Welcome to the third post in our series on urban planning and thermodynamic flows! Today, we’re diving into the fascinating relationship between urbanism and energy. To get a clear picture, let’s quickly recap how we got here.
In the first article of this series, we explored an alternative approach to understanding urbanism through thermodynamics. We established that, from a physics standpoint, cities behave similarly to other complex material configurations in nature that self-organize with the right, cyclical input of energy.
Building on this perspective, our second article delved into the intriguing issue of how urbanism seemingly defies the natural tendency of entropy to increase. We analyzed various interpretations of urban entropy and found that the creation of complex urban structures can actually lead to an increase in order within the system—at least during urban growth—while still contributing to the overall increase in entropy in the Universe.
These discussions naturally lead us to an open question: If cities, like dunes or natural ecosystems, can self-organize without top-down designers, what happens when someone else intervenes?
What can we do?
In our ongoing discussion on urbanism and energy, we’ve established that urbanism can be seen as a set of processes that manage the energy reaching a city, converting it into urban structures. These structures represent possible states where matter organizes itself in more or less stable forms, at least temporarily. Whether it’s the particles of inert objects or those of living organisms, the organization into stable structures requires an energy input.
Biophysicist Jeremy England offers a vivid metaphor for this process: imagine the distribution of particles in a system as a ball rolling from a peak (a low-entropy state) to a trough (a high-entropy state). Without obstacles or opposing forces (like a current of air), the natural path of the ball, according to the arrow of time, would lead it to the bottom of the deepest valley, where it would stay motionless. This state represents maximum disorder in the system, such as a dead tree decomposed into humus.
However, an adequate supply of energy can cause the particle distribution to organize into a stable structure. For instance, the clay molecules of bricks forming a wall are driven first by the energy of the furnace and later by the mason’s efforts. This is like the “ball” being pushed up a slope and settling into a small elevated valley. The clay molecules can remain in this “wall” state for a long time until the “ball” gradually slides down the valley as the wall disintegrates due to weathering.
If these energy dynamics occur in both inanimate objects (like a clay brick wall) and living beings, it stands to reason that they also occur in the mix of inanimate and living matter that makes up our cities.
A space of flows
Probably the sociologist and urbanist Manuel Castells was not thinking in physical terms when he suggested that a city is a physical manifestation of the flows of globalization. But, nevertheless, thinking of the city in terms of matter and energy fits perfectly with that interpretation. Whether it’s information, capital, merchandise, or people we are considerineg, the fact is that wherever the flows are most intense, that is where architecture manifests itself most powerfully.
This architecture, product of the set of processes encompassed under the term urbanism, is produced above all at the points where the energy meets matter, causing a discontinuity in the energy flow. For this reason, in that network of networks that is the city (it should always be remembered that every network has 3 elements: nodes, links and flows) the most interesting elements are the nodes. The other physical element of a network, the link, is not of much interest from an architectural point of view, although it is the main object of study in the engineering field.
To understand this interest in nodes versus links, just think about how the sun’s energy reaches the Earth. As the light travels down the link (in this case the interplanetary vacuum and then the atmosphere) it hardly hits anything, and so nothing of interest happens. It is when light hits the leaves of a plant, or heats a fluid, or hits the sown land, that the miracle of life occurs.
Engineering is interested in energy traveling down the link without dissipating heat. It is the logistical approach to urbanism.
On the other hand, architecture is interested in friction and discontinuity. Which, and through the heat generated, can trigger the construction of organized structures.
A thermodynamic approach to urban design
The two visions are complementary and necessary. It is advisable not to have cracks in the water pipes and that the subway arrives on time, fulfilling its function of efficiently transporting passengers. But, in the same way, shops at street level flourish in squares and pedestrian streets, so prone to friction and encounters. And the most innovative ideas arise from urban ecosystems in which spaces for interaction and friction between talent, knowledge and capital abound.
In a previous post I wrote that establishing a strong order in a city (equivalent to cooling down a system a lot) is expensive. This is equivalent to what happens in a refrigerator: the lower the temperature, the higher the consumption.
I also argued that a certain disorder in the city, to the extent that disorder contributes to the unexpected, was a desirable quality from the point of view of urban design. This idea broadly coincides with the entropic urbanism approach of Grávalos and Di Monte, and is consistent with Metcalfe’s Law, which regulates the value of the city as a social network. According to this law, the value of the city increases with the square of the number of connections created between its inhabitants, with the maximum social limit of a few hundred of them.
A circular urban design
In this post, I envision an innovative and efficient approach to urban design: redirecting the energy dissipated by friction at key nodes towards creating new urban structures and services. Think of it like harnessing the energy produced by gym equipment to light up the facility or using braking energy to power a motor, much like the KERS system does in cars.
Let’s take a closer look at a metro station, which serves as a node in the urban network. The main flow here consists of people arriving via various connections (the tracks and the trains on them). At the station, passengers face a disruption: they need to get off the train to continue their journey by another means (or by switching to another train). At this point, the passengers, who were in a highly organized state (low entropy) on the train, become a bit disordered. Some wander in search of the exit, others stop to chat, some browse shop windows, and the luckiest ones reunite with friends or family.
The smooth, efficient flow on the train turns into a bit of chaos, increasing entropy. And this is where it gets interesting—opportunities arise! Re-ordering these flows requires creating both physical structures and, in our digital age, digital services. The station building itself is a prime example, but simpler elements like signage and the navigation apps on our phones also play a role. Urban design today isn’t just about hardware; it’s about software too—bits and atoms working together.
Now, let’s flip this idea. A disorganized space, like a wild forest, doesn’t need architecture. But when we clear that forest and start cultivating fields, farms, huts, and eventually homes, infrastructure, and service buildings naturally follow.
In essence, urban design can harness the energy and chaos at these nodes to create more organized, efficient, and vibrant urban spaces. It’s about seeing potential in the flow and using it to build better cities.
Making cities energy-wise
This approach, which might seem like common sense when laid out like this, isn’t always adopted in urban planning. Too often, instead of promoting traditional market squares where the spontaneous exchange of goods and money takes place, shopping centers are built on the outskirts, leading to extra costs in terms of energy, capital, and time. Similarly, many housing policies push people from vibrant city centers (attractive both in terms of activity and desirability) to suburbs where “nothing ever (or rarely) happens.”
It’s like installing wind turbines where the wind doesn’t blow—expensive and inefficient. Economically, it makes little sense. In thermodynamic terms, these configurations are unstable and will decay faster because they don’t align with the natural self-organization that occurs when matter receives the right amount of energy at the right frequency.
However, when we talk about the energy that powers a city, we shouldn’t just think about electrons. Energy comes in many forms, and not all are obvious. Fortunately, by analyzing the data from our digital footprint in the city, we now have techniques to identify these cyclical energy flows. This improves the chances that urban projects will be efficient, sustainable, and slower to decline.
We’ll dive deeper into this topic in our next article on urban design, data and energy micro-flows .
Article published under Creative Commons free culture license. Some rights reserved.
