In the last few decades the humankind’s role on global warming and on climate change became undeniable, as recognized by virtually all countries with the signing of the Paris Agreement. The increasing energy demand due to a constantly growing global population, with the consequent carbon dioxide release to the atmosphere by burning of fossil fuels, accounts for the major anthropogenic contribution. In order to pursue a transition to a low-carbon energy system, the heating and cooling sector is crucial as it is responsible for half of all consumed final energy in Europe and the majority of the demand is provided by fossil fuels.