In space-tight Tokyo, it occasionally happens that a tall building needs to be done away with. Real estate markets shift, local needs change and anti-earthquake building technologies improve, making structures obsolete. But how do you get rid of a 40-story building surrounded by residents?

That was the problem faced by Taisei, a Japanese general contractor tasked with removing the formerly iconic Akasaka Prince Hotel. Dynamiting the structure was ruled out, as the noise, debris and resultant dust cloud would be inimical to local residents' quality of life. Thus they developed the TECOREP (Taisei Ecological Reproduction) System, whereby they can noiselessly dismantle a building floor-by-floor:

What's not mentioned in the video above is an incredible trick pulled off by the company's engineers. As parts of the building are dismantled and lowered down to the ground, the weight of those parts actually generate electricity, because the lowering hoists utilize a regenerative braking system. The weight of the building parts descending creates more energy than is needed to raise the empty hook back up to the top. This excess electricity is stored in batteries that then power the lights and ventilation fans on the jobsite.

The following video provides a lot more detail as to how the system works, including how they jack the temporary structure's supporting columns downwards:

Sources:

The Awesomer

Reddit

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