In the SARS epidemics in 2003, cluster of cases occurred in highrise residential(HRR) building blocks, especially in Hong Kong, which gave rise to the concern of the possible roles of air ow in all other airborne infectious disease spread. In this paper, the multiple parallel airborne transmission routes are discussed in a HRR. In particular, we closely investigated one of the most likely virus-spread airow paths, which are related to single-side ventilation air ow through open windows caused by buoyancy effects. Both tracer gas technique and CFD (computational uid dynamics) techniques have been employed to quantify the amount of the exhaust air coming out of the lower oor that re-enters the open window at the adjacent upper oor. It was found that the upper oor air can contain up to 7 % of exhaust air directly from the lower oor. The results can well explain the nding that RNA fragments of SARS Corono-Virus (CoV) were detected within the sampled deposits on the window sills of the upper oors of the two index patients ats during the SARS outbreak. Implication for ventilation design and infection control in HRR will be discussed.
Natural ventilation plays two essential roles traditionally in our buildings. On one hand, ventilation can modulate the indoor temperature for better thermal comfort in summer since outdoor air is usually lower than indoors; on the other hand, it also helps to dilute indoor air pollutants and improve indoor air quality in most cases. The required quantity and quality are actually different for these two purposes. The roles of natural ventilation in modern high rise residential buildings are more complicated. Especially, in the rapid developing Asian regions, a majority of the population live in high-rise, multiple-house holds apartment buildings. The climatic conditions also render airconditioning widely applied, with the windowtype and split-unit type airconditioners dominating in the residential buildings. Ventilation is provided via open windows, with exhaust fans provided in the toilets and kitchens. The exhaust air is typically not centrally stacked, but left to drift around the building blocks.
Auteur(s): Jianlei. Niu