This paper presents a method combining a top-down and a bottom-up approach, which has been developed to track energy saving opportunities. The top-down modelling method aims at correlating the energy consumption with the final products and the auxiliaries and at distributing the energy bill among major consumers. Based on the description of the thermodynamic requirements of the process operations, the bottom-up approach is used to define the energy requirements of these consumers. When compared with the measured consumptions, these energy requirements allow the identification of energy saving opportunities that are evaluated using thermo-economic modelling tools. The developed methodology has been applied in the food industry. It allowed identifying energy savings options ranging from good- housekeeping measures, optimised process operation to energy saving investments.