What is the main disadvantage of a centralized air conditioning system?

The main disadvantage of a centralized air conditioning system is that it is challenging to achieve precise control over individual room temperatures. In a centralized system, one main air handling unit serves multiple spaces, distributing conditioned air throughout the building. This can lead to situations where temperature regulation varies significantly between different rooms, especially those located far from the air handling unit. Each area may have different heating and cooling needs based on factors like occupancy, solar gain from windows, and the specific functions of the spaces, making it difficult to satisfy all areas uniformly.

While other aspects like noise from the air handling unit, the requirement of a roof deck, and bulkiness of the system can be relevant considerations, they do not directly impact the controllability of room temperatures to the extent seen in a centralized system. Effective temperature control is crucial for comfort and energy efficiency, which is why this is considered a significant disadvantage.