Heating and cooling networks

DHC networks, also known as district energy systems or district energy networks, are centralised systems that produce and distribute thermal energy (heat or cold) to residential, commercial, and industrial buildings, through a network of insulated pipes, within a specific geographic area, such as a city or neighbourhood.

A DHC network is composed of one or several plants that generate thermal energy using a variety of heat/cold sources or technologies and then distribute it to connected customers for space heating, hot water, or cooling, depending on the season and the needs.

These networks are an efficient and sustainable way of meeting the heating and cooling needs of buildings compared to individual, decentralised heating and cooling systems.

They enable tapping into sustainable heat resources that would otherwise not be possible to exploit at a large scale. Hence, they foster more renewable, circular, and energy-efficient energy systems. 

DHC networks are unique in their ability to leverage locally available renewable and waste heat sources such as: 

• Geothermal Energy: Utilising heat from the Earth's core through geothermal wells or ground-source heat pumps.
• Solar Thermal Energy: Capturing heat from the sun using solar thermal collectors.
• Sustainable biomass: Using organic materials like wood chips, agricultural and forestry residues, or biodegradable waste to produce heat.
• Recovered heat or ‘excess/waste heat’: Capturing and reusing heat from industrial processes or tertiary buildings such as metro stations, data centres or supermarkets to provide heating or cooling.
• Power-to-Heat: Using excess renewable electricity to upgrade heat from a low-temperature source to a higher-temperature one with a heat pump or utilising excess renewable electricity in an e-boiler to be consumed or stored for later use in a thermal storage unit.

The choice of heat source depends on local conditions, available resources, and the economic and technical viability of projects.

The European Union's Energy Efficiency Directive (EED) sets a definition for achieving efficient District Heating and Cooling (DHC) systems. The definition of Efficient DHC lays out a gradual pathway towards carbon neutrality by 2050.

Efficient DHC systems prioritise the utilisation of clean heat sources, such as renewable and recovered heat, to gradually reduce greenhouse gas emissions and the reliance on fossil fuels towards climate neutrality by 2050. The Directive foresees two possibilities to fulfil the criteria for an installation to be considered as an efficient DHC, by reaching the milestones below.

The definition also promotes the high efficiency of Combined Heat and Power (CHP) plants, which simultaneously generate electricity and heat from a single energy source, improving overall efficiency. From 2030, to comply with the criteria, no new fossil DHC capacity will be allowed to be built.