The high land use for settlement purposes and the increasing soil sealing are currently among the most important issues in spatial planning. The high land consumption is not only a quantitative but also a qualitative problem. Compared to other European countries, Austria is one of the leaders in terms of daily land use. While this has been declining slightly in recent years (currently 11.3 hectares per day) (Umweltbundesamt, 2020), it is still at a high level and far from the target value of 2.5 hectares per day by 2030 set out in the 2002 sustainability strategy and the current government agenda (BMLRT, 2021). From the point of view of a significant reduction of new building land up to no new zones at all, the pressure on the existing areas is increasing. The scarcity of building land leads, among other things, to an increase in land prices. Since the Corona pandemic, rural regions in particular have experienced increased demand and an influx of new residents. At the same time, large areas of building land are being hoarded and are not available. This results in a tension between population growth and building land availability. In order to break out of the "building land paradox" (Davy, 1996), to meet the goal of saving land and to ensure sustainable settlement development, effective spatial planning instruments and their consistent implementation are needed. The dissertation aims to develop a strategy for the reduction of the building land reserves (in rural municipalities) and thus to contribute to land saving. The focus of the thesis is the undeveloped building land, which is very high in many rural municipalities in Austria. It will be systematically analyzed for which building land reserves a rezoning would make sense and how this could be implemented within the legal framework. In addition, a step-by-step plan should be developed on how suitable but still undeveloped building land can be put to use as soon as possible in a way that conforms to the zoning regulations. The objective is to develop a sustainable settlement development for rural areas and an argumentation for the implementation of the recommended spatial planning measures by land policy measures.