Map of the Day: Average Annual Household Carbon Footprint by Zipcode

hhcarbonfootprint

Today’s map shows an estimate of a household’s carbon footprint based on consumption of various goods and services.  You can explore the map here.  The maps and data come from the CoolClimate Network at the University of California Berkeley.  One thing that becomes clear as you explore the map: the carbon emissions from goods and services doesn’t vary all that much as geography changes (at least in the Twin Cities metro).  The big changes across the transect are mostly due to changes in transportation usage and housing-related sources (energy usage).

This consumption-based emissions inventory differs from other approaches explored on streets.mn, like the geographic inventory, because it looks at emissions throughout the supply-chain related to purchases a household makes, regardless of where on earth the emissions originated (think of a computer you buy that is made in China, the emissions are still counted at your household).  Here’s a bit from the FAQ on the methodology:

The model uses national household energy, transportation, and consumer expenditures surveys along with local census, weather and other data – 37 variables in total – to approximate greenhouse gas emissions resulting from the energy, transportation, food, goods and services consumed by average households in essentially all populated U.S. zip codes. See the paper and online supporting materials for detailed descriptions of the methods.

The FAQ (and research it is based on), has some interesting discussion of the implications for local and regional planning (the title of the paper is Suburban sprawl cancels carbon-footprint savings of dense urban cores):

Population dense central cities have significantly lower carbon footprints than less dense central cites; however, these cities also have more extensive suburbs. When considering the net effect of all metropolitan residents (suburbs and central city residents together), larger, more populous and population-dense metropolitan areas have slightly higher average carbon footprints than less populous and lower population-dense metropolitan areas.

i. Note: this is the primary finding of the paper that is used in the title. The implication for policy is that suburban sprawl undermines, or cancels, the benefits of urban population density. Urban development planning should focus on impacts at metropolitan as well as more local scales, as is typical in regional transportation planning.

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4 Responses to Map of the Day: Average Annual Household Carbon Footprint by Zipcode

  1. David Levinson
    David Levinson January 26, 2015 at 9:42 am #

    This is interesting, the caution I would have is to remember that household ≠ population, in other words, household size is not uniform throughout the region. Suburbs tend to have higher average household sizes, and thus more energy consumption, even if per person consumption were equal (which it of course is not).

    • Alex Cecchini
      Alex Cecchini January 26, 2015 at 10:01 am #

      I will c/p a comment from the post Brendon made a while back:

      “David makes a good point that HH size matters in consumption, but for reference, the average household in Minneapolis is 2.22 (avg family size 3.11), and in Lakeville those numbers are 2.99 and 3.32.

      However, as a gut check, the households in Minneapolis zip code 55409 consume (guesstimate by eyeballing the charts) 19-20 mtCO2, and has an average HH size of 2.4 and family size of 3.27, while Lakeville households consume 26-27 mtCO2. This is a ~35% increase in consumption for an average household that is 25% larger. It’s only one data point (and I always use Lakeville since it’s where I grew up), but does show a mismatch.”

      and

      “If you fix income (for example, I picked $80-99k/year) and household size (3 people), consumption (food, goods, services) in 55044 is 33.1 mtCO2 and 27.24 in 55409, a 21.5% increase.”

      • Brendon Slotterback
        Brendon January 26, 2015 at 10:15 am #

        There are a lot of things you could control for in this data. For example, there are probably more kids living in the suburbs. This could be reflected in the data by showing suburban household taking more trips, more auto trips, and perhaps buying more (or more carbon-intensive) stuff. However, I would guess this would still be overwhelmed by the distance you have to travel (and singular mode choice) that enables living in some suburban areas, regardless of household size.

  2. Alex Cecchini
    Alex Cecchini January 26, 2015 at 10:10 am #

    I still find this comment from the report overview troublesome: “Surprisingly, population dense suburbs have significantly higher carbon footprints than less dense suburbs, due largely to higher incomes and resulting consumption.”

    I think they get causality backwards. I would very much like to see total lifecycle carbon analysis across suburbs varying in density when holding constant household size and income. My data points in the comment above are just anecdata. But pretty much every study I’ve seen says the same household in a denser (walkable) environment will be less resource-intensive when holding income/size steady. Not saying this is the best use of funds or activities in all areas of the country to reduce CO2, but the notion just doesn’t sit right.

    Also, one is there anything intrinsic about denser inner-cities that spur less-dense outlying areas (quote: A 10-fold increase in population density in central cities corresponds to only 25 percent lower greenhouse gas emissions, and “high carbon suburbanization results as an unintended side effect,” Jones said.”)? Or, again, does the study seem to imply a causal link that doesn’t exist? Is it simply a matter of when dense inner cities were originally built, their geographic constraints (relative to their suburban areas), timing/stringency of zoning, and level of affluence?

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