Cities, as main energy consumers, play a crucial role in achieving a more sustainable energy future. This means that there is an urgent need to transform the way of planning urban areas, focusing on more efficient and self-reliant energy production and consumption modes overall. In this framework, the aim of this study is to explore the Net-Zero energy balance between two spatial scales: the whole city with its diversified energy consumption patterns, and those urban blocks, neighborhoods, or industrial areas that can produce energy and supply it to other areas. This approach leads to the development of an energy zoning for the city, based on the geographical urban delimitation of solar energy exporters cells and the energy consuming ones. On the production side, cells are delimited according to their solar energy production potential. On the demand side, cells are delimited according to four specific criteria: construction timeline, population density, urban morphologies, and land-use patterns that permit the definition of a classification of urban areas, based on the different energy consumption levels. In this paper, the web platform "E-City", a tool for planning energy balance at urban level is presented, by describing its practical application in the city of Oeiras, Portugal. The platform integrates itself with the existing municipal Geographic Information System, exploring both spatial and statistical dimensions associated with zoning and the overall energy network system. Results from the use of this tool are relevant for urban planning practices, formulation of policies, and management of public investment that can be guided to more energy efficient solutions and supporting the transition towards nearly zero-energy cities. collaborative model between the customers and the distribution company. In this project, energy efficiency is promoted by increasing the use of renewable energy sources associated with the development of smart grids able to manage and store energy and optimize electric-vehicle charging [6].Different from the previous, the "Amsterdam Smart City" recognizes the need of a systematic framework of actions within the domains of energy transition and open connectivity [7]. This approach has led to the developing of 52 ongoing projects that promote the balance between sustainable energy supply and demand in neighborhoods by including the expected raise of electrical cars, integrating cooling and city heat system and investing in energy-efficient housing renovations [8].Within the Smart City planning process of Rotterdam, local authorities. The common understanding through these projects is that Information and Communications Technologies (ICT) coupled with digital visualization platforms can be used to improve cities, with special attention to their transition towards a low carbon future [9,10].Enhancing energy efficiency, increasing the share of renewable energy sources, and integrating smart grids and electric vehicles into cities are complex tasks with evident implications for urban developm...