29

URBANISM

Peter Calthorpe in Urbanism in the Age of Climate Change (2011) makes a convincing argument that urbanism needs to be a major component of society’s efforts to control greenhouse gas emissions. He compares high density city environments with moderate density, close-in suburbs, and finally with further-out, low density suburbs. The annual carbon emissions per household are 6 metric tons in the city, 10 metric tons in the close-in suburbs, and 21 metric tons in the low density suburbs (Calthorpe 2011, plates 4 and 5).

A suburban house can be made greener and the cars used to get around can be made more efficient, reducing energy use by about 30 percent (Table 29.1). A townhome in a close in neighborhood with public transit uses 38 percent less energy than a low density suburban house, even without solar panels or a super-efficient car. With a greener house and car, a close-in household uses 58 percent less than a suburban household. If an urban living unit is made more energy efficient and a more energy efficient car is used, the green urban existence uses 74 percent less energy than a suburban house (Calthorpe 2011, 19). These are significant reductions in energy use and, therefore, greenhouse gas reductions. The smaller energy use of urban living also translates into smaller utility bills and fewer new power generation plants. Urbanism reduces carbon footprint and is less expensive for the people living there and for the society as a whole (Calthorpe 2011, 10).

The current population of the United States is 296 million people, and we emit 23 metric tons of carbon per person per year. The population is growing at a rate that will add an additional 130 million people by 2050. Climate science suggests that we need to reduce energy use to 20 percent of our 1990 levels by 2050 to control greenhouse warming. This reduction, combined with population growth, means we need to reduce our per capita energy use to 12 percent of our current energy use (Calthorpe 2011, 8). If policy changes could move more of the population toward green urban living we would be well on our way to the 12 percent goal. Green urban living uses 25.8 percent of the current energy use of suburban living. Urban growth patterns can take us halfway with efficiencies in other sectors of the economy filling in the other half (Calthorpe 2011, 116).

TABLE 29.1  Household energy use for the outer suburban sprawl, the inner compact suburbs, and the urban core in MBtu/year