Following the Covid crisis and the war in Ukraine, the rise of fossil fuels prices demonstrates the insecurity of the supply in addition to the adverse impact it has on the environment. These crises could lead to a global shift in the strategy of building heating. Renewable systems are promising alternatives to fossil fuel heating system. One of them is the District Heating Network that has the advantages of recovering the waste heat from the industry. In the context of a neutral carbon objective set by the aluminium factory Novelis, the city of Sierre is interested in investigating the possibility of develop- ing a District Heating Network (DHN). This study develops a method to design a network between a heat source and a city, based only on open data building’s inventory. The method, applied to the case study of Sierre, shows that, coupled with heat pumps, the DHN could reduce the heating emissions of the connected buildings, between 88% and 96 % and that 50% of the Novelis’ heat is recovered when half of the city is connected to the network. In addition to that, using new generation of DHN, like CO2 based network makes possible to supply cold with the same infrastructure.