I recently had a four-hour conversation with a client of mine on the subject of urban density. Coincidentally, this is a conversation I keep having with many of my colleagues and contacts in the urban development arena, including in meetings with large land developers, boutique mixed-use developers, rural municipalities, and single and multi-family home builders.
"What all of these individuals and groups share in common is the responsibility to lead the creation of places and spaces for their clients or constituents."
In the conversation I mentioned above, the client expressed frustration that city planners felt his densities were 'far too high' in one of his development projects. While he felt his vision for density was ‘sustainable, resilient and comfortable’. It’s pretty evident that figuring out exactly what the right density (generally measured as the number of homes per acre) is for 'sustainable, resilient and comfortable' urban development is about as easy as finding the proverbial needle in a haystack. That being said, the shared responsibility of creating places and spaces for healthy future communities calls for collaboration, commitment and the strength to look beyond individual perspectives.
What we do know—supported by over 60 years of data collection and extensive research—is that low-density suburban communities, which sprung up all over North America in the second half of the 20th century, have proven to not be that 'sustainable, resilient or comfortable' despite their initial popularity. North American suburbs have added significant amounts of carbon emissions, pollution, and stormwater runoff to our environment. Moreover, they created less active/healthy people and instilled the illusion that the land was an unlimited resource.
Nevertheless, we also know that very high urban densities (found in many of our mega-cities) have their own set of issues. Some of these include light pollution, noise pollution, and carbon pollution; vehicular and even pedestrian traffic congestion; environmental degradation due to a loss of contact with nature; and erosion in the quality (or increase in the cost) of food.
My client’s quest to achieve a development density that made sense to all stakeholders involved, and to produce a ‘sustainable, resilient and comfortable’ project—a successful community by any standards—is not unique. It does seem, however, that there are as many different ‘solutions’ to this quest as there are sites, cities, and municipalities. So as a professional urban designer, what can I offer by way of insight?
Even though in urban planning and design, one size (or density, or solution) seldom fits all situations, some ideas have developed over time that, when applied to new challenges or circumstances, can still help show us the way. One set of ideas that I’d like to bring to this conversation is New Urbanism. The New Urbanism movement began in the late '70s and early '80s as a reaction to urban sprawl. Urban planners and architects started to come up with plans to model cities in North America after the much older and remarkably resilient cities in Europe.
Richard Bernhardt, a leading new urbanist who heads the Nashville Davidson County Planning Department in Tennessee, has identified seven fundamental principles of the “New Urbanism” as follows:
While the movement and its principles do not resolve every element in the quest for the most ideally ‘sustainable, resilient and comfortable’ design and density levels. It does pull these principles from neighbourhoods, communities and cities that have stood the test of time and demonstrated higher levels of 'sustainability, resilience and comfort'.
New Urbanism also brought the environmental (rural-to-urban) transect methodology into planning and development of human-scale-like complete communities. Now the human habitat can be analyzed as a continuum with the natural world. The rural-to-urban Transect is a system that places all of the elements of the built environment in a useful order, from most rural to most urban. For example, a street is more urban than a road, a curb is more urban than a swale, a brick wall is more urban than a wooden one, and higher density is more urban than less density. If all of the built elements are in sync—the place can be described as "immersive." The elements are symbiotic.
Andres Duany and other urbanists have applied this concept to human settlements, and since 2000, this idea has permeated the thinking of new urbanists. The rural-to-urban Transect is divided into six zones: natural (T1), rural (T2), sub-urban (T3), general urban (T4), centre (T5), and core (T6). The remaining category, Special District, applies to parts of the built environment with speciality uses that do not fit into neighbourhoods. The Transect has been especially useful as a framework to code complete communities. The SmartCode, an open-source, widely used form-based code, is based on the Transect and was first published in 2003.
I continue to reference the SmartCode in my work. I would suggest that while the answer to the question of density shall always remain unique to specific issues of municipality, site constraints and geography. By applying these principles, it will provide a more holistic urban design and identify your project within one of the six Transect zones will lead you to a more explicit notion of what the appropriate urban density should be.