Innovative new climate control technology at the French Polynesia Hospital Centre
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Since 2022, the climate control system at the hospital in Pira’e, Tahiti, has been operating using water from the deep ocean. This offers stable comfort for the building’s users and a drastic reduction in energy spending – a saving of 40%.
A saving of almost 9 GWh a year, equivalent to 5,000 tonnes of CO2 emissions: this is the energy impact attributable to the innovative climate control system in operation since 2022 at the French Polynesia Hospital Centre (CHPF) in Pira’e, on the outskirts of Papeete in Tahiti. This is a particularly significant benefit given that the refrigeration units producing chilled water previously accounted for 35% of the establishment’s total electricity consumption.
The driving force behind this performance can be summed up in four letters: SWAC – which stands for Sea Water Air Conditioning, a solution based on using water from the Pacific Ocean as a cooling source in climate control loops. How does it work? The principle behind SWAC is to pump water at around 5 °C from deep in the ocean up to a heat exchanger designed to cool a building’s secondary water circulation system. The seawater is then discharged back into the ocean at a depth carefully selected to avoid altering the surrounding ecosystem.
Appropriate seabed topography
“A project of this type requires certain conditions,” says Frédéric Dock, a local VINCI Energies director, who was involved in the Polynesian hospital project, working alongside several VINCI Energies Building Solutions business units in Polynesia to install technical equipment in the machine room and automate the regulation of pumps, heat exchangers, etc. Additionally, VINCI Facilities Polynesia was awarded the site maintenance and energy monitoring contract through to January 2029.
“You have to target buildings with higher climate control needs, such as hospitals, hotels and airports, where there is appropriate seabed topography(*) and easy access to deep ocean water. That’s why tropical island environments are particularly suitable.”
Multi-year energy transition plan
Boasting 3.8 km of pipes laid to a depth of more than 910 m, and 6 MW of cooling power, the hospital’s SWAC system is currently the largest installation of its type in the world. The project, which also involved the VINCI Construction subsidiary Geocean working alongside VINCI Energies, required almost three years of work at a total cost of €31 million, jointly financed by the French government and the overseas territory.
The SWAC system at CHPF is the largest installation of its type in the world.
Frédéric Dock continues: “This project is part of the multi-year energy transition plan in French Polynesia, where carbon emissions per head of population are higher than the national average. The territory aims to halve its emissions by 2030. The hospital alone accounts for 1.8% of Tahiti’s electricity consumption.”
Lower bills
Since installation of the SWAC system, the temperature of the secondary circuit feeding the hospital’s chilled water network has stabilised at around 6 °C. This constant temperature ensures a comfortable environment in the hospital’s various wards and rooms throughout the day, regardless of weather conditions.
Drawing as it does on an inexhaustible, cost-free resource, “The seawater loop meets most of the hospital’s cooling needs, reducing the need for refrigeration fluids at a time when global standards on emissions quotas are tightening and the financial penalties becoming stiffer,” according to the website of Club SWAC France, a federation of manufacturers promoting SWAC technology. In financial terms, the reduced energy consumption is worth an estimated €2.9 million a year, a saving of 40%.
The French Polynesia Hospital Centre is now planning to connect the new annexe buildings currently under construction. Meanwhile, different research projects are studying how replicable SWAC may be in other comparable building types.
01/16/2025
(*) Seabed topography refers to the depth and shape of the ocean floor. The study of seabed topography is known as bathymetry.
