Thanks to suburban sprawl and greater land, material, and
energy consumption, Americans have significantly diminished our sense of
community and the quality of our natural environment. One way to evaluate the
long-term sustainability of a community is a Community Sustainability Index
(CSI).
A CSI can help communities better balance the needs of the
individual, the community, the economy, and the natural environment. The
purpose of the CSI is to gauge the current sustainability of a community to
determine a benchmark to strive toward to achieve greater sustainability. The
CSI is based on research of current suburban development patterns and historic
European and U.S. town patterns.
The CSI can be used to
create environments that are more environmentally and socially sustainable by
reducing the footprint of urban areas, lowering energy and material consumption
per capita, and promoting greater social interaction. The CSI promotes
inclusive mixed-use places that encourage a healthy lifestyle with a sense of
community.
Under the CSI, an
ideal scale for a community is approximately 8,000 acres, or a 2-mile radius (about
the length of a 9-hole golf course). This distance encompasses a 40-minute walk
from the edge of town to the town center. To apply the CSI, communities that
are significantly larger than 8,000 acres might be divided into smaller
community districts/cells to improve their functionality.
The CSI encourages communities
to meet the following benchmarks:
Density
(20 points): Minimum density of 15 people per
gross acre of land area (goal is to have a density that supports mass transit)
Density
clusters (10 points): Two-third of the housing consists of
multifamily structures containing three or more units per building (goal is to reduce
the urban footprint)
Income
diversity (15 points): The distribution of low-, middle-,
and high-income households reflects the U.S. average (goal is promote better
social integration by having less segregation by income)
Alternative
transportation/means to work
(15 points): One-third of resident workers travel to work using means other
than private automobiles (goal is to reduce the use of private vehicles)
Alternative
transportation/adults per vehicle (10 points): Increase the
number of adults per vehicle within the community to two (thus reducing the
number of cars per household)
Employment
(15 points): Total number of employees within the
community is equal to or greater than the number of working adults from within the
community (goal is to reduce the commute distance by providing more jobs closer
to the employees homes)
Retail
(15 points): Total retail and restaurant supply is
equal to or greater than the amount of demand from the community (goal is to reduce
shopping trip distance)
The total value of
the seven benchmarks is 100 points.
Select U.S. Cities
Of the twenty-one cities
studied, Washington, D.C. had the highest CSI score, with 99.4 points, followed
closely by Boston with 99.3. Washington and Boston have a population density of
19.1 and 18.8 people per acre, respectively. The San Francisco area came in
third with a CSI of 98.6. These top-ranked cities are gateway urban cores that
have developed excellent public transportation systems.
The weaker CSI
communities were places such as Winter Park, FL (67.6); Huntington Beach, CA (64.8);
and Coral Gables, FL (61.8). These communities’ CSI scores were affected mostly
by their suburban low-density and auto-oriented lifestyles. They are awash with
cars and SUVs and a high density of vehicles (1.1 –1.3 adults per car)..
Although Huntington Beach has a relatively good population density of 11.8 people/acre,
its lower income diversity and lower employment and retail capture rates hurt
its overall score.
To achieve a better
score on the CSI, the lower-scoring suburban communities should continue to
urbanize, creating denser mixed-use centers with greater income diversity in
order to improve their long-term sustainability. Sustainability and
urbanization programs should include centrally located parks, lakes, and
natural areas that represent 15–25% of the community’s total area to help
absorb these increased densities.
For this analysis,
the city’s actual land acres or land acres within a 2-mile radius were used to
represent the size of the community.