Study Finds Households in Multifamily Rental Housing Face Greatest Heat Risk

Heat is the leading cause of weather-related death in the United States. A new paper published in Housing Policy Debate, “Housing and Urban Heat: Assessing Risk Disparities,” finds that households in single-family homes face the least heat risk, while households in market-rate multifamily housing face the greatest risk. The availability of central air conditioning (AC) appears to be a major contributing factor to these disparities. Households in neighborhoods with larger shares of Asians and Hispanics also face greater heat risk.

The authors of the paper – C.J. Gabbe, Evan Mallen, and Alexander Varni – created a parcel-level dataset that included housing characteristics, neighborhood characteristics, and heat risk in San Jose, CA. Housing-related variables included housing type (i.e., single-family, owner-occupied multifamily, market-rate multifamily rental, and subsidized multifamily rental), year of construction, and number of units on the parcel. Neighborhood, or census tract, characteristics included population density, age distribution, median income, race, ethnicity, and rentership rates from the 2019 5-Year American Community Survey (ACS). The authors constructed a heat risk index from spatial data on tree canopy coverage and land surface temperature and AC data from the American Housing Survey (AHS). Land surface temperature data were captured by satellite for a single day in August 2020.

Market-rate multifamily rental housing had, on average, the greatest overall heat risk, followed by subsidized multifamily rental housing, owner-occupied multifamily housing, and single-family housing. Access to central AC appeared to be the largest driver of disparities in heat risk among the housing types. The average likelihood of not having central AC was 44.9% for single-family housing, 50.5% for subsidized multifamily rental housing, 52.4% for owner-occupied multifamily housing, and 73.7% for market-rate multifamily rental housing. The housing types were more similar with regard to their tree canopy coverage and land surface temperature. The average percentage of a parcel without tree canopy was 81.5% for owner-occupied multifamily housing, 82.5% for market-rate multifamily rental housing, 83.1% for single-family housing, and 84% for subsidized multifamily rental housing. Average land surface temperatures were 110.1 degrees for owner-occupied multifamily parcels, 111.4 for subsidized multifamily rental housing, 111.6 for single-family parcels, and 112.1 for market-rate multifamily rental parcels.

The authors employed regression analysis to explore relationships between heat risk and neighborhood and housing characteristics, while controlling for other factors. Neighborhoods with larger shares of Asians and Hispanics were associated with greater overall heat risk, though a greater share of Black residents was not. The share of a neighborhood’s population that was made up of seniors, the share that was made up of young children, and neighborhood median income were not associated with any of the heat risk factors. Households in newer housing were generally at lower risk than households in older housing: though newer housing tended to have less tree canopy, it was also more likely to have central AC.

The authors conclude that public policy should better support a range of priorities related to reducing heat risk, including improving access to AC, increasing utility assistance for low-income households, equitably expanding urban tree canopy and human-created shade, and incentivizing energy efficiency features and upgrades in buildings. The authors further argue that heat mitigation interventions should focus on lower-income renters, including residents of subsidized housing, who may be more sensitive to heat, due to age and medical conditions, and who have less adaptive capacity.

Read the report at: