The Role of Air Handling Units in Buildings

Victor da Silvas, Project Manager, Skanska

Adequate ventilation within a building ensures air quality by removing toxins and controlling humidity, thus mitigating the risk of condensation

Ventilation is the vital process of replacing stale air with fresh air. Without apt ventilation, buildings become susceptible to stagnant air, where microbes make the indoor air more polluted than the air outside. Ventilation is the single most crucial element of any HVAC system. It influences air quality and energy efficiency, and proper ventilation controls air quality and inhibits the spread of respiratory diseases. Ventilation air is vital in buildings where many people congregate.

Air handling units, which generally have the acronym of A.H.U, are found in medium to large commercial and industrial buildings. Some buildings, ancient high rise building, will have one large AHU located on the roof. These will supply the whole building. They may not have a return duct, and some older designs depend on the air just leaking out of the building. This design isn't so standard anymore in the latest buildings because it's very inefficient. Now it is usual to have several smaller AHU's supplying many zones. The facilities are more airtight, so it needs to have a return duct to regulate the building's pressure. 

Air handling units' condition and provide air within a building. They take fresh air from outside, clean it, heat it or cool it, maybe humidify it, and then pressurize it through some ductwork around the building areas. 

Most units will have an extra duct run to pull the used, dirty air out of the building, back to the AHU, where a fan will dispense it back to the atmosphere. Some of this return air might be recirculated back into the fresh air supply to save power. Otherwise, thermal energy can be extracted and fed into the new air intake where that isn't possible.

AHU can help buildings ensure that the air is clean and purified. AHU attains this by pushing the air through many layers of filtration. Filtration assists in removing natural and man-made substance particles from the air. This system can help provide a safer environment for patients. The system also reduces the risk of people contracting illnesses.