Study of Thermal Comfort Determinants in the Urban Street Design in Hot and Arid Climate

Abstract

Preliminary bioclimatic design principles that are related to thermal comfort level of the urban street environment in hot and arid climate region were searched in this research. As methods of investigation included: literature reviews, empirical studies and case studies. In hot and arid climate region, most of physically unpleasant conditions in the street environment are found during summer time. However, street design standards and typologies on the basis of mere dichotomy of access and movement don’t refl ect diversity of existing streets and their bioclimatic requirements to provide physical comfort within them. Thermal comfort was used as a criterion to evaluate the physical condition of the street environment in the research and determinants of thermal comfort inthe street environment were researched. The preliminary literaturereviews conclude that the refl ectivity and the emissivity of materials are two main determinants of thermal performance. Field research were conducted for the numerical comparison of the ambient and the surface temperature by surrounding materials in the street environment. Paseo del Prado in Madrid Spain and Univeristy boulevard in Tucson, Arizona, United States are the measured streets. It is found that there is clear diff erence in the ambient temperature by surrounding material. Simultaneously, critical role of shades was revealed to decrease both ambient and surface temperature in the street environment. The ambient temperature measured in the shade maintained 20.0 F lower than nonshaded environments. Further investigations on urban climatology show crucial relationship of the street geometry, e.g. street orientation and building height to street width ratio (H/W) with thermal comfort in the street environment. Street case studies provide supplementary solutions for the street design such as vegetations and shading devices. Material uses, geometry, vegetation and shading devices are organized as a preliminary design recommendations in conclusion.