CAV system is composed of both primary and secondary subsystems. Primary subsystems are those that are vital in controlling temperature, moisture and particulates. For CAV, these subsystems are the:

 

• Air Handling Unit (AHU);

• Chiller;

• Boiler;

• Cooling tower.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Secondary systems, on the other hand, are those that distribute the products of the primary units to a given space. For instance, in CAV the secondary units are ducts and pipes, which distribute air to different zones.

 

The interaction of the primary and secondary subsystems are: the air is cooled through the chiller, and warmed through the boiler. The chiller is connected to the cooling tower to exhaust air, and to the AHU, where air is treated. The AHU contains: filters, heating and cooling coils, fans, dampers and humidifiers, which will regulate the HVAC parameters it controls. The AHU is then connected to the ducts, which distributes the chilled air into the zones. The boiler operates similar to the chiller, except that it supplies warm air into the AHU instead of cool air.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The components of the CAV system are typically made of metal, galvanized and insulated for protection. AHUs, for instance, are typically made of steel framing or metal insulated infill panels. Such configuration reduces heat transfer from the AHU, while at the same time providing acoustic attenuation. Insulation materials are chosen based on their thermal and acoustical performance, as well as its contribution to indoor environmental quality (IEQ).