Although a building lifetime is not predictable, it is an essential data in the yearly impact calculation. Yet, in the assessment of the environmental impacts of building the lifetime is considered as a fixed value. The purpose of this study is to introduce a new dynamic interpretation of LCA results, which aims at improving the reliability of assessment of buildings’ environmental impacts. To that end, are compared: - the environmental impacts assessed for 50, 70 and then 100 years of the building’s lifetime; - and environmental impacts assessed for anytime during the first 100 years of building’s lifetime. Since the impacts depend on the type of the building’s components and their quantity, in this study two scenarios have been applied: one compares two building projects that differ from each other on the shape and functionality; the other compares two projects that differ only on components and systems employed in the building. Possible projects of the smart living building have been selected as case studies. This building aims at reaching the goals of the 2000-watt society vision and will be built by 2020 in Fribourg, Switzerland. The dynamic interpretation of building’s impacts shows that the LCA results could vary up to 20%, according to the assumed building’s lifetime and thus, completely change the conclusion in the comparison of the impacts of different building projects when the projects differ from the components and systems. The dynamic interpretation assessed more reliable LCA-results, that are useful for strengthen comparisons in the decision making process.