The town of Joigny in Burgundy and ENGIE formalised their partnership on 3 November for JOIE (Joigny Énergie), the town's future district heating network. ENGIE holds a 27-year concession to design, build and operate it, with an investment the partners give as €17.5 million excluding tax.
The plan as reported by Energynews:
- 6.7 km of new pipes, plus the takeover of 1.3 km of an existing secondary network
- 69 substations in the long run, covering the needs of the equivalent of 2,700 homes, and about 18,000 MWh of heat a year
- a new boiler house on avenue d'Amélia with a 3.1 MW biomass boiler, an economiser and a heat pump, a 7.3 MW gas boiler as backup and 40 m³ of hydro-storage
- 90% of the heat from renewable and recovered energy, and an estimated 2,800 tonnes of CO2 avoided per year
A request for €2 million from the Heat Fund has been filed with ADEME; no decision has been announced. Studies run through late 2026 and early 2027, the main works at the boiler house start in September 2027, and heat delivery is due from October 2028, with connections added step by step from then.
Sixty-nine buildings, sixty-nine interfaces
For anyone who will work on the building side, the number to look at is the 69 substations. Each one is a point where the network water is separated from the building's own heating circuit, normally through a plate heat exchanger in an indirect substation. They get specified in a batch, but the buildings behind them are not alike: an old school, a hospital wing and a block of flats each bring their own return temperatures and their own water.
A network that wants good return temperatures from its biomass plant depends on those substations working as designed. It is worth agreeing early who cleans and inspects them, and how often, rather than finding out in the third winter.
Sources: Energynews
