FIELD SERVICES
Field Services comprise the core of TAB. Some of GAC’s most requested onsite services include air balancing, hydronic balancing, sound testing, duct leak testing, and space certifications.
Generally, Air Balance consists of measuring and altering the volumetric air flow rates (CFM) at each inlet and outlet of an air distribution system. Air Balance is a crucial component to an air distribution system. It has a significant effect on occupant comfort, occupant health, space pressurization, and energy efficiency.
Occupant Comfort: In order to ensure temperature uniformity, the design air flow rates must be established and verified. Poorly proportioned systems produce hot and cold spots within a building, thus decreasing occupant satisfaction.
Occupant Health: An engineered air distribution system includes ventilation calculations which intend to provide an adequate volume of fresh air into the occupant breathing zone. These calculations and results are also a part of building code compliance. Not providing the design airflows to each breathing zone jeopardizes occupant health and wellness.
Space Pressurization: Not having the proper proportion of supply and return/exhaust air within a space leads to excessive negative or positive pressure. This can lead to difficulties when operating doors, excessive breezes (“wind tunnel” effect), fume propagation, and code violations. Poor pressurization can also significantly jeopardize occupant safety when associated with life-safety equipment such as smoke control systems.
Energy Efficiency: If an air system produces hot and cold zones, it can drastically affect energy efficiency. During the cooling season, cold zones are over-cooled by excessive air flow, thus consuming more energy than necessary. The reverse is true for hot zones in the heating season. An even greater inefficiency occurs if the thermostat resides in a zone with inadequate air flow. This significantly increases the system’s hours of operation, as it tries to condition the space.
Much like Air Balance, Hydronic Balance consists of measuring and altering the volumetric water flow rates (GPM) at each hydronic coil within the system. Hydronic Balance is a key component to a water distribution system. It has a significant effect on occupant comfort and energy efficiency.
Occupant Comfort: In order to ensure proper heat transfer across hydronic coils, the design flow rates should be established and verified. A poorly proportioned system can produce undesirable energy transfer rates (BTUH), leading to poor water, air, and space temperatures.
Energy Efficiency: If a hydronic coil does not receive adequate water flow, it affects the overall system efficiency in various ways. For instance, poor discharge air and/or water temperatures can lead to hot and cold spaces within the building. In variable air volume systems, this causes the fan to increase speed and energy consumption. Additionally, poorly controlled heat transfer rates can significantly affect the temperature split between the supply and return water temperatures. Lower temperature splits lead to increased pumping power at the Central Distribution Plant.
Duct leakage testing determines the amount of air leaking out of a duct at a specific internal pressure, thus verifying a specified leakage class. It affects occupant comfort and energy efficiency. In extreme cases, it can affect building pressurization and safety.
Occupant Comfort: Duct leakage prevents air from reaching its intended zone. Excessive leakage can lead to hot and cold spots due to inadequate airflow. (See Air Balance.)
Energy Efficiency: When leakage exists in the supply duct, conditioned air escapes into unintended areas of the building. Since significant energy is spent conditioning the air, the overall system efficiency decreases. In variable air volume systems, duct leakage also causes the fans to run at a higher speed, thus increasing their energy consumption.
Building Pressurization and Safety: In extreme cases, large amounts of air enter the system from unintended areas. This can lead to pressurization issues. (See Air Balance.)
Extreme cases can also compromise occupant health. For example, if the area of intake includes sewer piping/gas or other undesirable fume sources, that air is then distributed throughout the occupant breathing zone.
Sound Testing involves determining the effective sound produced by a system or system component. During sound testing, a baseline sound reading is taken with the system/component inactive. A second set of readings is taken with the system/component active. A comparison of the results determines the system’s contribution.
Sound levels can affect occupant comfort and, in extreme cases, long-term occupant health. Sometimes sound testing is performed as a specified procedure. Other times, it proves a useful troubleshooting tool.
Occupant Comfort: Unwanted sound (noise) can become a nuisance and distract from occupant productivity. To that end, HVAC systems are often designed with maximum sound pressure levels in mind.
Occupant Health: Prolonged exposure to excessive sound levels can jeopardize long-term occupant health in the form of hearing damage. The long-term effects depend on the amplitude and duration of exposure.
Commissioning is a Quality Assurance/Quality Control process that provides an additional level of certainty of a project’s success and the resulting owner satisfaction. It often improves a building’s operational efficiency and reduces post-construction warranty service calls.
The extent of commissioning activities varies substantially project-by-project. It can include, but is not limited to, generating a Commissioning Report, reviewing Operations and Maintenance Manuals, witnessing and/or recording owner training, conducting scheduled onsite observations, performing pre-functional and/or functional performance tests, reviewing Design and Construction Documents, and/or generating Basis of Design and Owner Project Requirements documents.
Clean rooms are critical spaces with especially stringent certification requirements. As a result, they require testing and reporting beyond the typical TAB scope. These additional requirements include, but are not limited to, integrity leak testing of HEPA filters using poly alpha olefin (PAO), measuring the particle counts, measuring the room-by-room pressure cascade, and verifying that each room meets its air change rate requirement.
Many spaces within a hospital carry more stringent testing and reporting requirements. They include, but are not limited to, the direct measurement of the room-by-room pressure cascade and verifying that each room meets its air change rate requirement.
