Outdoor thermal comfort in the old desert city of Beni-Isguen, Algeria

Climate Research

Fazia Ali-Toudert¹  Moussadek Djenane Rafik Bensalem Helmut Mayer¹ 

关键词: Thermal sensation;    Street geometry;    Street orientation;    Hot-dry climate;    Vernacular architecture;    Physiologically equivalent temperature;    PET;   

DOI  :  10.3354/cr028243

来源: Inter-Research Science Publishing

【 摘 要 】

ABSTRACT: The present study addresses the issue of outdoor thermal comfort in a hot and dry climate in relation to urban geometry. This experimental work, conducted in a old desert city, aims to provide some quantitative knowledge on the effectiveness oftraditional design forms in ensuring a comfortable thermal environment outdoors under extreme summer conditions. The study focused on the role of the geometry of urban canyons. Air temperature, air humidity and wind speed were measured during summer 2003in various urban streets in the old Saharan city of Beni-Isguen, Algeria (32.40°N). The short-wave and long-wave radiation fluxes received by a human body from the 3D surroundings were also measured in order to allow an accurate calculation of theheat gained by a pedestrian. Bio-meteorological methodology was used and thermal comfort was expressed by means of the physiologically equivalent temperature (PET) index. The results show that the heat stress in a hot-dry climate is very high inunobstructed locations in contrast to sheltered urban sites. The vertical street profile is of prime importance in the resulting thermal sensation. Building materials were also found to play a decisive role. Deep streets together with high thermalcapacity materials mitigate the heat stress in the daytime. The high and heavy walls provide more shading and more heat storage, leading to lower surfaces temperatures. Hence, a human body absorbs less short-wave radiation owing to reduced directexposure, and also less radiant heat from the surrounding environment is absorbed by the body. In contrast, air temperature and air humidity show little dependence on the urban geometry. Therefore, these factors are less relevant indicators for outdoorthermal comfort in the summertime.

【 授权许可】

Unknown