Parinaz Mansourimajoumerd - Researcher, Department of Architecture, Faculty of Art, Tarbiat Modares University, Tehran, Iran.
Mohammadjavad Mahdavinejad - Professor, Department of Architecture, Faculty of Art, Tarbiat Modares University, Tehran, Iran.
Mahnaz Vanaei - Graduated student, Department of Architecture, Faculty of Art and Architecture, Bu- AliSina University,Hamedan, Iran.

From the beginning of humankind, people always attempted to increase thermal comfort in their houses throughout the year. In fact, due to the lack of technology in the past, architects of those old buildings tried to make maximum use of passive systems. For instance, utilizing sunlight, wind speed, and so on to raise the thermal comfort of the buildings. This article analyzes the effects of sunlight on Yazd's ancient buildings' layout to investigate how houses have been adapted to the hot and dry atmosphere. Those buildings are examined first in terms of rooms' area around the outer Courtyard, inner Courtyard, and the Second Courtyard. Finally, the way rooms received sunlight regarding different sides of the buildings are investigated. Consequently, this project shows that living in Yazd's old houses depends on constructions' orientation and courtyards' orientation towards solar radiation. Moreover, the area of each section of the house is determined based on sunlight which is an identifier to the time that habitats used them and those portion's functions. Thus, those passive approaches in countries like Iran can save plenty of energy for a better future if only they were used in the current building industry.

Summer portion, Winter portion, Direct sunlight, Indirect sunlight, Courtyard.