Gis Techniques for Mapping Urban Ventilation, Using Frontal Area Index and Least Cost Path Analysis

This paper presents the urban wind ventilation mapping from building frontal area index on the example of urbanised city, Hong Kong. The calculations of frontal area index for each uniform 100m grid cell are based on three dimensional building databases at eight different wind directions. The frontal area index were then correlated with land use classification map, and the results indicate that commercial and industrial areas were found to have higher values as compared to other urban land use types, primary because these areas have densely high rise buildings. However, with using the frontal area index map, the potential ventilation paths created using least cost path analysis of the city can be located, and the “in-situ” measurements were suggested the existence and accuracy of these ventilation paths. These high ventilation paths could play significant roles in relieving the urban heat island formation and increasing the urban wind ventilation, planning and environmental authorities may use the derived frontal area index and ventilation maps as objective measures of environmental quality over a city, especially human comfort of the urban climate.