The mechanical exhaust rate for uninhabited spaces should not fall below what value per square foot of horizontal area?

The guideline for the mechanical exhaust rate for uninhabited spaces is established to ensure adequate ventilation and air quality management in areas that are not regularly occupied. The specified value of 0.02 cubic feet per minute (cfm) per square foot of horizontal area ensures that even in spaces without regular human presence, there is sufficient airflow to dilute potential contaminants, control moisture, and maintain overall air quality.

This standard is particularly important in spaces such as attics, basements, and mechanical rooms where stale air or pollutants can accumulate due to lack of airflow. By maintaining the exhaust rate at or above 0.02 cfm, the code aims to promote safety and proper environmental conditions in these areas, preventing issues such as mold growth or the buildup of hazardous gases.

Understanding this requirement helps in the design and implementation of HVAC systems, ensuring compliance with the International Mechanical Code and safeguarding the health and safety of building occupants.