## 4 Discussion of Results
### Discussion of the Results of Computer Simulation  
From the analysis results (as shown in Figures 7-10), the extent of the convergence of the urban fabric of the study cities from previous sustainability factors became clear. Although the four study cities showed variations in the results, they confirmed the application of climate adaptation principles in various proportions and forms. Moreover, they were consistent with the proposed sustainability indicators for the traditional urban fabric. The residential district in Yazd city applied most of the indicators that we considered, drawn from the urban fabric, using an extremely compact fabric to decrease or prevent the hot sun's rays from accessing the streets and narrow alleys (Figure 7). The simulation results for Yazd city shown in Figure 8 indicated the use of an organic system with irregular, tight streets, with solid building facades to block approximately 80% of the solar radiation reaching the roads and alleys during the day, thus providing large shadow ranges for generating currents of cold air. It also houses mostly rectangular houses and vast facades toward the south and north, with narrow, winding alleys and shaded roads to keep the air more moderate inside the urban fabric and resistant to the impact of desert winds. Furthermore, horizontal expansion of the buildings and the variation in land uses according to the relationships and functions of buildings have led to the achievement of land use efficiency. The residential district in Al-Kadhimiya was identified as an area generally having an organic, traditional, compact fabric, arising from disjoined houses separated by some narrow alleys. Various overhangs shade them by facades and the neighboring buildings, containing a public urban courtyard with a fully integrated inner courtyard environmental system (Figures 7 and 9). Based on the computer simulation of Al-Kadhimiya, the compact traditional urban plan prevents solar radiation from reaching the urban spaces by approximately 65%, providing shading spaces to generate cooling air currents, and the urban spaces between the masses were aligned to the north, in order to be maximally shaded throughout the day. Total incident radiation analysis confirmed the success of the traditional planners in producing most roads and narrow alleys from south to north, as it achieved a reduction in the area of building facades. The residential district in the old city of Damascus was designed in consideration of planning in line with Islamic thought, changing from a grid style to the distinctive compact style, characterized by compressed residential units separated by some narrow, winding alleys. These alleys terminate towards public courtyards. Furthermore, the alleys are connected to the central courtyards of the houses, across the winding corridors in the house entrances. As only the ground floor is assigned to the public, enough privacy could be obtained (Figure 8). The results of the computer simulation indicate, as shown in Figure 10, that over 90% of the solar radiation reaching the street, alleys, and public spaces is blocked, as an extraordinary feature of the urban fabric and all houses is that the facades provide shade throughout the whole day. Moreover, trees and water bowls are used inside the courtyard to decrease the influence of solar radiation and create cooling air currents. Finally, we considered the residential district in Old Sana'a. Although the cities of the mountainous regions in Yemen are distinguished by tower houses, which differ from the horizontal housing patterns in the rest of the hot-dry climate regions in West Asia, the solutions and characteristics achieved the same performance. The vertical houses are typically compiled around shared gardens (orchards). The houses that define tower houses are a result of design evolution, benefitting from natural ventilation and sunlight, with tower houses having six to eight levels.