"The purpose of this Learning Brief is to share key lessons to inform future efforts to effect systems-level change in humanitarian response, seeking to create positive transformational change. Given that transformation is an unfolding, open-ended process, we acknowledge that our learning is an ongoing journey. Our key lessons derive from the systems impact assessment of the Renewable Energy for Refugees (RE4R) project, supported by the IKEA Foundation and implemented in a partnership between Practical Action and UNHCR, the UN Refugee Agency between April 2017 and February 2022. RE4R sought to reshape global humanitarian response to adopt (and adapt) market-based renewable energy (RE) models demonstrated in three refugee camps and host communities in Rwanda and the city of Irbid in Jordan. In addition to providing sustainable, efficient, affordable, and reliable RE solutions for refugees, host communities, and institutions in humanitarian settings, the market-based RE approaches piloted by RE4R sought to provide long-term economic improvement for target populations." (Introduction)