By Jonathan Lloyd, in The NEBB Professional – Q1 2022 Edition
Testing, Adjusting, and Balancing of air conditioning systems is an incredibly important phase of every building and facility, no matter its function or purpose. There are multiple stages to be considered during design, construction, testing, and even post-completion. In this document, I will provide insight into a few of the important and often overlooked essentials of building systems.
The opinions in this article are my own and, although they may align with other organizations, they remain solely my own opinions.
Conditions & Comfort
Temperature is probably the most obvious or perhaps, to put it better, the most talked-about element of air conditioning. Temperature to the tenant or occupant is a simple word that means simply “make me comfortable.”
Unfortunately, temperature has many deciding factors that stretch from design through the installation and commissioning even to the way the space is used.
To break this down, I’ll use an example. Let’s take a print/copy room (Only the engineer isn’t aware it’s a print room).
The engineer generates a flow rate on the room requirements, and it should work. No design review takes place, there just isn’t time, and the installation process gets underway. The flexible duct is to be installed to a standard, but that’s too costly and time-consuming, and no one does it right anyway.
Now the balancers come in and they proportionally balance the registers and walk away. The tenant finally moves in, and the complaints are immediate. Typically, we address some or maybe most of these items by peer review on behalf of the client. “Hey, this is a print room. You’re going to need more air to maintain conditions in this space.” “Before you continue with the installation, I want to witness that the duct is sealed correctly and installed to the nominated standard.” “I can see that you balanced the registers but what is the unit actually doing?”
Design Reviews
Design reviews are not intended to embarrass an engineer. If I had to focus on ten projects at one time, I would miss things as well. Thankfully, the intention of the design review is to catch any design issues that can easily be missed.
During this process, test plans and reports can be generated which can assist with the review by ensuring that heat transfer requirements are sufficient. If they are not, was this intentional or does someone need to call the manufacturer to change a piece of equipment?
During the completion of the test and balance report forms, we can review the equipment design data, duct shop drawings, commissionability, accessibility, and so forth, on paper. The design engineer (engineer of record) can then ensure it is correct to the owner’s project requirements and amend the contract documents if required. Then the development of a test plan of how to execute the commissioning process can take place.
Installation & Testing
U-Factors measure the rate of heat transfer of building materials and how well they insulate a space. Every substance has a rating that needs careful consideration when designing the HVAC (Heating, Ventilation and Air Conditioning) systems for a space. Just as important is the climate surrounding the building’s location. This allows the designer to select suitable materials for both the structure and the equipment.
Leakage testing is a major part of the installation process both for structure and for the HVAC systems. Energy consumption and heat transfer can be majorly affected if this process is not performed correctly. We perform the building enclosure testing to make sure that an allowable leakage rate is maintained to prevent excessive energy consumption and to always keep conditioned air within each space. The same is equally important for ductwork.
Ductwork is the conduit for the air to transfer heat from one space to the medium, where it is rejected. Heat transfer relies on the integrity of its path. If the ductwork leaks, the rejected heat is not truly rejected. In the same fashion, the energy consumed to overcome these leakages can be to the tune of 40% above the required consumption.
Setting Up the System
Testing, Adjusting, and Balancing (TAB) of environmental systems is critical in the temperature control process. All the ductwork has been sealed accordingly; however, all the air is passing through one register and not the other. This system is unbalanced and now has temperature issues.
If balanced correctly, each space will have sufficient heat transfer capabilities and will remove the desired quantity of heat from a given space. Balanced incorrectly, you will have hot and cold areas. TAB isn’t just proportionally balancing a few registers. In fact, TAB is effectively and efficiently tuning building systems to perform optimally as per the engineer of record’s (EOR) design intent.
To carry out the TAB process correctly, a thorough review of each process is a necessary component of every project. Can a system be tested and balanced correctly? Are there sufficient control points fitted to each system to ensure its most efficient setup? Does the design allow for best practices of the TAB process? How good is the equipment access? Has the design considered future service and maintenance? Has sufficient time been provided in the program to carry out the works? All of these questions must be addressed, or the occupants will suffer as a result. Once this review is completed, the execution of the test and balance process is equally important.
Testing, Adjusting, & Balancing (TAB)
Air Mixture
Air mixture is the term used when discussing outdoor air and return air. It is crucial that the right amount of outdoor air is supplied into each system’s space. Outdoor conditions can vary substantially.
The heat transfer process can be drastically affected by the incorrect delivery of the mixture. A system designed to a certain heat capacity will struggle to effectively operate if the mixture is incorrect. The designer has calculated the heat transfer process at a certain outdoor air infiltration percentage. If this mixture is incorrect, the system will struggle to maintain conditions. If there is too much outdoor air pressure, problems will become apparent.
Pressure
Pressure is another part of the process that requires careful attention to detail. Doors can be held open or they can be forced shut. Other components of a building, such as elevators and stairs, can be affected by too much pressure or not enough pressure. In a hospital, pressurization control is essential to contain infections and disease into a designated space.
Similarly, an operating room must keep all contaminants away from the operating table to keep the area clean. Both scenarios are achieved by controlling to a correct pressure gradient setting. The correct mixture of exhaust and/or return air, outdoor air and supply air are critical to system and building performance.
Filter Maintenance & System Hygiene
We can effectively contain, remove, or prevent contaminants from entering or leaving a space, but what do we do with the contaminants? Filtration is used to keep our systems clean. We all know this but what does it have to do with the test and balance? Setting a system correctly involves the testing of loaded filter pressures, to activate the dirty filter maintenance alarms.
The building manager needs to know when he needs to schedule a service request for filter changes. This is set by the Controls contractor through the building management system (BMS). The BMS system is also set up so that the loading of filters triggers a response by the HVAC system to maintain the correct airflow to each space, by simply increasing the speed of the fan.
All of these essential steps are carried out by the TAB contractor and provided to the Controls contractor.
Key Findings
Are You Getting What You Paid For?
A sad fact in the construction industry is that we live in an age of price-driven decisions. Quality is one of the last things considered when designs are submitted. “Value engineering” is more common and is essentially a cost reduction exercise. The cheapest price wins on installation and commissioning exercises. Many deficiency issues found during the testing process of the project are just swept under a very lumpy rug.
Quality Assurance
The Construction industry is aligning with organizations that simply cannot control quality. They do not police it and they have no contingency plan for it. This has opened the doors to poor practices and enables this very practice to thrive.
Compression of Schedule
The construction industry has further complicated the building process by consistently compressing the construction schedules to unachievable time frames. The processes that must be in place are either lost through a “corner-cutting” process or often left out altogether.
Conclusion
There are plenty of NEBB Certified Firms, NEBB Certified Professionals & NEBB Certified Technicians all over the world. As a Building owner, occupant or even a contractor in the construction process, you shouldn’t settle for less! The costs may vary slightly up front, but you never win or lose a job on the test and balance contract. To truly know that you are getting what you have specified and are paying for, you can trust and rely on a NEBB Certified Firm to assure quality during every task. NEBB Procedural Standards are second to none.
Key Takeaways
- Always specify NEBB in your contract documents
- Ensure the specifications are followed throughout the project
- You want your TAB firm to start as early as possible on the project
- Close monitoring of system design, installation and setup are essential
