The Effect of Street Orientation on Outdoor Thermal Comfort in a Cold Mountainous Climate

Abstract

Lack of due attention to the orientation of streets and establishment of urban blocks without regard for climatic characteristics and conditions of the environment have an adverse effect on thermal comfort in open urban spaces. Construction of new settlements without taking into account climatic requirements undermines thermal comfort for pedestrians and other users, especially in cold regions. Considering the coldness of the region under study and the significance of the orientation of streets in absorbing radiation and providing heat to outdoor urban spaces, this study investigates the effect of the orientation of streets on microclimatic comfort in one of the residential towns of Hamadan City in Iran. For this purpose, microclimate simulation was performed using ENVI-met software. A residential block with four different orientations (the most common orientations of its surrounding buildings) were simulated in the coldest day of winter and the hottest day of summer. The results suggest that streets have different thermal behavior in different orientations. Orientation affects mean radiant temperature (Tmrt), the duration of exposure to direct sunlight, wind speed, and physiological equivalent temperature (PET), which are all important factors in thermal comfort. Based on these findings, north-south streets in Hamedan receive more radiant temperature during winter compared to other simulated orientations and provide more desirable thermal comfort. The average PET value on a winter day at a point on the north-south passage was 4.5-8 °C warmer than other orientations. In summer, streets with intercardinal orientations (i.e., northeast-southwest and northwest-southeast) provided the lowest PET (about 2 °C cooler than other orientations) and better thermal comfort

The Future of Climate-Resilient and Climate-Neutral City in the Temperate Climate Zone

“…This parameter is responsible for the cross-sectional geometry image of the street, square, or courtyard and tells about its depth/openness and, in a way, solar exposure. The canyon height and width modifies the thermal conditions in the street space [ 201 , 251 , 252 , 253 ]. One can observe a special relationship between the elements which create the canyon aspect ratio.…”

“…Due to the greater sunlight access, shallow canyons in winter have the highest daily T mrt and are more comfortable than deep ones [ 119 , 256 ]. However, the increased street width does not improve thermal comfort equally in all orientations during the winter [ 253 ]. Increasing the building height and reducing the street width initially increases the minimum and average daytime and night temperatures [ 273 ].…”

“…For example, suppose the binary system is perpendicular to the wind directions. In that case, its ventilation and thermal comfort in summer can be improved by increasing the space between buildings along the road and creating small green areas [ 253 , 298 ]. However, this treatment will lower thermal comfort in winter [ 253 ].…”

“…In that case, its ventilation and thermal comfort in summer can be improved by increasing the space between buildings along the road and creating small green areas [ 253 , 298 ]. However, this treatment will lower thermal comfort in winter [ 253 ]. An example of traditional Greek city development shows how to eliminate this problem by using small linear blocks of flats and a complicated street pattern [ 132 ].…”

The Influence of Sky View Factor on Daytime and Nighttime Urban Land Surface Temperature in Different Spatial-Temporal Scales: A Case Study of Beijing

“…Residents that have lived in urban centers for a long time feel the increased effects of the surface urban heat island, which makes people feel physically and psychologically uncomfortable and affects the comfort level and quality of life of an urban living environment [3,4]. Therefore, the study of its influencing factors and mechanisms is particularly important in order to propose a scientific and reasonable strategy to alleviate the urban thermal environment [5,6].…”