What role do businesses and households play in smart and climate-neutral energy systems? Why does this pose challenges for energy modelling? Diana Süsser (IASS) and Andrzej Ceglarz (Renewables Grid Initiative) shed light on this in their article. The Paris climate goals, the European Green Deal and the Energy Union Strategy call for a climate-neutral economy and society by mid-century. For this to happen, our energy system must be profoundly transformed: from electricity and heat to transport and industry. That is why it is particularly important that different actors – such as companies and households – actively participate in the energy transition.