electrical, plumbing, and envelope; Cx included in TAB: CxP doesn’t have the field knowledge needed to perform a total system balance, instrument knowledge, and be able to troubleshoot issues that pop up daily.
Project and Procedure Issues
“… TAB is a component of the HVAC Cx process and as such has been offered as an independent 3rd party service by AABC agencies since 1961. I would say the AABC Total System Balance process carried out in its entirety is an early version of HVAC Cx…Even the most well-intentioned TAB technician cannot control a project or in many cases, the quality of work required to bring a project to a successful close. TAB technician should be an individual trusted and contracted by the end-user/building owner.”
Project Team Relationships. TAB engineers or techs that attempt to perform Cx on projects, even when they are not balancing those projects, experience a conflict of interest relative to their ongoing relationships with mechanical, controls and general contractors. TBEs and TBTs that attempt to perform Cx on projects, even when they are not balancing those projects, experience a conflict of interest relative to their ongoing relationships with designers who assume they will take TAB measurements for free as part of Cx diagnostics; this can be costly either monetarily or relationally. It’s difficult to go from relying on the mechanical contractor that hires you frequently to suddenly passing info to a 3rd party who reports to the entire project team. TAB personnel are in a tough spot because they have to work with contractors to accomplish their services.
Schedules. TAB company manpower schedules often conflict with Cx schedules and project deadlines; when a TAB agency cannot make a commitment to a particular project the CxP will be seen as the next level of authority to demand change in the TAB company’s schedule to meet the project schedule and this could be out of the CxP’s control: a bad situation.
Procedures. TAB procedures and FPTs are not similar. TAB procedures are executed based on standard forms; FPTs are uniquely created to match particular project specifications and design intent/owner’s project requirements. A TAB mentality of completing forms and “accounting” for air and hydronic flow capacities is crucial to project success. The means to this end might involve manually operating controls to achieve TAB requirements. FPT will subsequently put the system into verified sequence of operation.
Even when TAB is a component of the Cx process it is fundamental that different personnel should perform TAB than perform Cx. CxPs are compromised eventually if they are also asked to serve as TBEs or TBTs in addition to Cx role. Recognize that companies can exist without employees; in other words a TAB firm can provide labor to a Cx firm and vice versus. These are disclosure considerations to be taken seriously.
Successful TAB does not assure successful Cx.
A Case for Benefits of Cx/TAB Teamwork
by Jim Magee: “Independent third-party direct-for-owner Cx is my passion professionally.”
A large university near Indianapolis negotiated with FCG to include TAB in the Cx scope for their projects. We subcontracted local TAB firms. This led to FCG getting entangled in issues and responsible for TAB impacts. So we created an AABC-certified TAB agency (Synergy) owned and controlled by FCG that resulted in these observations:
· Cx engages in design and impacts TAB specifications that benefit the project and TAB firm’s ability to perform successfully.
· TAB incorporated into the overall sequence of Cx activities can increase project efficiencies (a TAB plan that sequences according to the Cx Plan)
· Troubleshooting can be more efficient in getting TAB onsite in conjunction with Cx Team mitigation meetings.
· Cx gains schedule control for TAB execution.
· CxP meeting participation can flag TAB issues where TAB may not be at meetings.
· Incorporating difficult to schedule TAB tasks like calibrating airflow monitoring stations and determining hydronic differential pressure setpoints is easier with Cx having more site presence continuity and the ability to coordinate directly with TAB agency.
· Cx monitoring of readiness reduces failed site visits because equipment is not ready for TAB.
· Achievement of follow up TAB work specified can be managed as an element of the Cx Plan for warranty phase and managed by CxP.
· Processing project documents like drawings, specs, addendums, submittals, change orders, RFIs and responses, and annotating same as projects progress and changes occur can be realized by bundling the TAB and Cx services.
· Flow of information such as duct air leakage tests, field reports, TAB reports, preliminary reports and pre-TAB site reviews can be effectively managed by Cx firm.
· Cx gains immediate access to TAB data and information as well as technical content, means and methods and reporting formats and media.
· Preliminary review of TAB documentation (document control) by Cx assures more thorough submittals and less rejection of TAB reports.
· TAB verification can be more efficiently executed with Cx affiliation, but design team member should be involved to serve as 3rd party if desired by the project team.
· Typical construction models include TAB as a sub of the mechanical subbed to a GC or GM; this affords “filtering” of TAB info to the project team that can be as subtle as when to release information, or as overt as not releasing TAB information at all.
· TAB benefits when performed independent from contractor interests; direct for owner is ideal, for CxP is good, architect direct and is necessary for the GC or GM.