Performance Optimization of Natural Ventilation in Classrooms to Minimize the Probability of Viral Infection and Reduce Draught Risk

Abstract

This paper presents a detailed analysis to optimize natural ventilation performance in educational buildings to minimize the probability of viral infection (POI) and avoid draught discomfort. A whole building energy simulation tool has been coupled with the Wells–Riley equation to predict the probability of infection and Fanger’s draught equation to estimate the draught risk for classroom environments. Several parameters have been investigated, including window opening fraction (WOF), volume-to-student ratio, number of source patients, and exposure time. The analysis confirmed a dual effect of space volume on the POI where the POI can be increased or decreased simultaneously when the space volume is increased. Therefore, the WOF/(Volume/Student) ratio is introduced, and an optimization analysis is performed to determine the optimum ratio that delivers the lowest POI. The results showed that a WOF/(Volume/Student) ratio between 0.1 and 0.17 is recommended to guarantee low values of POI for a standard Volume/Student ratio of 6 m3. Even though high ventilation rates are required to prevent viral infection, it will certainly increase the draught risk. Therefore, optimal ventilation rates are required to maintain low POI and minimum draught risk, which can be achieved by optimum design of windows and implementing control systems for window operations to minimize turbulence effects and reduce the possibility of draught discomfort.