“Yes, but not like this!” – Why densification often lacks public acceptance

The ETH researchers classify this as “NIMBY” behaviour, which stands for “not in my backyard”. This discrepancy also exists in the canton of Zurich, as the researchers found in a study, they published earlier this year in the journal Landscape and Urban Planning. Based on a study with a external page random sample of around 3,000 respondents conducted by the Canton of Zurich and the research company Anovum in 2013, the following picture emerged: while 57.5 percent of respondents support densification as an overall planning strategy, only 11.9 percent accept a concrete densification project in their own neighbourhoods. At the same time, the survey results show that also most of the respondents, who reject a specific densification project in their neighbourhood, nevertheless support densification as an overarching goal of urban development.

In cities, it’s about housing affordability

For the canton of Zurich, the ETH Zurich research group has shown that the acceptance of housing densification projects varies depending on the type of residential area and the neighbourhood: in areas on the city outskirts and in neighbourhoods comprising single-family homes, acceptance of residential densification is generally lower than it is in urban neighbourhoods, as residents might fear negative effects on residential property values, privacy, and green spaces. In urban neighbourhoods, meanwhile, acceptance of densification is generally higher. Here, people’s attitude depends more on the level of housing costs and rent. As urban densification often replaces older housing stock that tend to offer low-cost housing, local residents seem to fear that densification whether it will increase future rental costs.

The researchers have now built on their Zurich results by conducting their international city comparison of Berlin, Paris, London, New York, Chicago and Los Angeles. In this study, they focused on the urban population and more specifically on the role of project-related factors and planning instruments in explaining public opposition toward densification projects.

Their findings highlight the key role of project characteristics in driving public acceptance of densification in the six metropolises: “Acceptance increases when a project includes mixed residential and commercial use and is carbon neutral,” Kaufmann explains, “and conversely, projects of for-profit investors face more resistance.” In addition, Kaufmann’s team systematically studied the impact of three planning tools used in residential densification projects:

1. Inclusionary zoning, (requiring a minimum share of newly constructed affordable housing units),
   
2. rent control (regulating rent increases, also called the “rent cap” in Berlin) and
   
3. participatory planning (involving the public in planning processes).

In all six cities, the research showed that a fixed share of affordable housing units for lower income groups, rent control and participation increase acceptance. “Residential densification projects that provide affordable housing in cities are more widely accepted because they help mitigate the perceived negative impacts of that densification,” Kaufmann says.

It is particularly interesting to note that both rent control, which could well be motivated out of self-serving reasons, and a fixed share of housing for low-income households have the effect of increasing acceptance. This point towards the conclusion that affordable housing is a key concern in cities worldwide and it is important in shaping public opinion about urban densification, regardless of whether someone directly benefits from it or not.  

Berlin and London most sceptical about densification

In the more market-oriented than regulation-oriented US cities of New York, Chicago and Los Angeles, densification acceptance is higher than in Paris, London and Berlin. Simultaneously, accompanying planning measures for affordable housing have less of an impact on the acceptance of densification in US cities. Densification finds the least acceptance in Berlin and London, which in the German capital may have something to do with the current prevailing “rent cap” debate. In the UK’s capital, the debate is arguably more about which segments of the population actually benefit from international investments in the housing market.

As their next step, Kaufmann’s team will investigate densification acceptance across all of Switzerland in the “Densifying Switzerland” project, which is funded by the Swiss National Science Foundation SNSF. Among other things, the researchers will evaluate rental prices and all local land-use planning votes over the past 20 years to discover how economic, social, and political factors influence public acceptance of densification.