The most efficient operation of a fan occurs at:

The most efficient operation of a fan typically occurs at moderate pressure levels. This is because fans are designed to move air effectively across a specific pressure range, balancing airflow and pressure to maximize energy efficiency.

At high pressure, fans can become less efficient due to the increased load on the motor, which often leads to higher energy consumption without a proportional increase in airflow. Conversely, at low pressure, while there may be less resistance, it can result in insufficient airflow for effective ventilation or cooling, also impacting efficiency negatively. Operating at no pressure is not feasible for fan function since airflow is essential for cooling or ventilation tasks. Therefore, moderate pressure is where fans can optimize their performance, achieving a balance between airflow rates and pressure requirements, leading to the most efficient operation.