Thermal perception of outdoor urban spaces in the hot arid region of Cairo, Egypt

Urban microclimatic conditions affect the human body energy balance and individuals’ thermal perception; which in turn influences their usage of outdoor spaces. This study investigates users’ thermal comfort in an urban street in a hot arid climate of Cairo, Egypt. The investigation was carried out in two different climatic conditions; summer and winter, using subjective surveys on the perception of the thermal environment applying the seven-point ASHRAE 55 thermal sensation votes (TSV). The survey is complimented by a one week of field measurements in both seasons to examine the main climatic parameters affecting thermal comfort in term of psychological and personal factors. The thermal acceptability by means of thermal sensation votes was assessed based on physiologically equivalent temperature (PET). Analytical results indicate that the thermal comfort ranges were between 23 and 32 °C PET while the preferred temperatures were 29 °C PET in summer and 24.5 °C PET in winter. These values were higher than that of the temperate climates and European scale, confirming the existence of thermal adaptation and indicating that the physical environment and the psychological adaptation is argued to be complementary rather than contradictory, and consideration of this duality could increase the use of the city's open spaces.