Demystifying compact urban growth

Most developed countries now pursue policies that implicitly or explicitly aim at promoting compact urban form. This report analyses more than 300 academic papers that study the effects of compact urban form, and finds that 69% of the papers reviewed find positive effects associated with compact urban form. Over 70% of studies find positive effects of economic density (the number of people living or working in an area). A smaller majority of studies attribute positive effects to mixed land use (58%) and the density of the built environment (56%).
These averages hide significant variation across specific dimensions of urban development. In order to understand the effects of compact urban form, the report estimates the monetary per capita value of the change in 15 outcomes in response to a 10% change in economic density. The major benefits of economic density arise from improved productivity and better access to jobs and services. Further benefits are generated through the preservation of urban green space, greater energy efficiency, pollution reduction and safer urban environments. The major costs of higher economic density are related to congestion, health and well-being. Increasing compactness can also contribute to higher land values and housing costs, which are borne disproportionately by renters and first-time buyers.
Increasing economic density therefore requires accompanying policy interventions to maximise the benefits and minimise the costs associated with compactness. In particular, policymakers need to facilitate large-scale investment in housing supply and public transport networks to ensure efficient and equitable access to housing, services and jobs in compact cities.