As electricity decarbonises, the successful incorporation of heat pumps into heat networks is one route by which decarbonisation of heat can be achieved. One means of realising this is to use an ambient temperature loop. The ‘loop’ can be fed by waste heat, bodies of water such as rivers, the ground, or centralised heat pumps and is typically maintained at temperatures below 25oC. Each end-user then extracts heat from the loop (or dumps heat if cooling is required) via a small-scale heat pump within their property. Merits to this design are:
- Reduced likelihood of corridor overheating problems as corridor pipework will always be at an ambient temperature;
- Negates the need for separate heating and cooling networks as customers will source both from the same system;
- No air quality concerns associated with heat pumps. Also reduces riser space as no need for flues.
Ambient temperature loop systems have the potential to effectively integrate heat pumps into communal distribution systems. However, advocates should also be aware of the risks which come with considering this system in their design:
- There is a very limited operational history of this system being used, particularly on larger networks;
- Balancing the temperature of the ambient loop to ensure it does not drop during high heat demand or overheat during hot weather is crucial and can be challenging to get right;
- The cost of the system, both in installation and in operation, is likely to be larger than conventional heat network systems using gas-fired plant.
Therefore, whilst a promising option in the development of low carbon heat networks, the risks must be fully addressed at an early stage to ensure the system is technically sound and provides heat at a reasonable cost to customers.