A NEW MODEL OF URBAN DENSITY
part one of a public lecture given on October 21, 2020 at the UCLA department of Architecture and Urban Design.
Thanks for the invitation and the introduction. Before I start, I want to insist that while environmental issues drive my work, I’m not an environmental activist. I think it’s important to make a distinction between activism and design. Anytime we flip into crisis mode, the most important thing for each of us to do is our job. Given the state of things, one may feel the urgency to get quick results, by writing or speaking out, but these activities do not advance a case for design. The point is to engage environmental or political problems as design problems. While strength in numbers matter, politicians and social scientists ultimately do a better job at activism because that is their job. Meanwhile, there is a great deal that design can do that is not being done. While the following paragraphs are my take on the climate problem, they are set up in a way that leads into design responses — responses that only a designer could come up with.
view from the Sam Houston Toll Road
So, the question I would like to start out with is simple: what time is it? When are we? This is an image of Houston taken on August 28, 2017, when hurricane Harvey came through and transformed our assumptions about the city’s resilience as well as our sense of time. Before Harvey, I had presumed a time horizon that measured out perhaps twenty or thirty years before the effects of climate disruption would become real. 2050 was comfortably remote. Maybe I would see these effects, maybe I wouldn’t…. but when the floods came to Texas, and when California and Australia burned, and when it was announced that the Altes Glacier in Switzerland had receded over a kilometer in the last ten years, that distant horizon vanished. It was no longer clear when we were.
What seems to be happening is that time has accelerated to the point that we find ourselves amid a global transformation we were surprised to learn had already begun. It scrambled our most basic questions: is this the moment for action, should we cut back our consumption or is it already too late? The lack of answers has induced a kind of paralysis, or inaction, owing to a lack of temporal bearings. One way to describe the work I am going to show you is an attempt to engage this accelerated timeline and turn it to our advantage. The only way to do this is to show some ways forward, some plausible destinations tied to specific places and times.
RCP pathways, 2014
Some of you may recognize the graph above is of the Representative Concentration Pathways (RCP) published by the United Nations International Panel on Climate Change. Since 2014, the way they work is to break their prognostications down into four scenarios based on different levels of carbon in the atmosphere. Today, we are traveling up RCP 8.5, which tracks a scenario of business as usual.
But the reasons I really wanted to show is not to tell you that we are in trouble, which we are, but to show how, going forward, our timeline has exploded into an array of wildly divergent scenarios, each more deadly than the next and each accelerating into an impossible future. These scenarios run from the development of green energy and a rapid return to a stable climate (RCP 2.6) to large population draw-downs and alligators living at the north pole (RCP 8.5). Inhabiting the switch point of so many futures, with no way to control or even to understand our fate, we fall into inaction, victims of our scrambled temporal bearings.
carbon budget, 2030
The following numbers are an attempt to lay out a reasonable time frame for the present and future in the form of a carbon budget. Two degrees Celsius is the maximum temperature rise that we can endure and still have a planet that’s compatible with contemporary economic, political and cultural expectations. Three Degrees will result in massive displacement populations due to inclement weather, sea level rise, and global food shortages. That gives us a carbon budget of 565 gigatons of CO2 as the maximum load that the atmosphere can absorb and still limit warming to a two-degree rise. Given our present rates of emissions (RCP 8.5), it will take only 15 years until we reach this limit. This was Bill McKibben’s estimation of the time we have left. It was his attempt to establish a 10-year time horizon.
Today, it seems that many people have given up on limiting surface warming to two degrees, and some of them are even saying it out loud. The reason for this surrender can be found a third number that McKibben added to the equation. The fossil fuel industry claims that there are 3000 gigatons of unburned CO2 in their reserves. These are reserves that have been discovered but have not yet been extracted. The industry is valued on this number which is five times the number that will put us over two degrees. Those three numbers speak volumes about just how out of step we are with our accelerated timelines.
Cities count for two thirds of the world’s average energy consumption and 70% of greenhouse emissions. It has been determined that Americans will need to achieve a 75% per person reduction in energy expenditure over the next ten years to keep the fossil fuel industry’s reserves in the ground.
So, how do we think of this situation as a design problem? What we decided to do is to put this impossible number against a few numbers of our own. Specifically, we wanted to create an urban timeline. We did this by calculating the average lifespan of a building or the average length of time required for a building’s construction, consumption and replacement to occur. Projected at an urban scale, the building lifespan determines the duration of a city’s building cycle. The value of calculating a building cycle is to get a fix on the city’s metabolism — the interval in which cities routinely build and rebuild themselves.
the building cycle
The building cycle is, of course, counterintuitive, even for students of the city. Despite the fact that we see buildings being rebuilt every day, and that we have some sense that buildings are being built more cheaply and replaced more quickly, we still believe buildings and cities to be permanent. As with so many things, such beliefs have been upended by contemporary practices and our imaginations have been unable to keep up. Today, the average spec office building in the United States is amortized over a period of 25 years. What that means is that over a twenty-five-year period, its value is depreciated down to zero. So while we continue to believe that cities outlive people, we are nonetheless shocked to discover that we routinely outlive the buildings that were built within our lifetime.
The accelerating building cycles of contemporary cities have usually been the occasion of much consternation among architects whose traditions point to firmness, as well as to commodity and delight. While the downsides of cheap construction are obvious, there are upsides we often neglect. Buildings are not simply rebuilt, they are updated and improved with each succeeding generation. The accelerating churn of urban cycles allows designers to intervene in the building cycle with greater frequency, replacing old building stock with upgraded structures that meet the specifications of the day. Among those specifications today would be the need to significantly cut the city’s carbon emissions through the construction of larger more energy-efficient buildings built at ever-increasing densities. As the cycle continues, and new buildings replaced outmoded ones, the city can be completely reformed within a single building cycle. In other words, time, would be the design medium with which to write the specification of a city capable of reducing our carbon consumption by 75%.
the Great Acceleration, 1950
Before I discuss the temporal dimension of urban design, I need to make one more point about our accelerated timelines. By now, most of us have heard of the term Anthropocene, where human activities are acknowledged to be the dominant force in the planet inasmuch as we now show up in the stratigraphic record. The evidence of human activity in the earths crust signaled a shift from the present geological era, the Holocene, into a new era called the Anthropocene. in order to acknowledge this shift, the Anthropocene needed a start date. The first proposal was that the Anthropocene began with the onset of industrialization at the end of the 17th century. Following a stratigraphic study, however, the actual evidence pointed to another start date — the rise of mass consumerism at the middle of the 20th century. The proof they offered was these now infamous hockey stick graphs that pivot around the crucial year of 1950. The graphs are divided into two broad groups, human activity and natural stresses. Human activities are measured in GDP, urban population, international tourism, fisheries, urban population, and motor vehicles. Stresses to natural systems are measured in rain forest loss, carbon increase, ozone depletion and glacier melt. Common across all indicators is a spike in activity around 1950, the moment at which a global, wartime economy was retooled to produce an entirely new age of consumption. This moment was given a name, the Great Acceleration.
What the Great Acceleration produced was not just a change in number but a change in kind. A 2017 study attempted to quantify the sum of human production under a new name, the “technosphere.” The technosphere was the material prosthetic that humans have created in support of the species — massive fleets of cars and airplanes, continental expanses of managed landscapes, billions of buildings, and the physical and electronic infrastructure that supports it all — weighs in at 30 trillion tons, some five times the weight of the human beings that it sustains. That is approximately 4,000 tons of transformed earth per human being, or 27 tons of technosphere for each pound of a 150-pound person. A virtual “exoskeleton” for the species, everything we do, we do through the technosphere: prepare a meal, buy a shirt, message a colleague, fill a prescription, or bathe a child.
Despite its importance to basic survival, the technosphere has come to be perceived as the ultimates source of our carbon emissions whose reform is essential to bringing warming under control. Such an understanding of the built environment brings a wicked problem into existence. We have come to name and measure the technosphere as indispensable to our survival at the same moment that we recognize it as the principal threat to that survival. As it turns out, just being human and alive in the world today requires a significant carbon expenditure that cannot be simply sloughed off.
the energy corridor
These two recent formulations set off a series of questions within urban discourse. Is the technosphere synonymous with urbanism or has it replaced urbanism as a discrete category altogether? Is the technosphere simply the urbanism of the Great Acceleration? Shall we instead consider urbanism as a subset of the technosphere? To answer these complex questions, I will revert to some visual evidence. This image is of an area in west Houston called the “Energy Corridor.” It is aerial photograph taken by Alex McLean above the city’s major east/west freeway. At 29 lanes across and a right of way of 556 feet, it is the widest freeway in the world. Given its function as an energy center, and given the speed at which it was built (fifty years ago, the frame would consist of a single farm-to-market road), and given its massive scale, Houston’s Energy Corridor is as good an emblem as any for what the Great Acceleration has produced over the past half-century. It also reveals the characteristic urban trait of the Great Acceleration — urban dispersion.
The Great Acceleration affected the pattern of traditional urban growth in two respects, it accelerated growth from the rural areas into the city while simultaneously accelerating the pattern of the city’s growth out, away from the historical centers in dispersed episodes of spine-based development. This push/pull acceleration is familiar in that we know that people are moving into cities at an incredible rate, with well over half the globe’s population now being urban. But what we pay less attention to is that as we’re moving into cities in great number, the cities themselves are dissipating outward. Cities are getting much larger while also becoming much less dense. And the rate of urban dissipation has not decreased since the Great Acceleration began. At the scale of the greater region we become more consolidated while at the scale of the city, the seat of that unprecedented expansion, we become more atomized.
This inverse relationship between acceleration and dispersion, between consolidation and atomization, is a useful way to look at urbanism today. The UNIPCC’s (United Nations Intergovernmental Panel on Climate Change) described this inverse relationship in its Fifth Assessment Report (2014):
“the scale and speed of urbanization is unprecedented: more than half of the world population live in urban areas and each week the global urban population increases by 1.3 million. Today there are nearly 1000 urban agglomerations with populations of 500,000 or greater; by 2050, the global urban population is expected to increase by between 2.5 to 3 billion, corresponding to 64% to 69% of the world population. Expansion of urban areas is on average twice as fast as urban population growth, and the expected increase in urban land cover during the first three decades of the 21st century will be greater than the cumulative urban expansion in all of human history.“
Short of reviving rural economies by reverting to pre-industrial land practices, there is nothing we can do to halt the move from rural areas into cities. And while there are those who propose that we do just that, reversing the impact of the Third Agricultural Revolution would require a draw-down of the human population that is difficult to conceive. There is, however, something we can do about the dedensification of the city if for no other reason than we have no choice. A glance at the photo and it becomes clear that the pattern of urban dispersion brought on by the Great Acceleration is reaching a limit. Consider the absurdity of Houston’s 29 lane wide freeway. Its latest expansion was open in 2008 and within a year it was again at bumper-to-bumper capacity. The question that follows is if the doubling of the population over the next century will increase the lane count to 60 lanes wide? Putting aside questions concerning the functionality of 60 lane wide freeways, the amount of energy to required to fuel this outward dissipation, and the amount of carbon emissions it produces cannot be sustained a world limited to two degrees of warming. The proposals that we are working on asks what a city that slows this expansion and reverts back toward a trend of densification would look like in the twenty-first century. Can the next building cycle introduce a new model of urban density from within the dispersed fabric of contemporary urbanism with the aim of shrinking the physical and environmental footprint?
energy and urban dispersion
The effects of accelerated dispersion are best represented in two graphs. The first shows energy use in the vertical dimension and urban density in the horizontal. Increasing dispersion moves from left to right and increasing energy consumption moves from bottom to top. The less dense, energy intensive cities — Houston and Phoenix — land on the upper right-hand corner. The more dense cities — Hong Kong, Seoul — land in the lower-left corner. There is an enormous consumption and emissions gap between these two corners with the advantages of density being clearly spelled out.
The advantage of density in the cutting consumption and emissions is reinforced in the next graph which tracks energy consumption on a simple, per-capita basis. The per-capita consumption in the United States is the top line. Europe and Japan are represented in the middle group of lines. The bottom lines represent the world average and China. The third line in the bottom group is, surprisingly enough, Hong Kong. Hong Kong is surprising, not only because it is calculated as if it were a country, but because it shows that contemporary urban lifestyles can be maintained with relatively low consumption and emissions. This is a significant point because it shows us that we need not return to some pre-industrial idyll to bring consumption and emissions down to tolerable levels. In other words, higher-energy lifestyles can be achieved at significantly lower levels of energy consumption and carbon emissions. It means that we can build a city that makes sense in the context of our present society and keep warming at less that cataclysmic events.
Over the next building cycle, we can move our habits of consumption and emissions down to lower ranges of these two graphs. To do this, we will have to acknowledge that we have not built dense urban environments for decades and that a new model of urban density needs to be found, a model that can be integrated into our present conditions and then take us through the upcoming decades without increasing the level of climatic disruption that has already baked into the system.
the carbon Megalopolis, 1950–2020.
These conclusions regarding the efficacy of densification are verified in a map from Berkeley, the so-called “Cool Climate Network” where carbon emissions were calculated per zip code. What you’re looking at is analysis of carbon emissions in the southern extension of the Boswash Megalopolis. Household emissions were calculated with higher emissisons shown in red, lower emissions in green. The higher-density, prewar urban cores show lower emissions while the lower density, post 1950 “suburban” extensions show higher emissions. The boundary between the red and green coincides with the outline of prewar extents of existing urban areas. The urbanism of the Great Acceleration, the kind of urbanism shown in the aerial view of Houston’s Energy Corridor, shows up entirely in red. You probably know the word megalopolis as distinct from metropolis. The metropolis characterized urban production before the war and was largely built of dense and continuous blocks and streets. The megalopolis characterized urban production after the war and was largely built of discontinuous, low-density spines or cul-de-sacs. The first megalopolis, “BosWash,” accounts for the entire built-up region built around existing cities from Boston to Washington. The urbanism of the Great Acceleration which you see on the map as the red and orange smear, produces the highest carbon emissions. Any chance of controlling our emissions, and keeping surface warming down to tolerable levels, is riding on its reform.
It is obvious that the urbanism we have built over the past seven decades, and what we continue to build today, is simply not going to carry us into the future. We may end up taking that ride, of course, but it will come at an exorbitant, perhaps ruinous cost. In terms of what we need to survive the coming disruption, the urbanism of the last seventy years will turn out to be a significant burden.
Manhattan, 1939.
In the United States, we haven’t built dense cities the last 70 years. What we have done is build out our 19th century urban infrastructure by indiscriminately piling large buildings on top of our relatively small urban grid. This is less a coherent strategy and more like a collisions between the quaint dimensions of nineteenth century urbanism and the unprecedented force and scope of the Great Acceleration. Le Corbusier recognized this dilemma when he first came to the United States in 1939. His book of that trip, When the Cathedrals Were White, included this diagram, which contained both his assessment of contemporary density and its solution. For many, Le Corbusier’s solution was, and it remains, highly problematic. In the third scenario, allied “tomorrow ,” Le Corbusier offered his Radiant City of towers in the park as a solution. The Radiant City would achieve even greater densities than you had in the Manhattan he visited in 1939, but it was a distinctly modern form of density — a density without congestion. Throughout his life, Le Corbusier railed against de-densification and the anti-urban tendencies of the Garden City. In his estimation, advanced civilizations were predicated on sustaining a cosmopolitan existence and such an existence required, among other things, the concentrated interaction of people and things. The innovation of the Radiant City is that the required density is accompanied by a systematic production of open space.
You cannot randomly place large buildings on a relatively small grid and expect it to function well. It’s the greatest luck that mid-town Manhattan is bracketed by two huge voids on either side of it, and that the center of Chicago is built on the edge of a Great Lake. Those voids are necessary in that they relieve the extraordinary congestion that you would otherwise get with a build up of high-rise construction. But they were also flukes of the city’s location; open space cannot be left to chance.
Unité d’habitation, Berlin, 1957.
The most challenging aspect of our research has been to dial back our recent urban history in an attempt to look at it with fresh eyes. That exercise brought us to this photograph of the Unité d’habitation in Berlin designed in the fifties by Le Corbusier. The cooling tower in the background belongs to the massive, coal-burning Kraftwerk Reuter power plant that sits adjacent the project pumping water in from the Spree. The photo is compelling because it resonates on both a technical level and a cultural level. It reveals the project’s problematic energy source while drawing the obvious affinity between the cooling tower and Le Corbusier’s own work.
What the photo suggests yet another time warp; an urbanism of born of crisis that is doomed to repeat itself. By this reading, today’s climate crisis inaugurates a future projected over a half-century ago whose intent is still legible today in the faded drawings and spalled concrete which document the dream of a Radiant City. The photograph of the Unité conveys Le Corbusier’s interpretation of his basic unit of urban inhabitation as an analogous ocean liner. It shows this largely discredited icon of modern urbanism approaching the scene of a technical disaster fulfilling its historic destiny fifty years after the fact.
What we have learned in the interim is that modern urbanism was never about producing a utopia. It was instead about describing or “explicating” the ontological prospects of humanity going forward amongst the ruinous technologies of the past century. The Unité was no cruise liner; today we might describe it as a rescue ship. It spells out the terms of human existence in the unstable world that we increasingly struggle to inhabit. Finally redeemed from a tragic misunderstanding, modern urbanism comes into its own as an ontological degree-zero of contemporary dwelling, projecting the prospects for inhabitation in a moment of technical crisis.
The legacy of modern urbanism has been held in abeyance for almost fifty years. Whether in the form of the Garden City (articulated by Wright), or the Radiant City (articulated by Le Corbusier), the modern urban project was fully discredited by the postmodern polemic that seized on the abject failures of modern urbanism to declare a successor. What followed was a form of cultural speculation that was built on nothing more than the repudiation of the last. As a result, a replacement for modernism’s comprehensive urban project was precluded from the start. What has taken its place has been an indiscriminate revival of traditional urban forms that have repeatedly failed to come to terms with the grave urban and environmental problems of our time. The reason for this failure could not be more obvious. These urban and environmental problems are comprehensive in their scope. In repudiating the comprehensive approach of modern urbanism, these potential design problems have not only remained unsolved as they have simply gone unseen.
In the face of this failure, it makes sense to re-examine modern urbanism’s legacy — its 50 years of its progressive development. What one discovers is that, while the comprehensive project has certainly failed on its own terms, it is more useful to urban design than anything we have managed to articulate since. Seen in the light of explication rather than invention, the experimental ethos of modern urbanism can be rejoined in a new round of critical projections that directly address the full scope of the problems we face.
end of part one…link to part two:
https://zoneresearch.medium.com/ucla-part-two-promethean-modesty-dde29ae044ca
