Last month, I described how the air and water testing, adjusting, and balancing (TAB) contractor is brought into a typical construction project. In summary, it involves contracting with a TAB contractor early in construction and then bringing that TAB contractor onto the site to perform the balancing work at the end of construction. The entire construction phase spans these two milestones, and the TAB contractor is most often not involved during this phase when designs are clarified and system changes are made.
It goes without saying that the installing contractors must bring the TAB contractor up to speed regarding relevant requests for information and change orders before the TAB contractor can meaningfully balance the systems. In addition, many balancing specifications are generic in nature and do not necessarily stipulate the project-specific balancing requirements and documentation needed from the TAB contractor.
Ideally, and as documented in the AABC/ANSI National Standards for Total System Balance, the TAB contractor does have responsibilities during the construction phase. These responsibilities include preparing a project-specific balancing plan and TAB report. The AABC/ANSI standards also include specification language that binds the project coordinator to convening a TAB coordination meeting after the contract is awarded and as soon as the construction schedule has been developed. This meeting, which exists to “develop a testing schedule for the project,” is to include the TAB contractor; installation contractor; and the mechanical, electrical, and building automation subcontractors.
I can count on one hand the number of balancing plans I’ve seen over the past 30 years of my career; ditto for the number of TAB coordination meetings of which I’ve been made aware. Without analyzing why so many balancing contractors and the contractors who hire them do not follow these elements of the ANSI standards, I’d rather be pragmatic about how to efficiently and effectively integrate the TAB contractor into a construction project.
I recommend including a TAB integration meeting as a standard element of the commissioning process, just like we include a controls integration meeting. The TAB integration meeting should be held sometime after the controls integration meeting, because the controls meeting will identify issues that need to be coordinated with the TAB contractor. Realistically, the TAB integration meeting will be held approximately two to three months before the scheduled start of balancing.
A prerequisite to the TAB integration meeting will be the delivery of key project documents to the TAB contractor. These should include approved submittals for all air and water system equipment, answers to requests for information, and all change orders associated with air and water systems, the approved controls submittal, and the latest project schedule. The TAB contractor needs to be familiar enough with all of these to be able to ask questions regarding key elements that are missing and/or need further clarification in order for the TAB contractor to efficiently perform the balancing work correctly the first time.
The following are agenda ideas for the TAB integration meeting:
- Create a detailed list of systems and equipment to be balanced.
- A project-specific list is not typically provided in the contract specifications.
- Decide if you’ll be balancing just new equipment or balancing some existing equipment to be reused.
- Confirmation of balancing processes to be followed for complex, integrated systems.
- In what position should controls devices be during balancing?
- Should terminal unit fans be on or off during DOAS balancing?
- Requirements to measure systems’ performance in multiple modes of operation.
- Coordination with packaged equipment start-up and documentation.
- Rooftop units;
- Kitchen ventilation systems; and
- Computer room air conditioning units.
- Coordination with the controls contractor.
- Control system user interface access and training for the TAB contractor.
- The control system parameters to be determined by the TAB contractor.
End-of-project surprises are the bane of any project. Investing time and effort during the construction phase to clarify expectations and plan the process, communication channels, and schedule for air and water balancing will pay off in a much quicker completion of successful balancing. This can lead directly to more efficient completion of commissioning functional testing and on-time project completion.