First, there is much less energy used in distribution.
Fans are much smaller and pumps are essentially
non-existent. In addition, control of the smaller packaged
units is local and direct. Typically, the unit is either
on or off, which can be a disadvantage when the space
use requires that ventilation air not be turned off. However
there are some advantages associated with this control
flexibility. It allows individual thermal control and
accurate metering of use. In addition, if equipment failure
occurs it does not affect the entire building.