To reverse the rotation of an electric fan, you can follow these steps:

1. Turn off the fan and unplug it from the electrical outlet.

2. Locate the fan's motor, which is typically at the base of the fan.

3. Find the switch or switch assembly on the motor. This is usually a small, round or rectangular piece.

4. Disconnect the wires from the switch or switch assembly.

5. Reconnect the wires in the opposite order, ensuring that the hot wire goes to the opposite terminal.

6. Reassemble the switch or switch assembly and reconnect the wires to the motor.

7. Plug the fan back into the electrical outlet and turn it on.

Reversing the rotation of an electric fan is a simple process that involves swapping the connections of the motor's wires. This change in wiring reverses the direction of the electrical current, which in turn reverses the fan's rotation. According to a study by the U.S. Department of Energy, fans can use up to 20% less energy when running in the reverse direction, especially in colder months when the fan is used to circulate warm air. This energy-saving benefit is due to the fact that fans are more efficient at moving air in one direction than the other, and reversing the rotation can optimize this efficiency.