The German cities Frankfurt, Munich and Stuttgart approach their climate protection initiatives in the real estate sector with different measures although their goals are nearly the same. This paper examines the underlying efficiency understanding and further limitation factors in the municipal decision-making process. The focus is on the requirements and promotion of energy efficiency and greenhouse gas reduction in real estate.As a part of a research group supported by the Deutsche Forschungsgemeinschaft (DFG) we have an interdisciplinary look at these cities and make use of the Institutional Analysis Framework by Elinor Ostrom (1990) to collect and to aggregate decision-making impacts. Therefore, qualitative as well as quantitative data analyses based on a document analysis and interviews with representatives from the municipalities and the real estate sector are used to model the exogenous constraints of a city as well as the local decision-making arena.There seems to be evidence that cities take into account different efficiency approaches to legitimate their climate protection decisions. First results show that the decision-making process is characterized by an owner-, user-, or producer-oriented real estate management perspective. This fact heavily influences the measures taken, first and foremost the financial impact on the respective stakeholder.This paper categorizes urban strategies to reduce greenhouse gas emissions in the real estate business by identifying influencing factors in the municipal decision-making process. These findings will help to make use of the enormous greenhouse gas reduction potential existing in the metropolitan real estate sector.