Loja, 14 noviembre 2014

prof. antonio di campli

urban density

Urban density:

very specific measurement of the population of an urbanized area, excluding non-urban land-uses

3 different quantitative measurements of density:

dwelling units per hectare or acre

people per hectare or acre

and floor area ratio.

Although these are common measures of density, they are often used alone, without respect to the other measures. It is important to look at all three numbers to obtain an accurate depiction of density.

The diagram below details the three measures

measurements

Floor Area Ratio (FAR)

is the ratio of built area (a buildings total size) to the lot area (the property upon which the building is built). It is a measure used by planners, regulators, and developers to discern the intensity of a development. By itself, however, it is not sufficient to define density.

far

Coverage

Coverage is the relationship between the ground floor area of enclosed buildings and the area of the lot. Development scenarios with the same FAR but different coverage will produce varying types of development: for example, low-rise or high-rise.

The examples below are a classic case of varying perceptions of density for two areas with identical FAR.

dwelling units

Dwelling units

Another measure of density is the number of dwelling units built on the lot, often used by realtors or developers, as their focus is the marketable number of units in a given area. The density of an area can change based on the number of dwelling units although we use individual dwelling units as a measurement, we dont measure the size of the units. Large buildings may take up the same amount of space as small ones, resulting in similar levels of FAR. Is an area filled with McMansions as dense as an area filled with the same number of rowhouses?

population

Population

Measuring the number of people in a given area is helpful to measure density, however, it does not measure the amount of living space per person. Are dwelling units a comfortable size? Is there public space for people? How many people live in each household?

It is clear that there are complications with using only one of these three measures to analyze the density of an area. When looking at cases, you will understand the importance of looking and comparing all three measures. For example, Battery Park City may feel dense, however, individual unit sizes are fairly large, with few people per household a case of an area with high FAR, medium number of dwelling units medium to low population. Informal developments, by contrast, have low FAR, and a medium to high number of dwelling units and population, which can yield less square feet of living space per person.Understanding these numbers will help city planners and others determine the best mix of these measurements for their neighborhood or town. Two urban areas with very similar density levels can be arranged in very different ways. How a planner or developer manages the urban design process and qualitative factors of an area is critical in developing an area appropriately to its cultural context. And of course, the feel of a place is also dependent on the urban design features, lot coverage, open space, architecture and street design. These factors will contribute to the feel of a place but are independent from the quantitative measures of density. Our collection of case studies allows one to compare places to understand the similarities and differences caused by different levels of density. Two places may have the same quantitative measurement while looking very different.

scale

The term scale has many meanings, but here it refers to the extent of land being measured.

There are at least five levels of scale in a typical metropolitan region.There is no universal definition for block or neighborhood or district. Comparisons become especially difficult when looking at projects in different geographic contexts. For example, a neighborhood in the South End of Boston takes a very different physical form than a neighborhood in a new planned community in Shenzhen, China, such as Wonderland. On the surface, meaningful comparison seems unlikely because these neighborhoods look very different from each other.

We can focus on two scales: A (block or development parcel) and B (neighborhood). Additionally, each case may also describe characteristics of the larger planning district, city, or regional context.

area studio

A variety of other ways of measuring the density of urban areas:

Floor area ratio - the total floor area of buildings divided by land area of the lot they are built on

Residential density - the number of dwelling units in any given area

Population density - the number of people in any given area

Employment density - the number of jobs in any given area

Gross density - any density figure for a given area of land that includes uses not necessarily directly relevant to the figure (usually roads and other transport infrastructure)

Net density - a density figure for a given area of land that excludes land not directly related to the figure.

Weighted density - a density metric which measures the density at which the average citizen lives. It is determined by calculating the standard density of each census tract, assigning each a weight equal to its share of the total population, and then adding the segments.