What is actually happening here? are they supporting the building on jacks and taking out the lower levels and gradually bringing it down, if so it is very clever engineering. Safety issues spring to mind on this as does expense but a great idea that aside.

"How wasteful to be already demolishing it."

Yes, but it happens all over the world as the available building land in big cities is used up. Advances in construction techniques and revisions in planning laws often permit much taller buildings with small footprints,and you can't easily add ten floors to existing buildings.

The commercial centres in cities like Tokyo, Shanghai, London and Hong Kong are in a permanent state of change as buildings are demolished and replaced. Being able to remove a building from a cramped location using this technique is a real advantage.

I wonder if future skyscapper designs will take into account an easy clean demolition option?

But just blowing them up is much more fun!

"If you're going to dismantle a building instead of using a brute force demolition method then surely it would be easier (and faster and cheaper)to do it from the top down rather than the bottom up."

It's neither faster or cheaper to take down a multi-storey building from the top down.

The cheapest and fastest method is to drop the structure down with explosive charges. Setting the charges is a highly skilled and time-consuming process, but actual demolition takes a few seconds.

The method used in this Tokyo example is not cheap by any means, and it certainly isn't fast, but it negates the risk of injury to people and damaging nearby buildings, and eliminates the huge dust cloud that accompanies the explosive method.

Either way, you still have the waste clearance costs.

It's neither faster or cheaper to take down a multi-storey building from the top down.

When compared to doing it from the bottom as I originally said?

WTM