[KevinEldon]

It may also be that people like the idea of 'improvements in urban planning' when they are intangible, but if those changes involved limiting their land use or bulldozing their inefficient homes and neighborhoods they balk; they may also not like moving those planning decisions from their local communities to some bureaucracy outside of their direct engagement.

[microcolonel]

Don't need to bulldoze much of anything to do something though. The inefficiency of buildings is a tiny part of the problem, especially in temperate climates; more mixed use zoning, and the relaxing of single family dwelling zoning, will have a dramatic impact on excess travel.

Transport accounts for basically a third of U.S. energy use, though it has been hardly growing over the last few years, which is a good start.

The most efficient car, bus, or train, is the one that you didn't ride.

[KevinEldon]

I think we agree. I meant inefficiency in building density not energy use. I was thinking about row houses in San Francisco and brownstones in New York City. Old short and inefficient buildings could be torn down and replaced with tall, dense, efficient structures; but people who own row houses, or rent apartments with high rents, or like the way their neighborhood is now don't seem to want this kind of transformation.

[Udik]

And over what time period would you finally offset the excess co2 introduced in the environment by tearing down and rebuilding existing buildings? They're already medium-density buildings, with considerable historical and urbanistic value. Seems a crazy idea to me.