Lille, situated in northern France, is a culturally diverse city renowned for its historical significance and urban vitality. Characterized by its well-preserved architecture, the city serves as a hub of commerce, culture, and academia.
The XXL shopping center, spanning over 56,000 m² on the outskirts of the city center, offers room for a hypermarket, 105 boutiques, a hotel, 19 restaurants surrounding a 320 m² shared terrace, a rooftop, play areas for children, and 900 parking spaces, spread across 6 levels. The center, situated in a working-class district, is projected to create 900 employment opportunities.
Rudy Ricciotti, the recipient of the Grand Prix National d'Architecture, had envisioned and designed the building, with its iconic draped structure focusing on "light, fluidity, sky, and minerality," while meeting contemporary environmental standards.

1,000 m3 of Autoclaved Aerated Concrete for fireproof partitions
To realize this ambition, the developer Vicity, drew up a strict set of specifications, including the use of high-performance, responsible construction methods and materials adapted to the technical difficulties of the site. These requirements were expressed in the partitioning and separation of the commercial cells. This was a very sensitive point in terms of safety. Projex, the technical design office, specified autoclaved aerated concrete (AAC) for this purpose. "Vicity wanted separating walls that could be easily modulated, while ensuring maximum fire protection," explains Alexandre Thomas, the project leader for SOGEA Caroni, a subsidiary of VINCI Construction France. The choice fell on the Ytong Compact 20 solution. The block's mineral properties, which are perfectly suited to the tertiary sector (very high fire resistance, no toxic or flammable gases released), and the Xella group's ability to produce in large quantities were decisive arguments. All in all, 4,150 m² of AAC, i.e. around 1,000 m3, were required to partition the about 100 stores and restaurants.

Xella's technical service "particularly relevant".
The other Xella asset that made the difference right from the design phase was the competence and responsiveness of its technical department. Ludovic Dupont, the sales engineer overseeing the project on behalf of Xella comments: "In order to meet expectations as closely as possible and stand out from the competition, our support began very early on with a fire-stop analysis, as well as a study of load distribution, one of the site's technical constraints. In such cases, the lightness of our product, which limits slab overloading in the long term, makes all the difference". Alexandre Thomas adds: "The biggest problem we had to solve was that of linear overloading, since most of the floors were made of prestressed hollow-core slabs. And the technical information provided by the Xella design office, which included installation guidelines, particularly for vertical and horizontal ties, was relevant."

An environmental choice
AAC also corresponded to one of the developer's wishes: to create a project that is as environmentally friendly as possible. With Lillenium, Vicity is hoping to achieve "Very good" status under the BREEAM (Building Research Establishment Environmental Assessment Method) label. For this reason, the choice was made to give priority to local and sustainable materials, and to work on optimizing water, waste, and energy management. AAC fits perfectly into this logic. Its environmental performance is expressed throughout the product's life cycle: raw materials, manufacturing, transport, installation, use and recycling. And since architect Rudy Ricciotti wanted to emphasize minerality, AAC ticked all the boxes. With all the efforts made, the assessment was granted at the end.

Quick and easy installation, adapted to site configuration
At the time of the study, and even more so since the work began, location was a key factor. The site is located on a very narrow plot bordered by two boulevards and a railroad line. Under these conditions, it's difficult to ensure normal procedures for transporting and storing materials. There is no storage area, only one access for the entire site. Vehicles had to pass through one by one before being handed over to the crews. Once again, the choice of AAC made the job easier for Alexandre Thomas. "The blocks were supplied and stored on site before our tower cranes were deployed. The Ytong constructive solution then met my expectations thanks to its simplicity and speed of installation." AAC, which is lighter and easier to handle, cut and install, greatly accelerated this sequence.

"We were well guided during installation".
“Franck Favier, our trainer, and demonstrator-technician guided the workers on several occasions," explains Ludovic Dupont. The technical department produced layout plans for them, which reassured everyone. This phase of the project went smoothly and on schedule. “We appreciated the support provided by Xella's technical department, their numerous visits helped guide our partners in charge of installation.”