Re ECF Project: 2009-23

Project Title: Green features for improvement of air quality in buildings

Applicant: Prof. MAK Cheuk-ming of The Hong Kong Polytechnic University

Total Approved Grant: $408,480

Duration: 3/5/2011 to 1/11/2013

Project Status/Remarks: Completed

Scope:
The project aims to study, demonstrate and promote the usefulness of different types of green features including wing walls, windcatcher and balconies to improve indoor air quality in buildings so as to achieve a sustainable development and arouse the public awareness of sustainable building design.

Summary of the Findings/Outcomes:
Computational Fluid Dynamics (CFD) is employed to investigate the effect of these green features on the wind-induced airflow and inter-unit pollutant dispersion in typical multi-story residential buildings. Effect of balcony and wing walls on ventilation performance and pollutant dispersion are studied. In particular, two types of wing walls, including vertical and horizontal wing walls, are adopted in the target residential building under different wind directions. The result shows that the presence of balconies and wing walls plays a significant role in destroying the upward development of dispersion and accelerating the dilution process. The design of balconies with upper and lower vents can significantly increase the natural ventilation and reduce pollutant concentration on mid-level floors of high-rise residential buildings. In addition, the target building generally has a better natural ventilation performance when the wind obliquely incidents on the building. On-site measurements are conducted to study the ventilation performance and IAQ of high-rise residential units in Hong Kong. Key parameters, including the air change rate per hour (ACH), suspended particulate matters (PM: PM10 and PM2.5), and total volatile organic components (TVOCs), have been measured and analyzed. The result of measurement shows that ACH is acceptable in rooms with single-sided ventilation under normal wind condition. Particles exhausted from an upper unit are easy to make their incursion into its lower units through opened windows.