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>Skyscrapers also have a footprint that might no be immediately obvious - it's their energy, water and food demand. Assuming they're inhabited by humans, what's

by 0xDEF 4y ago

>Skyscrapers also have a footprint that might no be immediately obvious - it's their energy, water and food demand. Assuming they're inhabited by humans, what's the amount of agricultural land needed to provide for those humans? What's the energy demand, how many modular 100 MW nuclear power plants or hectares of solar PV panels (plus associated 24/7 storage/distribution centers) are needed to keep the elevator, lights, pumps, ventilation and heating/AC functioning? How much water do they consume daily? All of that is much more efficient in high-rise buildings than anywhere else. The same with cities vs. rural/suburban areas. The former is much more energy efficient and has a smaller carbon footprint.

photochemsyn 4y ago
Carbon footprint depends on energy sources, not population density. 100,000 humans supplied with coal-fired electricity have a radically different carbon footprint from the same populations supplied with solar PV and wind electricity, and it doesn't matter whether they live in isolated households or in one skyscraper.
- feoren 4y ago
  > Carbon footprint depends on energy sources, Obviously true. > Carbon footprint [does not depend on] population density. Patently false. Carbon footprint can depend on more than one variable, and indeed does. Transportation of goods and people is a huge source of carbon, all of which goes way down in cities. > it doesn't matter whether they live in isolated households or in one skyscraper. It's much easier to heat every room in a skyscraper than isolated households due to volume vs. surface-area scaling, even if you hold square footage equal. But square footage is not equal; people occupy less space in skyscrapers, because of redundancy in amenities (shared garages, laundry, recreational areas) and other reasons.
  - photochemsyn 4y ago
    Again 'transportation of goods and people' is only a huge source of carbon if your transportation system relies on fossil fuels. You're not grasping the argument, I don't know why.
- Schroedingersat 4y ago
  Isolated spaced out households need more roads, more travel for goods, more pipes, more stormwater treatment, more services (as each needs a larger buffer to smooth spikes in demand), use an order of magnitude more energy to heat/cool, take more materials to build, require more vehicles. You may only need to build up a little to fix most of it, but sprawl uses much much more of everything than building up.
Schroedingersat 4y ago
Is it though? If we have a thought experiment of a donut of mid rise 5 story apartments powered by its own footprint with a central park a couple km across and possibly commercial activity and outlying farms vs one colossal skyscraper in the middle. The donut has less transmission infrastructure (most of the energy travels under 100m). The food is less centralised, people could even go and get it from where it is packed on foot with no transport step if you wanted to go to the extreme. Each floor of the apartments is holding up on average 2.5 floors above it so doesn't need to be as strong. It takes less material. The center of the donut is free for other uses rather than needing to be entirely transport infrastructure to get people in and out. The donut has a better exposed surface area to volume ratio (unless the majority in the skyscraper have no windows or is made from impossible materials and doesn't taper) so needs less heating/cooling. The donut has more thermal mass available for heating/cooling loops so doesn't need some higher tech thermal store. Less energy is needed for water and sewerage per person. Maybe 10 or 20 stories is optimal, maybe it's 3, but the peak isn't at the as big as possible skyscraper end.

by 0xDEF 4y ago

photochemsyn 4y ago

Carbon footprint depends on energy sources, not population density. 100,000 humans supplied with coal-fired electricity have a radically different carbon footprint from the same populations supplied with solar PV and wind electricity, and it doesn't matter whether they live in isolated households or in one skyscraper.

feoren 4y ago
> Carbon footprint depends on energy sources, Obviously true. > Carbon footprint [does not depend on] population density. Patently false. Carbon footprint can depend on more than one variable, and indeed does. Transportation of goods and people is a huge source of carbon, all of which goes way down in cities. > it doesn't matter whether they live in isolated households or in one skyscraper. It's much easier to heat every room in a skyscraper than isolated households due to volume vs. surface-area scaling, even if you hold square footage equal. But square footage is not equal; people occupy less space in skyscrapers, because of redundancy in amenities (shared garages, laundry, recreational areas) and other reasons.
- photochemsyn 4y ago
  Again 'transportation of goods and people' is only a huge source of carbon if your transportation system relies on fossil fuels. You're not grasping the argument, I don't know why.
Schroedingersat 4y ago
Isolated spaced out households need more roads, more travel for goods, more pipes, more stormwater treatment, more services (as each needs a larger buffer to smooth spikes in demand), use an order of magnitude more energy to heat/cool, take more materials to build, require more vehicles. You may only need to build up a little to fix most of it, but sprawl uses much much more of everything than building up.

Schroedingersat 4y ago

Is it though? If we have a thought experiment of a donut of mid rise 5 story apartments powered by its own footprint with a central park a couple km across and possibly commercial activity and outlying farms vs one colossal skyscraper in the middle. The donut has less transmission infrastructure (most of the energy travels under 100m). The food is less centralised, people could even go and get it from where it is packed on foot with no transport step if you wanted to go to the extreme. Each floor of the apartments is holding up on average 2.5 floors above it so doesn't need to be as strong. It takes less material. The center of the donut is free for other uses rather than needing to be entirely transport infrastructure to get people in and out. The donut has a better exposed surface area to volume ratio (unless the majority in the skyscraper have no windows or is made from impossible materials and doesn't taper) so needs less heating/cooling. The donut has more thermal mass available for heating/cooling loops so doesn't need some higher tech thermal store. Less energy is needed for water and sewerage per person. Maybe 10 or 20 stories is optimal, maybe it's 3, but the peak isn't at the as big as possible skyscraper end.