Achieving urban sustainability has become imperative. The combination of Material Flow Analysis (MFA) and Life Cycle Assessment (LCA) could be considered an attractive method to assess the sustainability of a city's metabolism. However, the need for exhaustive data makes this method time-consuming and uncertain. This study carries out a simplified UM-MFA-LCA analysis of the city of Santiago de Compostela (Spain) based on 7 primary flows. This approach allows: i) to determine the environmental profile of a city never before studied and ii) to determine whether a simplified analysis provides environmental impacts results similar to those of more complete studies – i.e. those in which other flows such as manufactures and building materials were also considered in the inventory data. The findings of this analysis report that the flows considered, combined with the MFA-LCA methodology, provide a ‘sufficiently accurate’ environmental impacts account when no further data is available. Furthermore, the results are highly disaggregated and a comprehensive environmental strategy plan for a city can be developed. The LCA results of Santiago de Compostela indicate that most of city's impact happens outside its limits. Direct emissions are also identified and a number of improvement measures are proposed for both cases.