Although quite ideal for most systems, CAV also presents limitations that must be considered when using this system. Such limitations are the following:

 

• Inefficient Use of Energy: energy losses in CAV systems are much higher compared to other common HVAC systems (especially compared to VAV). Because of this, CAV is best used for residential and small buildings, and is not ideal for use of commercial and high-rise buildings. This increases costs over the life of the system.

 

• Constant Air Volume: affects the efficiency of the system when it supplies the same air flow rate when less would be sufficient.

 

• Oversized Ducts: increases design cost, as well as operational cost as there is more leakage in the air distribution, making the fans work harder and less efficient.

 

• Limited Temperature Control for Single Ducts: for systems using single duct CAV, temperature control may be difficult as the same temperature is supplied to the entire zone. If one area needs higher/lower temperature, the temperature within the whole zone has to be adjusted as well.

 

• Need for Additional System: additional subsystems are sometimes needed to help control moisture. In addition, for multi-zoned systems, subsystems are needed to service each zone.