The energy efficiency of a cooling fan is typically evaluated by the ratio of airflow to power consumption, i.e., the amount of airflow generated per watt of power. Higher energy efficiency means the fan can produce more airflow with the same power consumption, resulting in better cooling performance. Choosing a high-efficiency fan not only reduces energy consumption but also minimizes heat generation, extending the device's lifespan. Additionally, energy efficiency is related to fan speed, blade design, and motor efficiency.