INFLUENCE OF SKY VIEW FACTOR AND WATER FEATURES ON AIR TEMPERATURE

Abstract

This study is done under a joint research project between National University of Singapore (NUS) and JTC titled “Climatic Mapping of Business Park for Environmental Quality Assessment”. The urban heat island phenomenon, whereby higher average air temperatures and the diminishing of daily variation between the maximum and minimum temperature are observed within the urban areas, forms the background of this study. The high air temperature may be caused by reduction of evaporating surfaces, which assist in change sensible heat to latent heat, decrease in long-wave radiation loss due to urban layout, and the multiple reflection of short-wave radiation between urban surfaces due to the building geometry, which in turn decreases the effective albedo of the system. Sky view factor (SVF) is being used by previous studies as one of the means to account for the net radiation exchange condition between the earth surface and the atmosphere. Hence the effect of urban geometry on air temperature can be examined through SVF. In this study 30 measurement points, within the study area, One-North, are allocated for the collection of air temperature data and SVF. Water features add on to the water surfaces within the urban area, which may lead to an increase in the evaporative cooling effect within the urban area. Thus in this study, the water features located in One-North are used for the investigation. Hence the objectives of this study are to determine the relationship between the two parameters and air temperature, to explore the possible influence of sky view factor on air temperature and also to find out the magnitude of the presence of water features in altering air temperature. From the data collected, air temperature is positively correlated to the SVF and this is mainly due to the proximity of the surrounding vegetation and the amount of anthropogenic heat released to the surrounding air. Generally, there is no strong relationship found between air temperature and water features. Out of the three types of water features found within One-North, the water wall was found to be the most practical water feature to be situated in an urban setting. This is due to the higher possible cooling effect produced by the water wall and its advantage of being less space consuming.