Hot and cold water networks: Collective solutions for sustainable climate control
Heating and cooling networks are systems used for heating and cooling several buildings at a time (homes, offices, hospitals, etc.) Shared piping is used to carry either hot water, cold water or water at a constant temperature all year round (between 10 and 20 ºC).
What are heating and cooling networks?
A heating and cooling network connects different buildings through underground pipes. The pipes carry hot water (for heating and domestic hot water supply) or cold water (for cooling) from one or more generation points. This means that the connected buildings do not need to have their own boiler or air conditioning systems but instead receive their thermal energy directly from the network.
Types of heating and cooling networks
1. Centralised generation networks
In this conventional model, one main plant produces the heat or cold for the entire network. This plant can use different energy sources: biomass, natural gas, geothermal energy, solar thermal, or even the heat from industrial waste. Hot or cold water is distributed from the plant to all the connected buildings.
- Advantages:
- • High rates of production and distribution efficiency.
- • Enables use of large renewable installations.
- • Widely used in European cities and large-scale projects.
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Limitations:
- • Less flexible to changes in demand.
- • If the plant fails, the entire network may be affected.
- • Requires significant initial investment in civil engineering.
2. Distributed generation networks with water-source heat pumps
In this more innovative model, the network has several generation points spread throughout the district or city, using water-source heat pumps. Each heat pump is connected to the network and uses natural resources or waste heat to produce thermal energy at a higher temperature, or for cooling. In these systems, the energy output can be adapted to the specific needs of each area, allowing for improved efficiency and making better use of local renewable sources.
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Advantages:
- • Great flexibility: heat pumps can be installed wherever there is a demand.
- • High efficiency: make better use of local and renewable resources.
- • Less environmental impact: if renewable electricity is used, carbon emissions are very low.
- • Scalable investment: can be scaled up progressively to meet requirements.
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Limitations:
- • Require good planning to coordinate the different generation points.
- • May be less efficient in areas with low demand density.
Comparison: centralised v. distributed with heat pumps
| Characteristic | Centralised | Distributed |
| Main source | One large plant | Several distributed heat pumps |
| Flexibility | Less, depends on the plant | Greater, adapts to local demand |
| Efficiency | High, but depends on transport | Very high, makes use of local resources |
| Emissions | Depends on fuel used | Very low if renewable electricity is used |
| Resilience | Less, depends on the plant | Greater, several generation points |
| Initial investment | High, large-scale civil engineering | Scalable, progressive investment |
Where is it used?
Heating and cooling networks, both centralised and distributed, are becoming more common in this part of the world. They are being installed in urban districts, residential complexes, hospitals, universities, public buildings and industrial areas. They allow the thermal needs of buildings to be met more efficiently and sustainably, with less environmental impact.
