This report develops a sociotechnical understanding of energy prosumerism to investigate how energy prosumerism can lead to actual reductions of energy and resource demand. The report starts out by explaining what a sociotechnical and broad understanding of prosumerism means. Thereafter, the report summarises already existing research on energy social science and humanities relating to renewable energy generation, domestic energy use, and energy communities. The report then delves into the matter of energy sustainability by explicating the concept of sufficiency and achieving actual reductions instead of continued escalations of energy use. The report concludes with the main findings that a broader and more nuanced understanding of energy prosumerism can provide a novel conceptualisation relating to energy provision and everyday life that can lead to future reductions in energy use, as well as a more multifaceted policy response that moves away from business as usual and towards more variegated and radical propositions for achieving sustainable energy use in the future.