Dynamic evaluation of airflow rates for a variable air volume system serving an open-plan office

Area of Science:

• Building Science
• Environmental Engineering
• HVAC Systems

Background:

• Maintaining thermal comfort and indoor air quality (IAQ) in offices relies on precise airflow and outdoor air delivery.
• Measuring these parameters is difficult in buildings with variable air volume (VAV) systems.
• Current methods, like tracer gas analysis, are complex and resource-intensive, hindering regular monitoring.

Purpose of the Study:

• To develop a practical space zone model for calculating airflow parameters in air-conditioned offices.
• To evaluate the feasibility of using carbon dioxide (CO2) as a tracer gas for real-time ventilation assessment.
• To provide building managers with a protocol for monitoring airside system performance.

Main Methods:

• Utilized a tracer gas method with Sulphur hexafluoride (SF6) and carbon dioxide (CO2) in a space zone model.
• Calculated airflow parameters including outdoor air, VAV supply, return, and exfiltration rates.
• Compared results from SF6 and CO2 to validate CO2's effectiveness.

Main Results:

• Successfully developed a space zone model for comprehensive airflow parameter calculation.
• Demonstrated the acceptability and validity of using CO2 as a tracer gas.
• Showcased the potential for using metabolic CO2 to evaluate real-time airflow rates.

Conclusions:

• The proposed model offers a practical and resource-efficient protocol for building managers.
• Using CO2 as a tracer gas simplifies ventilation performance monitoring.
• This approach can lead to improved and consistently satisfactory indoor environmental quality.