Opinion – Claudio Bernardes: Nothing better than a biological vision to plan healthy cities

The analogy of cities with a living organism has been used for a long time because, in fact, the similarities are quite evident. It is not uncommon to refer to “arterial” roads as the areas located in the “heart” of the city, or even to parks as the “lungs” of certain regions. This approach has helped planners to understand and deal with complex urban problems.

Trillions of chemical reactions take place in the human body. A plethora of connections, enzymes and chemical processes that together make up our metabolism. This same metabolism can serve as inspiration for understanding another complex system: the city.

Our cities have a lot to learn from natural systems, especially the human body. If someone wants to be healthier, maybe they should gain muscle or lose weight. For this, the first step is to understand what is happening, especially in terms of the volume of calories that enter and leave the body.

A similar diagnosis can be made with cities. It is possible to look at them through a “metabolic” lens, which brings into focus a new framework for modeling urban flows: the metabolism of cities.

In urban metabolism, networks of things (goods, capital, information, people, etc.) enter and leave the body (city), where all these flows and systems interact. As mentioned, in human metabolism a large number of chemical reactions occur per second. However, although the construction of cities is millenary, only now is the understanding of the “chemical reactions” within them beginning to be understood.

To achieve a biological view of the city, some comparisons can be made. The lymphatic system, for example, is the network of tissues and organs that help the human body get rid of toxins, waste, and other unwanted materials. This process is not very different from urban systems. We can think of paramedics offering medical help in emergencies, police officers protecting the city from harm caused by anyone, or waste collection and disposal systems.

Our circulatory system allows blood to travel and transport nutrients, oxygen, hormones and blood cells. This works like a city’s gas, water and electric utilities, supplying needs where they are needed most.

Our respiratory system absorbs oxygen and expels carbon dioxide. This process is similar, but reversed, in parks, with their urban trees and gardens, which create healthy environments and fresh oxygen for people and animals to breathe.

Within this context of analogies, it is possible to say that cities will have to diet to stay healthy.

And the diet for a healthy city consists of its operation following the principles of the circular economy. A circular economy, and therefore a circular city, is one that is “regenerative and waste-free”.​

In a circular economy, materials are recycled with high quality, all energy is derived from renewable or sustainable sources, and natural and human capital is structurally sustained rather than degraded through activities incompatible with healthy development.

Achieving satisfactory levels of a circular economy requires a systemic redesign of the productive system, with a strong focus on how it relates to ecological and human capital.

More sustainable and resilient urban futures can be promoted using metabolism methods and approaches in an ongoing, iterative process.

A healthy urban metabolism, like a healthy ecosystem or organism, works best when it is monitored frequently and continuously adjusted.

Smart cities, with modern sensing technologies, collecting and processing expressive amounts of data and information, will reach new levels, definitively combining the biological vision with the planning of healthier urban areas.