What is the minimum outdoor airflow required to be supplied to each zone determined by?

The minimum outdoor airflow required for each zone is primarily determined by occupancy classification. This concept is rooted in the need to ensure adequate ventilation based on the type of activities taking place in a space and the typical number of occupants. Different occupancy classifications (such as residential, office, commercial, or industrial) have distinct ventilation requirements due to varying activities that may produce different levels of contaminants and varying needs for fresh air.

For example, spaces with high occupant density, like assembly places or classrooms, require more outdoor air to maintain indoor air quality than areas with fewer occupants, such as storage rooms. Standards such as those from the ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) guide these requirements and help in determining the appropriate airflow rates based on the occupancy type.

While building size, number of windows, and seasonal changes can influence ventilation strategies and the design of HVAC systems, they do not directly dictate the minimum outdoor airflow amounts as occupancy classification does. Therefore, focusing on the specific use of a space and its associated standards leading to airflow determinations is essential.