The residential building environment accounts to a large extent for the emission of greenhouse gases. In Switzerland, 27% of the carbon dioxide emissions are generated by heating houses and providing warm water and electricity. The employment of existing state of the art energy efficient technologies can reduce these emissions significantly. Why are the technologies not applied on a regular basis? In this paper, we focus on the decisions the individual building owner has to make during the house planning process. The paperís contribution is multifold: systematization of important decisions during the planning process, development of a static theory of decision making based on psychological action theories, enrichment of the static theory by empirical research, and development of a dynamic theory. From a superior content point of view, the paper sheds light on the decisions during the building planning process. From a methodological perspective, the paper adds to more traceability during the model conceptualization phase. In other words, the art of modeling is partially substituted by a rigorous, scientific research process. This paper is still under development; especially the formulation of the system dynamics model and the subsequent discussion will be developed further in following versions of the paper.