Analyzing the effects of building density and placement on shading and solar energy reception in residential areas

Abstract One of the significant issues arising from urban density in the present era, in addition to compression and visual obstruction, is the problem of overshadowing. Since casting shadows on neighboring land and buildings can constitute an infringement on their rights to receive light and energy, this issue becomes critical. This is because access to daylight, sunny hours, solar energy reception on different building facades, and shadow length are parameters that are not seriously considered in urban design due to its top-down design process. On the other hand, due to certain complexities in climate and energy calculations, the effects of overshadowing remain somewhat ambiguous, intangible, or seemingly unnecessary for designers.This research, utilizing the existing morphology and conventional urban fabric in Tehran, studies the impacts of current regulations through calculations and analytical discussions, presenting various scenarios as solutions. The first objective of this research is to investigate the amount of light and energy received in medium or low-density residential fabric in Tehran. The second objective is to provide practical solutions for improving environmental conditions in terms of light reception . To investigate and analyze this issue, a medium-density residential neighborhood in Tehran was selected. Analyses were conducted manually and computationally, as appropriate. A residential block consisting of four rows with forty buildings and a pathway, with completely detailed and precise dimensions and heights, was modeled in the Rhino environment based on a sun chart for the Tehran location. Climatic data were input using the Grasshopper plugin, and output and graphical information were obtained using the Ladybug plugin, which runs within Grasshopper. Manual drawings were performed based on the angle of incidence during the seasonal solstices. The results from both methods indicated that in the existing urban fabric, particularly for properties on the southern side and during the winter solstice, only the highest floors are capable of receiving direct sunlight during midday hours. Computer analyses also confirmed this disruption in receiving solar radiation on the lower floors. Seven different scenarios were proposed by altering the building layout or construction density, three of which, based on computational calculations, created more favorable conditions in terms of energy reception. In the best-case scenario among these, even in the worst situation (winter solstice), only the ground floor, which is typically a lobby or parking area, would remain in shadow. These solutions are primarily achievable by changing the building’s position on the plot, either without reducing density or with a minor reduction in density.