Fans and pumps use motors and drives. The electricity consumed by motors in buildings is significant. Globally electric motors are responsible for 40% of all electricity consumption [The Carbon Trust, Motors and Drives, 2011].
Operational costs of motors far exceed the initial capital costs; therefore there is the potential for huge savings in energy through efficient use of motor drives.

Oversized motors are inefficient. It is relatively easy to measure the electrical current to the motor and compare this to the rated current.

Incorrectly sized pumps should be sized so that they run at between 50% and 90% of their peak load capacity. Undersized pumps may be running constantly at peak load which is not efficient, while oversized pumps will be running at reduced efficiency (i.e. below 40% rated capacity) all the time.