In VRP, the outdoor airflow rate is determined based on which factors?

• A. Occupancy and space characteristics.
• B. Building age.
• C. Exterior color.
• D. Utility rates.

Answer: (A)

In the Ventilation Rate Procedure, the outdoor airflow is set by how much contaminant load the space is expected to generate and how large the space is. You end up calculating two values: one based on the number of people (outdoor air per person times the design occupancy) and one based on the space area (outdoor air per unit area times the floor area). The VRP then uses the larger of these two requirements, ensuring there is enough ventilation to dilute contaminants from both occupants and the space itself.

That’s why occupancy and space characteristics are the factors that determine the outdoor airflow. More people increase contaminant generation, and larger spaces can dilute contaminants over a greater volume, which both drive higher required outdoor air. The other options—building age, exterior color, and utility rates—do not determine outdoor air under the VRP.