External shading device, which is the part of passive solar systems, is an artificial environmental variable component to control interior solar radiation on the base of desirable orientation of a window space. In the design of shading devices, evaluation of many parameters such as window dimension, solar geometry, and climate data are present. In the present work, shading device of buildings in Adana at the latitude 37 degrees is studied. The paper describes an approach to simplify and clarify external shading device design. So phases and priorities of shading device criteria are classified for the Adana climate data, after which the Solar Tool computerized program analyzed the obtained data design criteria. It was found that, the application of horizontal shading device to prevent undesirable solar heat gain in Adana of latitude 37 works successfully. North is effective in all directions which the sun scans. With application of horizontal shading to a "P" type window in Adana of Latitude 37, horizontal dimension alternatives of shading devices and shading efficiencies were determined. The design strategies of shading devices that were developed in this study were found to be applicable any any built area for the region.