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The future centre, which is located in the heart of the Île de Nantes on Boulevard Vincent Gâche and 1 km west of the current administrative centre built in 1974, will house 9 government departments and thereby bring together a large number of services currently scattered throughout the Nantes metropolitan area. It will offer modern, light-filled spaces which will reflect the new ways in which work is organised, be an urban project incorporating landscaping and contribute to the renewal of the Île de Nantes. After 10 months of design work, site preparation and the demolition of two buildings, the structural work began in December 2022 and the building is scheduled for delivery in the summer of 2024. In all, the project will be designed and built in 30 months by a consortium led by Bouygues Bâtiment Grand Ouest.

A flexible, scalable building offering quality of use to its users
With a total floor area of 14,085 m2, or 20,000 m2 including parking, the centre will house 752 workstations and stopover areas for remote workers, shared meeting and training rooms, an intra-departmental restaurant offering 1,200 meals per day and a 150-space car park. The architecture of the building is scalable, modular and can be adapted to new ways of working, while offering offices which are conducive to well-being. The office floors will be divisible thanks to the long floor spans which will free up the space and allow it to be adapted to the size of the departments being accommodated and to their individual organisation.


A low-tech, understated and sustainable project which demonstrates its performance through its façades
The project embodies the State's policy on sustainable development and has multiple performance features (natural lighting, air quality, comfort in summer and energy consumption). These are subject to a financial commitment by the Group and are evident to the public through the play with light which also provides protection from its effects.

Employees working in the administrative centre will benefit from visual comfort thanks to very large windows which will take full advantage of natural light and provide spaces which are lit 50% of the time (without the need to switch on any lights).

The project’s bioclimatic and passive design will also make it possible to achieve outstanding thermal performance in the face of global warming. The design and construction consortium has committed to a performance of 46.9 kWhef/m2/year, which exceeds the regulations (40% savings compared to the maximum consumption permitted by the regulations).


In this project, the energy strategy was set at the E3 level of energy balance based on a low-tech approach adapted to the oceanic climate of Nantes using simple, sturdy technical installations requiring no complex maintenance. In practical terms, this design offers summer comfort without technical air-conditioning thanks to adapted solar protection (horizontal sunbreakers of different sizes depending on the orientation), adiabatic cooling (an innovative process for cooling the air by misting), natural night-time ventilation thanks to openings in the façade which are easily operated by employees, effective awareness-raising and training for users, and the building’s inertia and enhanced insulation. The project includes 560 m2 of photovoltaic panels on the roof to produce electricity for self-consumption.
The quality of the air inside the building is also good, as the air renewal rate is 40% higher than regulations require.

The carbon strategy ensures a commitment to the C1 regulatory level and is the subject of extensive refinement in order to minimise the emissions of each product with the aim of qualifying for the Low Carbon Building certification.

Low-tech: what is it?
The ‘low-tech’ approach involves using minimal resources and having a low impact on the environment. It is based on 3 principles: efficiency, economy and sustainability. It naturally places the user at the centre of the design and entails controlling resources and the budget, as well as focusing on the architecture.

An urban and landscaping project in the heart of the Île de Nantes 
The new administrative centre has a distinctive architectural silhouette with alternating heights (a 3-storey building in the lower part and two ‘blocks’ of 5-storey and 7-storey buildings which reflect the vertical nature of the neighbouring buildings), allowing light to enter the heart of the complex. Nature is also given pride of place in the centre thanks to a reduced footprint, a rainwater management system combining flood channels and grasslands, eco-grazing meadows, and a landscaping project improving the living environment which includes a hanging garden accessible to all, shared terraces accessible from all the common areas and planted patios. 

"Our approach was to think about the project at all the different scales, from the smallest (the workstation) to considering the urban setting and the creation of empty and filled spaces. Aware of the fact that tertiary buildings suffer from very rapid obsolescence due in particular to the low quality of urban design and badly thought-out work spaces, we sought to propose an alternative design based on environmental objectives.” Bruno Gaudin, architect.

Those involved in the project: 
Contracting party: The Préfecture de la Loire-Atlantique
Delegated contracting party: Ministry of Economy, Finance and Industrial and Digital Sovereignty
Members of the consortium for the performance-based comprehensive public procurement contract, (design/construction and 5 years of operation/maintenance): Bouygues Bâtiment Grand Ouest (main contractor and constructor in all trades),), Bruno Gaudin Architectes, Mélanie Drevet (landscaper), Egis (engineering consulting company), Inddigo (energy and environmental consultancy), Cegelec (technical packages), Cuisinorme (kitchen design), Métroergo (ergonomics), Manexi (commissioning), Idex (service and maintenance) and Elan (sustainable construction).
Value of contract: 36.3 million before tax (€43.6 million including tax)

The project schedule: a project designed and completed in 30 months (6 months of design and 24 months of construction)


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