There is a large number of traditional houses in the historical texture of Shiraz City that have during their history managed to meet the living needs of regional people from climatic and environmental perspective. The main problem of the present study was to investigate the physical characteristics of Qajar period houses in Shiraz City, Iran, from an environmental perspective and their effects on the thermal behaviors of these houses. The study’s methodology was descriptive-analytical and data were collected from library and documentary methods and field surveys. 88 traditional houses from Shiraz’s historical texture of the Qajar era were identified, with 48 houses, meeting the information required, selected for investigation and typology. Findings indicated that houses are mainly inclined to the southwest, which further reinforces the effect of the Qiblah that other factors in determining the angles of the houses’ orientation. Houses with four-front construction courtyards (around 38%) are assigned the highest frequency. most courtyards cover areas of 50 to 250 m. wide and extended courtyards are not common in Shiraz’s traditional houses. Around 52% of the houses have courtyards of length-to-height ratios of 2:2.5, with the most frequent width-to-height proportions (a total of around 71%) pertaining to 1.5, 2 and 2.5 ratios. Garden areas mainly cover areas of 5-30 m2. Meanwhile, pools and fountains account for the highest areas of 5-30 m2. Large areas assigned to pools and fountains not only provide humidity and reduce air dryness but also reduce the ambient temperature through evaporative cooling.