Higher density is believed to lead to more efficient energy use and lower climate impact. Dense cities are thus often promoted as climate friendly and more sustainable than less urbanized areas. However, all consumption causes emissions, and taken the higher affluence in cities, the more urbanized areas actually cause the highest emissions.
Research needs to take significant further steps to truly understand how the surrounding urban structure affects the consumption patterns and the emissions, but the very clear policy implication is that density is an insufficient indicator for environmental burdens. Three perspectives depict the affluence challenge:
Mobility may not decrease, it just changes the form
One of the strongest evidence supporting the higher sustainability of denser settlements is the observed reduction in private driving. However, the very phenomenon of reduction in driving together with affluence lead to an increase in air travel, which hinders the materialization of the gain from reduced driving.
High-rise living does not lead to reduced emissions
High-rise living does not contribute to emissions reductions as believed due to the economies-of-scale effects and weak incentives to environmentally friendly behavior. Housing companies taking care of the heat contracts and building maintenance lead to low energy efficiency. In addition, much smaller household sizes in comparison to low-rise living lead to all the housing emissions allocating to fewer people.
Money is only saved for consumption elsewhere
Reduction in private driving towards the denser urbanizations lead to a significant cost savings. At the same time the consumption opportunities get more and more diverse, as denser cities provide more purchasing power. This leads to increased consumption of all kinds of goods and services, of which many are relatively carbon intense. The gain from reduced driving is thus largely lost as the result.
Jukka Heinonen, Juudit Ottelin and Antti Säynätjoki, Aalto University