“There’s the desire of policymakers to ensure that affordable housing meets lots of other goals,” said Carolina Reid, an associate professor at the University of California at Berkeley who studies affordable housing costs. They tend to be worthy goals, she said, but they drive up costs, which results in fewer affordable housing units being built for those in need.

A report released in April by the nonprofit research organization Rand similarly said “unprecedented cost increases” in recent years have been due “in large part to the adoption of policies that prioritize factors other than the efficient production of affordable housing units.”