Dense Downtown vs. Suburban Dispersed: A Pilot Study on Urban Sustainability


The fashion among urban planners for “compact city” planning and intensification, emphasized as a substitute for “harmful” sprawl onto greenfields, has been supported by a substantial volume of advocacy and academic work. But as the authors of a new study, “Dense Downtown vs. Suburban Dispersed: A Pilot Study on Urban Sustainability” say in their abstract, most such work has been “…based on very large data sets of generalized data regarding whole-city energy consumption, or large-scale transport patterns, which often misses important nuances…”

These authors, Antony Wood and Peng Du, are to be commended for their academic integrity. Their study reveals some “surprising” (their term) realities. Dr. Wood notes:

“We’ve all grown up thinking that urban density and verticality is a good thing but there has never been a study that has really looked at this in any detail; they’ve all been generic studies, based on large sets of generalised data. So we thought we should undertake a more focused study to prove it. And the results have been quite the opposite to those we thought we would find.”

The data was collected from 249 households living in high-rise towers in the city of Chicago and 273 households residing in houses in the suburb of Oak Park, 11 kilometres from the Chicago CBD.

The high-rise residents energy consumption was 27 per cent more per person than the suburbanites, and even per average square metre of space, consumption was 4.6 per cent higher. Remarkably, the suburban homes involved not only had a typically larger floor area and greater surface-to-volume area (e.g. higher ceilings, roof cavities, etc.), they were also wooden-framed and significantly older – nearly 100 years old on average.

Some of the greater energy use in the high-rises was due to the lifts and the lighting and heating of common spaces and amenities. But on the “embodied energy” (in construction and materials) measure, the high-rise buildings required 49 per cent more embodied energy per square metre, and 72 per cent more per resident.

Ironically, the high-rise residents were found to own more cars per person, in which their overall travel was 9% greater. Their trip distances for daily commuting and shopping were significantly shorter, by car and all modes (and they did more cycling and walking) but the time spent traveling for these purposes was only a few percent less due to lower speeds. But travel for recreation and other purposes was so significantly longer that any advantage otherwise was more than negated.

These findings are not so surprising to those who were aware of Australian data that was crunched on “New Geography” by Phil McDermott a few years ago.

It is long overdue to have realistic study findings to clarify the realities about energy consumption. Anecdotal evidence and intuition have led some skeptics to question this fad long since. For example, there are numerous options to suburban residents that do not exist for high-rise residents. The sun and wind can be utilized much more effectively, for heating and cooling the home and for drying washing. The use of biomass (wood) for heating and even cooking, is possible. (In fact there are numerous “off-grid” and “self-sustaining” options at low density, which ironically was more of a focus of environmentalists a few decades ago).

McDermott points out that the correlation is overwhelmingly between income and sustainability, regardless of location. Higher income earners consume more resources on average, and inner city high income residents the most prolific in energy use. It is interesting to note in the latest Chicago study, that the suburb, as well as the high rise sample, was also relatively higher-income.

One important point that needs to be taken into account when studying this phenomenon, is just how steeply “exclusionary” a city is “by location”. It has often been noted (e.g. by the authors of the “Costs of Sprawl 2000” study) that the higher house prices are (e.g. expressed by a median multiple) in the entire urban area, the stronger the “drive to qualify” effect. Chicago is actually significantly cheaper in all housing options than Australia’s main cities. Explicit anti-sprawl growth boundary policies exacerbate this “spatial sorting by income” effect, inevitably forcing up the price of all urban land and housing of all types in all locations. This could be expected to worsen the “sustainability” outcomes using real data, for city centers versus suburbs.

But there is also a reverse effect which applies at the level of the “whole city” data comparisons: in cities where housing is cheaper, often due to the absence of anti-sprawl land-rationing policies, households at all income levels have more discretionary income to spend after housing costs. In the case of comparison of a city with high housing costs versus one with low housing costs, the correlation between income and consumption may not hold at the “city versus city” level (although it will within each city). An obvious flaw in the common interpretation of large-scale general-data studies that find lower energy use of all kinds in “compact” cities is that such cities have significantly higher housing costs and hence lower discretionary incomes to spend on consumption. Therefore the mechanism by which energy consumption is lower (if it is), is not necessarily inherent operating efficiency at all.

Many urban economists have been advocating all along for fiscal and “pricing” incentives to be used to achieve the alleged objectives of “compact city” policies; the latter having significant unintended consequences that fiscal and pricing incentives do not. Targeting the consumed resources themselves (land, energy, infrastructure use) with taxes, levies and pricing, allows everyone to change their lifestyle in whichever of a myriad of ways that they prefer. In all likelihood, lower density living with sustainability measures for which it is admirably suited may be the preference of the majority.

Anthony Downs summed this paradigm up with a witty analogy in his “Still Stuck in Traffic” (2004) – he likened it to a picture on a living-room wall that is in the wrong place: fiscal and pricing incentives would be like “moving the picture” while prescriptive urban planning policies are like “moving the wall around the picture”.

Phil Hayward is an independent researcher, writer and lobbyist on urban and transport planning. He is based in New Zealand.

Photo: Chicago north from John Hancock.