IMPACTS OF VENTILATION STRATEGIES AND OCCUPANT DENSITY ON BASIC REPRODUCTIVE NUMBER IN AN INDOOR ENVIRONMENT

Abstract

Airborne infectious diseases such as Tuberculosis and Influenza virus have caused worldwide morbidity and fatality, which resulted in social and economical impacts and Singapore is inevitably one of the countries affected by it. Therefore, it is vital to understand the dynamics of the spread of airborne infectious diseases, which helps in estimating the risk of being infected and hence providing a better protection for human beings. This study investigates the impacts of four different ventilation strategies namely, mixing ventilation, displacement ventilation, under-floor ventilation and personalized ventilation, and occupant density in an indoor environment. Experiments were carried out in a Field Experimental Chamber, which was designed to simulate an office environment. Measurements of the Basic Reproductive Number of influenza virus and tuberculosis were taken for each of the ventilation strategies; and comparisons of the behavior of the ventilation strategies when the occupant density changes were included in this study. Mixing ventilation system, which is a commonly used ventilation strategy in Singapore’s office buildings, has the 2nd highest performance in protecting occupants from being exposed to the spread of airborne infectious diseases. Personalized ventilation system has the highest performance in reducing occupants’ risk of being infected. Therefore, it allows a larger number of occupants in a space and this is necessary especially for a small country like Singapore whereby it has limited land. However, results in this study apply only to the specified conditions studied in an indoor environment. Another limitation is the assumption that all occupants in the room are equally susceptible to the infectious pathogens.