Urban Ventilation

An urban heat island results in higher urban temperatures than the surrounding area and is considered as the most documented phenomenon of climate change. This increase in urban temperature has a serious impact on the energy consumption for cooling and also contributes to higher urban pollution levels. Athens suffers from high summer temperatures that affect the quality of life of citizens. In response to the problem, a major rehabilitation plan was designed and applied, based on the use of advanced mitigation techniques.

In 2003, Hong Kong was hit by Severe Acute Respiratory Syndrome (SARS) from which many peopledied. The Hong Kong Government subsequently set up a Governmental Team Clean Committee toinvestigate possible urban design policies. Team Clean charged the task to the Planning Department,HKSAR. It initiated a study titled: Feasibility Study for Establishment of Air Ventilation Assessment(AVA) System. In 2003, the research contract was entrusted to a team of researchers of Departmentof Architecture, CUHK. A number of focused studies were conducted.

For energy conservation and good Indoor Air Quality (IAQ), it is crucial to improve Outdoor Air Quality(OAQ). For achieving good OAQ in urban areas, wind flow patterns among buildings should beimproved as well.In this paper, effects of building layout on outdoor thermal climate and air quality are investigatednumerically. In addition to the environment around pedestrians, enthalpy of outdoor air introduced intobuildings and its air quality are examined from the standpoint of IAQ.