New research from UC Berkeley’s Urban Displacement Project stresses the need for the production of both market-rate and subsidized housing, along with aggressive preservation of affordable units and protection for tenants, to resolve the San Francisco Bay Area’s housing affordability crisis.

“Our research suggests that both subsidized and market-rate housing development make a difference. But producing market-rate housing alone will not improve affordability for low-income households,” says Miriam Zuk, who along with UC Berkeley city and regional planning professor Karen Chapple heads the project based at UC Berkeley’s Institute of Governmental Studies.

The project’s latest brief, “Housing Production, Filtering and Displacement: Untangling the Relationship,” offers insights into the complex links between housing production, neighborhood affordability and neighborhood change/displacement.

Key research findings include:

In the San Francisco Bay Area, both market-rate and subsidized housing reduce displacement pressures, but subsidized housing has more than double the impact of market-rate units.

Market-rate production takes time to have an effect: It is associated with higher housing cost burdens for low-income families, but is linked to lower median rents in subsequent decades.

At the block group level in San Francisco, neither market-rate nor subsidized housing production has the same protective power as at the regional scale, likely due to the severe mismatch between local demand and supply.

The brief rebuts a February 2016 report from California’s Legislative Analyst’s Office that used project data to argue that market-rate development would be the most effective way to prevent displacement of low-income households from their neighborhoods in the state’s coastal areas.

Project researchers say the LAO failed to adequately investigate the lengthy and complex filtering process that can make market-rate housing more affordable over time.

“If you omit data on the impact of housing subsidized by low-income housing tax credits and other federal and state programs, you miss a key solution to the crisis,” says Chapple. By using that data, the Urban Displacement Project found that for every one subsidized housing unit, two or more market-rate units would need to be built to create the same reduction in displacement pressure.

The researchers’ report, “Housing Production, Filtering and Displacement: Untangling the Relationships,” concludes that “to help stabilize existing communities, we need to look beyond housing development alone to strategies that protect tenants and help them stay in their homes.”

These findings are the latest from the Urban Displacement Project as part of its two-year examination of gentrification and displacement, which has engaged dozens of local nonprofit organizations and regional agencies.

The project was funded by the Bay Area’s Metropolitan Transportation Commission and California’s Air Resources Board to determine the effect of transit and other public investments on displacement, and to search for ways to ensure future housing affordability.

Maps and reports are online at http://www.urbandisplacement.org/.