What's the difference between the Residential Multifamily building estimates and the Nonresidential Apartment building estimates?
The multifamily dwelling units data and the apartment building counts and floor area data are derived from very different sources and are intended to simplify two different types of policies. While in theory they reflect a similar concept, one was not derived from the other and there is no standard translation between them.
Why have different data about multifamily in both tabs?
Our priority is to simplify data-driven policymaking for CA local governments, which sometimes means allowing some overlap or inconsistency between sections of our tool. We created these building data resources (existing residential and existing nonresidential) in order to help CA local governments make two very distinct policy types.
The existing residential buildings data is geared toward mandatory upgrade requirements (i.e. time-of-retrofit requirements). Vintage and climate zone are important characteristic for such a policy, less so building count and square footage, and we used a combination of sources to estimate number of units. Seldom are these types of policies adopted for commercial buildings.
For existing nonresidential buildings, we geared that data toward helping policymakers develop benchmarking and BPS policies, where building size and number is critical. And since many such policies cover residential buildings, we made sure our data there included apartment buildings.
Apartment buildings can be excluded from the existing nonresidential analysis by toggling on the Building Type section on the left of the graph and unchecking the box next to apartments.