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The MESSAGEix framework

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MESSAGEix is a versatile, open-source, dynamic systems-optimization model. It was developed for strategic energy planning and integrated assessment of energy-engineering-economy-environment (E4) systems. The framework includes the possibility for integration with the general-economy MACRO model to incorporate the feedback from price changes on demand for commodities or energy services. The mathematical formulation is based on the MESSAGE Integrated Assessment model developed at IIASA since the 1980s.

The MESSAGEix and MACRO models are implemented in GAMS. This repository contains the GAMS code and a number of tutorials and examples using stylized national energy system models.

The MESSAGEix framework is fully integrated with IIASA's ix modeling platform (ixmp), a data warehouse for high-powered numerical scenario analysis.


Copyright © 2018–2020 IIASA Energy Program

The MESSAGEix framework is licensed under the Apache License, Version 2.0 (the "License"); you may not use the files in this repository except in compliance with the License. You may obtain a copy of the License at

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Please refer to the NOTICE for details and user guidelines.

Getting started


Documentation of the MESSAGEix framework, including the complete mathematical formulation and associated files, is automatically created from mark-up comments in the GAMS, Python, and R code. The online documentation is synchronized with the contents of the master branch of the message_ix Github repository.

For offline use, the documentation can be built from the source code. See doc/ for further details.


See ‘Installation’ in the documentation or the file INSTALL.rst.


Several introductory tutorials are provided. See ‘Tutorials’ in the documentation or the file tutorial/README.rst.

Scientific reference

Please cite the following manuscript when using the MESSAGEix framework and/or the ix modeling platform for scientific publications or technical reports:

Daniel Huppmann, Matthew Gidden, Oliver Fricko, Peter Kolp, Clara Orthofer, Michael Pimmer, Nikolay Kushin, Adriano Vinca, Alessio Mastrucci, Keywan Riahi, and Volker Krey. "The |MESSAGEix| Integrated Assessment Model and the ix modeling platform". Environmental Modelling & Software 112:143-156, 2019. doi: 10.1016/j.envsoft.2018.11.012 electronic pre-print available at

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