Energy saving operation of the inverter is represented by comparison with commercial power supply operation. 　

For example, to control air volume of an air conditioner:
- Motor driven by commercial power supply + dumper control: To reduce air volume, the fan generates the maximum air volume and the dumper escapes extra volume. Under this control, air leaking from the dumper is the energy loss.
- Inverter operation: The inverter lowers the fan rotation speed to control air volume. No air is escaped from the dumper and no energy is lost. This saves energy.

As the output (W) for fan control decreases in proportion to the cube of the air volume (rotations per minute), more energy can be saved as the rotations per minute decrease.