Visualizing Density

1. The Density Problem

Sprawl is bad. Density is good. Americans need to stop spreading out and live closer together. Well… that's the theory, anyway. But, as anyone who has tried to build compact development recently will tell you, if there's one thing Americans hate more than sprawl, it's density. This is evident in the public planning process as regulations are written and projects are reviewed. Across the country, efforts to increase density have met with stiff resistance. One reason people reject density is that they don't know much about it-what it looks like, how to build it, or whether it's something they can call home. We have very rational ways of measuring density, but our perception of it is anything but rational.

This type of low-density detached housing faces fewer obstacles than its denser urban counterpart.

Public aversion to density often makes developing compact housing a difficult process

2. Preconceptions

When you think of high density housing what comes to mind? Crowding? Monotony? Too much asphalt and not enough green? No privacy? These are some of the negative characteristics that people often associate with high-density development. Some dense neighborhoods are bleak, but it's not necessarily because they're dense. Crowding and monotony are the consequence of poor design, not the inevitable result of density.

Monotony results when the same form is repeated without variation.

At higher densities, overuse of one building design creates a tiresome uniformity.

Shifting the building orientation does not provide sufficient variety or privacy.

The bleakness often associated with density stems from homogeneity and lack of green space.

3. Design Matters

Density expresses a ratio-most often the number of housing units to the area of land. It tells us something about how much activity is compressed into a given area, but it reveals nothing about physical form. Two neighborhoods with the exact same density can look as different as night and day. Although they measure out at the same density they are not necessarily perceived to be equally dense. What really matters is how the streets are laid out, how the land is subdivided, how the buildings are arranged and detailed, whether trees are planted, where the sidewalks lead. These are all functions of design.

These two neighborhood blocks couldn't be more different, yet they have the exact same density of 11.7 units per acre.

5. What Does Density Look Like?

In any discussion of density, mental images are formed. Oftentimes they are one small piece of the picture. What do we mean when we talk about six units per acre? Or 12? What does a 50 unit-per-acre neighborhood look like? The answer is that it depends on the design approach.

These four blocks have a similar density level (10 units / acre) yet each takes a different form and provides a different type of living environment.

A mix of single and multi-family homes on small lots, Newport Beach, CA.

Side-yard houses on long, narrow lots, Charleston, SC.

Town houses and large single-family homes converted to apartments, Sandusky, OH.

Multi-family development, Tampa, FL.

7. Location, Location, Location

So much of a neighborhood's appeal depends on its context. If you imagine that this house sits in a landscape sprinkled with barns and rolling meadows, you might be surprised…

to see that it actually forms one small piece of an unbroken fabric of one-acre lots that extends for a few square miles. Although the house and lot may be well appointed, the context doesn't offer much in the way of diversity or other amenities.

Although these houses have small yards…

…they are close to both urban services and mountain wilderness. Density in the right location offers people convenience. A nearby job, shopping district, or beach can make daily life more comfortable.

8. Choosing Density

Density can be the result of many people wanting to be in the same wonderful place. Consider San Francisco and Boston, two of the most sought after real estate markets in the country. What's so special about them? Both offer the type of vibrant street life not found in many American cities. Two prerequisites for urban vitality are a pedestrian-friendly streetscape and a mix of uses. The third essential component is density. Shops, restaurants, and cultural institutions can't survive without a critical mass of people nearby to support them. As residential density increases above certainthresholds, these services and amenities become viable.

A mix of street level shops and upper floor apartments, San Jose, CA.

Relatively high-density housing within walking distance of a commuter rail line, Shaker Heights, OH.

9. Parking

Parking is a major consideration when designing for density. In high-density developments, parking facilities must be more highly organized and space efficient. Several alternatives can give higher density residents access to automobiles. The challenge is to keep cars and the asphalt that serves them from overwhelming the neighborhood.

Parking is placed in the interior of this block, reached by a service lane. (Longmont, CO)

This block demonstrates a variety of ways to store cars: on the street, in surface lots, below houses and in garages. (Celebration, FL)

Parking is located below this building, reserving prime space at street level for other uses. (Denver, CO)

This building wraps itself around a parking structure, hiding it from street view and offering direct access to the garage from all units. (Dallas, TX)

10. Design Tradeoffs

Low-density neighborhoods have appealing qualities to many people. They offer spacious yards, privacy, quiet, and convenient parking. At the other end of the spectrum, urban neighborhoods offer access to a rich array of services. As density levels increase and living units move closer together, yards become smaller and parking space shrinks. High quality architecture and careful site planning can maintain the best qualities of low-density living in new compact neighborhoods.

At 50 units per acre, this development offers a surprising amount of parking, private outdoor space and greenery. (Mountain View, CA)

Carefully formed public space, interior block parking and a lively streetscape, help compensate for the lack of individual back yards. (Addison, TX)

11. Building Up, Not Out

Single-story homes eat up green space by consuming a large proportion of each parcel. (Delano, CA-1.9 units/acre)

In designing for density, placing houses close together is important, but building vertically is essential. A two-story house provides the same living space with half the footprint. Given our penchant for large homes (the average new American house size is 2,200 sq. ft.), arranging single-story houses in a tighter pattern does not yield much density. Even at modest density levels (4-6 units per acre) it consumes an inordinate amount of open space. Building up rather than out not only allows higher densities, it offers opportunities to create significant green space.

Multi-story homes allow for more green space. (Dallas,TX-3.2 units/acre)

Stacking units on four levels helps raise the density above 20 units/acre with plenty of green to spare. (San Francisco, CA)

12. Vary the Pattern: High, Low, and No Density

What determines whether a place seems too dense? One important characteristic is the overall settlement pattern. If there is little variation-an even wash of development from one corner of town to the other, or the same block shape or building type repeated relentlessly, it will feel crowded, even if it has a low density. Contrast and diversity, at the neighborhood as well as the regional level are vital components of successful density.

South Central Los Angeles extends for miles in an unbroken pattern of low buildings. Kansas City, on the other hand, features a range of densities that provides contrast and variety.

- from the Lincoln Institute of Land Policy http://www.lincolninst.edu/subcenters/visualizing-density/tour/t1.aspx