Photo from cacophony76.

Density is one of the most important elements of any city, but also one of the most misunderstood.

The density of a site is often not what it initially seems. People will key on things like height, design, maintenance, and context rather than actually looking at what density means to them.

It’s a natural, emotional reaction, but often misses the underpinning reality. Educating people on what density looks like is vitally important, as density is a crucial element of sustainable, urban places.

In Washington, DC, like many other places, people often have a visceral reaction against density. They assume more density means taller buildings in a low-rise city, but that need not be the case. These fears of density are not unfounded, however. Complaints about density often reveal other concerns, such as traffic congestion or design.

Dan Zack is a planner for Redwood City, CA. He recently gave a presentation out in California which included the following ‘quiz,’ asking attendees to quickly assess how dense a building or development is based on a passing glance at a photograph of the site. The clip is just shy of 12 minutes long. Take a look and see how accurate your perceptions of density are:

Density often gives rise to fears from neighbors about traffic congestion, crime, environmental quality, and many other factors. Outside the immediate community, people scream about social engineering and forcing people to live in dense environments, despite the fact that increased density is a product of market forces and substantial pent-up demand. Mr. Zack’s quiz shows how density is often not what it seems.

Height, for example, is only one factor in density. Paris is almost uniformly low-rise in nature, yet has extremely high densities. For DC, the takeaway message is that the city can continue to grow and add density without fundamentally altering the low-rise nature of the city. As DC continues to grow, adding more housing supply will be of vital importance. More households can also help certain areas of the city reach a critical mass of retail buying power, enabling stores and restaurants to survive and thrive.

Just as height is only a factor in density, density itself is only a factor in the overall health of a city. Put in simple terms, a city needs the Three D’s — Density, Diversity, and Design — to thrive. As Mr. Zack’s quiz shows, diversity (of housing sizes, price points, neighborhoods) and design all factor in to how we perceive density. Each of the Three D’s is deeply interwoven with the others, and touch on all urban issues, from transportation to affordable housing.

Emphasizing the need for density at this juncture is important, as well. Cities are not static environments. They change a great deal over time. In the next 25 years, approximately 75% of the American built environment will either be renovated or built anew. Even accounting for a lull in demand from the Great Recession, American cities are in for a great deal of change.

The entirety of Mr. Zack’s presentation is well worth watching, and can be found below. His presentation is about 50 minutes long, and includes the ‘quiz’ clip above. In the remainder, he discusses at length all of the companion issues that need to be dealt with in addition to adding density, such as design, parking, transit, and walkability.

Cross-posted at City Block.

Alex Block is an urban planner in Washington, DC. Alex’s planning interests focus on the interactions between transportation, land use, and urban design.  He also blogs at City Block and currently lives in Hill East.