HVAC System Solutions by SM Clean Room Solutions

Understanding Air Handling Units (AHUs)

**Air Handling Units (AHUs)** are fundamental components of a building's HVAC system, responsible for the circulation and conditioning of air. They are utilized to supply fresh, conditioned air into a building or to extract stale air, playing a crucial role in maintaining indoor air quality and comfort.

• An AHU essentially consists of a large, insulated metal box containing several key elements: a powerful fan, heating and/or cooling coils, various types of filters, sound attenuators to minimize noise, and dampers for airflow control. In most configurations, the AHU is connected to a network of air distribution ductwork, directing conditioned air throughout the facility. Alternatively, for certain applications, the AHU can be designed to be open directly to the space it serves.
• The supply air passing through the AHU undergoes a thorough filtration process and is then either heated or cooled. This conditioning depends on the specified duty requirements for the space and the prevailing ambient weather conditions. In some building designs, Air Handling Units are exclusively dedicated to supplying fresh air for ventilation and extracting stale air, without active heating or cooling.
• For active heating or cooling, AHUs can be seamlessly connected to central plant equipment, such as boilers (providing hot water) or chillers (providing chilled water). These units facilitate heat exchange with the incoming air. As an alternative, heating or cooling can be generated directly within the air handler through electric heating elements or integrated direct expansion refrigeration units.
• When AHU systems are employed to extract stale air from a building, a controlled proportion of this extracted air can be strategically recirculated. This recirculation optimizes energy efficiency by reducing the need to fully condition 100% of the incoming supply air. Furthermore, AHUs can incorporate advanced heat recovery mechanisms, allowing them to efficiently extract heat from the air being expelled and cleverly repurpose it to pre-heat the incoming supply air, leading to significant energy savings.

Air Handling Units vary considerably in size, capacity, and complexity, as they are precisely designed to perform specific functions tailored to each unique application.