The city of Boushehr with its known Rich legacy of valuable traditional and native urban architecture is an established priceless site in architecture in the south of IRAN. The old fabric of this distinguished city with its unique Characteristic in traditional architecture can be introduced as a climatically compatible fabric. As the main concern in sustainability is consideration of the climate conditions therefore climatically compatible design is the closest way of getting the maximum condition, while at the same time the design minimizes the undesirable effects of the construction in that environment. The sustainable model of the old urban fabric of Boushehr is consistent with the principal methods that have long been used in local architecture in order to save valuable fossil energy. They were designed in a way that inflict the least damage to the priceless natural resources as well as the environment, that is the land, the green coverings of the earth, and water resources or other valuable elements in the nature. So we carried out enormous studies on recognition of environmental and physical characteristics of architectural elements in the old fabric of Boushehr. The reason being: Old fabric of Boushehr from the point of physical characteristics and sustainability in viewing human being and its natural environment has a rich source of information and invaluable architectural solution for the compatibility with the hostile climate of the region. Therefore, recognition of these local architectural values is our objective for designing climatically compatible architecture in the region. In order to identify the architectural elements of the region we shall examine the following aspects at three scales: A- At the scale of urban fabric. B- At the scale of architecture unit. C- At the scale of architectural details.