A Multi-Zone Optimal Ventilation Strategy for Post-Pandemic Hospitals: Balancing Infection Risk and Energy Efficiency Under Seasonal-Varying Respiratory Diseases Across Climate Zones

The COVID-19 pandemic has led to significant increases in morbidity, mortality, and energy consumption, primarily due to infection control measures. Hospitals, as frontline responders, are particularly vulnerable to infection risks due to dense populations and numerous viral carriers. Integrating natural ventilation to optimize air-conditioning systems is crucial for mitigating these risks while balancing energy efficiency. However, existing research has predominantly focused on mechanical ventilation upgrades, with limited attention given to the effective integration of natural ventilation. This study presents an innovative air-conditioning system that incorporates easily installable automatic window control units into existing fresh-air-handling units and fan coil unit systems. This approach allows for multi-zone simultaneous control, making it suitable for both new and retrofitted hospitals. Additionally, the study proposes an optimal multi-zone ventilation strategy aimed at reducing infection risks while enhancing energy efficiency. The performance of the proposed system and ventilation strategy is evaluated considering five common respiratory diseases, with their seasonal transmission characteristics across a wide range of climatic conditions integrated into a revised version of the traditional Wells–Riley equations. The results demonstrate that conventional systems, following China’s GB55015-2021 standard, incur high infection risks during peak-season hours for COVID-19 (1347 h), influenza (470 h), and measles (1386 h). In contrast, the proposed multi-zone ventilation strategy eliminates infection risks while only increasing energy consumption by 3–10%, utilizing outdoor wind pressure as a key resource. This solution not only enhances hospital resilience but also provides valuable technical guidance for the design and retrofitting of hospital buildings, ensuring enhanced infection control and energy efficiency across diverse climates.