The new building in La Ciotat, France, contains 127 apartments on 3 floors. The solar pump maintains a water temperature above 55°C over the whole year. The construction was finished in May 2018.

Key facts

Building Heat pump and source
Location La Ciotat, France
Number of HP 2
Construction 2017 Installed power 2×23 kW
Heat distribution Operation mode monoenergetic
Heated area Heat source solar panel
Level of insulation new building
Heating system Domestic hot water
Heat demand 27 kW Type of system central
Heating temperature 55 °C
Max. temperature 65 °C
Other information
Investments 1000 to 1500€/appart.
Gas fired condensing boiler
The Solar Pump maintains water temperature above 55°C 365days/24h. Electrical backup in case of a breakdown.

Description of the technical concept

A brine loop circulates between the heat pump’s evaporator and unglazed solar collectors. The evaporator cools down the brine temperature before going back to the solar collector to be heated. The energy transfered by the HP is recovered in the collectors. In sunny conditions, the brine temperature is up to 20°C above the ambient air temperature. Without sun, the brine temperature is about 5°C below the ambient air temperature. Wind, rain and humidity (condensation) affect the brine temperature. But 24h/day – 365d/year, the Solar Pump harvests its energy in the collector.
Unlike heating, DHW demand is de-correlated from the outside temperatures. As the Solar Pump is connected to a DHW tank, with the storage, the de-correlation and a smart control, the Solar Pump runs as much as possible during the hot sunny hours of the day. This maximizes the COP.
The DHW set point is above 55°C, to prevent from legionella. The DHW tank is split in two zones: a priority one maintained above 55°C and a storage one which can be from cold to >55°C, depending on DHW consumption and the strategy of the control.
Regarding to the piping length and its capacity a hot water loop circulates all day long at 50-55°C inducing important heat losses. Monitoring shows that the loop’s losses represent 40 to 70% of the annual energy needs. The solar pump compensates the loop’s losses in the tank achieving to double the energy savings.

La Ciotat Fact Sheet