In the iKlimEt research project, simulation tools (optimization, machine learning and energy analytics methods) are being developed for integral energy system planning taking into account the consequences of climate change and extreme events. The project goal is, among other things, the further development of a sector-coupled energy system optimization model (electricity, gas/hydrogen, heating/cooling, transport, demand-side management), which determines optimal expansion and operating decisions for the energy infrastructure. The validation of the developed tools takes place in a case study in the energy system of the Styrian energy networks in the spirit of climate neutrality in 2040.