Asked what he sees in post-war buildings, his answer is simplicity. “A column does exactly what a column should do, a slab spans exactly what it needs to span, and that honesty is precisely what gives these buildings their generosity.”

Strip away what was added later, he says, and “you’re left with a structural logic anyone can read at a glance.” In his words, it is “something our generation has almost lost, because we love to complicate things that don’t actually need to be complicated.”

Instead, it is about small adjustments that keep a building useful “without using too many new resources beyond what was originally placed in the ground many decades ago.”

How does he decide what stays? “I keep what gives the building character.” When a column or a water pipe gets in the way, he doesn’t try to hide it. He asks “how can this obstacle become integrated into design and even become a focal point for the design.”

“Let me be straightforward — Berlin is a tough city. The weather is tough, the people can be tough, and the architecture as well.” He sees that toughness as a kind of honesty and doesn’t apologise for it. “A building must have a sense of belonging to its location.”

Light and surfaces can add warmth, he says. “However mostly I believe the warmth comes from its inhabitants, the people and how they use a flat, how they fill it with life and objects.”

A snowboarder since his teens, he tries to get to the Alps at least twice a year. Looking at the chalets, he points to their honesty: “you can see exactly how a chalet holds itself up, the timber joinery is the decoration.”

Snow load, sun angle and wind shape the deep roof overhangs and thick walls. “None of that is decorative, it’s survival that happens to look beautiful.” The architect’s job up here, he says, “is basically to know when to get out of the way.”

The idea he would take back to Berlin: design a building “in such a way that it can be extended by the next generation rather than being replaced by them.” Many chalets have been extended and rebuilt over two hundred years and are still in use.

He wants “simple, sturdy details that can be repaired,” so that “fifty years from now someone will be able to open them up, keep the good parts and carry on.”

The trend he is watching is “in fact the opposite of a trend”: raw plaster, oak that gets darker, concrete that picks up a patina. He links it to AI-generated renderings that are “flawless but a bit lifeless.”