Limited budget, requirements of the site and its capabilities, and standards, codes of the construction process and other are constraints of building design, usually space program for office buildings and prepare design before the client approval, sometimes the architect explores that the budget is low allocated to the client's requirements During an advanced stage, and this process was analytical It is analyzed by a traditional technique, which may cause a decrease the quality of building increase the cost and decrease efficiency, so the research assumes the possibility designing of a mathematical model that can be used within the stages of a specific approach to calculate the areas and determine values of optimization area that achieve the aim of project, the linear mathematical model was designed and input data to ( lips) program can calculate areas and efficiency , cost at office buildings in Fayoum University after The stages of the proposed approach to calculating the spaces by default were shown for the same requirements, users, and location of the building and its requirements ... etc. The results appear positive of the project's programming results by default compared to the results of the programming for the existing building prepared by traditional methods, and the study ended with a set of measurements related to (areas, efficiencies and costs) of the two programs and their comparison concluded between program of building executor and virtual program which suggests the research. The study suggests recommendations for the client or the decision maker, the architectural designer.