On-site measurements of ventilation performance and indoor air quality in naturally ventilated high-rise residential buildings in Hong Kong

Single-sided ventilation rate is difficult to accurately predict because it has a complex relationship with many factors, including the direction of the approaching wind and building envelope features. In addition, the incursion of outdoor pollutants into the interior through a ventilation opening has been recognized as a serious threat to indoor air quality (IAQ). This article presents on-site measurements of the ventilation performance and IAQ in four high-rise residential rooms in Hong Kong. Key parameters including the air changes per hour, respirable suspended particulate matters (PM: PM10 and PM2.5), and total volatile organic compounds were continuously recorded over a specified period. A comparison of cases with floor-extended and window-like openings is made. The results indicate that single-sided ventilation performs well regardless of the orientation of the apartment room and the configuration of the opening. Previous empirical models based on single-room buildings are not reliable in determining the ventilation rate of high-rise buildings. The measurements reported here also identify an important route for the incursion of outdoor pollutants, namely the downward re-entry of aerosol particles from an upper unit to a lower unit in the same building. A combination of gravitational and wind effects means this downward transport route significantly increases the PM10 and PM2.5 concentrations in the lower room.