When we were living in Tokyo I worked in an office building in the Akasaka area. During the cherry blossom time it was the best place to be: rows and rows of beautiful trees full of blossom in the middle of one of the most densely populated areas in the world. Surreal. The building that I was facing from my office on the 28th floor was the Grand Prince Hotel Akasaka, a 139 meter high Tokyo landmark hotel. That hotel now needs to make place for a new building. But how to demolish a tall building without causing disruption or damage to the surrounding areas? After having investigated different options for almost 5 years a Japanese construction company invented a new approach: removing the building floor by floor, starting from the top.
Hideki Ichihara of the construction company Taisei Corp explains in the Japan Times:
The key idea is to disassemble a structure in an enclosed space, unlike the traditional way of working in the open air. Taisei looked into using a building’s roof to create a closed working site and bringing cranes inside the building. The roof is held up by temporary columns that are lowered by jacks as the higher floors come down.
“It’s kind of like having a disassembly factory on top of the building and putting a big hat there, and then the building shrinks” from the top, said Ichihara. This “hat” benefits everyone, according to the company: By working in an enclosed space, outside noise is reduced by 17 to 23 decibels while dust is cut by as much as 90 percent. What’s more, it’s safer for workers than being in the open air, Taisei said.
The new method is also environmentally safer and more energy-efficient, according to Ichihara. Much like how hybrid cars generate energy when their brakes are applied, the cranes can do the same when lowering debris inside the building. The power this generates can be used to run lights and other equipment. “The crane can generate more energy when it brings things down from a higher position,” so it can take advantage of buildings over 100 meters, Ichihara said.
The idea is that anything that can be reused, is. With the interior salvaged and clean energy used to dismantle it, Ichihara says carbon emissions are reduced by 85 percent.
I think that many Japanese people will think they have lost their minds if they walk out of a karaoke bar in the middle of the night noticing that the building is lower than when they entered the bar! Look at this video to see how the destruction evolves!
