IESopt

IESopt (Integrated Energy System Optimization) is a modeling and optimization framework for integrated energy systems. It is developed and maintained at the Center for Energy at AIT Austrian Institute of Technology GmbH. The framework is designed to support the optimization of energy systems that are characterized by a high degree of integration between different energy carriers and sectors. The source code of IESopt is available on Github at https://github.com/ait-energy/IESopt.jl for the core developed in Julia and at https://github.com/ait-energy/iesopt for a Python interface. IESopt has been used in various projects and publications for different purposes, like the optimization of Energy Communities (Mariuzzo et al., 2025), heat transmission network optimization (Marx et al., 2023), as a global hydrogen market model (Ortmann et al., 2024), or for the evaluation of market values of renewable energy sources (Monsberger et al., 2024).

In the Fair-Grid project, IESopt will be used on the one hand for a European energy system model to evaluate fuel consumption, electricity exports and imports, emissions, investments in power plants or transmission lines and electricity market prices for different scenarios. On the other hand, it will be used to evaluate the impact of different grid tariff design options on the electricity bill of different customer groups and the optimal response of flexible customers to investigate the incentives different grid tariffs provide.