The 5th generation compact district heating and cooling networks in a temperature range of 10 to 16 °C have a great potential for energy savings by providing a heat source for decentralized heating heat pumps, a cold source for air-conditioning and a heat sink for refrigeration or cogeneration units. The energy balance of the network is achieved by a central plant equipped with a heating heat pump in winter operation and a heat dissipator in summer operation. They typically facilitate the synergy between users and allow the concept of a city without chimneys or cooling towers in the various buildings. One such concept is based on using the latent heat of the transfer fluid (CO2), with one saturated CO2 vapor pipe and one saturated CO2 liquid pipe. Studies show that up to 80 % of the final energy can be saved in urban areas, at a cost that is lower than the conventional technologies.