A method for evaluating solar rights and shading requirements in an urban environment is presented. The method is embedded in a CAD tool developed and adapted for this purpose. With this tool one can analyze the mutual shading between buildings and other objects like trees. The purpose of this CAD tool is to allow the designer to plan efficiently the various functions of spaces among different structures, like buildings, as well as determining the location of the passive and active solar collectors. The method is a general one and allows a fast and efficient calculation of the ratio between insolated and total surface areas of any given examined object that is shaded by other irregular and nonplanar elements. The calculation of this ratio is carried out for all the months and hours for which either shading or insolation is required. The information obtained may serve as hourly input data for any dynamic simulation model which evaluates the thermal performance of the different external or internal shading systems. For a visual and a qualitative evaluation of the shadows among buildings, the suggested model permits a very realistic representation, in which the light source is defined according to the azimuth and the altitude of the Sun at the particular time of examination. The self shading and brightness of the different surfaces and the shadows cast by the various elements at the designated time are then generated and can be evaluated visually.