[transect]

> Further, the definition of "city" can include a lot of sprawl in places like Houston, Phoenix, and even Beijing and Tokyo.

Is it the case that you get to cherry pick which urban center is a real city based on how green it is?

[onlyrealcuzzo]

The point is, there's likely a certain density at which it gets progressively more green to live in. If you're treating all cities equally, there's hardly a point in distinguishing between cities and small towns. There's not much of a difference between Omaha, Nebraska and Podunk, Kentucky. There's a gigantic difference between Manhattan and Yonkers.

I wouldn't be surprised if Dallas is "less green" than small towns in Italy, even adjusting for income/wealth. I would be surprised if the same is true when you compare to inner Tokyo (Shibuya).

One thing that would be interesting to know -- high rises can use a ton of energy to heat & cool. And the taller they get, a significant portion of the building is just stairs and elevators. I wouldn't be surprised if density gets "less green" at a certain maximum. Manhattan & Shibuya could very well be past that point.

[magduf]

>One thing that would be interesting to know -- high rises can use a ton of energy to heat & cool.

Sure, but how does that compare to the energy needed for lots of smaller buildings, which can provide the same floor space to the same number of people? I suspect the high rise is more efficient: it has far less surface area on the outside. The more surface area that borders the unheated/uncooled outside, the more energy you need to expend.

>And the taller they get, a significant portion of the building is just stairs and elevators.

Again, how does that compare to smaller buildings? Once you get past 1 floor, you're going to have to use space for stairs and elevators. You can't have a city with 1-floor buildings; the sprawl would be ridiculous.

>Manhattan & Shibuya could very well be past that point.

Have you been to Shibuya? Buildings really aren't that tall in Tokyo, especially in Shibuya. Remember, Tokyo (and pretty much all of Japan) is a highly tectonically active area, with frequent earthquakes. Manhattan has no earthquakes and has a huge layer of bedrock under it; it's basically the most idea place on the planet for building skyscrapers, except for being close to the sea (because of hurricanes, but these are rare because it's pretty far north). There are some reasonably tall buildings in Tokyo, but nothing like the 100-story behemoths in Manhattan.

[baddox]

Yeah, skyscrapers have a lot of stairs and elevators, but I'm pretty sure switching to a bunch of smaller buildings and replacing the stairs and elevators with roads and automobiles is not going to come out ahead on environmental impact.