The environmental performance of new and existing buildings can best be improved by respecting the life cycle perspective. Conducting a Life Cycle Assessment efficiently supports the identification of environmental improvement potentials. The research project “Environmental Improvement Potentials for Residential Buildings” (IMPRO-Building) was initiated by the European Commission (JRC-IPTS). It aims at reducing the environmental impacts from residential dwellings throughout their life cycle, evaluating the current situation of residential buildings in the EU-25, before analyzing improvement options. A generic life cycle model for buildings has been developed to address this question efficiently. It is used to identify the environmental hotspots and to evaluate improvement options. More than 70 building types are assessed consistently. The LCA model makes a distinction between existing (use phase and end-of-life) and planned buildings (construction phase included as well), accounting for different perspectives. Results are demonstrated for examples of different building types from different geographical zones.