The aim of this Final Thesis is to generate a base of environmental and economic crite-ria to support the decision on a specific combined thermal energy supply system. Via the method of Life Cycle Assessment (LCA), the differences between each type of system will be evaluated from an environmental perspective, followed by the economic assessment through the method of Life Cycle Costing (LCC). With the GaBi software for Life Cycle Engineering, an assessment of the current status of a residential building will be modeled, followed by different scenarios of mixed energy provision. To work with GaBi, the available professional database of components and materials will be used for the modeling of the case study, in order to evaluate the envi-ronmental impacts of different heating systems. This will be complemented through the LCC study of each system. To conclude, environmental and economic results will be integrated and analyzed through suggestions on results presentation.