The Open Energy Modelling Initiative (openmod) is a grassroots community of energy system modellers from universities and research institutes across Europe and elsewhere. The initiative promotes the use of open-source software and open data in energy modelling for research and policy advice. The Open Energy Modelling Initiative documents a variety of open-source energy models and addresses practical and conceptual issues regarding their development and application. The initiative runs an email list, an internet forum, and a wiki and hosts occasional academic workshops. A statement of aims is available.

The application of open-source development to energy modelling dates back to around 2003. This section provides some background for the growing interest in open methods.

Just two active open energy modelling projects were cited in a 2011 paper: OSeMOSYS and TEMOA. Balmorel was also public at that time, having been made available on a website in 2001. As of October 2021,^[update] the Open Energy Platform lists 17 open energy frameworks and about 50 open energy models.^{[citation needed]}

This 2012 paper presents the case for using "open, publicly accessible software and data as well as crowdsourcing techniques to develop robust energy analysis tools". The paper claims that these techniques can produce high-quality results and are particularly relevant for developing countries.

There is an increasing call for the energy models and datasets used for energy policy analysis and advice to be made public in the interests of transparency and quality. A 2010 paper concerning energy efficiency modelling argues that "an open peer review process can greatly support model verification and validation, which are essential for model development". One 2012 study argues that the source code and datasets used in such models should be placed under publicly accessible version control to enable third-parties to run and check specific models. Another 2014 study argues that the public trust needed to underpin a rapid transition in energy systems can only be built through the use of transparent open-source energy models. The UK TIMES project (UKTM) is open source, according to a 2014 presentation, because "energy modelling must be replicable and verifiable to be considered part of the scientific process" and because this fits with the "drive towards clarity and quality assurance in the provision of policy insights". In 2016, the Deep Decarbonization Pathways Project (DDPP) is seeking to improve its modelling methodologies, a key motivation being "the intertwined goals of transparency, communicability and policy credibility." A 2016 paper argues that model-based energy scenario studies, wishing to influence decision-makers in government and industry, must become more comprehensible and more transparent. To these ends, the paper provides a checklist of transparency criteria that should be completed by modellers. The authors note however that they "consider open source approaches to be an extreme case of transparency that does not automatically facilitate the comprehensibility of studies for policy advice." An editorial from 2016 opines that closed energy models providing public policy support "are inconsistent with the open access movement [and] publically [sic] funded research". A 2017 paper lists the benefits of open data and models and the reasons that many projects nonetheless remain closed. The paper makes a number of recommendations for projects wishing to transition to a more open approach. The authors also conclude that, in terms of openness, energy research has lagged behind other fields, most notably physics, biotechnology, and medicine. Moreover:

Given the importance of rapid global coordinated action on climate mitigation and the clear benefits of shared research efforts and transparently reproducible policy analysis, openness in energy research should not be for the sake of having some code or data available on a website, but as an initial step towards fundamentally better ways to both conduct our research and engage decision-makers with [our] models and the assumptions embedded within them.

A one-page opinion piece in Nature News from 2017 advances the case for using open energy data and modelling to build public trust in policy analysis. The article also argues that scientific journals have a responsibility to require that data and code be submitted alongside text for scrutiny, currently only Energy Economics makes this practice mandatory within the energy domain.

Issues surrounding copyright remain at the forefront with regard to open energy data. Most energy datasets are collated and published by official or semi-official sources, for example, national statistics offices, transmission system operators, and electricity market operators. The doctrine of open data requires that these datasets be available under free licences (such as CC BY 4.0) or be in the public domain. But most published energy datasets carry proprietary licences, limiting their reuse in numerical and statistical models, open or otherwise. Measures to enforce market transparency have not helped because the associated information is normally licensed to preclude downstream usage. Recent transparency measures include the 2013 European energy market transparency regulation 543/2013  and a 2016 amendment to the German Energy Industry Act  to establish a nation energy information platform, slated to launch on 1 July 2017. Energy databases may also be protected under general database law, irrespective of the copyright status of the information they hold.