What happens to outdoor air amount in a VAV system?

Prepare for the Certified Indoor Environmentalist (CIE) Exam. Study effectively with flashcards and multiple choice questions. Each question includes hints and explanations to enhance understanding. Ace your exam with confidence!

Multiple Choice

What happens to outdoor air amount in a VAV system?

In a VAV system, outdoor air is introduced as a fixed percentage of the total supply air. As the system reduces the overall airflow under part-load conditions to save energy, the outdoor-air amount scales with it, so the outdoor-air delivered decreases proportionally. This keeps ventilation proportional to the amount of air being circulated. In practice, there’s usually a minimum outdoor-air rate to meet ventilation codes, so the outdoor-air amount won’t drop below that minimum. The other ideas aren’t correct because outdoor air isn’t kept at a constant volume regardless of total air, it doesn’t increase when total air decreases, and it isn’t eliminated.

In a VAV system, outdoor air is introduced as a fixed percentage of the total supply air. As the system reduces the overall airflow under part-load conditions to save energy, the outdoor-air amount scales with it, so the outdoor-air delivered decreases proportionally. This keeps ventilation proportional to the amount of air being circulated. In practice, there’s usually a minimum outdoor-air rate to meet ventilation codes, so the outdoor-air amount won’t drop below that minimum. The other ideas aren’t correct because outdoor air isn’t kept at a constant volume regardless of total air, it doesn’t increase when total air decreases, and it isn’t eliminated.

More practice questions