The Surprisingly Important Role of Symmetry in Healthy Places

New research suggests there might be a “symmetry deficit disorder” in today’s built environments, with significant impacts on health, well-being, and even sustainability.

Michael W. MehaffyNikos A. Salingaros 

Courtesy of our friends at Planetizen planners’ journal.

Urban Symmetry
Two environments in London. Left: Seven Dials, dating from the 17th century. Right: a typical office complex from the 20th century. These environments can be better understood as geometric structures manifesting different degrees and kinds of symmetry. Left: John Sutton via Wikimedia Commons. Right: Michael Mehaffy

Among the many factors influencing health and well-being, the environment might be the least appreciated — but in many ways, it’s one of the most important. Intriguing new research is indicating that, within human environments, the mathematical property of symmetry plays an outsized role.

The relationship between mathematics and architecture is an ancient one, and the topic of symmetry has long been central to both. But the “symmetry” described by classical writers like Vitruvius and Alberti was not limited to the idea of mirroring two sides, as is commonly thought. Rather, symmetry was a much deeper concept, covering many other complex kinds of geometrical relationships. What was important was that there was some kind of measurable correspondence, some sym + metros, or “same measurement,” among the parts as they formed a whole.

Symmetry continues to be a central concept in the sciences today, with important applications to the built environment—as our own recent research has documented. Exciting new developments in mathematics, environmental psychology, neuroscience, and other fields are transforming the scientific understanding of the essential role of symmetry in human experience, and where it goes wrong (and right too). Perhaps surprising—and most important—is an emerging understanding of the key role these characteristics seem to play in human health and well-being.

The field of architecture, for all its aspirations to cutting-edge modernity, has so far been notably backward in applying these insights. Instead, the applications of symmetry, where they exist at all, are mostly confined to superficial explorations of ever more extravagant new aesthetic packaging over what are still relatively primitive object-buildings. The lessons for public space networks, and for healthier human environments more broadly, are largely ignored.

One of the fundamental questions lost in this fashionable mix of art and technology is the ancient topic of beauty, one of Vitruvius’ famous triad of essential architectural components (which he termed “venustas”). Few people today deny the great beauty of many historic and traditional buildings. We often marvel at the incredible diversity of these beautiful structures across innumerable geographic locations, cultures, and periods. Indeed, some wonder why so many buildings of our time seem so inferior—let’s face it, so much uglier—by comparison.

It’s common to assume that this loss is just the price of progress. Perhaps the “beauty” of the built environment nowadays (if we can even agree on what that is) exists only in the powerful, machine-like logic of buildings, their daring structural innovations, or the clever abstract expressions of their designers. Perhaps the current era pays for its modern conveniences by relegating the experience of “beauty” to the status of a dispensable consumer good.

This is a common view of things—but new research shows that it’s simply not true. Semir Zeki, a neurobiologist at University College London, has surveyed neurological research, including his own team’s, and concluded that the experience of beauty in the environment “is not a luxury, but an essential ingredient in nourishing the emotional brain.” Research in other fields reveals that experiencing places that are perceived as beautiful (including “biophilic” places with natural vegetation, for example) actually lowers stress in the body, improves health and well-being, and even (as one famous study showed) shortens recovery times from surgery!

Common types of symmetry that are widely perceived as beautiful, in (left) a child’s kaleidoscope (using pieces of shell that also include sub-symmetries), a “fractal” pattern generated mathematically on a computer (center), and the natural environment of Bryce Canyon in Utah (right). These beautiful structures typically combine different forms of symmetry, such as reflectional, rotational, translational, and scaling symmetries (including fractals).  Image credits: Left, Pixabay (public domain); center, Pixabay (public domain); right, Michael Mehaffy.

These and other studies unveil a surprisingly strong relationship between aesthetics, well-being, and health. Findings in environmental psychology, neuroscience, medical science, and related fields are pointing to a profound (if under-appreciated) effect of environmental structures–including their aesthetic properties–upon our health and quality of life, along with other more obvious factors. These findings seem all the more important for those who are already more vulnerable, including children, the elderly, and the poor.

The research also disproves the simplistic modern assumption that the experience of beauty is just a subjective phenomenon—merely “in the eye of the beholder.” While there can be great variation among people as to some of what they find beautiful, there are also broad areas of commonality. For example, many geometric characteristics of natural environments and of the human body (like the symmetry of faces) are almost universally considered beautiful. This universality is anchored in shared biological roots, and in the shared ways that we react to certain kinds of structures, according to Zeki: “mathematical principles of symmetry, harmony, and proportion…are part of the cognitive apparatus of all brains.”

This is true not only of natural environments and beautiful “biophilic” vegetation, as Zeki notes, but built structures too: “What universality architectural beauty may possess probably lies in satisfying inherited brain concepts of proportion, harmony and geometric relationships that are more formally expressed in mathematical terms.” In other words, there are discernible geometric properties in surroundings that most people unconsciously find beautiful, and those properties are also conducive to physical well-being and quality of life. That’s a finding with potentially momentous implications.

Environmental designers surely have a professional responsibility to avoid harm to users, and indeed, to actively promote their well-being. The question is not whether there is a place for artistic creativity, novelty, and individual expression—surely there is—but rather, how designers can anchor this creativity within a common framework of sharable characteristics that are most likely to produce physiological benefits for users. It is the business of science to provide exactly that kind of knowledge for built environment professions–just as the practice of medicine relies on the health sciences, for example.

What science reveals is that nature has shaped unconscious preferences so that humans are instinctively drawn toward conditions most beneficial to health and well-being. When we are forced into “ugly” or stressful environments (as revealed by medical measurements), it creates much more than superficial annoyance. The task for designers, then, is to start with those documented factors that will best promote the health and well-being of users, and then explore the infinite possible varieties of expression using those factors.

When it comes to identifying these “salutogenic” (health-giving) factors, our own work on environmental symmetry has yielded fruitful results. Once again, we are referring here to “symmetry” in the broader mathematician’s sense, as a kind of structural correspondence between parts. In addition to the familiar mirror symmetry, we can add translational symmetry (where patterns are replicated), scaling symmetry (where patterns recur at different scales, as in fractals), rotational symmetry (as in the iris of an eye), and other combinations.

Examples of different kinds of symmetry in nature, and in human architectures. Top row: reflectional or mirror (tiger), rotational (Sun), translational (ducklings), and scaling (fern). Bottom row: reflectional (Classical building), rotational (stained glass), translational (Islamic tilework) and scaling (Alhambra). Image credits: Top row, left: S Taheri via Wikimedia Commons; center left: public domain (via Pixabay); center right, public domain (via Maxpixel); right, public domain (via Free Nature Stock). Bottom row, left: Ryan Kaldari via Wikimedia Commons; center left, Thomas Ledi via Wikimedia Commons; center right, public domain (via Pixabay); right, public domain (via Pixabay).

In most natural environments, the different forms of symmetry occur together and in combinations with others. Our work and others’ has found that this compound symmetry has a particularly strong association with the experience of beauty. When these compound symmetries contain high levels of interrelatedness, as is evident in many natural structures, we refer to this as “deep symmetry.” (One could say that there is a “symmetry of symmetries” in these structures.) Such structures (including built environments) have many layers of symmetrical sub-structures built up into a very complex interrelated whole.

“Deep symmetry” also interrelates specific objects with their surroundings, and to us as viewers too. This deep symmetry extends mathematically to the larger scale of urban spaces, neighborhoods, and city regions (and ultimately to the Earth, and even the Cosmos). This new understanding of the symmetrical relatedness of buildings and cities rejoins the sadly separated disciplines of architecture, urban design, and planning, within a larger natural framework.

The human body as a whole incorporates such “deep symmetry”—especially so in bodies universally regarded as particularly beautiful—as do many natural environments. This kind of structure can be contrasted with what we might think of as “shallow symmetries”—merely pasted together symmetrical structures that do not interrelate. By contrast, many contemporary designs exhibit shallow symmetries (like the endlessly repeated window units in the example at the top right of this article).

Some examples of “deep symmetry,” in the human body (left), in a natural environment (center) and in human architectures (right). In each case, multiple symmetries and distinct kinds of symmetries are combined and interrelated through further symmetries. In the sculpture of Michelangelo’s David, the irises have rotational symmetry, the face has reflectional symmetry, the hair has scaling symmetry, and so on. The rotational symmetry of the sun in the middle is combined with the reflectional symmetry of the water and the translational symmetry of the repeating birds, and the scaling symmetry of the water patterns. Taktsang Monastery in Bhutan repeats translational groups with reflectional symmetry as well as elements with rotational symmetry, and elements with scalar symmetry, all in translational symmetry as they adjust to their positions over the rocks. Image credits: Left, George M. Groutas via Flickr; center, @Chiaralily via Flickr; Right: Douglas J. McLaughlin via Wikimedia Commons.

It’s important to note that the mathematics of symmetry is not some mysterious occult realm of knowledge, or mystical set of secret formulas. In fact, it is widely comprehensible, and widely useful in practice (as Vitruvius, Alberti and other pioneers demonstrated). Indeed, as the cognitive scientists George Lakoff and Rafael Nuñez pointed out, mathematics itself is simply the symbolic manifestation of the human process of cognitively ordering the environment—that is, of modeling the symmetries of experience. (What we call a “formula” is nothing other than a mathematical symmetry between one side of an “equation” and the other.) The ability to model these symmetries of experience was the key to the evolutionary survival of humans, and, more recently in history, to the development of advanced language, mathematics, and science.

This symmetry-modeling is an example of our inherent order-seeking, meaning-seeking behavior. We are constantly striving to find “meaning” in the world—that is, to relate ourselves to experienced structures, to find patterns of coherence and consistency, and to replace informational disorder with a coherent understanding of our surroundings and ourselves within them. (We might call this view of things a “symmetric structuralism.”) We evolved to instinctively seek this kind of meaning in environments, and it is reassuring and satisfying when we find it—whether in a formal and symbolic sense, or a more tacit and perceptual sense. Justifiably, we refer to this experience as “beautiful.” (In a similar sense, mathematicians often describe certain formulas as “beautiful.”) The unsurprising corollary is that environments in which we do not find this meaning—commonly called “ugly”—are stressful, and potentially harmful to well-being.

It turns out that the built environments that most people find most beautiful, including historic and traditional ones, possess this meaning-rich structure that we refer to as “deep symmetry.” Importantly, there is also a strong (and not coincidental) correspondence with those environments that produce the most positive measurable effects upon well-being.

The architect Christopher Alexander set out to catalog the forms of this deep symmetry, referring to “fundamental properties” that we observe repeatedly in things that we experience as beautiful or full of life. He found that he could do it empirically with just 15 geometrical categories (Figure Four). Many of them correspond directly to forms of symmetry (e.g., “local symmetry,” “levels of scale,” “echoes”, and so on). Others are more complex mixtures. Nonetheless, Alexander’s work shows that it is possible to empirically map the geometric characteristics of deep symmetry –  and moreover, to find a surprisingly close congruence to the vast and diverse array of natural and historic human environments that possess it.

Alexander’s “Fifteen Properties,” found repeatedly in common natural structures, and human structures that we experience as beautiful and full of life. Image credit: Michael Mehaffy, from open sources under fair use.

What about the many contemporary environments that do not display this deep symmetry? They may have a very shallow or learned, cerebral form of symmetry, or a mere veneer of symmetry (like a thin product packaging). Research is beginning to reveal that this shallow symmetry is associated with environments that produce stress, and may contribute to illness, depression, and other disorders.

For example, Penacchio and Wilkins (2014) show that visual scenes that lack the scaling and other multiple symmetries found in natural environments “provoke discomfort, and even headaches and seizures in susceptible individuals.” Le et al. (2016) confirm that “patterns with unnatural statistical properties are uncomfortable to look at … with consequences for brain metabolism, and possibly also for health.”

The journalist Richard Louv coined the term “nature deficit disorder” to highlight research evidence he found documenting the negative impacts from lack of contact with natural environments and forms, especially for children. Now we can see an even broader phenomenon, and one that is closely related: we’ll call it “symmetry deficit disorder.” The deficit in the experience of deep symmetry in modern environments causes an actual disorder in human beings—that is, we identify a geometrical condition that can impair the function of the body and mind. The cause of both disorders is ultimately the same: people seem to have an innate need to connect with the biological structures, and their symmetries, that drove the evolution of humans.

How did this “symmetry deficit disorder” come to be so pervasive in contemporary times? Was something as serious as this accidental? After all, we noted earlier that places and periods throughout history produced beautiful buildings and environments with deep symmetry as a matter of routine—in spite of many other problems those societies faced.

As also noted earlier, some people think that society simply made a calculated trade in the modern era, sacrificing this ordinary—and older—environmental beauty based on deep symmetry for sanitation, medicine, technology, and the like. Very well, they say, we got more sterile, machine-like buildings, but they were orderly and functional, and occasionally costumed with imaginative artworks. What’s wrong with that?

Too much, actually. It’s not only that these environments are taking a documented toll on human health and well-being (by the evidence of data regularly emerging from the medical professions). They are, like the resource-guzzling technologies that made them, profoundly unsustainable (by the evidence of data coming from energy and resource use).

Once again, history offers important and humbling lessons. Consider the Pantheon in Rome, say, which has lasted 18 centuries, in large part because it has been treasured as beautiful by each of the 80 or so generations that kept and sustained it. Yet today we pat ourselves on the back for calling a building with a lifespan of 60 years “sustainable,” and very many new buildings are demolished or fall into disuse after only 40 years or so.

On the left is the Pantheon in Rome, built 18 centuries ago, and exhibiting many forms of compound symmetry. On the right is a new “green” skyscraper, whose symmetries derive mostly from its veneer of plants. The underlying structure is a fairly ordinary stripped-down object-building, of the kind that has been fashionable since the early 20th century. It is common for such buildings to be demolished within a half-century or so. Image credits: Left, Evan Qu via Unsplash. Right, Victor Garcia via Unsplash.

A deeper level of unsustainability is caused by the disordered processes that disrupt ecologies, resource bases, and, no less, the human quality of life. In that sense, the mathematical ugliness of the built environment is a manifestation (and a warning indicator) of deeper dysfunctions, and deeper asymmetries. This problem cannot be dismissed as “merely” an aesthetic one. The remedies, therefore, must be more than aesthetic—they must dig at the core of the processes that generate these ugly places, as well as the ugly products themselves. Process and product are inseparable.

Chief among these processes are the economic and cultural valuations of consumption, disposability, and novelty. Most people already recognize (or suspect) that our cultural and technological systems do not rest on a durable footing. As we have written about before, one way to address that shortcoming is to reform the runaway economies of scale and standardization, which are proving so destructive. While there is a useful role for these economies—in nature and in human systems too—there is also an essential, and largely missing, need to temper them with economies of place and differentiation. Rebalancing systems in this way is essential to the transition from an unsustainable “depletion economy,” to a more sustainable, regenerative, “repletion economy.”

Similarly, while we can welcome visual novelty and excitement in human environments, durability, profoundness, and deep symmetry play a much more essential role. The latter qualities maintain the human race on a viable evolutionary trajectory, whereas their neglect or suppression could trigger catastrophic consequences. Unfortunately, contemporary systems of production over-value the shallow appeal of the new and exciting, with the consequence that there is a “race to the bottom” to build ever cheaper, ever more disposable, but ever more superficially exciting, environments lacking deep symmetry altogether.

Architects have become complicit in this auto-destructive system, for fateful reasons. At the turn of the 20th century, architects signed up to support the unbridled industrialization of the human environment (and its unsustainable development, and ultimately its dehumanization). Fatefully, they became essentially a marketing arm for this unsustainable economic transformation. Rhapsodic theorists from great universities legitimized the cachet of a novel type of fine art, by eulogizing its allure, thus providing compelling packaging for this new—and toxic—industrial product.

Ironically, it is not altogether easy for architects themselves to see this. (We say this as researchers and teachers of architecture ourselves.) Through a process we have previously called “architectural myopia,” architects—like other professionals—have their own lenses through which they see the world and their work. For example, the research literature repeatedly documents that architects have fundamentally different judgments from common people as to what constitutes a beautiful building.

For architects, a “good” building is more likely to be stripped down, dramatic, unadorned—an example of what we have previously termed “geometrical fundamentalism.” From their cognitive perspective, this geometry seems most appropriate for contemporary times, with its focus on machinery and power. At the same time, they have a prevalent aversion for the ornate patterns of nature, and of historical design forms. Instead, trained architectural taste is consistent with an early 20th century fantasy of a “modern” future defined by that bygone era’s stripped-down futuristic images.

The new research coming from social psychology, environmental psychology, and other fields, is helping us to understand what is going on—how those individuals who are removed from the flesh-and-blood reality of a situation must substitute their own “construals” for that reality, often with negative impacts on others. The lesson is that all of us see the world through our own cognitive biases, and with our own “bounded rationality“—sometimes with unintended consequences.

Architects (and other futurists) do experience beauty, just like everyone else. But as research shows, the beauty they experience largely ignores key attributes of the natural and physical world that all of us share—the structura naturalis as we refer to it (Latin for “natural structure”). Rather, they are much more focused upon the beauty of their own mental constructions (shared mostly among other architects)—what we refer to as structura mentis.

There is an essential place for both kinds of structure. After all, the beauty of literature and of other arts comes largely from the mental symmetries of structura mentis. This is the important domain of symbol, allegory, metaphor, and all the other rich capacities of literature and the arts.

But when it comes to the impacts of the actual physical environments where humans live their lives, specific geometries do matter, as the research shows. The health and well-being of users (and of the natural environments upon which we depend) must take priority over the individual prerogatives of artistic expression.

The new insights on symmetry in the built environment offer fertile ground for further development of practical tools and approaches. They cut through the meaningless “style wars,” and transcend considerations of which kind of object-building we might like or dislike, or whether or not we are “modern” and “with it.” Instead, they simply provide a growing body of evidence about why certain environmental characteristics are beneficial, and how we can create more of those beneficial environments. 

This comes at a particularly urgent time when the world is urbanizing at a historically unprecedented rate, with profound impacts upon future resource use, ecologies, and quality of life. Clearly, we cannot afford to remain mired in the same old “business as usual” patterns.  Professional responsibility and good citizenship demand that we recover the methods for enriching the symmetries of our human environments. As the new research shows, these places do have profound impacts upon us — and increasingly, it appears, upon our future.

A few more buildings that exhibit high degrees of compound and deep symmetry. Left, Santa Caterina del Sasso Monastery, Lake Maggiore, Italy; Center, Central Market, Valencia, Spain; right, Byodo-in Temple, Hawaii. Image credits: left, public domain (via Pixabay); center, @nosoylasonia via Photohere; right, @little_plant via Unsplash.

Michael W. Mehaffy, Ph.D., is a researcher in architecture based at the Centre for the Future of Places at KTH Royal Institute of Technology in Stockholm, and director of the International Making Cities Livable conference series.

Nikos A. Salingaros, Ph.D., is a professor of mathematics and architecture at the University of Texas at San Antonio.

How COVID-19 is threatening our health in more ways than one

Increasing “drive-through” lifestyles have already fueled a dramatic rise in obesity-related illnesses, and the pandemic could make it worse – or we could do something about it

Car culture meets pandemic, a story by the US news channel CBS, explores how drive-through lifestyles are being encouraged by the COVID-19 pandemic, notably with drive-through testing.

Richard J. Jackson, M.D., M.P.H. and Michael Mehaffy, Ph.D.

One of the great dangers of the coronavirus pandemic is that it is exacerbating the worst tendencies of increasingly car-dependent cities and towns – the encapsulated, sedentary habits that have already left many communities more isolated and less healthy. As we move toward a post-COVID world, too many neighborhoods offer too little choice, except to continue and even increase this drive-through lifestyle.

Among other things, that is an unjust burden on those who are unable, because of income or age or illness, to own and operate a car. It seems that, as with so many other aspects of the pandemic, we are being forced to confront the structural inequalities and other failures of our existing ways of doing things.

One of those failures is an alarming growth in obesity — itself a risk factor for COVID-19 death, and also a problem that falls disproportionately on low-income and minority communities. In the past 50 years, worldwide obesity rates have tripled, and today in the USA — often a trend-leader — 70% of adults are overweight or obese.

The trend in children is especially ominous: in 1960 in the USA, for example, fewer than one in 10 children were overweight or obese, but today, that number is one in four. Formerly very rare (and very serious) childhood diseases like Type 2 diabetes have become increasingly common.

For adults, the increase is no less alarming. From 2000 to 2018, the prevalence of obesity in the USA increased from 30.5% to 42.4%. That’s contributing to soaring health costs – over $190 billion a year in the US alone, or 21 percent of all health care spending, according to a Cornell University study.

The pandemic is not helping. A recent international survey by Web MD indicated that 55% of men and 34% of women had gained weight during the lockdown. Of US respondents, 25% said they had gained 10 pounds or more. As we emerge from our lockdown, we need active living again – not sedentary drive-through lifestyles in drive-through-only neighborhoods.

Of course, there are other factors that contribute to the obesity epidemic, including the growing consumption of junk food and the lure of sedentary activities online. But there’s also evidence of a close correspondence between obesity and unwalkable, car-dependent neighborhoods. People in these neighborhoods are likely to be heavier, more sedentary and less fit, a deadly pattern that begins when we are young.

For those over 40, a little experiment is telling. In our talks, we often ask our audiences how many of them walked or biked to school. Most hands usually go up. Then we ask them how many of their kids, grandkids or friends’ kids now walk or bike to school. Almost no hands go up. We have wrought a huge change in the lifestyles of our children, one that is taking a tragic toll. We chose to do it when we created unwalkable (and unbikable) suburban environments. No wonder our kids stay indoors on their screens, with too much junk food and too little activity.

Safe, walkable neighborhoods are not just an amenity, they’re a matter of life or death. Not only do we need to be safe from injury and violence – and pathogens, with proper social distancing – but we need to be in walkable environments where we can live active, engaged lives. As the sociologist Eric Klinenberg has pointed out, these neighborhoods create “social infrastructure” that can be a life-saver in a crisis (including a pandemic). And more walking brings more social interaction, more time outdoors, more recreation, more smiles and more “life” in every sense.

But in modern times, aren’t we stuck with these car-dependent neighborhoods? No, we aren’t. As the PBS series Designing Healthy Communities showed, there are plenty of good examples of neighborhoods that point the way. More walkable, transit-oriented suburban neighborhoods such as Oregon’s Orenco Station prove that it’s possible to offer places where people will choose to walk more. At Orenco Station, a study by the sociologist Bruce Podobnik showed that in 2002, 17 percent of residents reported walking to shopping 5 or more times a week, a remarkably high number. By 2007, that number was up to an amazing 50 percent. Neighborhoods can change – for the better.

We suggest that it’s time to “retrofit the suburbs,” adding living streets and centers for humanity – young and old, rich and poor – to formerly sprawling areas. That’s what happened in Orenco Station (left), showing what can be done. These places are not just healthier, they offer a better quality of life, and if they have a mix of services and public transit, monthly transportation costs can be lower, too. Livability, affordability and health can go hand in hand.

The idea is not to “take away people’s yards,” or any other choice. The idea is to provide more choices, for more people, in how to get around and what to do outdoors. Especially it’s about offering more healthy choices. You might still live in your current suburban house, if you want, but find that you can now walk to a small town center nearby, offering a small park for recreation, a market and other shops, and lots of ways to get around by foot, bike, transit or car. As a result, you can get a quart of milk and don’t have to burn up a quart of gasoline. Along the way, you might see a neighbor, exchange some news, or bring the kids for a walk or bike ride.

And you might not just be improving your life: you might be saving it.

Dr. Richard J. Jackson is Professor Emeritus at the Fielding School of Public Health at UCLA, and former Director of the National Center for Environmental Health at the Centers for Disease Control. Michael W. Mehaffy, Ph.D. is an urban researcher with the Centre for the Future of Places, KTH Royal Institute of Technology in Stockholm, and Executive Director of the Lenanrd Institute for Livable Cities and IMCL.

Why “a building is not a tree”

Or, how Christopher Alexander’s landmark 1965 paper can still guide us in thinking about the coronavirus, and other urban challenges

The UK Urban Task Force demonstrated in this figure that the same population density can take very different forms, with very different connective properties (red lines added), and different impacts on health and vitality — including disease transmission.

The coronavirus pandemic has forced a sober reassessment of a number of urban characteristics, and none has been more maligned – inaccurately so, I fear – than urban density. A closer look reveals that clustering of people in certain environments (like nursing homes) is far more likely to spread infections than in other places with similar population densities – notably public spaces. As I have written elsewhere, it’s quite possible to maintain “sociable distancing” in many kinds of public and semi-public spaces.

What are the lessons for urban density in private places? One of the topics that needs careful assessment in the wake of the pandemic is the impact of tall buildings, which also tend to bring many people into close contact — notably in their elevators, lobbies, and other spaces.

Epidemiologist Shai Linn has observed that the incidence of infectious spread can be high in tall buildings. He draws an analogy to the spread of coronavirus and other diseases in cruise ships: in both environments, people tend to crowd into elevators, stairs and other common areas. In both environments, infections (of all kinds) can spread rapidly.

There is an important point to be drawn from Linn’s work and others’. The issue is not merely that many people are in spatial proximity, but that they must pass through “choke points’ of centralized spaces, where airborne transmission is much more efficient. (Successive touching of “fomites” like door handles and buttons is also part of the problem, but can be controlled more easily.)

What is the deeper problem with these centralized spaces? One can think of the structure of a tree, where all the branches, twigs and leaves are connected only through the trunk. Similarly, in a tall building or a cruise ship, all the parts are connected through central elevators, stairways and common areas.

By contrast, a web-network doesn’t have to concentrate everyone into central spaces – even when a given unit of space has the same number of people, that is, the same “density.”

The drawing at the start of this post makes this point. We can contrast a tall building with a street lined with tightly packed rowhouses, or a series of small apartment buildings, each with its own entry on the street. Such a web-network allows people to be in social proximity – able to practice what I have called “sociable distancing” – without being forced into the kind of adjacency that allows transmission of pathogens.

As it happens, the urban and architectural theorist Christopher Alexander described these two kinds of structures in a famous 1965 paper. Alexander, who is better known as the author of the classic book A Pattern Language, wrote in his paper that “A city is not a tree” – or at least, a good city is not. That is, the best cities are not dominated by centralized tree-like structures, but rather, they have many web-like sets of connections that he referred to as “semi-lattices.”

An obvious example of a tree-like structure can be seen urban street patterns. Many sprawling suburban communities show a tree-like pattern that is easy to differentiate from, say, the web-like grids of many older cities (as in the figure below). The trouble with tree-like patterns is that they force traffic into limited “choke points” where it becomes congested and hostile to pedestrians. This pattern doesn’t allow vehicles or pedestrians to connect through other shorter trips between the branches, as is the case with the web-network. That usually means neighborhoods with tree-like structures are not walkable, are not very well suited to transit, and are prone to traffic congestion.

For Alexander, there is an even more fundamental problem for cities organized as “trees.” Cities get their vitality and their dynamism from these inter-connections — from the diversity of people who come into mutual contact, from the mixing of different activities and movements, and from the “overlaps” that happen when things are not neatly segregated into tree-like schemes.

He concluded:

It must be emphasised, lest the orderly mind shrink in horror from anything that is not clearly articulated and categorised in tree form, that the ideas of overlap, ambiguity, multiplicity of aspect, and the semilattice, are not less orderly than the rigid tree, but more so. They represent a thicker, tougher, more subtle and more complex view of structure.

If good vibrant cities are not “trees,” what about buildings? It seems the same logic applies: at the scale of buildings too, and especially as they connect to the public realm, we should seek overlap, multiplicity of aspect, and the other characteristics that Alexander celebrates. We should seek buildings that are more fine-grained, with redundant connections to the street, rather than one centralized “tree trunk,” as tall buildings typically feature.

In structural terms, we can compare a tall building to a kind of “vertical cul de sac” – or a kind of vertical gated community, with all the same potential problems of that problematic structural form.

And as we can now see, for similar structural reasons, such structures are also more resilient in the face of a pandemic.

The diagram at the top of the post, developed by the UK Urban Task Force in 1999, shows three schemes, each with exactly the same relatively high population density (75 Units/Hectare or 30 Units/Acre), but with very different network structures. The scheme of small flats to the lower right offers many different connections to the street, and it avoids centralized “choke points” where everyone must come into close proximity.

It’s often assumed — wrongly, as research has shown — that tall buildings are necessary to achieve higher population densities. Yet these three schemes all have exactly the same density. They only differ in the way that those populations can connect — as “trees,” or as “web-networks.” The tall building is clearly a tree, with all its structural vulnerabilities.

Unfortunately, at this moment in urban history, the growth of tall buildings around the world is nothing short of explosive. As research is showing, the factors that propel their growth seem to have less to do with best practice knowledge, and apparently more to do with the dynamics of short-term capital, images, branding, and even the egos of their promoters. This is not the path to sustainable or resilient cities. It may in fact be the path to catastrophe.

Let us hope that, as this pandemic prompts a reassessment of recent urban orthodoxy, the tall building, along with other mega-structures, will be part of a much-needed critical re-assessment.

How will the coronavirus pandemic affect public space?

Porch - for FOPRN
During the pandemic and at other times, it’s possible to maintain “sociable distancing” — to control our level of exposure to others for a variety of reasons.

Its biggest impact may be in prompting a re-assessment of the way we think about public space and density, says Michael Mehaffy of the Centre for the Future of Places.

EDITOR’S NOTE: In a podcast at public radio station WPKN of Bridgeport, Connecticut, architect and author Duo Dickinson talks to Centre researcher Michael Mehaffy about lessons from the current pandemic.   The link to the podcast is here, and the transcript below has been lightly edited for readability. 

Duo Dickinson: Well, I guess we’re back on Home Page Radio. In the miracle of wired radio, we’re having Home Page Radio generate from five separate sites this month, and this is the fifth site we’re going to be connecting with.  Which is Michael Mehaffy – Michael, are you there?

MM: I’m here, hey Duo!

Duo: Good to talk to you. We had just been on the phone before with Steve Mouzon, who told us the plain and simple truth, that things like copper door knobs and multiple entries are the old lessons of safety in a pandemic world, that are lost on, perhaps – it was Governor Cuomo that said that density is our enemy. We also talked to Ann Sussman who talked about the fact that design is not necessarily from on high or from a big box, but the way we think about the world actually empowers us to rethink the way our world is when we are sequestered at home, sheltering in place.

Well, Michael Mehaffy is an author and educator, a researcher, designer, consultant, all over the world… A Senior Researcher at the Ax:son Johnson Foundation, the Centre for the Future of Places, and he’s also Executive Director of something called Sustasis, and Sustasis Press. And he’s also taught all over the place, but he’s really very well-known. And how I’m associated with him is working with Christopher Alexander, author of A Pattern Language, a very famous book, and other people that deal with design in a different way than I think is usually presented in the press or by public perception.  And in that way, Michael, I’m going to ask you a very interesting question.  We’re all living at home now, we’re all sort of separated and segregated intentionally from each other.  In your lifetime of looking at congregating people in a good way, tell us what we can learn from this forced separation.

MM: Yeah, I think it’s really interesting actually. I think in a way this is a “teachable moment,” because it really forces us to think about how we interact with other people, and how we do that through the places that we live. You know, by the way, I’ve seen a lot of people just anecdotally, or heard about a lot of people, coming out onto their porches and their stoops, and trying to visit with each other, in spite of the social isolation that’s required in this pandemic.  And creating a kind of, I would call it, “sociable distancing” – you know, where we are still in proximity to each other, and that’s very very important, to still have that human contact. And in fact the research is showing that that in itself is really an important component of resilience, and of the way that people survive these kinds of crises.  The sociologist Eric Klinenberg has written about that, about the need for “social solidarity.”

And so I think we’re beginning to really re-assess the way that we have been building over the last 50 years or so — you know, as Steve was talking about: the sort of single-family detached, often isolated home that’s not very well connected to the public realm, that’s very car-dependent and so on.  And what I’m afraid of, frankly, is that this will reinforce some of those tendencies, of, you know, exclusion and isolation and car dependency.  You know, people holing up in their houses, binge-watching TV and so on. And not recognizing that we have to have that other component too, that sociable interaction – “sociable distancing” I would call it.

And also that density, as Steve was alluding to, is not just one thing. It’s not just all hyper-density all the time, but many different forms of density, and many different ways that we can sort of dial in our own comfort, our own degree of interaction with people – whether it’s because of a pandemic, and we have to be a little bit further away from people, you know, or just the level of comfort that we have as individuals at different times of our lives. That we want to be jam-packed and, you know, elbow to elbow with people at one time, and maybe we want to be more secluded at other times. And the spaces of our houses and our buildings, if they’re designed well, they allow us to do that, they allow us to self-organize our relationships with one another. And in turn, self-organize the buildings, and the way the buildings evolve and change over time.

Duo: Well let’s take that one step further.  So, where are you calling us from – or where are we calling you, actually?

MM: Well, I’m actually in a little town called White Salmon, right around the corner from where my daughter lives, one of my daughters.  The other daughter lives in the next town over, and she has a big wraparound porch that’s a great space. I was just over there visiting them – on the porch, because, you know, we can’t get too close to each other! But we –

Duo: (Laughs) What state is that in?

MM: They’re actually on the Oregon side of the Columbia Gorge, and I’m on the Washington side. It’s a really beautiful area.

Duo: Wow. This is pretty exciting to me, to basically see an entirely different world through your eyes. What I’d like you to – you know, I know of your work – you’ve actually studied I think the way humans live together as well as anybody that I know of. And I’d like to you sort of – now that you’re forced to essentially detach yourself from other people as much as possible – could you let everybody listening to you, with all of your experience, tell us of any things you’ve learned in this last week or two, where you’ve been forced to be alone in your place.

MM: Well, I think it’s just reinforced to me the importance of this social solidarity, as Klinenberg refers to it. And “sociable distancing.”

You know, both of my daughters and I live in small towns, but they are very urban places, they’re walkable, they’re very well interconnected. And you know, as Steve was talking about with Barcelona, a city that has lots of spaces that interconnect with the public realm. Not just one big tall building where everybody is, you know, they come down and they’re suddenly in a very very high density environment, like might be the case in Manhattan, for example. I mean that’s one extreme of density, but the other – it’s not just two choices here, it’s not that versus holing up in your apartment alone.  In fact that, as Klinenberg showed us, is very very dangerous in a crisis, because people tend to die. They lack the social connections that help them to adapt and survive.  So we need all those different gradients of interconnection with each other, and we need them in our environments, in our built environments.

So you know, I think people tend to look down their noses, some architect friends of mine who are avant-garde designers, at the idea of porches, for example. Well that’s, you know, old-fashioned or something.  Well, no, it’s simply a form of evolution that’s very intelligent, and we need to start thinking that way.  And I think, get off this – Ann Sussman alluded to this a little bit too – get off of this sort of industrial art approach to human environments.  That we’re sort of costuming up with our avant-garde abstract art, these industrial products that are often quite toxic to human well-being. And we need to get back to the kind of thing that Steve Mouzon is thinking about, of a more natural, evolutionary way of thinking about human environments.  And why human environments are healthier for us, and easier for us to connect to one another – easier for us to make changes that make us more comfortable, so we are actually more willing to be sociable and interact.

So I think that – to me, this experience has been fascinating, and scary, and disturbing in many ways – but also inspiring in many ways. You know, when I heard about the people in Italy coming out onto their balconies and opening their windows and singing, and seeing people coming out onto their porches and stoops, and you know, having “sociable distancing” rather than just isolating themselves. And so I think we’re seeing in a way, first-hand, this kind of self-organization that happens, this kind of resilience that happens.  And we’re seeing it working really well in some places, and not so well in some places. And I think that’s a really interesting lesson right now.

Duo: So as you’re dealing with these macro issues of how people live, in terms of creating, for lack of a better word, walkable places – places which are not dependent on gigantic cars and gasoline, really places that are not, don’t even have sidewalks, the normal mid century American lifestyle. And you’re thinking about this reality, that humans should be closer together, that’s actually becoming now, I think, a general social consensus, humans should be denser. When you’re looking at the present situation, where density can be called toxic by the governor of New York, tell us – because this is a rare opportunity, now that you’ve had a chance to really self-separate, from a life of extreme social integration and intellectual thinking about what has happened – tell us what you think of the future of the world after this. Because this will change, I think, the way people think about the way they live.  And tell me what you think, how that will change.

MM: I hope so. Again, I think it’s a teachable moment – I hope it’s a teachable moment. Because we do have a moment of opportunity to rethink some of our assumptions. And one of them is that whole idea of density, as you said. People think of density as sort of being all one thing or all not one thing. It’s like either super crowded, you know, Manhattan streets or it’s nothing, it’s isolated behind your, you know, gated community and your car dependent neighborhood. No! There’s a whole tissue of relationships and kinds of urban spaces that can exist, and should exist, and does exist in many places, including the small town where I am right now. And I think it’s important for us to think polycentrically that way – that there’s big cities, there’s small towns, that everybody can have that kind of interconnected web of relationships in their neighborhoods and their towns.

And there’s international policy agreements that are really beginning to describe that in detail. There’s something called the New Urban Agenda, which was agreed to by all 193 countries of the United Nations – a lot of this language described in it. We’ve been involved in that for a number of years now. And there are other things going on – you mentioned Christopher Alexander, I think a lot of people are beginning to come back to his work. And we have a new book as I think you mentioned, A New Pattern Language for Growing Regions, which describes some of the work that’s going on in the New Urban Agenda, and the idea of walkability and sociability, and all these ideas that we’re beginning to in some cases discover, and in some cases rediscover. And I think it’s an exciting time in that sense.

Duo: Well, in these closing minutes, the one thing I’m really fascinated by is the fact that the zeitgeist of a month ago, the zeitgeist in, really, the world, of massive systems of connection, of massive ways of eating, of interacting, where people would essentially cook less and less at home, would be more outside of the home, would be completely engaged in stream behavior, now that the pandemic has forced us to snap a lot of that, and actually depend more on streams to connect rather than disconnect, and also to cook as opposed to order food, I would love to hear your analysis of – and if you don’t know him out there in radio land, Christopher Alexander, who has for fifty years, recreated the way architects should think about things in the world and how they design – tell us how the pattern language book that you’re dealing with now… tell us how the essentials of that relate to how people might look at their homes in this house-bound time.

MM: Well, I think you put it very well.  I think this moment, this crisis, is forcing us to recognize how non-resilient a lot of our systems are, how non-adaptive they are, and how vulnerable we are. And the antidote to that is to be more resilient, and that means more interconnections, more sort of polycentric approaches instead of the too-big-to-fail approach, which is obviously getting us into trouble. And the idea that we can have different levels of scale of things going on in our lives, that allow us to cope, and to interact, and to solve problems.

You know, that’s a whole other subject, what is resilience and how do we get it.  But I think this moment is really forcing us to think about that in a way that I think is a great opportunity, if we’ll use this crisis to, again as I said, as a teachable moment, to think about how we can make more resilient, more sustainable kinds of ways of living.

And I think Chris Alexander is one of the guidestars for that way of thinking, along with people like Jane Jacobs and a number of others. Again, people are beginning to come back to read these folks again, and recognize that what they’re saying has a whole lot to do with where we are right now in history with this pandemic. So again I think it’s a time to move forward with some innovations, but also to recognize some of the mistakes we’ve made with the, you know, novelty approach, and the abstract art approach, and begin to focus more on human beings, and human adaptation, and human environments.

Duo: Well it’s been great to have you on the show, Michael Mehaffy, and we really appreciate your time, and we’ll have you back again! So thank you very much.

MM: Delighted, Duo.

Is it time to revive the pattern language?

Software and other fields have made brilliant progress with the methodology, while built environment fields lag badly – mired in parochial debates over a 1977 bible-like volume

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Launch of A New Pattern Language for Growing Regions: Places, Networks, Processes book and wiki at the 2020 World Urban Forum in February. Wiki inventor Ward Cunningham was interviewed by collaborator Michael Mehaffy.

Although virtually everyone uses Wikipedia routinely today, what is remarkable is how few know its surprising provenance in the world of planning and architecture.

Wiki, the methodology that powers Wikipedia, was invented by a computer scientist seeking to create a web-based system to share “pattern languages of programming” – an idea he and his colleagues had exported from architect Christopher Alexander’s 1977 classic A Pattern Language: Towns, Buildings, Construction.

Pattern languages are, at heart, nothing more than “a method of describing good design practices or patterns of useful organization within a field of expertise,” as Wikipedia describes them. The “pattern” encapsulates some key relationship within the set of design elements, which, if configured in the “right” way, will produce the desired outcome. Each pattern typically includes a name, problem-statement, discussion conclusion, and hyperlinks.

The genius of the method is that each pattern is nested within many other patterns, connected by hyperlinks, and forming a relational web-network. The patterns can then be applied in a contextual, language-like way. Software designers clearly found the method enormously productive: pattern languages of programming (or “design patterns”) have been put to use in most game software, many other programs, and many operating systems.

Ward Cunningham, the wiki inventor, actually envisioned each wiki page as a kind of pattern in its own right, with title, photo, summary, discussion, and hyperlinks.  A few years after his 1990s invention, the developers of an early online encyclopedia enthusiastically applied the new system (and its name) to their embryonic creation, with now-familiar results.  Nor is wiki limited to Wikipedia, of course, but it permeates the web (Google Sites, Wikihow, Mediawiki, etc).

Pattern languages have had other phenomenal applications too, growing out of software (leading directly to Agile, Extreme Programming and Scrum) and also an astonishing range of other fields, from molecular biology to sociology to engineering to manufacturing, to seemingly countless others. One can find online citations to papers on pattern languages for music composition, pattern languages for weddings, even pattern languages for writing patterns. (!)

The one field that has lagged most conspicuously is, curiously, the very one for which pattern languages were invented, the built environment. What can explain this anomaly? It seems there are a number of likely factors – the bias of architects against anything that they imagine might limit their “creative freedom” (a debatable idea at best), the greater willingness of other fields, especially technology,  to embrace functional innovation (not just novelty for its own sake), and the more pragmatic, less ideologically constrained nature of other disciplines in relation to architecture.

But perhaps the most powerful explanation is the very success of the 1977 book. Resembling a nothing so much as bible, it is full of pronouncements that were forever locked in print, and never allowed to be tested and refined.  The cult-like veneration shown by some was matched only by the contempt held by others.

Yet this outcome was contrary to the explicit aims of the authors, as they made clear in the introduction:

You see then that the patterns are very much alive and evolving. In fact, if you like, each pattern may be looked upon as a hypothesis like one of the hypotheses of science. In this sense, each pattern represents our current best guess as to what arrangement of the physical environment will work… But of course, no matter what the asterisks say, the patterns are still hypotheses, all 253 of them — and are therefore all tentative, all free to evolve under the impact of new experience and observation. (Alexander et al., 1977, pages xv-xvii)

But that evolution never happened, of course.  Instead, the 253 patterns became trapped in their original bible-like volume, protected even by copyright, and never to be altered, added to or differentiated. Other fields, unencumbered by such a dominant first corpus, made brilliant progress, while work in the built environment stagnated.

So what can be done now to push forward more productive work in the built environment?  Two developments offer an opportunity for a fresh start.  One of them is the development of a new framework agreement on urbanization, adopted by acclamation by all 193 countries of the United Nations, and known as the New Urban Agenda. Many of the elements of the New Urban Agenda can be expressed in pattern-like forms, offering the potential for a new collection of patterns based on this document.

The other development is a new generation of wiki, authored by the original inventor, Ward Cunningham. This “federated” wiki allows copies to be made, shared and altered more easily, using handheld or desktop devices. Its limitations are as broad as the limitations of new app capabilities – data calculations and modeling, field measurements, augmented reality visualization, and a host of other new capabilities undreamt of by the original pattern language authors.

Accordingly, our team, based at the Centre for the Future of Places at KTH University in Stockholm and at Sustasis Foundation in Portland, Oregon, have partnered with Ward Cunningham and other collaborators to develop a new pattern language collection, together with a companion wiki. A New Pattern Language for Growing Regions contains 80 new patterns, many encapsulating elements of the New Urban Agenda.  The companion wiki, at, contains the same patterns in wiki form. The wiki is currently read-only, but will become editable and shareable in the near future.

The companion wiki (available online at can be used on a smartphone or desktop. Each pane is a pattern, linked to other patterns through networked hyperlinks, and able to be navigated and assembled for application in specific projects. The wiki will soon be editable, allowing the revision and addition of patterns for a wide range of potential project applications.

The new patterns reflect not only the New Urban Agenda, but the new thinking about urbanization and its requirements for a more sustainable age – reformist ideas going back to the work of Jane Jacobs and others. They include patterns on mixed use, walkability, public space, multimodal transportation, interconnected street grids, and other characteristics of diverse, well-connected urbanism.  There are also patterns covering historic regeneration, slum upgrading, suburban retrofit, and other timely issues.  Other patterns cover new technologies, like citizen data and autonomous vehicles.  Another category covers implementation tools, including financial mechanisms, governance structures and the like.  A more experimental category covers geometric characteristics – similar to those later explored by Alexander – including local symmetries, fractal patterns, grouping and framing.

As with the first generation of patterns, the aim is to set out normative propositions supported by evidence, and accordingly, each pattern has one or more research citations justifying its claims.  Of course these can all be debated, and the aim is not to end discussion, but to begin it.  If another party has an alternative pattern, justified by alternative evidence, let them present it, and let us have a proper debate on the evidence.  Let us not continue to argue ex cathedra for sectarian dogma. That is not how the other fields have made such progress in meeting their challenges.

Another point is the normative nature of the patterns. These are unabashedly so, in the belief that all work in the built environment is shaped by normative judgments, and the only question is whether these values are on the table for examination and challenge. As Kevin Lynch pointed out in Good City Form, the danger is not having values, but failing to make them transparent. Too often these values are cloaked behind claims of expertise or artistic privilege, rather than sound examination and collective evaluation.

Some will note that we adhered closely to the original design of the patterns as printed in the book.  This is because the original patterns have been proven user-friendly and successful, and attempts at altered versions in the built environment have proven less so. Furthermore, a similar format also helps to make the original patterns more useful as part of larger project-based collections.  Alexander and his colleagues also described “the essential purposes behind this format,” which suggest that alterations without cause are unwise. This project is intended to be rooted in evidence of what works, and the evidence that the original pattern structure has worked is undeniable.

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Copes of the new pattern language book on display at the World Urban Forum.

Finally, this project is meant not as an end but a beginning.  The first collection of 80 patterns is only a small and partially representative sampling of what is possible, and surely necessary, as we confront a new generation of challenges.  The wiki should make it possible to produce many hundreds or thousands more, just as Wikipedia grew from a few hundred entries to today’s vast collection. The patterns can be collected periodically into print editions, or continue in online form, or both. More importantly, they can be applied to specific projects and specific contexts in different parts of the world, adapted, refined and added to, so that the most universal patterns can be widely shared, and the entire collection can grow and diversify.

Whether or not this particular project is the spark of a revival of pattern languages in the built environment, we are convinced that such a revival is long overdue.  A profound transformation is under way in our technological systems, reflected by Agile Methodology, Scrum, wiki, and yes, patterns. The transformation is driven by a recognition that the old linear methods have failed us, and we need better web-networked ways of working. In the built environment especially, the need for ways to document and share successful evidence-based design methodologies, capable of achieving desired goals, is matched only by the current gap in achieving them.

Michael Mehaffy is Senior Researcher at the Centre for the Future of Places, and Executive Director of Sustasis Foundation and International Making Cities Livable ( He was a student and long-time collaborator of Christopher Alexander, and he has been a collaborator of Ward Cunningham for over a decade. More information is available about the wiki and book at