London, like many other cities, is facing a severe housing shortage and affordability crisis. The GLA’s Strategic Housing Market Assessment estimates that, just to keep up with growing demand, 66,000 new homes need to be built every year over the coming two decades (GLA 2017). As the policy aim is to accommodate this growth within London’s current footprint an increase in the density at which London is built is inevitable. However, we know that any new development and especially higher density development is likely to meet resistance from existing residents with local politicians facing a backlash. Over half of the new housing development is planned for outer London, in suburban boroughs, where existing housing is built to a much lower density than in the inner city. Therefore, densification will be more evident in the suburbs as it strongly differs from vernacular or traditional built forms. Given this, densification is likely to draw strong opposition from suburban residents.
Against this backdrop, our basic idea was to test whether incorporating traditional design elements (pitched roofs, front gardens, off road parking, use of familiar materials), could make higher density development more acceptable, including by making it appear to be less dense. We recognise that design is only one among many elements that require attention if we are to reduce resistance to new housing. Other factors include concern about a deterioration in the quality of local services, access to GPs and schools for example and pressure on public transport as new residents move in. Therefore, our findings must be read alongside a broader set of concerns with the impacts of densification.
The study’s empirical data were gathered through a survey circulated on the online platform www.urban-experiment.com in May and June 2020. In total 1,019 individuals completed the survey of which 939 were outer London residents. 58% of these respondents were female and 41% male with 85% identifying as White and 9% as BAME. Other key characteristics are shown in the table below.
The survey had participants rate on a scale of 1-10 a set of images of low, medium and higher density development. All our options represented an increase in suburban densities with our ‘low density’ examples being about twice as dense as existing housing in the suburbs. Each of the density options was varied by differing design treatments to test for the effects of these. For example, a mid-density building would be given different window treatments, alternative roof designs and greater or lesser amounts of greening in front of the building. An example of the alternative images can be seen in an accompanying video. Participants rated the images according to either how acceptable they found the given density or how dense they perceived the development to be.
We found a strong inverse relationship between density acceptability and perception. This means that, for a given density level, buildings which are perceived as less dense are deemed more acceptable. Our findings show that design treatments applied to our lower density housing options are most likely to impact positively on acceptability. There were fewer design treatments that made medium and higher density development more acceptable or to appear less dense.
In addition, people were asked to respond to statements and questions regarding future development in London and local belonging and influence. Of particular significance is that that residents who are convinced of London’s housing crisis tend to find increases in density more acceptable, and to perceive the options we presented to them as less dense compared to those who did not accept there is a crisis. As views on the extent of the housing crisis effect the perception and acceptability of increased density, this is a key area for policy makers to work on.
Our headline findings include:
- There are some design features that make density more acceptable, pitched roof buildings are significantly more acceptable at all densities. Public greenery makes medium density more acceptable. This suggests that echoing the traditional suburban form could bring some benefits
- But overall, few design treatments make medium and higher density more acceptable to existing residents in the suburbs. Echoing elements of suburban design was more successful with our low-density options. However, as our low-density option is around twice existing density there are still significant gains to be made by paying attention to design.
- Working with residents’ attitudes and information will be important as suburban residents who accept that London has a housing crisis are more tolerant of higher densities (independent of design treatments)
The research team comprised Pablo Navarrete-Hernandez, Alan Mace, Jacob Karlsson, Nancy Holman, and Davide Zorloni.
The research is reported more fully in our 2021 Urban Studies paper, ‘Delivering higher density suburban development: The impact of building design and residents’ attitudes’.