Urban Geometry and Microclimate of Street Canyons in Cold Semi-Arid Climate

The recent reports issued by the Intergovernmental Panel on Climate Change (IPCC) emphasise the need to reconsider the design of urban built environments [1]. In the past twenty years, research has demonstrated that geometry parameters of urban street canyon play a significant role in influencing the microclimatic conditions and energy performance of the buildings within urban environments [2,3]. Urban canyon geometry affects the overall energy consumption of buildings and has the potential to reduce energy usage by as much as 30% for commercial structures and 19% for residential structures. Besides, the air and surface temperatures of urban street canyons are highly influenced by sunlight access, shadowing, and other factors. Canyon’s form and parameters, such as aspect ratio (H/W) and street direction, impact sun access, shading, and ventilation, which are also affected by length-to-height ratio (L/H). The aim of this paper is to assess whether geometric parameters of urban street canyons affect the microclimates and energy consumption in cold semi-arid climate. The research was carried out in Kayseri, Turkey, which has been developing city. According to those statistics, the real heating energy consumption in residential buildings ranges between 100 and 200 kWh/m 2 (the average is obtained as 175 kWh/m2) in Turkey. However, in European countries, this value is 100 kWh/m2, including energy use of heating, cooling and ventilation [4]. A total of 18 scenarios, including both configurations with and without space between buildings, were simulated. The scenarios varied in their aspect ratio, which is the ratio of height to width (H/W). There were three types of canyons: avenue canyons (H/W < 0.5), regular canyons (H/W = 1.0), and deep canyons (H/W > 2.0). Additionally, the scenarios differed in their length-to-height (L/H) ratio. There were three types of canyons based on this ratio: short canyons (L/H < 3.0), medium canyons (L/H = 5.0), and long canyons (L/H > 7.0) [5]. The performance of the canyon was evaluated by comparing the air temperature, on the hottest and coldest day of a typical year. In parallel to microclimate analysis, energy consumption analysis was carried out for a hypothetical case study building throughout the day and night. Envi-met and EnergyPlus are used as a computational tool. The comparative study will show how and to what extent urban canyon geometry parameters, in this case, contributes to modifying the magnitude of microclimate impact on daytime and nighttime energy loads.

Keywords: Street Canyon, Urban form parameters, Urban geometry, Energy performance