What is ventilation effectiveness?

• A. A measure of how well the ventilation system dilutes indoor contaminants.
• B. The noise level of the ventilation system.
• C. The energy consumption of fans.
• D. The total outdoor air supply only.

Answer: (B)

Ventilation effectiveness measures how well the air that’s brought into a space actually dilutes and removes indoor contaminants. It’s about the distribution and mixing of fresh air so that pollutant concentrations drop throughout the room, not just the total amount of air that comes in or how loud the system is. So it focuses on dilution performance, not acoustics, energy use, or simply the quantity of outdoor air. The other ideas describe noise, energy consumption, or ventilation rate, which don’t directly capture how effectively contaminants are reduced in the occupied space.