What is the minimum continuous exhaust rate for a bathroom fan in R2 occupancy?

The correct minimum continuous exhaust rate for a bathroom fan in R2 occupancy is 20 cfm. This value is established by the North Carolina Mechanical Code requirements, which aim to ensure proper indoor air quality and ventilation in residential settings.

In R2 occupancy, which typically refers to multifamily dwellings like apartments, the ventilation needs are crucial due to the increased moisture and odors produced in bathrooms. A continuous exhaust rate of 20 cfm is designed to effectively remove humidity and pollutants while maintaining energy efficiency. This rate is deemed sufficient to provide adequate ventilation for smaller spaces, like bathrooms, thus preventing issues related to moisture buildup, which can lead to mold growth and other indoor air quality problems.

Choosing a higher rate, while it may seem beneficial, can lead to unnecessary energy consumption without significantly increasing the effectiveness of moisture and odor removal for typical bathroom use. Proper adherence to the specified minimum helps balance efficiency and functionality in ventilating residential bathrooms.