The Test, Adjust and Balance (TAB) Kick-off!
One of my favorite components of our job is participating in the work completed by the TAB contractor. Their behind the scenes roll is critical to a well-functioning building and TAB work is often squeezed into a challenging time frame at the very end of a project. They balance pumps, valves, fans, and air dampers throughout an entire building, often with challenging access. Their final work product is a detailed report and a building that operates per design, in large part, thanks to their efforts.
The commissioning provider has a tremendous opportunity to contribute to this critical process. Built into Elevate’s commissioning (Cx) specifications, Cx Plan and Cx scheduling is a TAB kick-off meeting that happens at the start of the onsite TAB effort (prior to the TAB work beginning). The meeting is scheduled and coordinated by the CxP and requires the attendance of the TAB contractor, the building automation system (BAS) contractor and ideally the owner operating team. The mechanical contracting team and general contractor are both invited as well for scheduling and coordination purposes.
The goal of the TAB kick-off meeting is to create shared objectives and a cohesive team made up by the TAB, BAS, and Cx project leaders. This is the first point on a project in which this trio will spend significant time together, providing a strong foundation for the complex TAB and controls work ahead. This is also the perfect time for the owner operating team to become involved with the commissioning process!
Here is a sample list of agenda items for this meeting:
1. Review the TAB work schedule (previously determined and set by contracting team). Specifically detail how the schedule will integrate with TAB verification (Cx process) and Functional Performance Testing (Cx Process).
Review and agree on the TAB reporting requirements, typically provided in the project specifications.
Review the Cx TAB verification process including the Cx TAB report review and Cx onsite verification that will occur after TAB work is completed.
2. Review the mechanical equipment schedule. The CxP should prepare a list of equipment highlights or challenges to review during the meeting. These items might be populated from the equipment schedule, the project BAS integration meeting (completed earlier in the project), or the commissioning design review comments populated before construction began.
3. Review the BAS and verify that the TAB contractor has the proper controls access they need to achieve their scope of work.
4. Related to item 5, review the supporting roll to be provided by the BAS contractor.
5. Review processes of the mechanical system’s “sequence of operation” that require balancing inputs and results. This will prevent big issues that might otherwise come up during the functional performance testing commissioning phase that follows TAB work. The following is an example of a fan sequence which integrates with building static pressure and requires the TAB contractor’s work. (Note: this exhaust fan is part of a 100% outside air ventilation unit.)
Exhaust Fan Enabled (with variable frequency drive):
1) Modulate fan speed between the minimum speed setpoint (initial setting: 25%) and maximum speed set point (initial setting: 100%) to maintain the exhaust air flow setpoint (EAFS). EAFS is determined by the following equation:
a. EACFM = SACFM – BPCFM – EFCFM where:
b. SACFM = Supply Air Flow
c. BPCFM = Building Pressure Air Flow as determined by the TAB contractor to achieve space pressure +0.03 inH2O between interior and exterior spaces.
d. EFCFM = Exhaust Air Flow. This value is equal to the sum of the associated exhaust fans within the controlled area as indicated by the scheduled values.
No different than other Cx processes, this TAB kick-off meeting should be planned and built into the job on a project specific basis. Ideally, this meeting is held several weeks before TAB is scheduled to begin. Budgets may prevent this from occurring but in some instances, budget problems can be solved by having the operating team be part of the Cx team. A more complex (or critical) building like a lab, data center or hospital should absolutely have this meeting scheduled ahead of the work. The commissioning specifications for the project (prepared by the commissioning provider) can provide the framework for the project-specific meeting requirements.