Metro Area Carbon Footprints

A recent study, conducted by the Metropolitan Policy Program at the Brookings Institution, compiled partial carbon footprints for the 100 largest metropolitan areas. The study compared 2000 and 2005 data describing passenger and freight highway transportation and energy consumption in residential buildings. Note the use of the word “partial” - the footprints don’t include emissions from commercial buildings, industry, or non-highway transportation. In addition, much has happened since 2005 to increase awareness of and response to levels of carbon emissions. Nonetheless, the exercise provides useful baseline and trend information and provides perspective on the sustainability of metropolitan areas.

The trend information

1. Carbon emissions have increased approximately 1% per year since 1980 in the U.S.
2. Carbon emissions increased more slowly in metropolitan America than in the rest of the country between 2000 and 2005.

Per capita emissions were found to vary by metropolitan area, reflecting the impact of development patterns, availability of rail transit, fuel used to generate electricity, pricing of electricity and weather. High density cities with good rail systems fared well. Lower density cities with high heating and cooling loads and those that rely on coal to generate electricity suffered.

Surprises emerged from the rankings. Los Angeles fared well – the region’s freeways and autos were apparently offset by increased rail ridership and a mild climate. Madison, Wisconsin fared poorly, notwithstanding the area’s often-recognized livability, quality of life and high percentage of bike ridership. In Madison, it was the harsh winter, lack of rail transit and reliance on coal that created high per capita emission levels.

The study recommends a number of targeted policies that are directed at reducing per capita carbon emissions in metropolitan areas:
1. Promote more transit and compact development options.
2. Work toward more efficient, regionally planned freight operations.
3. Require home sellers to provide historical energy cost info and allow homeowners to finance. energy efficiency improvements using energy savings.
4. Use Location Efficient Mortgages and other incentives more aggressively.
5. Issue a challenge to all metropolitan areas to develop and share innovative approaches.

The perspective on sustainability

Notwithstanding the rather incremental approach to the recommendations, the underlying analysis did serve up a number of factors that affect carbon emissions across contemporary metropolitan areas:

• Location and weather


• Density of development


• Availability of transit options


• The interplay between development and transit


• Efficiency of freight systems


• Fuel used to generate electricity and unit pricing

Metro areas with high heating and/or cooling requirements really have no choice but to improve performance. This means attention on a number of fronts: effective community and neighborhood design, siting of buildings and use of passive design techniques, implementation and enforcement of energy efficient building codes, and use of efficient hvac and lighting systems.

While not the best housing solution for everyone, high density developments served by public transit have to be a significant part of the housing mix. There is recent evidence that exurban property values and sales have suffered disproportionately as a result of higher gas prices. Other evidence suggests that demand for housing in transit-oriented developments is increasing. These changes - perhaps trends - also represent incremental thinking that assumes little change in transportation and communication technologies at least in the near term.

Finally, as directed in the Architecture 2030 Blueprint, the subject of an earlier article, coal power plants have to be replaced with cleaner means of generating electricity.

Subsequent articles will examine other perspectives regarding sustainable development patterns and changing technology.