The MEU GIS-enabled web-platform [1] has been developed in close collaboration with four Swiss cities. The tool enables detailed monitoring and planning for both energy demand and supply at individual building, neighborhood and whole city scale (http://meu.epfl.ch). This web-platform acts like an interface between different tools and allows to establish detailed energy balances for entire cities comprising several thousand buildings. In its present configuration, the MEU tool does not allow yet to simulate energy networks behaviors, based on the real or projected energy demand in an urban zone. In order to meet this need from energy utilities partners, a specific data model, as well as an user-interface giving access to networks attributes and edition/simulation tools were developed, which will be then functionally integrated in the MEU platform. The idea is to create a “Natural Gas Networks” module built for energy utilities. The objectives of this project within the larger MEU endeavor were the following: - Create a platform gathering topological and geo-referenced data - Develop a gas network pre-design/planning methodology including demand characteristics and gas supply for buildings in a selected area. - Interface with gas distribution system operators existing tools and add new functionalities within a single platform. - Include gas distribution system operator constraints and operational realities in the pre-design/planning process. In order to achieve those objectives, two tools and several visualization concepts have been created, along with an ad hoc data model: (i) a data model able to allow data import, storage and centralization from energy utilities databases: networks, buildings demands and specifications, as well as interface between edition, simulation and visualization tools; (ii) a network edition tool prototype (LEAFLET JavaScript based web page), which allows to display a network on a map, to add/delete or drag&drop pipes, nodes, consumption and biogas production/injection points and pressure let down stations; (iii) a network flows, and pressures simulation device (MATLAB® compressible fluids model) which computes the network behavior for each hour (pressures, flows, power equivalent and temperatures in each point); (iv) a detailed mock-up for visualization and display concept with interactive and GIS data: buildings area, networks paths, pipes characteristics, results from simulation, studied area energy balance, etc. This paper focuses more specifically on the visualization and network edition tool, as well as simulation results interactive representation on the MEU platform.