The assessment of optimal operation and planning of multi-energy systems (MES), considering network constraints, requires the modelling and simulation of multi-energy networks. This paper presents the development and testing of a simulation framework for the analysis of MES, which integrates network calculation software, supply and load scenarios as well as coupling technology models. The framework is applied to an existing urban energy system, which was modified and extended for this case study to demonstrate the distribution of renewable energy generation among the energy sectors. Additionally, the developed framework and the software SAInt© are compared with regard to calculation results and the modelling approach adopted in SAInt© with its novel joint system of energy flow equations for electricity, gas and heat networks.