In the Zaventem borough of Nossegem, the Dutch company InterXion is building a new data centre. Remarkably, only six months passed between the start of the file and the start of construction on site.

In 2020, InterXion merged with Digital Realty - also the new brand name since September 2022 - and offers the largest data centre platform in the world, with locations on all continents. In Nossegem, a completely new building will be constructed adjacent to the existing data centre with a ground area of 4,800 m2.

The building is close to Zaventem airport. Therefore, the height had to be limited to a ground floor and two upper floors, with services on the roof on top. To avoid interference between the data centre and air traffic, the facade of the building had to be made of concrete - rather than steel.

Simple prefabricated concept

The concept of the building is quite simple and completely prefabricated to allow for fast execution. Thanks to the good soil, the screw piles for the foundation are only about ten metres deep. On them come the 20-metre-high precast columns, which follow a grid of 7.8 by 7.8 metres. Precast beams are placed between them and vaults on top. A stepped core provides horizontal stability.

A special feature of this project is that all floors have a load-bearing capacity of 2.2 tonnes/m2. This is a particularly high load for a building with a rather limited height.

Piling puzzles

An additional challenge was the fact that the new data centre had to connect to the existing one, which made for complex detailing. The basement of the existing building - with a span of 14 metres - runs underneath the new building, which thus uses spans of only 7.8 metres. We therefore had to fit the new foundations around the existing basement, so that it only absorbs the floor load of the ground floor and not the vertical loads of the upper floors of the new building.

Next to the existing data centre, there is also an 8-metre-deep and 60-metre-long underground space with diesel tanks feeding the emergency generators. To be able to work simultaneously and quickly on both the new building and the tank zone, we installed a Berliner wall as an earth retaining wall between the two.

Because the existing data centre remained in service during the works, we also had to build over the sprinkler pit and the underground cooling tower - 8 metres deep. This required precise positioning of the pile heads in each case.

Techniques on the roof

The cooling groups and ventilation units that control the large heat generation in the building are mounted on a large steel structure on the roof. 6-metre-high panels placed on the roof edge not only provide acoustic shielding, but also make the techniques aesthetically invisible from the street.

Short preparation

To continue growing, InterXion / Digital Realty is building additional data centre capacity. Quick realisation is important in this regard. This project was started in February 2021 and fully designed and tendered in 6 months. The contractor was appointed in September 2021. So a mountain of work was done at a very short notice, but without compromising even a millimetre on the quality of the detailing of the plans.