New building projections for Single Family Homes, Multifamily Buildings, and Accessory Dwelling Units (ADUs) are now available on the Cost-Effectiveness Explorer. These projections use the existing building stock data in the Explorer and calculate new units for the 2025 code cycle using the CEC's expected growth for 2026, found in Table 48 of the Single Family Buried Ducts CASE Results Report, and Table 53 of the Multifamily Indoor Air Quality CASE Results Report.
Residential new construction forecasts are projected from 2026-2031, due to Assembly Bill 130's restriction on residential building codes until June 1, 2031.
Accessory Dwelling Units are calculated from projected Single Family Homes based on the California Department of Housing and Development’s publicly available Housing Housing Element submissions (Housing Element Implementation and APR Dashboard). Using this data, we calculated the ratio of new ADUs to Single Family Homes reported from 2021 - 2024, and applied this ratio to the original Single Family Homes projection to break them out into separate building types.
These forecasts can be reviewed, edited, and otherwise customized. To do this from the Building Estimates page, click on Assumptions, and then select New Construction. You can change the projections based on building type and year, simply selecting what breakdown is of interest to you.
When policy creation is enabled for the 2025 Code Cycle, these estimates will be used to model policy impacts.
Forecasts from the 2022 Code Cycle can still be viewed on the Explorer and will remain attached to any 2022 Code Cycle New Construction policies you have created. To view these from the Building Estimates page, click the year range next to New Construction on the top right hand of the page and change the year range to 2023 to 2025. The image below shows changing the year range as described.
