District heating and cooling networks for an energy-efficient city

How can we heat and cool the city of tomorrow while promoting energy sobriety? That is the challenge that district heating and cooling networks address. ENGIE, the world leader in this field, supports cities and local authorities in their transition to carbon neutrality.

header réseaux de chaleur


A growing demand for district heating and cooling networks

The world is continuing to urbanise at a frenetic pace and on a large scale. Globally, more than 50% of the population now lives in urban areas compared to only 29% in 1950.
By 2050, the pace is expected to accelerate further: 7 out of 10 people will live in urban areas.
In this context, the global demand for heating and cooling in urban environments will continue to increase. The demand for district cooling networks, for example, linked to the development of air conditioning, is expected to increase by 200% between 2016 and 2050(1).

ENGIE, world leader in district heating and cooling networks

Chiffres clés chaud froid

What are district heating and cooling networks?

Heating networks produce and transport heat in the form of hot water or steam for heating or domestic water use (hot water). 
Cooling networks produce and distribute cooling energy through a chilled water network to cool buildings. Reflecting a perfect balance between industrial and operational performance, they integrate advanced digital technologies and solutions to manage the networks.
For example, the City of Paris' district cooling network, developed and operated by Fraîcheur de Paris, a subsidiary of the ENGIE group, cuts CO2 emissions by up to 50% compared to stand-alone installations.

How does it work?

Video of a cooling system in action


Video of a heating system in action


District heating and cooling networks to promote energy sobriety

District heating and cooling networks play a major role in reducing greenhouse gases and in the transition to carbon neutrality. 
Heating and cooling networks offer several modes of production capable of promoting energy sobriety. That is particularly the case when the cooling network directly uses the coldness of a local water source to cool the water in its network (a method known as free-cooling), or when the heating network uses biomass as a fuel. Other processes exist, such as geothermal wells or fatal heat recovery from a cooling network located near a heating network. 

A key role in the circular economy 

Based on the circular economy principle, district heating and cooling networks play a key role in integrating and pooling the resources of the various available energy sources. First and foremost, they use local energy by exploiting a variety of resources such as fatal heat, energy from the ground and subsoil with geothermal power, local forest resources managed on a sustainable basis, heat co-generated by local methanisation units or solar power with solar thermal energy. These district heating and cooling networks significantly promote energy efficiency and sobriety.

Heat or cold can be produced from all energy sources that can be harnessed:

-    Free-cooling (air, rivers, lakes or sea)
-    Recovered heat from industrial processes, household waste incineration, data centers, metro, etc.)
-    Renewable energy sources (biomass, geothermal, solar thermal, wood energy, biogas, and green hydrogen)
-    Cogeneration - much more efficient - that produces highly efficient heat and electricity (or heat, cold and electricity for tri-generation, also known as combined cooling, heat and power (CCHP))
-    Conventional fossil sources (gas) 

Our references

Cooling network in Paris (France)

Paragraph content

In Paris, Fraîcheur de Paris uses river water from the Seine to refresh its cooling network 

Since 1991, Fraîcheur de Paris, a subsidiary of the ENGIE Group and concession company of the City of Paris, has been operating and developing the largest urban district cooling system in Europe, in Paris, and the 11th largest in the world. In practice, more than 700 customers, including hotels, residential buildings, department stores, museums, restaurants and theatres in Paris, are cooled by Fraîcheur de Paris via a network of chilled water running through more than 80 km of pipes.
Ten production plants, including three Seine-sourced water power plants, produce around 500 GWh per year. The Seine water power plants are particularly energy efficient. They offer several methods of production, including free-cooling. This allows the water in the network to be cooled directly thanks to the cold energy of the Seine. Free-cooling represents 5% of annual production on average.

Heating network in Paris (France

Paragraph content

In Paris, CPCU operates the biggest district heating network in France 

CPCU is a concession company of the City of Paris and a subsidiary of ENGIE, and is responsible for the public service of heat distribution in Paris. CPCU operates and develops the biggest district heating network in France: 8 energy production sites and a 510 km underground distribution network to meet the needs of nearly 1.5 million Parisians.
CPCU draws on an energy mix that favours local and renewable energies: more than 50% of local renewable energies, heat recovery from waste to the energy systems surrounding the city, geothermal power plant, data center heat recovery, etc. Thanks to this, the heating network improves the quality of the air breathed by Île-de-France residents. As a major player in the City of Paris' Climate Plan, day after day CPCU contributes to the energy transition and sustainable development goals of the Paris Region.

Heating and cooling network in Marseille (France)

Paragraph content

In Marseille, the Thassalia geothermal power plant uses sea water to produce heat and cold

In partnership with Euroméditerranée, ENGIE Solutions meets the hot and cold energy supply needs of the EUROMED district, thanks to an innovative energy production solution: Thassalia, a marine geothermal power plant, produces heat and cold simultaneously from sea energy. With a total power of 40MW, it can supply a surface area of more than 500,000 m². The distribution network extends over 3.5 km.
Thassalia supports the Aix-Marseille metropolitan area to improve its carbon neutrality. 

Heating and cooling network in Barcelona (Spain)

Paragraph content

Districlima, district heating and cooling network

Districlima was the first district heating and cooling network in Spain. The project was initially located in an area of Barcelona that has been remodelled in terms of urban planning and that includes the Forum of Cultures 2004 (Besos waterfront).
The project incorporates the design, construction and subsequent use, over a period of 25 years, of the Forum's energy production plant and energy distribution network. 

Combined cooling, heat and power in Lisbon (Portugal)

Paragraph content

Climaespaço in Lisbon, Portugal: a tri-generation plant producing heat, cold and electricity 

As part of its urban renewal, Barcelona City Council wanted to provide its districts with advanced infrastructures. All the district's water, heating and cooling, electricity, waste and telecoms networks have been redesigned. Energy efficiency and the responsible management of natural resources have guided the technical choices. For example, the district has been equipped with a selective pneumatic waste collection system and accessible underground galleries, which make it possible to repair and improve service networks without having to dig up streets. In Lisbon, the heating and cooling network operated by Climaespaço is recognised as the first centralised urban-scale thermal energy distribution network. It cuts CO2 emissions by 40% per year and serves 130 buildings.

(1) Bloomberg NEF - Air Conditioning Heats up Electricity Demand