Silver Opening Depot Boijmans Van Beuningen with the Spherical Mirror Façade
The new icon of the Rotterdam skyline through its unique mirror façade engineered and executed by Sorba
The silver opening of Art Depot Boijmans Van Beuningen adds a new icon to the city of Rotterdam, The Netherlands. The unique design by architect Winy Maas, MVRDV, included the spherical mirror façade. A unique challenge and great addition to the portfolio of Sorba.
Museum Boijmans Van Beuningen’s new art depot is unique in the world, because of its function but also in design. This is the first art depot that will be accessible to the public, but its design is also unique. The depot is built in the public Museumpark and therefore architect Winy Maas, MVRDV, wanted to compensate for the space the building would use. He has done this by making a spherical and reflective building, through which the park and the building can strengthen each other. Main contractor BAM asked Sorba for the development, production, and installation of the spherical mirror façade.
Engineering double curved mirror panels
The scheme for the mirror façade of the Depot was so innovative and challenging that only a few other companies dared to take on the project. “At Sorba we want these complicated projects to keep innovating.” tells Jan Maarten Lieverdink, Sorba Sales Manager in The Netherlands. “We showed this in complicated schemes like Public Transit Terminal Arnhem and London Crossrail Projects.” The biggest challenge for the project was the combination of a completely spherical façade and the use of glass for the mirror effect.
The spherical shape of the building made it hard to develop a 3D model, since you don’t have any reference points to work from. Hereafter the façade was divided in individual panels with the maximum size to minimize the effect of the junctures in the mirror. Eventually a division was made into 26 rows with 64 panels each. In total 1664 panels had to be produced, of which each of the 26 rows has a difference in curvature.
The production of the glass panels was a challenge, because the panels had to be curved horizontally as well as vertically and the mirror coating had to be added. The requirements that Sorba had put on the production of these panels could only be met in China. “Our project manager has visited China regularly for quality checks and an onsite external quality officer was appointed. This way we made sure we could guarantee our quality standard.”
South of the Depot is a Medical Centre, therefore the southside of the façade is covered with a matte foil. This matte cloud is installed to prevent reflection and brightness towards the hospital.
Construction of the façade
Sorba started on the structural concrete base of the building. At first anchors were installed in the concrete, the measurements had to be based from the 3D model, because you cannot measure accurately on a spherical shape. After placing stainless steel consoles on the anchors, the façade was insulated. The lower sections had to be filled out with a mineral wool to be able to follow the round shape of the building. After the insulation, the hooks are installed on which the glass panels will be installed. These consist of a plate with 4 adjustable hooks, that can be adjusted horizontally and vertically to perfectly align all the panels and junctures.
On the back of the glass panels Sorba installed black aluminium frames. These frames are glued to the glass under specialized conditions. With this frame the glass mirror panels are installed to the façade. “Because the city of Rotterdam requires a safety measure for glued panels, little black hands are installed. These keep the panel in place in case the glue wouldn’t hold on the panels.
Insulated Glass and Doors
The windows and doors of the Depot are unique as well. These follow the same spherical shape as the rest of the façade. The windows are fitted with special 3D curved insulated glass panels. In total there are 186 of these insulated glass panels. On the lower levels the resistance of this glass is WK4, and on the higher levels we used WK3 glass. Part of these window panels are transparent instead of reflective. The transition between the reflective and transparent parts is made gradual.
In the façade there is a total of 8 doors: 3 double doors and 5 singular doors. These doors are made to disappear when closed. To make this possible the team developed, together with Walasco, special steel frames for these doors. The doors will be recessed into the façade when closed and open like bus doors, first outside and then to the sides. This way there are no visible hinges, so it seems like the façade is continuous.
The Depot is ready for the silver opening, on the 25th of September 2020,. In the weekend following the opening the public can admire the empty depot inside and out. After this weekend, the Depot will close its doors for a year, before opening again in the Fall of 2021. Until then, we will have to make do with the mirror façade of this new icon.