To support transition towards more sustainable urbanization, the New Urban Agenda identifies compactness of cities and densification as key issues to tackle. Urban growth is happening everywhere, but studies of urban land expansion have shown that in the last 20 years, cities are becoming less dense, which leads to issues like urban sprawl, congestion and segregation, especially in countries with a high rate of urban population growth.
Low-density settlements aggravate issues like long commuting, poor access to services, weak institutional capacities, making the costs of infrastructure high and inefficient and vanishing the sense of urbanity.
This was the focus of the Global Experts Group Meeting organised by UN-Habitat in Seville, Spain. Luca D’Acci, Head of Urban Environment, Sustainability and Climate Change at IHS and honorary fellow at the University of Birmingham, attended this seminar as one of the three speakers invited for Panel 1: “The physical/environmental perspective of densification”. The other two panels referred to the economic and governance perspectives of densification. The focus on the meeting was to explore the possibilities and limitations of densification, as a tool for urban transformation. From a physical standpoint, densification is an essential tool for obtaining land that can be used for new infrastructure or public spaces.
In his talk, Luca introduced the difference between the compact, small sized city, and the mega city of today, which is very dispersed. By showing the costs and the disadvantages from a financial standpoint as well, he illustrates the issues mega-cities raise. As they are structured now, mega-cities are a tremendous source of pollution and negatively contribute to global warming, because of the large amount of CO2 emissions released during long daily commutes; they have huge peripheral anonymous areas where people with a higher income aim to settle, due to a cleaner, calmer environment or where the poor are able to find cheap housing. However, this leads to congestion and increased use of cars, as often these are monofunctional areas and it also creates the necessity to provide parking spaces for all of the vehicles. Even worse, there is a lack of adequate public transport because of the number of people, which is below the critical mass necessary to pay back public transport and multifunctional services/amenities costs.
Solution? Luca believes Isobenefit urbanism might be one of many potential positive approaches.
In introducing the concept of “Isobenefit urbanism”, Luca also mentioned previous typologies of cities, such as “La Ville Radieuse”, the “Broadacre City”, the “Garden City” and his own ideal “The Punctiform City”.
In order to understand isobenefit urbanism better, here is a short explanation of its main principles.
Isobenefit urbanism mainly states that the city morphology and amenities allocation should ensure that all individuals have equal access to facilities and the same quality, regardless of their residence area. There is no particular shape and there are no fixed rules, but the novelty is the separation between urban and nature. There should be dense built settlements, with buildings in close proximity and in a sufficient amount to reach the dimension of urbanity. Urban areas should be large enough to produce enough economic activity that sustains the community within that area. At the same time, the green space should be large enough to give a real sense of nature.
Among different possible scenarios for creating the ideal city, Luca’s vision is the “punctiform city”.
How does that work? Each city has dense urban “islands”, called unit points, which are all interconnected with continuous automatic sky-train. This network of small points (with around 1-8km distance between each other) enables them to reach the right size for the economies of scale, while keeping a small size to avoid diseconomies of scale.
Within each unit point (with a diameter of around 2-3km), one should see a mix of the more human dimension – small cosy buildings, with the business side – predominantly tall buildings and urban business spaces, and a mix of functions, in order to be autonomous regarding the daily services (shops, residences, work places, local basic services), all reachable within walking distance. This would help each unit point sustain daily walking urban life. There would be jobs, businesses, shops, entertainment and culture within each unit point. All unit points should be well connected and each one should be dense and walkable.
The intriguing element of this perspective is that following the current rules and letting the economy develop organically does not lead to the development of this kind of city. Sometimes companies and some services avoid city centres for lower costs, while rich inhabitants want to live further from the city centre to have a nice green environment, or the poor are pushed in the unpleasant periphery because of the real estate market. So this kind of new city would not be the result of natural evolution and to create it, one would need strong land regulations, that state where you can build and where not, to preserve natural environment and encourage densification in the unit points. This is a controversial perspective, as if would disrupt the deep rooted way cities evolve and would imply strong land use planning and real estate price control – which might be a bit too restrictive for many, even if its driver is a well-intended purpose. However, for Isobenefit urbanism in general (where the punctiform city is only one of an infinite number of scenarios), this land use regulation would be flexible as offering a large range of alternative adjacent lands.