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Abstract
The COVID-19 pandemic has underscored the need for effective ventilation control in public buildings. This study develops and evaluates a smart ventilation control algorithm (SIREN) that dynamically adjusts zone and system-level HVAC operation to maintain an acceptable COVID-19 infection risk and HVAC energy efficiency. SIREN uses real-time building operation data and Trim & Respond control logic to determine zone primary and system outdoor airflow rates. An EnergyPlus and CONTAM co-simulation framework was developed to assess its performance across various control scenarios and US climate zones. Results show that SIREN can flexibly control infection risk within a customized threshold (e.g. 3%) for every zone, while traditional controls cannot. At the building level, SIREN’s HVAC energy consumption is comparable to a fixed 70% outdoor airflow fraction scenario, while its infection risk is lower than the 100% outdoor airflow scenario, illustrating its potential for safe and energy-efficient HVAC operation during pandemics.
Acknowledgment
We would like to extend our appreciation to Mr. William Stuart Dols for his guidance and support in integrating CONTAM and EnergyPlus.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Abbreviations
| ACH | = | Air Change Rate Per Hour |
| ANN | = | Artificial Neural Network |
| ASHRAE | = | American Society of Heating, Refrigerating and Air-Conditioning Engineers |
| BAS | = | Building Automation System |
| CAR | = | Chinese Association of Refrigeration |
| CDC | = | U.S. Centres for Disease Control and Prevention |
| CFD | = | Computational Fluid Dynamics |
| CO2 | = | Carbon Dioxide |
| COVID-19 | = | Coronavirus Disease 2019 |
| CVRMSE | = | Coefficient of Variation of the Root Mean Square Error |
| DCV | = | Demand-Controlled Ventilation |
| EMS | = | Energy Management System |
| FMI | = | Functional Mock-up Interface |
| GN | = | Gammaitoni-Nucci |
| HEPA | = | High-Efficiency Particulate Air |
| HVAC | = | Heating, Ventilation, and Air-Conditioning |
| IAQ | = | Indoor Air Quality |
| IECC | = | International Energy Conservation Code |
| KPI | = | Key Performance Indicator |
| MO | = | Medium-sized Office |
| OA | = | Outdoor Air |
| OSHA | = | Occupational Safety and Health Administration |
| PHEIC | = | Public Health Emergency of International Concern |
| R2 | = | R-squared |
| REHVA | = | Federation of European Heating, Ventilation and Air Conditioning Associations |
| SIREN | = | Smart ventilation for Infection Risk mitigation and HVAC ENergy Efficiency |
| SVM | = | Support Vector Machine |
| T&R | = | Trim and Respond |
| TMY3 | = | Typical Meteorological Year 3 |
| UV-C | = | UltraViolet-C |
| UVGI | = | Ultraviolet Germicidal Irradiation |
| VAV | = | Variable Air Volume |
| VRP | = | Ventilation Rate Procedure |
| WHO | = | World Health Organization |
| WR | = | Wells-Riley |
Acronyms
| = | Temperature Gradient of the Fluid | |
| = | Rate of Dissipation of Turbulent Kinetic Energy | |
| = | Dynamic Viscosity | |
| = | Density of the Fluid | |
| = | Turbulent Prandtl Number | |
| = | Effective Viscous Stress Tensor | |
| = | Zone Air Change Rate Per Hour | |
| = | Number of Infection Cases | |
| = | Ratio of Virus Carriers | |
| = | Number of Virus Carriers | |
| = | Zone CO2 Concentration | |
| = | Maximum CO2 Concentration Given a Maximum infection Risk Level | |
| = | Minimum CO2 Concentration | |
| = | Mean Diameter in the Discrete Phase Model | |
| = | Design System Minimum Outdoor Airflow Rate | |
| = | Design System Uncorrected Outdoor Airflow Rate | |
| = | Design System Primary Airflow Rate | |
| = | Zone Occupancy Density | |
| = | The Total Energy of the Fluid (including internal energy, kinetic energy, and potential energy) | |
| = | Specific Enthalpy of the Fluid | |
| = | Number of Ignored Requests | |
| = | Number of Infectors | |
| = | Mass Flux of the Fluid | |
| = | Turbulent Kinetic Energy | |
| = | Effective Thermal Conductivity | |
| = | Number of Data Points | |
| = | Spread Parameter in the Discrete Phase Model | |
| = | Air Change Rate per Hour | |
| = | Pulmonary Ventilation Rate of a Person | |
| = | Pressure of the Fluid | |
| = | Probability of Infection | |
| = | Generation of Turbulent Kinetic Energy | |
| = | Quanta Generation Rate | |
| = | Outdoor Airflow Rate | |
| = | Total Number of Requests from the Zones | |
| = | Outdoor Airflow Rate per Unit Zone Area | |
| = | Zone Critical Ratio based on the CO2 Concentration | |
| = | Zone Critical Ratio | |
| = | Outdoor Airflow Rate per Each Occupant | |
| = | Zone Request Number | |
| = | Zone Infection Risk based on the Prediction Model | |
| = | Number of Susceptibles | |
| = | Heat Generation of Absorption | |
| = | Initial Setpoint of Outdoor Airflow Rate | |
| = | Maximum Setpoint of Outdoor Airflow Rate | |
| = | Minimum Setpoint of Outdoor Airflow Rate | |
| = | Respond Amount | |
| = | Maximum Response per Time Interval | |
| = | Trim Amount | |
| = | Exposure Time Interval | |
| = | Timestep | |
| = | Delay Timer | |
| = | Velocity Component in Direction | |
| = | Velocity Vector of the Fluid | |
| = | Zone Volume | |
| = | Breathing Zone Outdoor Airflow Rate | |
| = | System Outdoor Airflow Rate | |
| = | System Minimum Outdoor Airflow Rate | |
| = | Minimum Zone Primary Airflow Rate per ASHRAE 62.1 Requirements | |
| = | Minimum Zone Primary Airflow Rate based on the Heating/Cooling Load | |
| = | Design Maximum Zone Primary Airflow Rate | |
| = | Design Minimum Zone Primary Airflow Rate | |
| = | Minimum Zone Primary Airflow Rate based on the Infection Risk Requirements | |
| = | Mean of the Actual Values | |
| = | Actual Value | |
| = | Predicted Value | |
| = | Mass Fraction of Droplets of Diameter Greater Than |