Last month, I wrote about the well-intentioned but short-sighted green building ordinance under consideration in Stockton that would have required costly upgrades for energy efficiency in the renovation of older homes.
In that article I wrote that while older homes do use more energy, those emissions pale in comparison to automobile emissions from newer areas where driving is required. Rather than saddle potential homeowners with more costs, it makes more sense to encourage people to live in older neighborhoods that require less driving.
Earlier this year, research released by UC Berkeley’s CoolClimate Network reaffirmed this view, finding that most of the Central Valley’s emissions come from suburban areas.
It found emissions in the region rise farther out from each city’s core. In fact, homes around downtown Stockton (95202 ZIP code) have the lowest emissions by far, averaging less than half of some suburban homes in the far northwest corner.
As you venture farther out, older ZIP codes exhibit slightly higher emissions, and the areas on the outskirts turn out to be the biggest polluters overall. Stockton’s highest polluting ZIP code is 95209, with homes accounting for an annual average of 51.2 metric tons of CO2. ZIP code 95357 in Modesto accounts for 51.4 (the national average is 48).
This shouldn’t come as a surprise as residents in outlying areas have to drive more, thus emitting more pollution.
While emissions come from different sources, the Berkeley report confirms that driving is the main culprit behind the Central Valley’s pollution woes, with most automobile emissions coming from suburban ZIP codes. The report breaks down household emissions by source, and the differences between central and suburban ZIP codes are stark. Transportation takes up the largest share of emissions for each ZIP code, except for downtown Stockton. As you move farther from the core, transportation emissions rise.
The information presented by the Berkeley report tells us two things. First, emissions are worst at the periphery, largely because of driving patterns. As I have written before, the real problem with our air quality is excessive sprawl and the driving habits it encourages.
While older homes are leaky, they are close to amenities and therefore do not require as much driving. The data from Berkeley shows the region’s greenest ZIP codes are the ones closest to city cores. The greenest policy a city could undertake would be to focus new growth inward.
Second, if we want to get serious about cleaning the air through better land use, infill development alone won’t get us there. The report’s authors conclude that even though there is a positive correlation between density and air quality, those gains vanish once you take into account the corresponding increase of suburbanization that generally follows in a growing region.
This is of particular concern here in the Central Valley. Even if Stockton were to reach its goal of 4,000 new downtown housing units by 2020, there are still around 30,000 “paper lots” already approved for development on the city’s outskirts. And even if Stockton halted all suburban development, building in other areas may negate any air quality gains. Lathrop, for example, has broken ground on a suburban project that will eventually include 11,000 new homes.
While we may see infill development take hold in the coming years, allowing sprawl to continue would easily negate any real air quality progress. Will Central Valley leaders resist new suburban homes, even in the face of increasing pressure from suburban developers? I certainly hope so, because if not, it’s bad news for anyone breathing Central Valley air.