The accurate determination of operating costs and the knowledge of significant influential factors on these costs are crucial foundations for a holistic assessment of planning alternatives during the life cycle of real estate. The quantitative approach of the research study is based on empirical data of operated buildings in Germany. The study is dedicated to the development, validation, and evaluation of statistical models for an investigation of causal interrelationships between operating costs and a variety of potential influential factors on these costs. The main objective is the provision of essential information, models, and adequate cost indicators for an accurate determination of operating costs for an application in the field of cost planning of real estate. The practical application of the results is demonstrated in detailed implementation examples. The results of the study are directed towards architects, planners, and the real estate management and can serve as the basis for decision making and budgeting.