A San Diego Housing Commission study published Monday analyzed vacancies among homes in the city as a potential factor in the housing crisis and found fewer than 1% of residential housing units were vacant for at least six consecutive months during a five-year period before the COVID- 19 pandemic.
"This study provides important data — based on best practices from similar studies in other communities — to inform discussions and decision making as the City of San Diego continues to address housing affordability challenges," said Richard Gentry, SDHC president and CEO.
To help determine the extent to which homes are vacant in San Diego, the SDHC Board of Commissioners directed staff to identify units vacant for six months or longer.
SDHC staff worked with San Diego Gas & Electric and San Diego's Public Utilities Department to obtain anonymous data about utility and water usage as indicators of potential vacancy. SDHC then contracted with Circulate San Diego and Evari GIS Consulting to analyze the data.
Residential water and electricity data were used because nearly all occupied residential units use these utilities, which are provided citywide and are billed regularly.
A six-month term represents a significant period for a unit to be unoccupied and helps to avoid periods that could reflect low-energy use but not vacancy, such as residential turnover and extended vacations.
SDHC obtained a dataset of 468,352 unique SDG&E premises IDs with utility usage for five calendar years — 2015 through 2019. This produced 86 million anonymous records of residential utility usage.
A housing unit was determined to be "unoccupied" if the utility usage for a particular month fell below three standard deviations of the unit's respective 60-month average. For comparison, the study also analyzed the number of units for which utility usage was below two standard deviations from the 60- month average. Based on monthly utility usage, between 1,500 units — 0.32% — and 3,700 units — 0.79% — could reasonably be considered potentially vacant for six months or more in the city in the time period analyzed.
The housing commission also obtained public utilities data for 33,848 residential accounts that had active water meters but no contract accounts at some point between 2015 and 2019. This was a subset of 253,324 individual metered accounts in the city. For this study, a residential record was considered to be potentially vacant if it had no active metering for six consecutive months or more. The study identified 2,138 potentially vacant units or around 0.85% of the 252,324 individual metered accounts in the city.
The study, Residential Vacancies in the City of San Diego, was published on SDHC's website, www.sdhc.org
