Methodology

Sustainability approaches tend to address combined environmental, economic, and social issues, while environmental management approaches tend to focus on issues like pollution or habitat restoration in isolation. The beginning of the 21st century represents a turning point for cities as sustainability subsumes environmental management practices and polices. SustainLane believes sustainability is a more appropriate approach for urban areas because it recognizes people and institutions as the primary actors that benefit from change, with indirect benefits also accruing for natural systems as a result.

The SustainLane website gives people the resources they need in order to make choices that can make their lives healthier and more sustainable in terms of their home, community, and the environment in general.

Methodology

The 2006 SustainLane US City Rankings were developed using a combination of primary and secondary research directed by SustainLane. Fifty US Cities were included in the study. Data and information are drawn from surveys and interviews from 2005-2006, and publicly available sources published in the period between 2002-2006.

Overall Rankings

Overall rankings were determined by averaging 15 individual category rankings, each of which was given a weighting of 0.5, 1, or 1.5 (see below for details). Cumulative averages ranged from 85.08 out of 100 for the highest-scoring city (Portland, Oregon) to 32.50 out of 100 for the lowest-scoring city (Columbus, Ohio).

Criteria for Selecting Cities for the Study

The largest 50 US cities by population (based on 2004 US Census data) were selected as the universe for the study. Data was collected on a city basis except for four categories, due to availability. Regional public transit ridership, roadway congestion, and metro area sprawl (a subcomponent of the planning category) data was collected on a metropolitan area basis. Air quality data was gathered on a countywide basis.

How Data or Information Categories Were Chosen

There are two criteria for how data was selected:

a.) Data or information sets that would be of relatively equal importance to cities across the United States. For example, water conservation programs were not included because they would be much more important for a desert city in the Southwest than for a city with a plentiful water supply.

b.) Ease of standardized collection. Air quality data, for instance, is available in a standardized format freely available (Median Air Quality Index) from the US EPA.

2006 Data Collection and Research Methods

Primary research consisted of e-mail and phone surveys administered to the 50 subject cities during the period between December 2005 and April 2006. City subjects included environmental or sustainability departments, energy offices, departments of solid waste, water departments, mayor’s offices, and planning departments. Non-Governmental Organizations (NGOs) working directly with subject cities were also surveyed or interviewed. A total of 37 cities responded to the survey. For the cities that did not respond to the survey, rankings were determined by data from public and non-governmental data sources.

Data was adjusted on a per capita basis for local food and agriculture (farmers markets and community gardens), as well as for green (LEED) buildings.

In total, over 100 respondents were surveyed by e-mail or telephone, or interviewed in person. A list of these people and their city or organizational affiliations is included at the end of this methodology.

Weighting of Data

Of the 15 data categories, 11 received a weighting of 1. The remaining four categories were weighted as follows:

Commute to work: 1.5

Weighting was assigned a higher value than all other categories because of the numerous direct and indirect impacts on numerous other categories, including air quality, water quality from surface run-off, greenhouse gas emissions contributing to global climate change, road congestion, economic efficiency (expenditures for gas leave the local economy; roadway congestion damages personal and local productivity; air pollution can have numerous health-related economic impacts).

Congestion: 0.5

Weighting was assigned a lower value based on secondary nature of impacts (less fuel efficiency, less public transportation efficiency).

Affordability: 0.5

Weighting was assigned a lower value based on secondary impacts—higher housing prices hurt the environment because they force more residents or service workers to commute.

Natural disaster risk: 0.5

Weighting was assigned a lower value because information modeled reflects natural disaster risk only, which depends on climatic probability, insurance information based on past history, etc.

Public Data Sources

Public data from the most current sources were combined in each category to provide ranking metric by issue, listed in italics.

Commute to Work

2004 US Census/American Fact Finder commute-to-work information (released in 2004): Public transportation ridership percentage, walk to work percentage, bike to work percentage; carpool to work percentage, drive alone to work percentage.

Regional Transportation

Data from 2003 Texas Mobility Study analyzing regional general public transit ridership.

Congestion

Data from 2003 Texas National Mobility Study analyzing regional freeway and surface road congestion by metro region.

Air Quality

US EPA air quality data and information from Fall 2005 (Median Air Quality Index, combined with US EPA Clean Air Act Non-Attainment information, converted to a numerical scale).

NGO and Public information

NGO and public data sources were combined in each category to provide ranking metric by issue, listed in italics.

Tap Water Quality

Environmental Working Group’s December 2005 US city drinking water database.

LEED Building

Number of US Green Building Council’s Leadership in Energy and Environmental Design (LEED) certified and registered buildings from US Green Building Council, adjusted per capita. A greater weighting was given to data for LEED Certified (over LEED Registered) and for LEED Platinum or LEED Gold buildings (versus LEED Silver or LEED Certified).

Local Food & Agriculture

Number of farmers markets per city, and number of farmers markets, with additional credit given to those farmers markets accepting WIC and Food Stamps. This data came from both NGOs and the US Department of Agriculture, as well as from cities themselves. Cities and/or NGOs provided the number of community gardens per city. Farmers markets were weighted by the number of each city’s markets accepting food stamps and WIC credits.

Planning/Land Use

Urban sprawl data from Smart Growth America's December 2002 study.

Percent of city land area devoted to parks came from Trust for Public Land (2002 study) and from 2006 SustainLane primary research.

Housing Affordability

Measure of median housing ranking; median income was also analyzed as a mitigating affordability factor. Cities with Living Wage ordinances were given extra credit.

Natural Disaster Risk

Data from Risk Management Solutions’ 1999 “Catastrophic Risk in the United States” and SustainLane primary research: cumulative measure of hurricane risk, flood risk, tornado super outbreaks, earthquake risk, and devastating hail risk.

Green Economy

Whether the city has a clean technology incubator; whether it has a city or private green business directory; and the average of farmers markets per capita and LEED buildings per capita data.

Exclusive Primary Research Categories

Energy

SustainLane primary research on greenhouse gas reduction tracking, goals and inventories, overall renewable energy use percentage for a city, and alternative fuel fleet data (credit given for cities with 12% or more of fleet comprised of alternative fuel-using vehicles).

City Innovation

SustainLane primary research on Environmentally Preferable Purchasing programs, commercial and residential green building incentives, carpooling coordination, car sharing programs (public or private), and extra credit city innovation (general category).

Knowledgebase/Communications

SustainLane primary research on whether cities have a sustainability plan; department to manage environmental/sustainability functions; research partnerships with federal laboratories and/or non-governmental organizations. These management functions and collaborations are critical to ensuring long-lasting sustainability program metrics and success.