The Effect of Traditional and Modern Urban Morphology Patterns on Wind Flow and its Interactions with the Energy Efficiency Approach (Case Study: Esfahan)

The development of wind energy in built environments is an old topic concerning sustainable urban residents, which has appealed to many researchers with the enhancement of new technologies and CFD techniques. This work seeks to study wind energy flows from the perspective of urban morphology.

In this research, the average numerical wind data have been collected from Isfahan meteorological station on the hottest day (21 July 2017) and the coldest day (20 January 2018) in the corresponding Iranian year for CFD studies on wind distribution in three urban configurations (traditional, gridded, and high-rise buildings) in local scale, which represents the overall structure of the morphological types in the city of Isfahan, Iran. The CFD have been numerically simulated and illustrated in the ENVI-met and DesignBuilder software to visualize the wind energy results obtained from each urban fabric.

The simulation results demonstrate the following. 1) The results for the traditional fabric based on the maximum value of wind speed and direction obtained from the software include 2.26 m/s on the hottest day and 2.68 on the coldest, lying in the category of gentle breeze based on the Beaufort scale. In terms of the comfort zone for activities such as sitting, standing, and walking, this does not cause problems for citizens, and the texture lies in the comfort zone. 2) The results involving the maximum value of wind speed and direction in the gridded fabric include 2.73 m/s on the hottest day and 2.80 on the coldest. For high-rise buildings, maximum wind speed is 4.26 m/s on the hottest day and 4.08 on the coldest. On the basis of the Beaufort scale, therefore, gridded and high-rise buildings lie in the medium breeze category. Moreover, the comfort zone for the sitting and standing activities in the gridded fabric is not a problem for citizens, but makes them feel a little uncomfortable with the walking activity. For high-rise buildings, however, there are many problems, and citizens feel plenty of discomfort based on the comfort range for the sitting, standing, and walking activities. 3) The results obtained from the study of the two pieces of software demonstrate that the power and accuracy of the numerical simulation made by ENVI-met is greater than that of DesignBuilder due to the focus and design of the former software in the field of urban planning, providing researchers with more accurate documentation.

The results of the analysis are as follows. 1) The traditional fabric has been designed entirely based on the principles of sustainability. The urban morphological parameters indicate the important role that urban architects and designers can play in optimal energy consumption with respect to wind flow by determining the morphological parametric criteria. 2) The overall analyses of the geometry of the two new fabrics (gridded and high-rise buildings) demonstrate that modern urban planning is in less accordance with the natural environment, including climatic conditions and indigenous culture. 3) The large differences between the three fabrics in terms of the different characteristics of urban morphology and the different effects of wind energy flow indicate the significant effect of urban morphology on potential wind flows, showing that the urban morphological indicators are significantly correlated with wind flow. 4) The results can be used as a practical guide for evaluation of the effects of urban wind flows and their interaction with urban morphology. The methods proposed in this study can be used as maximal analyses made for practical measures taken to reduce the negative effects of wind flow for urban management in Isfahan. Future extensions of this study, which is currently under investigation, will be aimed at a comprehensive examination of all climatic factors affecting urban morphology and, finally, achievement of an optimal, sustainable model for Isfahan and all climates in Iran along with the factors examined in this research.