FLEX

Overview

FLEX is a modeling suite for households' behavior, energy system operation, and interaction in the energy community. It is developed by Fraunhofer ISI and TU Wien (Energy Economics Group) in the framework of the H2020 project newTRENDs.

FLEX contains three modules:

First is FLEX-Behavior, which models the energy-related behavior of a specified household. For each individual household member, the activity profile is modeled at a 10-minute resolution based on a Markov chain model. Then, the activity profile is converted to the profiles of appliance electricity and hot water demand, as well as building occupancy. Finally, household members' profiles are aggregated to the household level in hourly resolution.

Second is FLEX-Operation, which focuses on the operation of the household's energy system. Taking the results from FLEX-Behavior, FLEX-Operation is further configured with the household’s building envelope and technology system, including the heating system, PV, thermal and battery storage, and EV. The model calculates the system operation in hourly resolution, as well as the energy consumption and cost. It can run in both simulation and optimization modes, with the latter minimizing the energy cost and representing the use of SEMS.

Third is FLEX-Community, which takes a group of households' results from FLEX-Operation as input and models the operation of an energy community from an aggregator's perspective. The aggregator can make a profit by using the following options: (1) Facilitate the peer-to-peer (P2P) electricity trading among the households in real-time, and (2) Optimize the operation of the batteries of its own or community members to buy at lower prices and sell at higher.

Getting started

To work with FLEX, please first follow the steps for installation

1. Clone the repo to your local computer;
2. Open the project and install the requirements with pip install -r requirements.txt in the terminal;
3. Install a solver for the FLEX-Operation model (setup with Pyomo). We suggest to use gurobi, and if you would like to try other solvers, we appreciate if you could inform us the experience. In the model_opt.py file, you can switch to others solvers in pyo.SolverFactory("gurobi").

In the "tests" folder, we created three examples using the three FLEX models. They are good starting points for you to understand how to use the models.

Citation

Yu, S.; Mascherbauer, P.; Haupt, T.; Skrona, K.; Rickmann, H.; Kochański, M.; Kranzl, L.; (2025). Modeling households’ behavior, energy system operation, and interaction in the energy community. Energy, p. 136338. doi: 10.1016/j.energy.2025.136338

Other related work using FLEX:

• Mascherbauer, P., Martínez, M., Mateo, C., Yu, S., & Kranzl, L. (2025). Analyzing the impact of heating electrification and prosumaging on the future distribution grid costs. Applied Energy, 387, 125563. doi: 10.1016/j.apenergy.2025.125563
• Gnann, T., Yu, S., Stute, J., & Kühnbach, M. (2025). The value of smart charging at home and its impact on EV market shares–A German case study. Applied Energy, 380, 124997. doi: 10.1016/j.apenergy.2024.124997
• Mascherbauer, P., Schöniger, F., Kranzl, L., & Yu, S. (2022). Impact of variable electricity price on heat pump operated buildings. Open Research Europe, 2, 135. doi: 10.12688/openreseurope.15268.1
• Mascherbauer, P., Kranzl, L., Yu, S., & Haupt, T. (2022). Investigating the impact of smart energy management system on the residential electricity consumption in Austria. Energy, 249, 123665. doi: 10.1016/j.energy.2022.123665
• Yu, S.; Mascherbauer, P.; Kranzl, L. (2022). Modeling of prosumagers and energy communities in energy demand models. (newTRENDs - Deliverable No. D5.2). Fraunhofer ISI, Karlsruhe.
• Thomas Haupt (2021). Prosuming, Demand Response and Technological Flexibility: an Integrated Optimization Model for Households' Energy Consumption Behavior. Thesis for Master of Science. Hochschule Ulm.

Lisence

As mentioned, FLEX is developed by Fraunhofer ISI and TU Wien (Energy Economics Group) in the framework of the H2020 project newTRENDs. The developers (2021-2024) include:

• Songmin Yu: songmin.yu@isi.fraunhofer.de
• Philipp Mascherbauer: philipp.mascherbauer@tuwien.ac.at
• Thomas Haupt: thomas.haupt@hs-ansbach.de
• Kevan Skrona: kevan.skorna@bdew.de
• Hannah Rickmann: hannah.rickmann@iwr.uni-heidelberg.de

FLEX is licensed under the open source MIT License.