Onwards and Upwards: the Emergence of the Vertical 15-minute city
Debates about the feasibility of the 15-minute city take on a new dimension
Verticality as a solution to urban challenges
As city populations continue to rise cities face the challenge of accommodating ever-larger numbers of people within a finite space. Increasingly cities are evolving from two dimensional spaces to three, as high-rise mixed-use developments become a common feature of the urban skyline. Vertical urbanism, it is argued, is a concept that is poised to re-define how urban space is created and used in the coming decades. The need to think upwards rather than outwards is already a feature of urban strategies in high population small area cities like Dubai, and Hong Kong. Cities in China contain 5 of the 10 tallest buildings in the world. The demand for the more efficient use of urban space is now a pressing concern in other cities around the world which have hitherto relied on sprawling outward and consuming large tracts of land in an increasingly inefficient and unsustainable way.
Vertical urbanism challenges the conventional paradigm. It is becoming much more than a way of piling residential units on top of each other to higher and higher levels. The latest examples are mixed-use structures providing spaces for residences, workspaces and offices, hospitality, health, and recreation. Such developments are underpinned by cutting-edge architecture and new construction technologies. and offer the possibility of addressing important issues of the time such as efficiency in the use of resources, the housing crisis and coping with fast-growing populations.
Re-thinking the skyscraper
The evolution of the skyscraper has been remarkable. As building technologies have advanced and architects have responded to a variety of social and environmental concerns, so the skyscraper has developed from large steel constructions to highly sophisticated sustainable mega-structures.
The evolution is exemplified in the case of the Shard in London which stands over 300 meters tall (1016 feet). It opened to the public in 2013 having replaced a 24 story single-use office block built on the same site in 1975. It is a mixed-use development which contains 26 floors of high-specification office space, 3 floors of restaurants, a 19 floor hotel, 13 floors of residential apartments and London’s highest public viewing gallery. In combining work, leisure and living spaces it therefore combines several key features found in a ‘horizontal’ city in its vertical format.
Amenity-rich high-rise developments are now prominent features in many cityscapes around the world. Vertical urbanism isn’t just about height. As progressive architects and planners see it, the approach is about harmonizing functionality, sustainability, and community. As Arkose argued in a recent TED talk, by rethinking the way skyscrapers are designed, vertical urbanism can address the twin pressures of population density and resource scarcity while fostering a sense of belonging and shared purpose. He envisages new structures which not only employ cutting-edge architectural and technological techniques but also respond to social and community needs and aspirations. As such they can be transformative, offering possibilities for new models of shared ownership, promoting communal living and addressing housing supply and affordability.
Creating more but occupying less
Vertical urbanism is an approach which is a fundamental change in the use of urban space. When facing demands to accommodate large numbers of people drawn to cities while also aiming to provide accessible housing at more affordable prices, vertical cities are increasingly seen as a possible response by city planners. When it becomes so inefficient to extend a city’s borders outward, technically advanced high-rise buildings allow for the expansion of cities upwards.
Whist high-rise buildings may be intended to include housing primarily, they increasingly offer other services that people are able to access within the structure. Healthcare, shopping, workplaces, and homes are stacked on top of each other. It is important to consider whether this still somewhat idealistic concept can serve the common good and improve the quality of life and economic wellbeing of residents.
The vertical 15-minute city
The sometimes controversial 15-minute city is an urban planning concept that aims to create complete neighbourhoods where all essential services and amenities are within a 15-minute walk or bike ride from residents' homes. This model promotes local living, active travel, reduced commuting time, and can enhance the quality of life by making cities more walkable, inclusive and sustainable. I have written about the concept in previous posts.
The 15-minute city shares some of the features of the mixed-use developments described above in so far as it combines residential, commercial and recreational space in close proximity. But in addition the 15-minute city concept provides for convenient accessible public services such as education and health, public spaces designed to encourage social interaction and a sense of community, and parks and green spaces for recreation and well-being. By encouraging living locally, they support the local economy, and provide creative spaces for small business and commercial enterprises. They promote environmental sustainability through efficient public transportation and reduced dependency on the car, and public health through walkability and promoting active travel.
New developments are taking shape that add many of these elements to the more established high-rise mix of residential, recreational and office space. One in Fort Lauderdale in Florida, for example, includes co-working spaces to facilitate remote working and networking. The facility is also designed to attract younger residents by including rental apartments and some small ‘micro-units’ with very low monthly rentals. The building has abundant common spaces to encourage personal and business relationships and community activities amongst neighbors. The same developer is also building a 41-story tower in Miami which is described as ‘a compelling and unique blend of exceptional entertainment, retail, residential and commercial offerings set among a pedestrian-friendly environment and green spaces’. The development is within walking distance of a sports arena, a college campus, and public transit. it will only include just over 2,000 parking spaces, a small fraction of the number of residential units, suggesting that many residents are expected to live car-free.
Challenges for the vertical 15-minute city
Even if these examples suggest an apparent convergence in the features of the 15-minute city concept and the inventories of the latest vertical city developments, the feasibility of implementing a vertical 15-minute city comes with its own set of issues and challenges.
In the first place, building vertically integrated neighbourhoods presents design considerations beyond simply layering different kinds of facilities on top of each other. Patterns of movement and interaction amongst residents and other users as they go around their day-to-day living will likely be different. Creating the informality of street interactions and personal mobility over different levels will require innovative design. Open spaces and green spaces will have a different feel within a building. Elevators, escalators and ramps will bring a different notion of walkability and active travel.
Any notion of neighbourhood requires some form of local identity and attachment. Successful implementation of vertical communities will require active participation from communities in the space. Community engagement will be important throughout design and build if the building is to take a form which adapts to community needs and preferences.
Social inclusion and social equity are issues over which ‘horizontal’ 15-minute cities have already been criticize. Ensuring that all residents regardless of socio-economic status, age or disability have access to essential services and the opportunity to participate in community activities is both a design challenge and a social challenge.
The economic viability of such projects has several aspects. The residential mix of type, size, price and tenure of residential units is important both for social inclusiveness and equity as mentioned above. People will be living at a high density, which may be off-putting to some and represents a huge change from traditional lateral suburban living.. The standing of the development in relation to the local property market may also determine the attractiveness of the development and the economic security it could provide for residents.
The developments must also provide sustainable conditions to attract businesses and services to operate in these vertical neighbourhoods. Public services too may have to find new models for delivery. Ensuring a diverse range of businesses, services and amenities is essential for the concept of the 15-minute city.
The developments are likely to rely on smart technology for the management of the structures over such issues as energy management, control of the building’s environmental footprint, and arrangements for mobility within the building. This may involve some smart city solutions to transportation and resource management and adaptation to climate change and in responding to heat and increasingly unpredictable weather events.
In the 21st century, sustainability and environmental consciousness have become increasingly important considerations in architectural design. Energy efficiency, renewable energy and occupant comfort are driving design and incorporation of smart systems. How the vertical development is able to incorporate meaningful green space and links with natural environments so vital for public health and wellbeing will require imaginative use of space, including walls and roofs. The emergence of the vertical forest offers a model to follow.
Any developments on this scale will require very significant infrastructure investment to support the move to vertical living. Connectivity between elements of the vertical city and with other ground-based spaces will need to focus on innovative approaches to urban transportation. New models for the delivery of public services will need to be developed and resources. Digital and smart technologies will be vital.
Possibilities
This is a daunting agenda, but already modern skyscrapers are becoming increasingly complex in their design and functionality, with features such as wind turbines, green walls and roofs, and self-cleaning glass. The Shanghai Tower demonstrates possibilities in its unique twisting design to reduce wind loads and save energy.. The Bank of America tower in New York City is a LEED (Leadership in Energy and Environmental Design) Platinum-certified construction, using energy-efficient systems and incorporating features like rainwater harvesting, smart shading and natural ventilation.
As cities extend vertically, dense vertical living becomes an important pathway for sustainable urban development. Vertical urbanism in compact cities is characterized by placing lateral urban systems on multiple levels, in what amounts to 3 dimensional urban space. Human activities become distributed laterally and vertically depending on varying spatial arrangements. The success of a diverse set of design solutions for integrated mixed-use developments will be found in their ability to translate ground level urban activity to elevated vertically integrated social spaces. We need to understand more about this vertical extension of horizontal socio-spatial networks. There is more research to be done before we can talk with confidence about the development of vertical urban neighbourhoods. Such neighbourhoods are vital if the vertical 15-minute city is to be a feasible concept.