Reaching everyone through an extended and decarbonised district heating network in Besançon

Located in Eastern France, in the region of Bourgogne-Franche-Comté, Besançon is recognised as one of the most liveable cities in Europe, partially because of the abundant green spaces which make it France’s greenest city. Besançon is now aiming to make its heating system equally green, and it can count on its district heating network as a powerful base for its heat detox. 

A historical district heating system 

The district heating network in Besançon dates back to 1968 in a newly built neighborhood designed to accommodate the growing population of the time, housed within the social housing sector. The first heat production source was a waste incinerator, aligning with a circular approach to also manage the increasing waste generated by the expanding population. The oil crisis and the impoverishment of the neighbourhood accelerated the social role of the heating network in Besançon, enabling it to supply the most vulnerable population as well as local industries and even the Hospital with clean and locally sourced energy at a controlled cost, even during the energy crisis.  

The most compelling argument for the heating network is its proven track record. In recent years, the network has achieved an 80% renewable energy mix and offered prices 30% below market rates, providing even greater savings during the energy crisis. This reliable service and cost control have fostered trust among customers and encouraged local stakeholders to join the expansion project. The network's exceptional reliability is demonstrated by its near-perfect uptime, with less than one hour of service disruption per customer per year. Due to these factors, the connection rate for the expansion area has exceeded expectations, with nearly all eligible buildings opting to join the network. 

Building on this experience, Besançon has decided on an ambitious westward expansion of the network for the next twelve years, thus proving that the energy transition makes both ecological and economic sense. 

Environment and economy: how the extension of DHC aims at improving both 

The westward extension project of Besançon's district heating network, which covers an area equivalent to half the size of the city, will reduce an average of 35,000 tons of CO2 equivalent per year (calculated over the twelve-year duration of the operating contract) and will cover 18% of the current heat demand in the metropolitan area. Moreover, the network will be powered on average by 85% local renewable energy sources. At the same time, connecting local industry and major buildings such as the hospital to the network helps to make the local economy more sustainable.  

The extension project is also a technological feat, making this future network the most decarbonised of its size in France, as it will emit only 37g of CO2 per kWh of heat delivered over a network spanning 74 km. This reduction in emissions will be made possible by recovering the heat generated from combustion gases during biomass incineration, which will also enable nearly 100% efficiency of the burned biomass. With a continued focus on energy efficiency, lowering the network's temperature will increase distribution efficiency to 86%, allowing the greatest number of local actors to benefit from this local infrastructure. 

Overcoming challenges and building a healthier future 

Besançon is a medium-sized city, meaning that the extension project required a significant mobilisation effort from technical services and elected officials to move from the identification of the need to the diagnosis, then to the adoption of a decision and the signing of a complex concession contract in order to deploy a technically sophisticated and economically advantageous solution for the territory. In this process, all stakeholders had the opportunity to provide input on the breakdown of heating costs, the various pricing options, and connection fees, in a completely transparent manner. 

Reaching everyone: the project’s focus on vulnerable populations 

Planoise, where the district heating system was first introduced, is the city's most vulnerable neighbourhood, with one in three households experiencing energy poverty. The existing district heating system currently provides residents of this neighborhood with 30% cheaper local and renewable energy compared to market rates. 

The City of Besançon has also implemented a comprehensive program to address energy poverty, providing in-home services to vulnerable residents to lower energy costs and enhance comfort. Thanks to a partnership with the district heating network and its operator, this service has expanded its presence in the neighborhood, where a third of beneficiaries live. Through this program, residents have been educated on energy-saving practices, received minor home improvements to increase energy efficiency, and learned about the district heating system, including billing processes and the operation of the heating plant through informative tours. 

Where Besançon is in the heat strategy:

Besançon's Heat Detox

Key Heat Figures

• Km of DHC planned: 74km
• Percentage of renewables in the heating system: 80%
• Other interesting figures: DHC offers prices 30% below market rates 

Covenant Figures

• Signatory to the Covenant of Mayors since 2009
• % GHG emissions reductions by 2050: 100% renewable energy