||Considering the economic effort and the ecologic impacts of the building industry, optimization embedded in the design process of buildings is desirable as a flexible tool. To apply Multidisciplinary Design Optimization (MDO) to building design, adaptations to the special needs of this field are required. In this paper, first, appropriate objectives are discussed, which distribute to three major groups: economic performance, ecologic performance, and preference accordance concerning aesthetics and functionality. Second, the decomposition by components specific for building-design, which link non-numerical qualities with physical, economic, and ecologic quantities, is discussed. The steps are illustrated by means of a demonstrational hall design. Finally, the results of a test run presented for this example reveal the nature of the design space. In conclusion, the specific objectives and components and the system-oriented decompo-sition provide the basis for a CAD-oriented usage of optimization during the design process.