Understanding The Importance of Air Handling Units in Office Spaces

by Rudra S. Consultant

An Air Handling Unit (AHU) is a critical part of a building’s air conditioning system. It is designed to cool down bigger spaces and also helps in ensuring optimum Indoor Air Quality (IAQ). Each structure may have several AHUs and the quality of the air that prevails in an office space depends largely on the overall functioning of the AHU and its related elements. Another important thing is how properly is the AHU upheld. Many times, it remains a neglected part of a HVAC system workers which cause poor IAQ issues inside the workspace.

Due to the outbreak of COVID pandemic, it has become important than ever for HVAC workers to understand the importance of Air Handling Units (AHUs) in office spaces and their maintenance in delivering optimum indoor air quality. According to a leading Air Handling Unit manufacturer in India, the rise in Covid infections were primarily seen in office spaces where AHUs were not maintained properly.”

Basics of AHU Design

The formula that it primarily used in this domain is Q=1.1 x CFM x T, in which Q refers to the sensible load, T means the temperature variation between the incoming and outgoing air supply, and CFM refers to the volume of air that is meant to be supplied for keeping a particular temperature. All these elements can be used to find out the amount of air that circulates to eradicate the sensible heat. The conversion aspect for the atmospheric pressure under which the AHU takes charge is 1.1, with 1.1 denoting to operations at sea level.

The air velocity over the heat transfer exteriors plays an important in regard to the design of cooling coil. The coil will be smaller and the pressure drop will be greater as the velocity goes up. The opposite is true when coil velocity is brought down. The fan size tends to be affected by the stated velocity, which will then have a say on the amount of energy that AHU utilizes.

The filtration system in use greatly affects how perfectly the AHU takes charge since filters are the heart of the AHU because they prevent dust and other pollutants from entering the office environment. Aerosols, which include contaminants including dust, mites, smoke, and others, are gauzed in unit of microns (micrometre).

Controlling Capacity of AHUs

A workspace's heat load tends to change throughout the daytime which takes place due to the prevailing changes in occupant density along with the external loads such as temperature variations. Hence, a method to determine capacity management becomes crucial to ensure that the workplace is cooled in a seamless manner. An AHU manufacturer in India can choose from the following techniques for this:

• Installing a bypass line between the chilled water ingestion and outward paths to change the flow of chilled water over the heat exchanger. The charge on the bypass line is managed by experts to allow the passage of more (when room temperature is on the upper end) or less (when room temperature is at the lower end) water to the heat exchanger given the incoming room temperature.

• By controlling the volume of the air going to the room through a damper, chilled water has been found to maintain a uniform temperature. Depending on the temperature of the return air, the damper opens or closes accordingly.

• The CFM is modified dependent on room temperature through the placement of a Variable Frequency Drive (VFD) on the Fan motor. Considering the power consumption changes as a cube of the motor speed, this is undoubtedly the most viable approach to change the capacity.

Maintenance of AHUs

Comparatively speaking, maintaining the AHU is easier than maintaining other, more complicated building equipment. The following are important considerations for AHU maintenance:

• Filter health, which includes checking for any damage to the filtering surface as well as the requirement for clean filters. The differential pressure between the filter's input and exit is a metric used to assess the filter's condition.

• Air flow measurement helps in ascertaining the condition of the Fan as well as the filters. The CFM value during operation when compared to the design values will give the maintenance team an idea of how the whole AHU is running

• As the air from AHUs gets into the office environment, cleanliness becomes crucial. In a bid to prevent the AHU rooms from being utilised as warehouses, the HVAC handlers should make sure they remain free from dust and other contaminants.

• The motor and belt are checked at regular intervals as part of the drive system's safety inspection.

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Created on Sep 8th 2023 06:40. Viewed 149 times.

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