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San Francisco’s recent adoption of a new Housing Element and its commitment to build more than 82,000 new homes offer good news to a surprising community: climate and environmental advocates.
The climate benefits of cities may sound counterintuitive, yet the evidence is clear: Households in denser, walkable areas contribute less carbon pollution than households in less-dense suburban and rural areas.
The UC Berkeley CoolClimate Network makes this easy to see. Researchers calculated an average household’s carbon emissions across every U.S. zip code. Maps of nearly every metro area, including the San Francisco Bay Area, show that denser neighborhoods emit less carbon, while less-dense suburban neighborhoods emit more.
(This may look familiar: The New York Times published an interactive article on housing density and climate using recently updated CoolClimate Network data.)
The average San Francisco household emits 40 tons of carbon dioxide equivalent (CO2eq) per year, a measure of climate-warming emissions. Our neighbors living in zip code 94111, one of San Francisco’s denser neighborhoods, emit 35 tons of CO2eq per year.
Compare this with Tracy, California, one of the nearest areas where housing is affordable. Tracy’s average household emits 52 tons of CO2eq per year. That’s a whopping 30 percent more than the average San Francisco household.
This isn’t an anomaly: The same UC Berkeley researchers find that similar-income households in denser areas emit a third less CO2eq than those in less-dense areas. Welcoming more people to a more affordable, denser, pedestrian- and transit-oriented San Francisco allows households to emit less. This is the Housing Element’s promise.
Three main factors are behind the lower emissions of denser homes:
1. Less car-centricity: Transportation is the largest single category of emissions from the typical Californian household. Suburban residents must drive to work, school, stores, restaurants, and entertainment, which in denser areas are a short walk, bike, or transit ride away. The bulk of climate savings comes from fewer cars and less driving.
2. More efficient homes: Residences are the second-largest personal emissions category, with most carbon pollution coming from heating and cooling. Denser multifamily homes tend to be smaller than suburban single-family homes, reducing the energy necessary to heat or cool them. Shared walls and ceilings in multifamily buildings offer further efficiency. And smaller homes are filled with less “stuff,” from furniture to swimming pools, which means less “embodied” carbon, the carbon it takes to produce goods.
3. Preserving natural and working lands: Suburban sprawl gobbles up natural landscapes, farmlands, and managed forests. The smaller footprints of multifamily homes allow more nature to be preserved and enjoyed while conserving natural carbon sinks.
These benefits are so great that encouraging denser housing is the most impactful climate policy San Francisco could realistically enact. ClimateCool Network’s local policy scenario model maps the impact of various policies under city influence. Encouraging denser walking-friendly housing (“urban infill”) is the top-ranked policy type.
A chorus of national environmental organizations agree, from the Sierra Club (“development should be dense”) to the Rocky Mountain Institute, which recently advocated for a reduction of vehicle miles traveled “by investing in inclusive, complete, compact, transit-oriented communities.”
In fact, our city’s climate action plan specifies exactly this. Increasing density is one of six core pillars of the plan, which calls for building at least 5,000 new units a year in dense transit-connected areas. The plan states: “Providing more housing in San Francisco makes it easier for people to live close to where they work, instead of commuting long distances by car.”
The state concurs as well. As recently as November 2022, one of California’s environmental regulators, the California Air Resources Board (CARB), called on cities like San Francisco to increase density.
But for too long, cities in the Bay Area have gone in the wrong direction, limiting and slowing construction, driving up home prices, and pushing households to far-flung suburbs like Tracy. Large areas of San Francisco have had exclusionary zoning policies intended to segregate by race and class, preventing denser multifamily housing in many neighborhoods, even those near transit.
Families looking to move within or to the Bay Area are faced with frustrating housing choices — live far away in an area that requires driving to work, school, and shops, or pay exorbitant prices for cramped housing.
This is a result of unfortunate policy choices the past half-century. Hopefully, it will change.
The single best climate policy action San Francisco can take is to welcome more neighbors into inclusive denser neighborhoods with effective transit.
San Francisco’s Housing Element delivers on a commitment to build more than 82,000 new homes, mostly near transit and in the less-dense areas of the city.
Work remains to make this plan a reality. City lawmakers and planners need our support to change zoning to allow denser housing and slash costly arbitrary reviews and fees. Our extraordinarily long timelines (627 days just for permits!), onerous processes, and high fees often mean that new denser housing isn’t financially viable, even when it becomes legal.
More housing means we all benefit. More housing means more financially sustainable public transit due to greater ridership, more walking-distance businesses, restaurants, and grocery stores, lower rents, more inclusive neighborhoods, more tax revenue for services of all kinds.
The single best climate policy action San Francisco can take is to welcome more neighbors into inclusive denser neighborhoods with effective transit, and that starts with turning the Housing Element from a plan into reality.
Garen Checkley is a 11-year SF resident and a volunteer lead with Urban Environmentalists, an initiative of YIMBY Action.
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