Heating and cooling networks

Four million French people (6% of the population) are already connected to heating networks—an area of expertise in which Dalkia has established a pioneering position.

France’s 2015 Energy Transition for Green Growth Act aims to achieve a fivefold increase in the amount of renewable and recovered energy delivered through these networks by 2030. This would take the number of housing units connected heating networks from two million today to more than eight million by 2030.

Heating networks can supply heating and domestic hot water to an entire neighbourhood, city or metropolitan area. They can also produce electricity (through cogeneration). Cooling networks are based on the same principle and provide cooling to a group of buildings.

Dalkia networks: key figures


heating and cooling networks managed

2200 Km

of pipes

Heating networks comprise four separate parts:

  1. The main heat production plant (heating plant).
  2. A system of pipes connecting the heating plant to buildings. Hot water flows through a closed loop at a temperature of between 70°C and 180°C depending on the technology used. This closed loop is commonly known as a "primary" network and is usually underground.
  3. Substations are installed in the buildings connected to the network and are supplied with hot water from the heating plant. They replace the building's own boiler room, which overcomes problems related to combustion and maintenance in individual buildings. A substation includes a heat exchanger, which transfers the heat from the primary network to the water flowing through the building's central heating system (known as a "secondary" network). The water leaving the substation is slightly cooler, having delivered part of its heat to the building. Once it has supplied heat to all substations in the network, the water returns to the heating plant to be reheated. Substations can be used to warm a whole range of buildings, including homes, schools, public buildings, factories, offices and hospitals.
  4. The building's internal heating system, or "secondary" network. Once the water has been heated in the substation, it flows through the pipes to radiators, heated floor systems and hot water systems in the building.

Heating networks are modern systems that promote the transition towards more sustainable solutions for cities through improvements in energy efficiency and the increasing use of renewable and recovered energy sources. They offer a range of benefits:


Easy access to heating and hot water.


No risk of carbon monoxide poisoning (in contrast to individual boiler systems).


A mainstay of the drive to meet energy transition targets through the use of renewable and recovered energy sources and the reduction in CO2 emissions.

Increased purchasing power

Lower, stable prices because the energy is produced in bulk, making it possible to pool purchasing and production methods. Heating network users benefit from reduced VAT when their energy mix includes more than 50% renewable and recovered energy sources.


Heating networks promote secure local jobs. They benefit the local economy through contracts for local construction companies, create new markets for equipment makers and generate long-term jobs in companies that operate the networks.

The French sustainable development authority (Commissariat Général au Développement Durable) expects heating networks to create between 20,000 and 25,000 jobs a year between now and 2020:

  • 6,000 in boiler making
  • 4,000 to 5,000 in operating established and extended networks
  • 10,000 to 15,000 in downstream services (boiler servicing, distribution etc.).

Securing the country's energy supply

Through the use of local, non-intermittent renewable energy sources, heating networks allow regions to develop an energy strategy that is less dependent on fluctuations in the price of fossil fuels such as oil, gas and coal (and on the countries that produce those fuels).

Dalkia: leader in heating and cooling networks in France

Dalkia draws on extensive expertise in building and operating facilities to produce and distribute heating or cooling across an entire district or city. We use non-intermittent local renewables such as biomass, geothermal, seawater and solar power along with recovered energy sources to offer customers efficient, low-carbon energy solutions. We operate 350 heating and cooling networks in France, comprising 2,220 km of pipes.

A range of connection solutions for heating and cooling networks