Equans France supports the energy performance of the Carrousel de Nantes

It stands out for its energy efficiency, driven in particular by the solutions implemented by Equans France through its Axima division. The building relies on comprehensive heating, ventilation, air conditioning, and smoke extraction systems, including underfloor heating throughout all office floors—a first on this scale for a commercial building. These technical choices make the Carrousel a pioneering building, aiming for an energy reduction of approximately 75% compared to a building constructed according to the RT 2012 energy standards.

A technological innovation serving environmental performance

The teams from Axima, a subsidiary of Equans France, handled the building services engineering packages, including plumbing, heating, ventilation, air conditioning, and smoke extraction (HVAC). Approximately twenty employees were involved in the project, utilizing subcontractors and local suppliers. The project notably includes the installation of underfloor heating across 12.000 m² of office space, spread across two 7-story buildings with a capacity of up to 2.000 workstations.

Underfloor heating systems, typically reserved for the residential sector, are rarely deployed in office spaces of this size. Axima took on the challenge of designing and installing a system capable of guaranteeing not only office heating, but also a continuous supply of filtered fresh air throughout the year, and even keeping the offices cool during hot periods.

This solution is particularly timely, given that heating represents the largest energy expense in commercial buildings – sometimes accounting for up to 50% of consumption, depending on their configuration and use – in addition to cooling and ventilation requirements. Designed from the outset according to demanding standards, and particularly advanced at the start of construction, the Carrousel building in Nantes relies in particular on this HVAC system and a building management system dedicated to monitoring usage and managing consumption. These technical systems are complemented by a bioclimatic design, connection to the renewable heating network, and large-scale photovoltaic energy production. Together, these features allow the building to achieve Energy Level 3 of the E+C- standard, with a 75% reduction in primary energy consumption compared to the RT 2012 standard. The project thus aims for high levels of environmental performance, with a BREEAM Very Good objective, anticipating the requirements now set by the RE2020 environmental regulations.

An exemplary project for the sustainable city

The Carrousel complex comprises two office buildings and a multimodal transport hub (PEM) directly connected to Nantes TGV station. A true hub, it offers connections to the train and bus station, car rental agencies, and houses the largest bicycle parking facility in France, capable of accommodating up to 1.200 bicycles.

Launched in September 2022 and carried out by Bati Nantes in co-promotion with Nantes Métropole Aménagement, this project is fully in line with the new sustainable development dynamics promoted by the city.

A virtuous building by nature, the exemplary nature of the building also lies in its architectural design: with its facades and its largely open wooden structure, the reuse of solid wood floors and its bio-sourced materials.

According to Solène Cosnefroy, Director of the Nantes branch of Axima, a subsidiary of Equans France: “With the Carrousel, we are demonstrating that it is possible to combine technical innovation, energy efficiency and sustainability, while improving user comfort. The large-scale underfloor heating system we have installed is a strong illustration of this and showcases our expertise.”