Anergy networks
Especially in Switzerland, the term "anergy network" is widespread and refers to fifth generation district heating and cooling (5GDHC) networks.
What are anergy networks?
Anergy networks are district heating networks that provide heat to buildings at a very low temperature level (-5 bis 25 °C). The temperature in anergy networks is so low that it is not sufficient to heat the building directly. Therefore, water-to-water heat pumps must be installed in all heated buildings to raise the temperature of the heat from the network. The special features of anergy networks is that they can also provide cooling energy due to the low network temperature. More information on anergy networks can be found on our pages on 5th generation district heating and cooling (5GDHC) networks.
What is anergy?
In thermodynamics, the terms exergy and anergy are introduced to describe the quality of energy. Anergy is the part of an energy which cannot be converted into work. For example, a waste heat flow at 30 °C is much less "valuable" than a heat flow at 500 °C. The reason for this is that only a very small proportion of the low-temperature waste heat flow can be converted into work (e.g. electricity). In the case of a heat flow to 500 °C, the proportion is much larger. Quantitatively, this is expressed by the Carnot efficiency. Since anergy networks are operated at ambient temperature, they provide almost only anergy.
Differentiation of anergy networks from other types of heat networks
Anergy networks differ from conventional heat networks in their temperature level. In conventional heat networks, the flow temperature is usually more than 60 °C. This is sufficient to supply the buildings directly with heat for space heating and domestic hot water preparation. Conventional heat networks are divided into 1st to 4th generation, with the first generation representing steam networks with the highest flow temperatures and the 4th generation representing modern low-temperature networks that use renewable energies such as solar thermal collectors and heat pumps. In addition, the term low-ex network is in common use. Although it is sometimes incorrectly used for anergy networks, a low-ex network refers to a 4th generation heating network, i.e. a network that does not require decentralized heat pumps in buildings.
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