The last time Hamburg's hulking air raid bunker saw use, it was 1945—and locals were taking cover from Allied bombs inside its six-foot-thick concrete walls. That was almost 70 years ago. This year, the bunker is serving a new purpose: Supplying the city with renewable energy.
After the war—only two years after the bunker was built—British forces occupying Hamburg attempted to tear it down. After blasting their way through a few of the massively thick floors, they gave up, fearing a catastrophic structural collapse.
The bunker before renovation.
The structure sat abandoned for 65 years, a bleak reminder of the war years, until, in 2006, Hamburg's city government commissioned Hegger Hegger Schleiff Architekten to turn it into a power plant. And not just any power plant—one that, as part of the city's International Building Exhibition, would showcase emerging forms of clean energy to visiting engineers, architects, and the general public.
The ensuing renovation was nothing short of heroic: The building was a hulking shell, full of massive amounts of rubble and trash—25,000 tons of which were removed from a large window blasted through one facade. An entirely new structure was rebuilt inside its walls—including not only a unique storage system, but spaces for events and education, along with a cafe.
Over the course of two years and $37 million, the architects replaced the wartime refuse with four distinct energy sources: First, the solar arrays you see arranged around the building's facade and its giant flak towers. Then, waste heat from an industrial plant, wood combustion, and biomethane gas. All told, it's capable of powering a half square mile of the city.
As to the decision to keep the building rather than tear it down and start over? It's a question that's been rehashed over and over again in Germany. According to the architects, the decision to leave the bunker standing, while gutting it completely, was a way to move the city into the future, while still acknowledging the past. [Architectural Record; Designboom]