December 18, 2013
The population of SF has been growing steadily over the past decade and the rate has increased by a wide margin over the last couple of years. While the housing stock of the city appears to have kept up with population growth, the increasing rate of vacancy means that the housing supply is inadequate by about 10,000 units. Lowering the vacancy rate could be significant in bringing the city's housing supply to adequate levels.
As of the 2010 Census 805,000 people live in San Francisco county and the estimated population for 2012 is 825,000. In 1990 and 2000 respectively, the population was 723,000 and 776,000. That means that in the 90s SF grew by 52,000 people or 7.2%; in the 2000s by 28,000 or 3.6%; and in the last couple of years by 20,000 or 2.5%. (Sources: 1, 2, 3)
There are two things worth noting. First, while the 2000s have been slow compared to the 90s, the population grew by about the same number (about 50,000) in the 90s as over 2000 - 2012. Second, more than half of that growth has been over the last couple of years. This is not too surprising, given recent growth of the tech sector. If that growth proves more sustainable than what happened in the 90s, we can expect the population growth over the 2010s to be much faster than over the 90s.
As of the 2010 census, there are 376,000 housing units; 123,000 are owner-occupied, and 222,000 are renter-occupied. In 2000 there were 346,000 housing units, which implies that SF has been adding about 3,000 units per year. This also means that the average owner-occupied household has 2.6 people in it and the average renter-occupied household has 2.1 people in it. (Sources: 1, 3)
At first glance, it would appear that the housing stock of the city has kept up with population growth. The population grew by about 50,000 over 2000 - 2012 and in that same period about 30,000 units were added. However, the number of vacant units has grown over the same time period. The number of occupied units in 2000 was 330,000 and 346,000 in 2012, and so the “effective” growth of the housing stock has been about 16,000 units over 2000 - 2010. (Source: 3)
The number of owner-occupied units has grown from 115,000 to 124,000, which should accommodate about 19,000 residents. Similarly, the number of renter-occupied units has grown from 214,000 to 222,000, which should accommodate about 21,000 residents. That is not enough to accommodate the population growth.
For clarity, a housing unit is vacant if no one is living in it at the time of the census interview, unless its occupants are only temporarily absent. (Source: 4)
In 2010 there were 31,000 units vacant, that's 8.2%. For comparison, in 2000 SF had 346,000 housing units with 16,000 or 5% vacant. The number of vacancies has almost doubled over 2000 - 2010. (Sources: 1, 3)
In 2010, 12,000 of the vacant units are for-rent and 3,000 are for sale. The data is unclear about whether the for-rent and for-sale vacancies are counted in the vacancies, so it is unclear whether SF had about 46,000 vacant units in 2010, with about 16,000 “on the market” or SF had 31,000 vacant units with about half “on the market”. Assuming, that it is the latter, that means that there are about 15,000 housing units vacant, which could house another 39,000 renters. In the other case, the vacant units could house 119,000 renters. To put that in perspective, those numbers are about 80% of or double the number the population growth over the past 12 years – theoretically, just about all of the new population from 2000 - 2012 would fit in the vacant housing units.
For comparison, Sacramento County has 41,000 vacant units out of a stock of 556,000 total units (7.3%) and Los Angeles Country has 204,000 out of 3.4 million housing units vacant (6%). California has 1.1 million housing units vacant out of a total stock of 13.6 million (8%). The similarity of these numbers to the SF vacancy numbers suggests that the vacancy-rate may be driven by state-level conditions. In fact, California has a higher rate of vacancies than the regional average (5.9% in 2013). (Sources: 5, 6)
Rent control data is remarkably difficult to find.
As of 1998, 71% of the rental units in SF were under rent control. (Source: 7)
San Francisco is one of the few cities in the country that has rent control. Notably, New York City, several other cities in New York State and New Jersey also have rent control. Also, Seattle and Portland, which are cities with similar characteristics to SF do not have rent control. (Source: 8)
It is unclear whether there is a link between rent control and other tenant-favorable housing regulations and vacancy rates, but the connection seems plausible.
List of sources:
Discussion on /r/sanfrancisco. I'll be reading and responding to comments there.