How are ventilation rates and outdoor air quality verified during Cx?

• A. Rely only on BAS setpoints.
• B. Only measure indoor air.
• C. Ignore CO2.
• D. Measure OA intake, verify sensor accuracy, ensure outdoor air proportion meets design and codes; monitor CO2.

Answer: (D)

During Cx, ventilation rates and outdoor air quality are verified by measuring the actual outdoor air being delivered, confirming sensor accuracy, and ensuring the outdoor air fraction in the supply meets the design and codes, while also using CO2 as a practical indicator of ventilation effectiveness. This means checking OA damper positions and flow with calibrated instruments, documenting the delivered outdoor air flow, and validating that sensors (including CO2 and airflow sensors) are calibrated and placed so readings reflect real conditions. By confirming that the proportion of outdoor air in the mixed air matches the design and code requirements, you ensure the system isn’t just following a setpoint but actually delivering the intended ventilation. Monitoring CO2 provides a live check on occupancy-driven air quality and helps reveal issues like inadequate ventilation or sensor drift; if CO2 levels rise, it points to a need to adjust ventilation or verify sensor accuracy. Relying solely on BAS setpoints, measuring only indoor air, or ignoring CO2 would not provide a complete, real-world verification of both rate and air quality.