Which of the following factors does NOT affect the efficiency of a fan in a ventilation system?

The efficiency of a fan in a ventilation system is influenced by several factors that dictate how well it can move air. Fan size, air density, and humidity of the air each play crucial roles in determining the overall performance of the fan.

Fan size relates to the volume of air that can be moved. A larger fan can generally move more air than a smaller fan, assuming all other conditions are equal. Air density impacts the mass of air that the fan moves; as density changes (for example, due to temperature or altitude), the fan’s efficiency can change because it must work harder or easier to move the same volume of air.

Humidity affects the density of the air as well; humid air is less dense than dry air. Consequently, the presence of moisture can change how efficiently the fan operates, adjusting the amount of work needed to circulate the air.

Conversely, the color of the fan does not have any impact on its efficiency. While factors like color may influence heat absorption or aesthetic considerations, they do not affect the dynamics of airflow or the mechanical function of the fan. This makes it clear why this option stands out as the one that does not affect ventilation efficiency.