What is an Air Handling Unit (AHU)?

air handling unit

An air handling unit is also known as the AHU, is a collection of parts that are housed in huge, easily accessible boxes, also known as modules that keep the proper airflow requirements for purifying and regenerating the indoor air inside a building or other premises.

They are typically erected on the roofs of buildings. Through pipes, the air is circulated to every room in the building.

AHU on top of the building
Air handling unit on building rooftop

The primary roles of an AHU

Alongside managing properly the ventilation in the inside through outside air, in addition, the AHU also performs the following functions:

  • Control and filtering on the quality air that enters the interior are made possible by air purification filters and, depending on the longevity of these filters the air will be free of contaminants.
  • Control of the temperature that regulates the system of air conditioning whether it is hot or cold to ensure that the thermal sensation inside the room is satisfied.
  • Monitoring relative humidity for better indoor comfort.

The locations where the AHU is designed are the ones where the circulation of people is extremely vast and can hold a large number of people simultaneously and where natural ventilation is not sufficient such as hotel dining rooms, restaurant rooms, function rooms, or rooms for conventions.

It’s also a good choice for spaces that have the highest hygiene requirements, such as clean rooms, laboratories, or operating theatres, for instance.

The air handling unit is also a good choice for areas that require high hygiene standards. AHU can also be utilized to cool areas in which air conditioning is supplied through radiant heating or underfloor heat for instance.

What is an AHU compose of?

Air intake units: air handling units take in the air outside, which is then treated before being distributed to the rooms. Alternatively, the air inside can be “recycled”.

  1. Filter: based on the need for purity of the air, the filter that is used will contain higher or fewer particles, viruses, and bacteria, odors along with other contaminants in the air.
  2. Fan: This is an electromechanical device that lets air out to move it out of the AHU through the ducts which are used to distribute the air across the rooms.
  3. Heat exchangers: Devices that transfer temperature between two fluids, in this instance air and coolant, separated by the solid barrier.
  4. Cooling coil: air that passes through this unit is cooled. Through this process, water droplets are created and then collected in a condensate tray due to the built-in droplet separator.
  5. Silencer: Coatings that greatly reduce the level of sound in the installation.
  6. Plenums are empty spaces where the flow of air is homogenized.
parts of air handling units
Components of Air Handling Unit
AHU parts

The efficiency of the energy used by air handling unit

The main goal of the air handling system is energy efficiency. This is now a legal requirement as of the European Ecodesign Regulation 1235/2014.

Through the use of heat recovery units AHU, the AHU helps to reduce the amount of energy for air conditioning. Because in the exchanger, indoor and outdoor air are mixed.

As a result, when the air is brought into the coil, the temperature contrast is reduced and consequently, the contribution of the climate is smaller and the energy consumption is well reduced.

The variable regulation of the system means that the fan can operate according to flow demands, which reduces their energy consumption.