January 8, 2026
Equans France Supports Energy Efficiency at the Carrousel de Nantes
Directly connected to the SNCF train station and located in the heart of Euronantes, the leading business district on the Atlantic coast, the Carrousel is one of the Nantes metropolitan area’s flagship real estate projects. This 27,000 m² mixed-use complex—featuring offices, retail spaces, and a multimodal transit hub—has been welcoming its first users since May 2025.
It stands out for its energy efficiency, driven in particular by the solutions implemented by Equans France through its Axima division. The building features comprehensive heating, ventilation, air conditioning, and smoke extraction systems, including underfloor heating installed throughout all office floors—a first on this scale for a commercial building.
These technical choices make the Carrousel a pioneering building, aiming for a reduction of approximately 75% in energy consumption compared to a building constructed according to the RT 2012 energy standards.
A Technical Innovation That Enhances Environmental Performance
The teams at Axima, a division of Equans France, handled the mechanical and plumbing work, including plumbing as well as heating, ventilation, air conditioning, and smoke exhaust systems (HVAC). About twenty employees were assigned to this project, with the support of local subcontractors and suppliers. The project notably includes the installation of an underfloor heating system in a 12,000 m² commercial office space, spread across two 7-story buildings capable of accommodating up to 2,000 workstations.
Typically reserved for residential use, underfloor heating systems are rarely installed in office spaces of this size.
Axima took on the challenge of designing and installing a system capable of not only heating the offices but also providing a continuous supply of filtered fresh air year-round and keeping the offices cool during hot weather.
This is a particularly timely solution, given that heating is the primary source of energy expenditure in commercial buildings—sometimes accounting for up to 50% of consumption, depending on their configuration and use—in addition to cooling and ventilation needs.
Designed from the outset to meet stringent standards—and particularly ahead of its time when construction began—the Carrousel de Nantes relies in particular on this CVCD system and a building management system dedicated to monitoring usage and controlling energy consumption. In addition to these technical features, the building incorporates a bioclimatic design, a connection to the renewable district heating network, and large-scale photovoltaic energy generation.
Together, these features enable the building to achieve Energy Level 3 under the E+C- standard, with a 75% reduction in primary energy consumption compared to the RT 2012 code. The project thus aims for high levels of environmental performance, with a BREEAM “Very Good” rating that anticipates the requirements now set forth in the RE2020 environmental regulations.
An Exemplary Project for a Sustainable City
Le Carrousel consists of two office buildings and a multimodal transit hub (PEM) directly connected to the Nantes TGV station.
A true hub, it offers connections to the train and bus stations, car rental agencies, and is home to France’s largest bicycle parking facility, capable of accommodating up to 1,200 bicycles.
Launched in September 2022 and developed by Bati Nantes in partnership with Nantes Métropole Aménagement, this project is fully aligned with the city’s new sustainable development initiatives.
An inherently sustainable building, its exemplary nature is also reflected in its architectural design: with its largely open wooden facades and structure, the reuse of solid wood flooring, and its bio-based materials.
“With the Carrousel, we’re demonstrating that it’s possible to combine technical innovation, energy efficiency, and sustainability while enhancing user comfort. The large-scale underfloor heating system we installed is a powerful example of this and serves as a showcase for our expertise,” explains Solène Cosnefroy, Director of the Nantes office of Axima, a division of Equans France.
