The main part of this thesis consists of a specific case study. We examine the life-cycle environmental impact of a certain residential area that was built following a passive house standard. In the process, we compare the expenditure of energy and the bounded emissions of the embodied energy (construction) and the red energy (operation). By analysing the life-cycle phases - divided in construction and operation - the CO2-emssions (GWP), the primary energy demand (PEI), and the acidification potential (AP) are identified and compared. Based on a feasibility study, we investigate the ecological expenditure of embodied and red energy for two different variants of the building standard. Thereby, we are able to gain knowledge about environmentally relevant products in the building, the influence of the selection of different materials on the life-cycle assessment and the performance of different energy types of buildings, taking into account time scenarios of 20, 50 and 80 years. Within the first comparison, the passive house in its current building state and with its measured energy consumption is ecologically assessed. We identify the proportion of embodied energy with respect to the total energy expenditure. We carry out the life-cycle assessment for the building in question, providing two alternative calculations: in one case we neglect all the pipes and plumbing within the building, and in the other we take them into account. As a result, the actual proportion of building equipment and appliances to the embodied energy in the building can be determined. In terms of an ecological approach, it is interesting to find out how a solid construction behaves in comparison to a wooden lightweight construction. To this end, we create an optimization variant with a timber construction instead of a concrete one. With this optimized version, it is possible to determine how the ecological performance of the passive house can improve if the massive construction is replaced by a timber construction. In the second variant study, we analyse whether the achieved reduction of energy demand during the operation of the passive house justifies the increased use of materials during construction. Thereby, the carbon footprint of the passive house is compared to that of a low-energy house. While in low-energy houses less material is used, their energy consumption is also higher. Through three different time scenarios, we are able to determine at which point the passive house variant offers a better ecological return than the low-energy variant.