"It's especially beautiful when the sun is low"

The golden crown of the monumental Santos warehouse in South Rotterdam has received a lot of attention in the (trade) press even before it was officially opened as the Dutch Photo Museum. The aluminum skin with a pattern of triangles appears to be mediagenic. Beautiful photos with reflection and shadows are discussed. Architects Karin Renner (Renner Hainke Wirth Zirn Architekten) and Karin Wolf (WDJARCHITECTEN) talk about the lengthy process that led to this geometric additional floor that can be felt deep in the building.

The “Santos” project started seventeen years ago. Karin Renner remembers conversations in 2007 with urban planner Riek Bakker about an initial consultation for the future of Rijnhaven, which Renner Hainke Wirth Zirn Architekten (RHWZ) had created in collaboration with Egbert Kossak, the then urban planner of the city of Hamburg. “This warehouse already had a special role in the plan,” says Karin, “It was a characterful building in the visual axis, which would be preserved as a reference to the history of the area. But then came the 2008 crisis and development was halted.”

Everyone knows Santos

The project was only resumed in 2016. WDJARCHITECTEN had done a study into a possible transformation of the monument, “a reorganization of the inside”. A client came. This organization had already transformed a few similar locations in Germany into creative stopping places and now wanted to combine that concept with short-stay apartments. Rotterdam would become the first Dutch location. That was also the moment that Karin Wolf joined in: “It was one of the first projects I got at WDJA. What struck me: everyone knows the Santos building. All engineering students have made a plan for it at some point.”

Eight years ago there was a vision (urban planning, zoning plan) and a sketch, in which the building was 'added' two floors. Karin Renner: “Something special had to be placed on the monument. Two floors and a place to let the light in.” Karin Wolf: “With Stilwerk there was a program that fit very well. With co-working places, a restaurant and the showroom as a transition to the private apartments.” The project finally went into implementation in 2022 with Burgy Bouw as main contractor.

Lots of models

Karin Renner: “We made many models for that 'optopping' (additional floors) on a scale of one to five hundred. In the beginning the shapes were quite asymmetrical. We wanted to emphasize the sculptural strength of the structure in the shape of the five facades. Five facades because the roof is also visible from the new towers in the area. An additional advantage of the roof structure was that it created space for the installations.”

“It was also important that we followed the lines of the monument exactly. The Santos grids are special: they are vertical elements that we wanted to make visible in the roof and facade,” says Karin Wolf. “You want to continue to see it as a whole. Like a spaceship landing on an old building. Now there is a very subtle touch. As if the new part kisses the old part.”

A striking staircase in the heart

The transition from the fifth facade to the inner world of the old building was a long procedure in the design process. “The danger is that the new becomes too dominant in the experience. That is why we added a strong interior element to the top floor: a staircase with the same cladding as the roof and facades of the structure,” says Karin Renner. “The connection is clear and visible.” The stairs from the dream ship descend into the monument and take in a lot of daylight. “The heart of the monument has been kept open and transparent, so that the horizontal floor layers are clearly visible,” says Karin Wolf. “On the lower floors the stairs look modest.”

Shining light gold

Choosing the color for the skin of the construction was a process of “testing and tasting”, both architects laugh. “Although the first models also had a golden structure,” Karin Wolf remembers. “We also looked at corten steel, but we thought that was a bit dark. And heavy, also in terms of weight!”, says Karin Renner. Ultimately, 'light gold' was chosen - anodization with AluGOLD01. “Silver was too cold, yellow-gold too intense. This light gold color gave the most beautiful combination with the Santos bricks.”

Full-scale experience

The design of the pattern was also a special process. During construction meetings, the architects came to the construction site with 'perforated' A0 cardboard models. “Yes, you are unsure about what effect the pattern has on a 1:1 scale. It is good to test this on a full scale, near the building,” says Karin Renner. Other issues were investigated, such as the effect of the pattern on bird behavior and sound. Karin Renner: “You cannot answer those questions without research. For example, at the Elbphilharmonic in Hamburg, the birds are kept away with a sound that is inaudible to humans. That would also be a solution here.”

From the west with evening light

When creating the patterns, the architects worked with various 3D programs and daylight simulations. Yet there are effects that feel like an unexpected gift. Karin Wolf: “It was wonderful that we were able to provide daylight at the ends of the corridors at the apartments. When the sun enters there, you get reflections on the inner walls. That is a very nice effect.” Karin Renner believes that the patterns from outside are also richer than expected. “In certain sunlight it gives a 3D effect in the facade, like a soft textile curtain, while they are really flat aluminum plates with a perforated pattern. Especially if you look from the west with evening light… that works very well.” The architects agree: with a low sun, the light comes in very far and the patterns create enchanting effects.

Nice collaboration with Metadecor

It has been a complicated project for all parties in the construction process. During construction, a new client came for the building: the Dutch Photo Museum will open its doors in 2025. “Also a wonderful match between program and building,” says Karin Wolf. The production of the structure was already in full swing under the direction of Burgy Bouw, the design has not been changed. “The collaboration with Metadecor has really supported us,” says Karin Renner. “You need someone who understands what you want. We found that understanding with Martin Eslo, the senior engineer. Even when developing the less visible elements, such as the rear structure, he continuously asked for our opinion about possible solutions. That collaboration was really nice.”