[ExI] Serious topic

[Anders Sandberg]

Mike Dougherty wrote:
> I have long wondered why we are still spending so much engineering to
> build UP the cities, rather than burrowing into the earth.
>   
I think the energy budget is tricky - in excavation you need to move 
more than the weight of the building up to the surface, and then you 
need to add the building below. Another aspect is that we have plenty of 
well developed building techniques for above-ground buildings (many 
making use of the affordances of access from the side and top while 
building) while below ground building techniques are less well 
developed. Building a subscraper is not the same as building a lot of 
basements.

Energy-wise I guess the big benefit would be if subscrapers are more 
efficient than skyscrapers. I am not sure - you trade convective heat 
losses for conductive heat losses, and they can be pretty substantial. 
Besides, the whole place will require an active air conditioning system 
anyway.

 From an greenhouse gas standpoint, anything that can reduce our use of 
concrete is a good thing. It is very energy intensive, spews out a lot 
of CO2 and is responsible for a surprisingly noticeable fraction of 
total GHG emissions. Recycling of concrete is actually a good idea. 
Hence it might be interesting to make buildings modular so that you can 
actually recycle the concrete modules when you do not want that 
particular building.

-- 
Anders Sandberg,
Future of Humanity Institute 
James Martin 21st Century School 
Philosophy Faculty 
Oxford University