The InSMART concept brings together cities, scientific and industrial organizations in order to establish and implement a comprehensive methodology for enhancing sustainable planning addressing the current and future city energy needs through an integrative and multidisciplinary planning approach. This approach will identify the optimum mix of short, medium and long term measures for a sustainable energy future, addressing the efficiency of energy flows across various city sectors with regards to economic, environmental and social criteria and paving the way towards actual implementation of priority actions. Extensive technical expertise and specialized tools and models will be used to create a platform for implementation of the project idea. Each city’s energy system will be analysed, covering all relevant sectors and a comprehensive GIS energy database will be developed. Apart from being a valuable planning tool the GIS database will inform and be linked to the TIMES planning model. This model will be used to analyse the cost-optimal mix of measures required to meet sustainable energy targets taking into account exogenous parameters (e.g. environmental targets, city expansion). These measures will be further assessed with respect to non-technical criteria using a multi-criteria decision making method (PROMIΤHEE) that will address economic, environmental as well as social issues. A detailed economic analysis of the mid-term measures identified through this two stage optimisation procedure will be undertaken, identifying all relevant investment indicators. Finally, a detailed, realistic and applicable mid-term implementation plan will be developed to describe the necessary steps, required resources and monitoring procedures for each city. The approach will be used on the four city partners, all actively involved in developing a more sustainable energy system. Further on, the proposed approach will be replicable in other cities with sustainability target.