These days it seems that like fashion models, buildings can’t be too tall or too thin. Because everybody knows that we need tall buildings to accommodate all the people who are moving to cities, that we have to stop pandering to what Felix Salmon called the “Nostalgists and NIMBYs” who are holding back those who would let a thousand towers bloom.
Except that as I have tried to point out, It's time to dump the tired argument that density and height are green and sustainable. Because these towers are are not, in fact, dense at all, nor are they the only way to achieve higher density. Kaid Benfield makes this very clear in is post For smart growth, not all urban density is created equal. He demonstrates that low and medium rise buildings can achieve pretty significant population densities. He writes:
I’m not going to argue that we should never build above five or six stories (although some architects do). I can go higher, especially in the right context. But I do think that, in their passion for the highest possible densities as an antidote to low-density sprawl, too many urbanist advocates overlook the considerable benefits of still-relatively-high city density at a human scale.
In fact, in many cities the population density has been dropping dramatically. Look at New York City, where buildings have got higher but population density has gone way down. Shlomo Angel of NYU Stern writes in the Decongestion of Manhattan:
The figure above shows census tract densities in Manhattan in 1910 and 2010. The column height displays densities in persons per hectare, not building heights, since buildings in 2010 were much higher, on average, than those of 1910, but they housed fewer people in smaller families that consumed much greater amounts of living space per person.
Or as the National Trust for Historic Preservation noted in their study Older, Smaller, Better:
In Seattle, San Francisco, and Washington, D.C., streets with a mix of old and new buildings have greater population density and more businesses per commercial square foot than streets with large, new buildings. in Seattle and Washington, D.C., these areas also have significantly more jobs per commercial square foot.
Kaid concludes with the statement “I fail to see why we should be supporting density for its own sake.” I think this is badly phrased; he noted earlier that low rise buildings achieve pretty much the same population density as high glass towers.
We have to separate the issue of population density from building height; they have very little to do with each other. We can rebuild our cities to achieve the kind of population densities we need to support good transit and local businesses without building glass towers. Because as Kaid concludes, “we should remember that we usually sell our ideas with images of human-scaled developments for a reason. They work for people as well as for ideology.”