This dissertation, "Urban Design Factors Influencing Outdoor Temperature in High-risehigh-density Residential Developments in the Coastal Zone of HongKong" by Giridharan, Renganathan, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled Urban Design Factors Influencing Outdoor Temperature in High-rise High-density Residential Developments in the Coastal Zone of Hong Kong. Submitted by Giridharan Renganathan For the degree of Doctor of Philosophy at the University of Hong Kong in October 2005. One of the most critical issues affecting urban Hong Kong are poor air quality and the monetary and environmental costs of partially cooling internal space due to high outdoor air temperature and humidity in summer. During summertime air quality in Hong Kong deteriorates because of the deep heat islands formed in densely built up locations. As a result, space conditioning during summer months accounts for nearly 60 percent of total electrical energy use in Hong Kong. The interaction of outdoor spaces created by designers with natural forces has been modelled previously. These models, however, were limited to climatological and system design parameters. This study uses multiple regression models to analyze the impact of built form-fabric, density and land-use descriptors that are central to urban design on outdoor temperature differences at various points in selected residential estates in the coastal zone of Hong Kong during the extended summer months of June to October. The dependent variable (Urban Heat Island Intensity) is the outdoor temperature differences measured between a station in a residential estate and the Hong Kong Observatory at a specific time. Twelve independent variables were used. These are: solar radiation, wind velocity, sky view factor, surface albedo, altitude, proximity to sea, vegetation above 1 m in height, vegetation below 1 m in height, average height to floor area ratio, location quotient, Total non-residential to total floor area in the development and emission index. Data from 17 residential estates in the coastal area of Hong Kong covering Hong Kong Island, Tuen Mun, Sha Tin and Ma On Shan were used. Totally the study has 216 data sets representing considerable variations in seasonal and geographical influences, as well as in terms of layout, thermal properties, and vegetation level in the various residential estates. The multiple regression analyses were carried out combining all data sets as well as in controlled subsets of disaggregate data. The data sets are divided into three seasonal subsets and seven geographical subsets. A further categorization into five subsets in terms of vegetation level and thermal massing was also carried out. During peak summer clear sky days, the mean maximum UHI within the estates and 0 0 between the estates are 2.1 and 1.5 C respectively while the mean maximum nocturnal 0 0 UHI within the estates and between the estates are 1.0 and 1.4 C respectively. Available general theory on the impact of urban design variables has been developed for temperate climates with moderate population densities. Significant variations from this general theory were observed in the high-rise high-density context of Hong Kong. The peak summer clear sky days daytime and nocturnal models were found to be the clearest indicators of the impact of urban design variables on UHI. The sky view factor emerged as the most influential variable on most occasions. The study also reveals that surface albedo, altitude, vegetation above 1 m in height, a