Traditionally, the environmental performance of ships in terms of air emissions has never been among the primary concerns of the maritime industry. However, this situation is bound to change considering that the greening of the transportation sector is imminent and unavoidable. This tendency is manifested with activities ranging from regularly published statistics regarding the air pollution of general industrial activity up to the Energy Efficiency Design and Operation Index that are currently being considered at IMO.The greening of shipping operations has to do with more than just the amount of NOx, SOx and CO2 gases emitted at any period of time: the fact that for every tonne of fuel burnt approximately three tonnes of CO2 are produced indicates that the environmental performance of ships is linked to their cost-effectiveness. As a result, consistent energy management onboard will become a priority for rule compliance, and robustness against unpredictable financial fluctuations.Acknowledging that newly build ships will comply with the environmental regulations from the outset and will be more advantageous in comparison to existing ones, REFRESH will address the aspects of retrofitting that are essential for improving the energy efficiency onboard. The central concept of REFRESH is the dynamic energy modelling, i.e. the simulation of the energy production, consumption and losses over time. This idea will be implemented in a decision support tool that will allow onboard and ashore personnel to monitor the performance of the ship and adopt appropriate practices as a function of its operational profile.The objectives of REFRESH are:• Development of dynamic energy modelling routines;• Optimisation of the energy efficiency and air emissions for retrofitting and operation;• Development of a monitoring and management methodology for operation; and• Development of a decision support tool for operation.