| Annual savings potential: Annual public cost: Public cost per ton: Implementing agency: Horizon year: | 79,800 tons 0 Revenue neutral Planning Department, Redevelopment Agency 2030 |
Assumptions
- Each new housing unit permitted in San Francisco will replace one housing unit that otherwise would have been built elsewhere in the region, yielding a VMT reduction equal to the emissions difference between San Francisco households and the regional average household
- Residents of the typical new housing unit built in San Francisco will drive, on average, 15 miles per day less than the regional average
- The net public costs for infrastructure and services for new San Francisco residents will not exceed the costs that would have been incurred providing infrastructure and services to the same households in other parts of the region.
Analysis
The shape of the city plays a critical role in how much and how often people travel by car. When neighborhoods are compact and many of a person鈥檚 daily needs can be found within a few minutes鈥 walk, vehicle trips per household decline rapidly. There is a very strong correlation between households per residential acre and both the number of vehicle miles per year that a household drives and the number of vehicles that a household own.
Compact, transit oriented land use development allows for reduced driving in two ways. First, residents of these areas tend to use transit more often than average, particularly for commute trips. Second, they make more walking and biking trips. When they do drive, their trips tend to be shorter.
The relationship between compact land use development and reduced VMT has been documented extensively in the San Francisco Bay area. A study by MTC, for example, estimated that San Francisco Bay Area households living within half a mile of rail or ferry stations typically drive 15 miles per day less than the average household in the region.1
Extensive research has also documented that there is significant unmet demand for this type of housing.2 Throughout the Bay Area the supply of housing in denser urban areas tends to be limited not by the willingness of the market to supply this housing, but by land use regulations that do not permit it. Height and density limits, minimum parking requirements and other local land use regulations limit the amount of new housing that can be built in existing urban areas near transit, including inside of San Francisco.
What we do now
San Francisco is home to approximately 345,830 households. Allocations from the Association of Bay Area Governments state that the city is likely to grow to 398,280 households by 2030. Several ongoing planning processes aim to increase residential construction in the city, including the construction of new neighborhoods in Mission Bay and the conversion of some industrial lands to residential uses in the Eastern Neighborhoods. While these plans will permit more housing in San Francisco, land use regulation continues to suppress residential construction below market demand, particularly in the city鈥檚 most transit-rich areas.
What we could do
San Francisco could aim to increase the rate of residential construction by rezoning to permit residential land uses, relaxing density limits, reducing minimum parking requirements, and permitting the conversion and legalization of in-law units. With careful planning, increases in residential densities can be accomplished without compromising the character of existing neighborhoods, and can provide opportunities to add new vitality, amenities, and services to established communities. By providing more households the opportunity to take advantage of San Francisco鈥檚 compact, walkable neighborhoods, rich transit services,and access to job centers, the City can reduce regional VMT, congestion and CO2 emissions.
A policy that aims to generate new housing in San Francisco beyond current ABAG allocations would reduce regional CO2 emissions. In this analysis, we examine the impact of targeting 10 percent more than ABAG allocations by 2030, a net gain of 40,000 households.
Cost
The relationship between public cost and housing development is complex. In many cases, local governments must pay to provide sufficient infrastructure for new households. In new neighborhoods, infrastructure can mean new roads, transit, and utilities, as well as schools and parks. In existing neighborhoods, these amenities sometimes must be upgraded to accommodate new density. In some cases, tax revenues generated by the new population may not cover the cost of these investments over the long term.
In theory, new housing expands the city鈥檚 tax base, and it therefore 鈥減ays for itself鈥 over time, even without taking i