Re ECF Project: 2014-18

Project Title: Envelope design to improve ventilation performance of residential buildings in dense urban environments

Applicant: Prof. Mak Cheuk Ming of The Hong Kong Polytechnic University

Total Approved Grant: $441,240

Duration: 14/5/2015 to 13/5/2017

Project Status/Remarks: Completed

Scope:
The principal objectives of this project proposal are to study, demonstrate and promote the appropriate envelope design to improve natural ventilation performance in residential buildings located in dense urban environments such as Hong Kong, so as to improve the indoor air quality and thermal comfort as well as to reduce energy use of air-conditioning, and ultimately to achieve a sustainable development and arouse the public awareness of sustainable building design.

Summary of the Findings/Outcomes:
This project dealt with ventilation of residential buildings in Hong Kong when considering both air-conditioned and naturally ventilated scenarios. The environmental issues under both scenarios were identified first through a systematical literature review and envelope-design-based solutions were then proposed and investigated. Since room air-conditioners provide no or very limited fresh air, insufficient ventilation and excessive carbon dioxide concentration are common problems in air-conditioned residential buildings. Several possible ventilation strategies for air-conditioned residential buildings were examined and the short-term mechanical ventilation strategy was recommended. Optimization of short-term mechanical ventilation strategy was conducted and a general design framework and detailed guidelines were proposed. Owing to the moderation of local wind field and the accumulation of traffic related pollutants in street canyons, low ventilation rates and penetration of outdoor pollutants are two key risks involved in naturally ventilated residential buildings. Existing knowledge tends to suggest that reasonable urban planning and careful building envelope design are the primary methods to ensure acceptable indoor environmental quality and maximize the utilization of natural ventilation. Street configuration influences ventilation rate and its distribution among rooms along height of buildings, while envelope design provides a possibility to enhance the adaptability of buildings to dense urban environments.