08.01.2026
Equans France supports the energy performance of the Carrousel in Nantes
Directly linked to the SNCF train station and located at the heart of Euronantes, the 1st business district on the Atlantic seaboard, Le Carrousel is one of Nantes' most emblematic real estate projects. This 27,000 m² mixed-use complex - offices, shops and a multimodal interchange - will welcome its first users in May 2025.
It is distinguished by its energy performance, thanks in particular to the solutions implemented by Equans France through its Axima entity. The building is equipped with comprehensive heating, ventilation, air-conditioning and smoke extraction systems, including an underfloor heating system for all the office floors - a first on this scale for a commercial building.
All these technical choices make Le Carrousel a pioneering building, aiming to reduce energy consumption by around 75% compared with a building built to RT 2012 energy standards.
Technical innovation for environmental performance
Teams from Axima, part of Equans France, were responsible for the HVAC and sanitary engineering work packages, including plumbing, heating, ventilation, air conditioning and smoke extraction. Some twenty employees were mobilized on this site, using local subcontractors and suppliers. The project includes the installation of an underfloor heating system for 12,000 m² of office space in two 7-storey buildings, accommodating up to 2,000 workstations.
Usually reserved for the residential sector, underfloor heating systems are rarely deployed on office surfaces of this scale.
Axima set itself the challenge of designing and installing an installation capable of guaranteeing not only office heating, but also the maintenance of continuously filtered fresh air throughout the year, and keeping offices cool in hot weather.
A particularly timely solution, given that heating is the main energy expense in commercial buildings - sometimes accounting for up to 50% of consumption, depending on their configuration and use - to which must be added cooling and ventilation requirements.
Designed from the outset to exacting standards, and particularly ahead of schedule when the project was launched, the Carrousel de Nantes is supported in particular by this HVAC system and a BMS dedicated to monitoring usage and controlling consumption. These technical features are complemented by a bioclimatic design, connection to the renewable heating network and massive photovoltaic energy production.
Together, these features enable the building to achieve E+C- level 3 energy performance, with a 75% reduction in primary energy consumption compared to RT 2012. The project thus targets high levels of environmental performance, with a BREEAM Very Good objective that prefigures the requirements now set out in the RE2020 environmental regulations.
An exemplary project for the sustainable city
Le Carrousel comprises two office buildings and a multimodal interchange hub (PEM) directly connected to the Nantes TGV station.
A true hub, it offers links to the train and bus stations, car rental agencies and the largest bicycle parking facility in France, capable of housing up to 1,200 two-wheelers.
Launched in September 2022 and built by Bati Nantes in co-promotion with Nantes Métropole Aménagement, this project is fully in line with the city's new drive for sustainable development.
A virtuous building by nature, the exemplary nature of the building is also reflected in its architectural design: with its wide-open facades and wood structure, the reuse of solid wood floors and its bio-sourced materials.
"With the Carrousel, we're showing that it's possible to combine technical innovation, energy performance and sustainability, while improving user comfort. The large-scale underfloor heating system we installed is a powerful illustration of this, and a showcase for our expertise", explains Solène Cosnefroy, Director of the Nantes branch of Axima, part of Equans France.
