Procedure and software work to tap TAB’s full potential.

Regular readers are aware of my quest to elevate the air and water testing, adjusting, and balancing (TAB) contractor to a third-party TAB firm working in sync with the third-party commissioning firm instead of a being a subcontractor to the mechanical contractor. During this period, our firm has been very successful with making this happening on jobs where we are the owner representative or commissioning firm.

My analogy of what a commissioning firm and a TAB firm do together is to draw upon the making of an automobile. The commissioning engineer (a.k.a. commissioning/car technician) is responsible for making sure all the interactive electronics work (electric door package, etc).

The equivalent to the TAB engineer when building a car is another car technician who is responsible for tuning up the vehicle so that the vehicle will achieve the rated mpg noted on the invoice sticker and posted on the car window.

When it comes to a building project, the commissioning engineer can verify that the sys-tems interact per the basis of design, whether the building is operating at 28 mpg or 18 mpg. It is up to the TAB engineer to tune up the building so that the energy consumption is achieved per the basis of design.


Integral to our firm’s commitment of championing third-party TAB is the writing of the Division 18 specification (commissioning being Division 17). We insist the TAB firm use the standards they publish in their organization’s book (e.g., AABC National Standards for Total System Balancing or NEBB Procedural Standards for Testing, Adjusting, and Balancing for Environmental Systems).

Interestingly, getting the TAB firm to follow their own industry standards after years of not being able to apply their procedures (TAB services routinely selected as a subcontractor to the HVAC contractor on low price) has been a challenge. You see that “deer in the headlights” look when you remind them to go to the job site and then submit their field report and attach their pre-TAB observation checklists per the specification and their organizations standards. We also specify the TAB firm complete a design review and submit their comments early in the project preferably at the time of the trade contractor’s field coordination drawing phase. We want their expert opinion on the ability to air- and water-balance the HVAC systems long before ductwork and pipe have been installed.

Leading up to the shop drawing submittal phase, Division 18 specifies the TAB firm shall submit system flow diagrams noting what they have determined to be the design engi-neer’s pressure drops before and after each air and water system component as they build the system profile.


To help this process along, I have created the TAB 1-2-3™ process in sync with the Commissioning 1-2-3™ process, which includes a system flow diagram software (TAB-3) that both a designer or a TAB engineer can use to establish the air system static pressure profile or the water system pump head profile.

After the TAB firm has created and submitted his system flow diagrams, he can then use these flow diagram documents to insert the actual pressure drops when doing the actual adjusting and balancing of the system. When an actual pressure drop reading is significantly different from the design estimated pressure drop, the TAB firm will be able to immediately recognize this and get the design engineer involved if needed. To quote Mr. W. David Bevirt, P.E. (NEBB Environmental Systems Technology manual):

“Testing, adjusting, and balancing personnel no longer can be just instrument readers, they must understand fully how to perform their work. Furthermore, they must understand at least the fundamentals of how these systems function, and use this knowledge to determine what is malfunctioning and how to correct it.”

A byproduct of the TAB-3 software system flow diagrams and its design-to-actual data is the ability to toggle “on” data for each of the flow diagrams (wide open flow, maximum flow, minimum flow) and print each diagram out, laminate the diagrams, and then bind the entire collection of flow diagrams into a TAB system book. These individual system books can then be hung on the associated unit for quick reference in the future when spot-checking system performance, troubleshooting, or considering alterations that would affect the system. These books should also be included in the final electronic TAB report.

Air and water balancing is as important as commissioning and its encouraging to see that we are making progress in elevating the TAB process, getting better results, and receiving better final documents. If you want to learn more, check out my podcast at and go to my website at to learn more about TAB 1-2-3™.  ES