The main objective of the project is the estimation of the overall energy and material flows in a mountain hut and of their ecologic impact assigned to climate change, measured in CO2-equivalents, and from a life cycle perspective (life cycle assessment (LCA)). For this purpose a user tool is designed. It should support the owners of mountain huts, when retrofit or demotion and rebuilding of huts is required by offering possible solutions for appropriate/the most suitable  energy systems,  building materials and components according their ecologic impact in terms of CO2-equivalents. In addition to the usage phase of the hut, the / CO2-equivalents of the construction or retrofit phase is also taken into account. With the help of four selected huts, the feasibility of the user tool is tested and its deficiencies are remedied.