What is ventilation air in a building?

• A. Air recirculated within rooms
• B. Outdoor air introduced to dilute pollutants and improve indoor air quality
• C. Air that is exhausted to outdoors only
• D. Air cooled by the chiller

Answer: (B)

Ventilation air is outdoor air introduced into a building to dilute pollutants and improve indoor air quality. This fresh air is brought in through outside-air dampers and mixed with return air to reach a healthy balance for occupants. It’s different from air recirculated within rooms, which stays inside and doesn’t provide new outdoor contaminants are diluted, and from air that is exhausted to the outdoors, which leaves the building rather than entering it. While cooling can be a part of the system, ventilation specifically means supplying outside air to dilute contaminants like CO2, odors, and VOCs to maintain good IAQ.