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

Abstract

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: PM 10 and PM 2.5 ), 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 PM 10 and PM 2.5 concentrations in the lower room.

Large eddy simulation of wind-induced interunit dispersion around multistory buildings

“…Based on the present physical model, the non‐dimensional times required to achieve one whole‐unit air replacement for the typical naturally ventilated ACH values of 5, 10, and 20 are 53.3, 26.7, and 13.3, respectively. Here these ACH values occur commonly in naturally ventilated buildings (Ai et al., ; Niu and Tung, ). Such comparable magnitudes are to be expected as interunit dispersion occurs based on the natural ventilation system and the interunit dispersion is governed by the indoor and outdoor airflow exchange mechanisms.…”

Design and Development of a Nearable Wireless System to Control Indoor Air Quality and Indoor Lighting Quality

“…In the first case, the level of IAQ is determined considering the concentration of CO2 [16]. In this case, the main technical standard is EN 15251:2008 that identifies the optimal values of air exchange for different types and classes of pollution of the buildings, in addition to the concentration threshold values of pollutants in air and in building materials.…”

Design criteria for outdoor air intakes and exhaust air outlets located on an external wall

“…The issue of contaminant transfer from an exhaust outlet to the outdoor air intake in different building types with mechanical ventilation has been reported in several studies, including single-family and multifamily residential buildings [5][6][7][8][9][10][11][12] and nonresidential buildings [13][14][15][16]. In addition, re-entrainment has been extensively studied in buildings with singlesided natural ventilation where airborne transmission of infectious biological aerosols [17,18], particulate matter [19] and gaseous contaminants [20,21] route has been shown from one dwelling unit to another through open windows via outdoor air along the external wall due to the effect of wind and buoyancy. Therefore, proper consideration should be given to the correct specification of designated outdoor air intakes and exhaust outlets to minimize the risk of indoor air pollution caused by the re-entry of contaminants previously discharged from the ventilation exhaust outlet to the outdoor environment.…”