Curved forms have always been an important part of architecture for visual, structural, religious, or environmental reasons. Nowadays, in many parts of the world, curved surface shapes in building structures quite common, particularly in the hot climate regions. In addition to the traditional curved surfaces (domes and vaults), convex walls have also been extensively used in the construction of modem buildings. Accurate and specific distribution of direct solar radiation on curved surfaces is desired in a variety of fields and an important parameter when simulating the thermal performance of buildings. In this thesis, a computer model is developed to predict the quantity of incident direct solar energy on curved surfaces with a variety of forms and with different cross-sectional ratios at different orientations under a clear sky. The model based on a mesh represents the curved geometrical shape and simple mathematical equations to calculate the direct solar radiation at certain coordinates. In general, the results of the simulations indicate that the amount of direct solar radiation received by horizontal surface can be reduced using the curved surface. Results also reveal that the efficiency of curved surfaces can be significantly improved by choosing the proper design and orientation, which in tum can reduce the overall cost of cooling in hot months. The code has been tested against a number of computer programs for a set of geometrical conditions and. the results show a good agreement. Such a model can provide the architects and building engineers with a new easy-to-use tool that may help them during the early design stages.