With the increase in urban construction, the thermal comfort range of human life has also been more affected by the damages caused by climate imbalance.

Understanding the impact of the physical proportions of semi-open spaces on their thermal performance based on improving the thermal comfort index and reducing the thermal stress of the surrounding environment is the most important goal of this research.

How do physical proportions affect the thermal performance of semi-open spaces in areas with high thermal stress in Shiraz? This was the most important question of this research.

The research method was quantitative research, which was carried out in 2 historical and 1 middle urban areas of Shiraz city through field tests and then simulation. The results were collected by temperature and humidity sensors along with physical measurements. Then, validation was carried out by Envi-met software and the PET thermal comfort index was extracted from this software.

The most important achievements of the research indicate that the structure of the veranda in the hot and dry climate of Shiraz has the most suitable climatic structure. The orientation of the veranda on the northwest-west front has the lowest temperature. The most optimal physical proportions, by expanding the area of the veranda on the facade and, in this regard, increasing the width to the height of the veranda (L/H>1), reducing the height for shading, and increasing the height of the veranda from the ground, the PET thermal comfort index has experienced a more appropriate temperature effect.