The Not So Green Metropolis: More Proof that Density Isn't Everything

Census via Archinect/Public Domain

Poor David Owen must be having a very bad week. First the conundrum in his latest book The Conundrum, that efficiency doesn't matter, is dismantled by Shakeb Afsah and Kendyl Salcito, who demonstrate that there is no "Prius Fallacy. (Brian covered it here)

Then the new census data question the thesis of his previous book, The Green Metropolis, where he notices that people who live in New York and Hong Kong use less energy per person, so therefore energy use per capita is inversely proportional to density.

The only problem is that the numbers don't back this up. In fact, according to the latest census data,

The nation's most densely populated urbanized area is Los Angeles-Long Beach-Anaheim, Calif., with nearly 7,000 people per square mile. The San Francisco-Oakland, Calif., area is the second most densely populated at 6,266 people per square mile, followed by San Jose, Calif. (5,820 people per square mile) and Delano, Calif. (5,483 people per square mile). The New York-Newark, N.J., area is fifth, with an overall density of 5,319 people per square mile.

Newman and Kenworthy in Wikipedia/Public Domain

In fact, transport fuel used per person doesn't significantly differ between Los Angeles and New York, according to the famous Newman and Kenworthy study. Copenhagen and Vienna don't look much like Manhattan but are a lot denser, they just aren't as spiky. And why are Australian cities use half the gas that people in American cities of the same density use?

I should note that the idea that LA is, by some standards, more dense than New York, is not new and not accepted by everyone. Economist Ryan Avent looked at this four years ago and wrote:

Average density is a foolish measure to use here. The New York core is far, far denser than Los Angeles’, and the only reason LA comes out ahead is because its suburbs are geographically constrained by topography and are therefore denser than New York’s distant exurbs. No one in their right mind would visit New York City and come away thinking it was less dense than LA. That’s because it isn’t, not in any meaningful sense.

But nobody in their right mind would go to Copenhagen and come away thinking that it is more dense than New York, but it is, because of planning constraints and protection of surrounding farmland.

The fact is, the single factor that determines how much energy people use per capita is a function of how much they drive, and there are a lot more factors at play than just density, such as gas prices, investment in alternate infrastructures like transit and bike lanes, and the basic walkability that you can find in small towns and midsize cities as well as Manhattan. Just because it's denser doesn't mean it's greener.

Lloyd Alter/CC BY 2.0

I wrote earlier about what I call the Goldilocks Density:

In the end, what we need to do is not, as Glaeser and Owen suggest, to make everything like Manhattan; It is more likely that we in fact want to make everything like Greenwich Village or Paris, with moderate height buildings that are more resilient when the power goes out. That's the Goldilocks density: dense enough to support vibrant main streets with retail and services for local needs, but not too high that people can't take the stairs in a pinch. Dense enough to support bike and transit infrastructure, but not so dense to need subways and huge underground parking garages. Dense enough to build a sense of community, but not so dense as to have everyone slip into anonymity.

Not too high, not too low, but just right.

Tags: Cities | Economics | Urban Life | Urban Planning