Most energy in the built environment is used in the form of heat. This heat is produced for 75% from natural gas. Large scale electrification of the heat supply (with heat pumps) will need significant investments in the electricity networks. This doesn't even take into account that most heat (and hence electricity when decoupled from the natural gas network) is needed when the sun is not , or less, shining: at night and in the winter. So it is now of utmost importance to work on heat storage in the form of for instance PCMs (Phase Change Materials) or TCMs(ThermoChemical Materials) that can be integrated into the built environment.