ENRenovation of buildings depends on three most important concerned groups involved in the process: - customers; - design organizations; - construction organizations. In traditional design relations among participants and objects are couricrlike and cannot be optimized. The entire process of design from an idea to complete documentation must be planned and executed in consideration of the interests of participating parties - customers, designers and construction organizations. This process should realize the cycle of design, co-ordination and the expertise of a final solution. Nowadays a great deal of graphic and economic data, accepted standards and rules are used in the designing process. In designing a building the information flow can be controlled with the help of intelligent systems of design. Separate information systems can be attached to different parts of a building. Any part of an information system is a complex object. The structure of some elements in an information system and their internal relations are complex and manifold, so control is possible only by an integrated design system. Integrated system elements are information systems of some lower level containing changeable information (Table) where numerical and graphic parts must be controlled by a computer. During the process of integrated design participating parties are the same like those in a traditional process: customers, architects, design organizations, construction organizations, but the relations among them have a new quality.