Understanding district heating networks and their decarbonisation levers
District heating network: principle, substations, and job-site points to watch
A district heating network produces heat at a central boiler plant, then distributes it via pipework to the buildings. At the foot of each building, the substation, with its heat exchanger and metering, transfers the energy to the internal circuit. Job-site point: validate footprint constraints, temperatures, pressures, and maintenance access with the network operator early on.
Why the energy mix weighs on the carbon footprint (and on your business)
CO2 mainly depends on the network's sources. Biomass, geothermal, recovered heat, and solar thermal pull the footprint down. Gas and oil pull it up. Good reflex: a greener network secures your files and your pitch to clients.
Indicators to track: renewable share, carbon content, supply stability
Before proposing a connection, track three benchmarks. To check: the renewable share, the network's carbon content in gCO2/kWh, and the robustness of supply (diversification, biomass contracts, operational continuity). This trio clarifies the real gain, and the risks of cost drift.
Building a low-carbon energy mix suited to the local area
Wood energy, geothermal, recovered heat: when to prioritise them on a district heating network
Prioritise local resources when they're stable and available. Wood energy works if the supply is secure and air quality is controlled. Geothermal is relevant with favourable subsurface conditions and a regular heat demand. Recovered heat makes sense as soon as an emitting site nearby is reliable over the long term.
Network heat pumps and heat recovery: the technical conditions for it to work
A network heat pump works well with low return temperatures, correctly sized heat exchangers, and controlled flow rates. Plan for a robust electrical supply point, fine-grained control, and a buffer tank to smooth out peaks. Aim for a COP that's consistent year-round.
Gas and top-up: how to reduce it without weakening service continuity
Keep gas as a top-up or backup. Reduce its use by increasing the renewable share, adding storage, and improving hydraulic balancing. Set seasonal setpoints and switchover scenarios to maintain service continuity.
Sizing and operation: securing the performance of the district heating network
Lowering temperatures: a key lever for decarbonising the energy mix
On a district heating network, switching to low temperature where possible reduces losses and makes it easier to integrate renewable and recovered heat. Correct sizing is based on actual needs, the return temperature, and the quality of the controls, not "just in case" margins.
Thermal storage and control: smoothing peaks without oversizing
A buffer storage volume absorbs the morning and evening peaks. With weather-compensated control, time-based setpoints, and source prioritisation, you limit the power called for. The result: a boiler plant and pipework that are better calibrated, without sacrificing comfort.
Efficiency and losses: insulate, balance, and check on site
Performance is decided on site. Reinforce insulation, track down leaks, and carry out hydraulic balancing to keep a useful delta T. Regular measurements (flow rates, temperatures, metering) let you quickly detect a poorly adjusted substation or a loss drift.
Connections and work: what the tradesperson must get right for real decarbonisation
Building connection: hydraulics, controls, metering, and fine-tuning
On a heat pump, a biomass boiler, or a district heating substation, the connection is what makes the performance. Take care with the hydraulic diagrams, the balancing of the networks, the air vents, and water quality. On controls, aim for a stable weather-compensation curve, well-placed sensors, and consistent setpoints. Add metering where required, then do genuine fine-tuning, not guesswork.
Emitter compatibility: radiators, underfloor heating, hot water, and flow temperatures
Before changing the heat generator, check what the emitters can handle. Oversized radiators, underfloor heating, fan coil units — they don't all have the same needs. Aim for low temperature whenever possible, that's where decarbonisation pays off most. For hot water, plan for a tank, recirculation, and anti-scald protection, without unnecessarily pushing temperatures up.
Installation quality: lagging, sealing, tests, and end-of-job file
The "small" detail often causes the biggest losses. Continuous lagging, sealed penetrations, insulation of singular points. Run the tests — pressure, flow rate, temperatures — then record everything in a test report. Hand over a clear file: diagrams, settings, manuals, and usage advice, so the installation stays efficient over time.
The 2026 framework: subsidies, requirements, and sales arguments around district heating
Subsidies available in 2026: MaPrimeRénov', CEE, and connecting to a district heating network
In 2026, connecting to a district heating network can be funded via MaPrimeRénov' (subsidy by measure or pathway) and a CEE bonus. Combining them is possible if the file is set up before signature and if the invoice details the supply, installation, commissioning, and power output. Also check that the network shows a high share of renewable and recovered energy, often required for eligibility.
RGE certification and inspections: securing your files and avoiding non-compliance
The simple rule: no subsidy without solid supporting documents. Keep the RGE proof when required, the CEE operation references, and dated photos. Inspections can be on paper or on site. A discrepancy in the address, the scope, or the dates blocks payment.
Selling without overselling: pricing, decarbonisation proof, and client expectations
To convince, talk figures. Compare the subscription, the price per MWh, and the associated works. Bring CO2 proof for the district heating network via the operator's documentation and a before/after calculation. Clients expect a clear gain, without promises about the bill, which depends on usage.
Key figures
66%
Renewable share 2023
75% renewables
2030 target
25%
Gas share
Frequently asked questions
On the building side, the 5.5% VAT rate generally applies to the connection and the equipment if the network is majority-supplied by renewables and recovered heat. Depending on the project, you can also point the client towards MaPrimeRénov' (by measure/pathway) and CEE: often several tens of euros per cumac MWh depending on the scheme sheet and the zone. Remember to ask the network operator for the renewable-share certificate and the carbon content to secure eligibility.
Louis Airy
COO of Argile
