This paper presents an innovative analytical framework to address incomplete interpretations and dispersed data of the energy system in cities, which usually generate multiple inefficiencies. Integrative city planning takes the city energy system from the supply to the demand while considering its spatial representativeness, and drives optimal cost-efficient assessment towards future sustainable energy targets. This holistic approach delivers more adequate policies and measures towards higher energy use efficiency. The proposed analytical framework has been developed within the INSMART EU funded project and focuses on data gathering procedures and data processing tools and models, covering a wide range of city's energy consumers, as residential buildings, transport and utilities. The results, mapped into a GIS, can be further exploited either for awareness increase of citizens and for decision support of city energy planners.