Exhaust ventilation performance in residential washrooms for bioaerosol particle removal after water closet flushing

Abstract

Potential bioaerosol infection risk associated with toilet flushing has not been sufficiently addressed in the design of residential washroom exhaust system. This study evaluates the performance of exhaust ventilation for residential washrooms in terms of air change rate, washroom size, washroom geometry, and locations of door louver, exhaust and water closet. Three bioaerosol species namely Escherichia coli (ATCC 10536), Serratia marcescens (ATCC 6911), and Cladosporium cladosporioides (ATCC 16022) are included in the simulations. By shortening the distance between the locations of exhaust and emission source (i.e. water closet), the fractional counts of bioaerosol particles exhausted can be increased. An increased air change rate and a louvered door can also improve the exhaust ventilation performance, yet with a longer time to steady state. This study should provide a useful source of reference for washroom exhaust designers to minimize bioaerosol infection risk. Practical application: This paper shows for residential washroom with an exhaust fan installed, the ventilation performance can be improved by an increased air change rate, and by shortening the distance between the locations of exhaust and emission source.