Selecting efficient ventilation fans and keeping them in good working condition will keep operating costs down. Efficiency Factors Fan efficiency is often measured by the amount of air moved per unit of electrical energy input to the fan motor. At least five design factors influence the energy efficiency of a ventilation fan. These factors should be considered when comparing and purchasing fans. Motor efficiency can have a major influence on overall fan and ventilation system energy efficiency, and hence operating costs.
Some manufacturers offer fan models with high efficiency motors.
Although usually more expensive initially, high efficiency motors can require over 20 percent less energy to operate than low efficiency motors. Speed of the fan motor and blade also influences fan efficiency. As the speed of a fan increases, turbulence of the air moving through the fan increases and efficiency decreases. Turbulence is a primary factor influencing the noise level of a fan. A fan or ventilation system does not need to be noisy.