Application of Computational Fluid Dynamics to the Study of Designed Green Features for Sustainable Buildings

Abstract

Continuing urbanisation has implications on preservation of our common resources and has caused global and mirco-environmental pollution. It affects our public health and causes damage to the prospects of future generations. Although the timely provision of resources and environmental mitigation measures could resolve some of the issues, others may require fundamental reconsiderations of the implications on long-term sustainability. The understanding of the benefits of sustainability development in urbanisation and its implementation in the practice of building design is of importance for the long-term sustainability of a city. Natural ventilation is increasingly being used in modern urbanised residential buildings to minimise the consumption of non-renewable energy and the reliance on active means for environmental control. Increased consciousness of the environmental problems has aroused people’s interest of sustainable urbanisation, especially the application of green features in buildings. Green features are architectural features used to mitigate migration of various air-borne pollutants and to moderate the transport of heat, air and transmission of daylight from outside to indoor environment in an advantageous way [Mak et al., 2005a]. Green features such as a windcatcher [Li & Mak, 2007], wing walls [Mak et al., 2005a; Mak et al., 2007], skygardens [Niu et al., 2005] and balconies have made use of natural ventilation in residential buildings for increasing ventilation rate. However, the ventilation performance of these green features is not fully understood. In recent years, Computational Fluid Dynamics (CFD) has been widely used to study building airflow and the indoor environment, as well as the wind environment. An overview of applications in ventilation [Chen, 2009] has indicated that the CFD models were a most popular tool used to predict ventilation performance of buildings. CFD can be used to perform combined simulation of the wind environment around the buildings and the airflow inside the buildings [Awbi, 1989; Chen & Srebric, 2000; Chow, 1996; Jones & Whittle, 1992; Niu & Kooi, 1992] and modelling of different green features to study their ventilation performance since it can provide detailed airflow velocity distribution and thermal conditions. For most applications of ventilation and turbulence flow, the results have been approved to be useful and reasonably accurate. CFD has therefore become a reliable tool for flow analysis in buildings. It is believed that natural ventilation in buildings can be