Energy aspects of urban planning. The urban heat island effect

Abstract

The research aims to analyze the tight relationship between the conformation of the city and the urban climate. The “heat island” phenomenon, typical of big urban centers, has a great impact on external temperatures, causing their increase compared to the surrounding rural areas. The study points out that the main factors responsible for such phenomenon are: the high percentage of built-up areas, the considerable presence of impermeable areas at the expense of the permeable ones, particularly green areas, the introduction of artificial heat in the atmosphere, generated by the combustion of hydrocarbon for transportations and domestic uses. Moreover a pivotal role is played by the urban canyons (which are generated by the geometrical configuration of the spaces among the buildings), the morphology of the urban tissue and the radiation properties (such as albedo and emissivity) of the surfaces. These considerations are confirmed by the results obtained in the experimentation conducted, in the city of Bari. Actually the results demonstrate that light color surfaces, with a higher level of albedo and wider green areas in some neighborhoods of Bari leads to a drop in temperatures of the external air, even of some degree days in the summertime.
The experimentation conducted outlines a guideline which considers the energy aspects of urban planning, thanks also to the possibility of realizing simulations by means of some particular software (suitable for the study of surfaces-vegetation-air interactions in the urban context) and to define different scenarios of project planning.