Which statement best describes occupancy density in VRP?

• A. It has no effect on outdoor air requirements
• B. It determines the color of the air
• C. It helps determine the outdoor air required per space
• D. It determines the cost of equipment

Answer: (C)

In VRP, how crowded a space is directly sets how much outdoor air that space needs. The ventilation rate isn’t determined by room size alone; it combines two parts: a per-person rate and a per-area rate. The number of people is found from occupancy density (people per unit area) times the space area, N = density × area. That N then drives the outdoor air requirement through the per-person component, and the space area drives the per-area component. So higher occupancy density means more people, which increases the required outdoor air to maintain IAQ. This is why occupancy density is used to determine the outdoor air required per space.

This isn’t about the color of the air or the cost of equipment, and it does have a direct effect on outdoor air requirements because it sets the occupant count that influences ventilation needs.