Water heat recovery system thermal
About this good practice
The town of Evaux-les-Bains owns two hot springs (58° and 60°C) with a constant flow rate of 10m³ per hour. In 2017, the town council is considering how to improve the spa, including the sustainable development with a calorie recovery and the environmental protection.
The goal of this system is to do without fossil fuels as much as possible (propane gas). It also helps to use less chemical products within the resort by switching from a chemical disinfection to a heat disinfection (75°C).
The system uses the most energy-efficient infrastructure possible, two air-cooling towers (energy-consuming) were replaced by an adiabatic tower, which uses humidified cardboard. A refrigeration unit provides additional cooling in very hot weather. The system pays particular attention to use of refrigerant gases with the lowest possible Global Warming Potential. A heat pump forms the central system, producing both cooling and heating.
The aim is also to protect the environment, by discharging water at a maximum of 21°C into the river, without using fossil fuels for cooling.
The energy recovered is used to heat the sanitary waters and the heating of the spa, the Grand Hôtel and the wellness centre.
The temperatures distributed in the heating network have been reduced to optimise its energy efficiency.
The heating and cooling network enables customers to benefit from advantageous pricing, the VAT is reduced to 5.5% (compared with 20% for energy produced from fossil fuels at a rate of over 15%).
Resources needed
Hot springs are needed, in Evaux-les-Bains 58 and 60°C with a constant flow 10m³.
The total cost is 2 million euros, 80% financed by State and Department, 20% by the Energy Savings Certificate.
The network has an average cost of 770 euros per metre (variable amount according to local context).
Evidence of success
With the propane energy system, emissions were 270kg CO²/MWh. With the new system, emissions are 45kg/MWh. The current network avoids the emission of 500t of CO². If all the energy potential is deployed, that's 960t per year.
The system has been operating since October 2023, it serves 5 subscribers. The network will be extended to social housing and the hospital.
The municipality is confident that the investment will pay for itself, as it will be offset by subscriptions and lower energy costs.
Potential for learning or transfer
This new system will significantly reduce energy costs, making it possible to extend the opening period of the Grand Hôtel and the wellness centre all year round. In all, around twenty permanent jobs have been created.
The engineering is easily replicable, but a study is needed to adapt it to the local thermal cycle (water temperature, flow rate per hour, health and environmental standards, etc.).
The most energy-efficient and robust equipment has been used to reduce servicing and maintenance costs. For example, screw compressors have been chosen for the heating network, as they are more resistant over time.
Good practice owner
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