Saturday, August 14, 2010

Do We Really All Have To Live Like New Yorkers? Does Density Matter?

by Lloyd Alter
Reading David Owen's The Green Metropolis, one would conclude that density is everything, that New York is, as he wrote in the New Yorker, "The Greenest City in America":
"Barring an almost inconceivable reduction in the earth's population, dense urban centers offer one of the few plausible remedies for some of the world's most discouraging environmental ills. To borrow a term from the jargon of computer systems, dense cities are scalable, while sprawling suburbs are not. The environmental challenge we face, at the current stage of our assault on the world's non-renewable resources, is not how to make our teeming cities more like the pristine countryside. The true challenge is how to make other settled places more like Manhattan."
Click to enlargeUrban density and transport-related energy consumption. (2009). In UNEP/GRID-Arendal Maps and Graphics Library. Retrieved 15:38, July 27, 2010 from density-and-transport-related-energy-consumption1.
But just as the Archtypes survey of Canadian cities calls this into question, so does this graph prepared by UNEP. While New York has the lowest transport-related energy consumption in the States, it is still higher than Toronto, the only Canadian city listed, every major city in Australia, and just about every city in Europe. Hong Kong is the exception that proves the rule; incredibly dense and just as efficient. At the other end of the scale is Houston, the highest energy consumer per capita on the chart. But as one wag said, "In Houston, a person walking is someone on his way to his car."
In the end, a lot of smaller, medium density cities in Australia and Europe do a lot better than New York. Density is clearly not the only factor in energy consumption per capita.
A quick look at this illustration comparing gas prices shows a much closer correlation of energy consumption per capita than does a density to energy consumption comparison. Why is Toronto more efficient than New York? I live there, and it ain't Copenhagen. The only possible reason is that gas is significantly more expensive. Of course Hong Kong is the most expensive, but the Netherlands is close behind. And lo and behold, everyone there rides bikes. (Oslo is an aberation caused by the fact that it is such a big oil exporter, see the Economist Big Mac index to see how it is out of whack). Putting these two graphs together, one has to conclude that energy prices are a bigger determinant than density. It appears that long term, consistently expensive gas, cars and parking make alternative patterns of transportation and development viable.
Guelph, Ontario, with the highest walkscore I have found.
In my spare time I volunteer as president of a heritage preservation organization in Ontario, Canada, and tour the province lecturing about how heritage conservation districts are really energy conservation districts. Everywhere I go I use Walkscore as a proxy of energy efficiency and am constantly blown away by how walkable these towns are. They are usually built on rivers and have water, nearby farms, even their own hydro power generation. They were designed in a time when people didn't have cars, so things are built more closely together. But Manhattan, they are not.
David Owen, and after reading his book, this writer, were seduced by the bright lights of the big city. But the key drivers of energy efficiency appear to be less about density and more about walkability, with a big dose of gas prices thrown in to promote the latter. And in such communities where gas prices are the determinant, it is no surprise that new development is built at a walkable, cycleable density.
You can't have walkability at suburban densities, but you don't need to be New York or Hong Kong either. There is something in the middle, and it is in our smaller cities and towns all over North America.

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