Optimal Aspect Ratio and Orientation of the Building, Based on Solar Energy Receiving in Different Climates, Iran

The design of climate compatible buildings that use solar energy efficiently causes to reducefossil fuels’ consumption. The aim of this research is to determine the most appropriate aspectratio and orientation of the buildings for receiving optimal solar radiation in the cities of Ardabil,Rasht, Kerman and Bushehr with cold, temperate, hot-dry and hot-humid climates, respectively. Inthis research, the square and rectangular forms with North-South and East-West orientation werestudied. All of the studied forms had the same floor area and elevation with orientation to the South.The aspect ratios of the rectangle form were 1:1.2 to 1:3 (by step 0.2), and the orientation of thestudied optimum aspect ratios were 180º to 105º (by step 15º) SE and SW. The amount of directenergy received by vertical surfaces of buildings is calculated and processed, using the “Law ofCosines” computational method, for different months and in 24 geographic directions, in terms ofthe cold and hot periods of the year. The maximum amount of energy received by vertical surfaces incold and hot periods is related to the rectangular form with East-West and North-South orientation,respectively. The results of the research show that the appropriate form of the buildings in studiedcities is the rectangle with East-West orientation. The most suitable aspect ratio for EW rectanglularform is 1:1.2 in Ardabil, 1:1.4 in Rasht and 1:1.6 in Kerman and Bushehr cities. The best orientationsfor the determined aspect ratios in Ardabil is 165º SE and in Rasht, Kerman and Bushehr cities is180º South.