The METREX EU CO2 80/50 project is an initiative that seeks to enable European metropolitan areas to assess their GHG emissions by inventorying the main energy sources and their use, as well as to explore effective mitigation measures through joint action scenarios involving stakeholders.

The 18 regions participating in this project are: Athens, Bologna, Brussels, Frankfurt, Glasgow, Hamburg, Helsinki, Madrid, Napoli, Oslo, Ljubljana, Paris, Porto, Rotterdam, Stockholm, Stuttgart, Torino and Veneto.

The first phase of this work consisted of the elaboration of emission inventories and is summarized in the report "Greenhouse Gas Emissions Inventories - Brochure for Individual Regions: Porto".