A Japanese construction company is using giant jacks and electricity-generating cranes to dismantle a high-rise tower in Tokyo, floor by floor.

Taisei Corporation is using its Ecological Reproduction System (Tecorep) to gradually lower the Grand Prince Hotel Akasaka, and bemused passersby have already witnessed the 140m-high (about 460 feet) tower quietly shrink to 110m (about 360 feet). It's a far more elegant method when compared with the much-unchanged tack of getting something big and heavy and smashing it into a building, or the presumably fun but incredibly messy process of blowing it up. Buildings are of course dismantled using cranes already, but only from the exterior and for towers under 100m — and they're far from green. Having investigated new methods since 2008, Taisei is suggesting that for buildings over 100m we need to adopt a new approach.

[partner id="wireduk"]First off, everything inside the building that can be removed, is — this includes anything non-structural. Floors being worked on from the top down are enclosed to limit the mess and then taken apart, bit by bit. This means starting with the floor itself, removing beams and concrete, which are then transported to the ground using a crane inside the building that actually generates electricity from this motion (this is then used to run other equipment used in the demolition). The idea is that anything that can be reused, is. With the interior salvaged and clean energy used to dismantle it, Taisei's head of construction technology development Hideki Ichihara says carbon emissions are reduced by 85 percent.

The floors are held up during this process using temporary columns and giant jacks, which will eventually be used to lower what's left of the floors — all the while retaining the building's original look, since the roof remains intact till the last.

"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," Ichihara told Japan Times.

According to Taisei Corp, the entire process reduces noise by between 17 and 23 decibels, reduces dust levels by 90 percent and can be carried out at any time, regardless of the weather conditions.

The company has trialled its method on one other building, but garnered attention with the takedown of this city landmark. It's expected that we'll see much of the Tokyo skyline change in the coming decades according to Ichihara, who told *Japan Times *that the majority of buildings over 100m are demolished after 30 or 40 years: 99 of Tokyo's high rises fall will fall into this category within the decade.

"We thought, is it really possible to safely disassemble buildings over 100m?" said Ichihara. "We thought we needed to research that, which is how Tecorep's development started."

If Ichihara's predictions about the number of high rises that Tokyo will soon need to demolish are correct, it would explain the sudden burst of innovation in the region from construction firms planning ahead. Kajima Corporation, for instance, takes buildings apart floor by floor, but from the bottom not the top, as seen in this video.