Demystifying compact urban growth

Abstract

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.

Development and analysis of land-use/land-cover spatio-temporal metrics in urban environments: Exploring urban growth patterns and linkages to socio-economic factors

“…Changes in employment have been previously related to LULC change in Portugal, where changes in land uses had a direct impact on labor (Meneses et al, 2017). In summary, we determined that built-up and urban core compactness are the most influential metrics for all the socio-economic variables analyzed, which has also been previously noticed by other authors (Angel et al, 2020;Ahlfeldt et al, 2018).…”

“…Urban areas and cities bring new opportunities and economic growth, are more resource efficient, provide better access to employment, education, services and amenities, etc. (Seto et al, 2017;Ahlfeldt et al, 2018). Therefore, cities can be the solution for a better future, since the agglomeration of people, energy and resources creates hotspots for innovation and governments usually get involved in global and local affairs towards sustainable future, such as climate, resilience, health, cultural tolerance, and race and gender inequality (Acuto et al, 2018), ultimately improving the well-being of urban dwellers.…”

Housing policies for sustainable and inclusive cities

“…Although compactness offers significant advantages, evidence shows that compact urban growth can contribute to higher house and rent prices unless carefully managed (Ahlfeldt et al, 2018). As this primarily affects renters and first-time buyers, who tend to have lower levels of income than the average population, it can lead to rising inequality (Ahlfeldt et al, 2018). This concern is exacerbated by the general rise in rents and house prices that many OECD countries have experienced in recent years (OECD, 2020: indicator HM1.2).…”

“…open space, better access to jobs and services) to renters and first-time home buyers should outweigh the negative impacts (e.g. higher housing costs) (Ahlfeldt et al, 2018). However, these offsetting benefits may be difficult to quantify and measure, leading to an ad-hoc placement of development restrictions.…”

Improving well-being through better housing policy in New Zealand

“…Agglomeration economies generated by cities are an important factor in knowledge diffusion and thus productivity growth, and population density has been a strong predictor of economic performance in European countries (Ahrend and Schumann, 2014[39]). Lowdensity urban sprawl undermines agglomeration benefits through longer travel times within a city if jobs fail to disperse in line with housing, higher fiscal costs of supplying infrastructure and public services (Adams and Chapman, 2016 [40]; Ahlfeldt et al, 2018 [38]), higher transport emissions (though greater use of electric vehicles would reduce this effect) and loss of environmental amenities within and at the borders of urban areas. On the other hand, density can have negative implications for open space preservation, traffic congestion, health and self-reported well-being (Ahlfeldt et al, 2018[38]).…”