Typical densities of existing or approved residential developments at a similar… — Housing Element Sites Inventory Guidebook (AB 1397)

While using typically built densities to determine realistic capacity has long been an option to be used as an adjustment factor, the statute now requires this factor to be adjusted based on approved project by affordability level. For example, if a site is identified to accommodate the lower income RHNA, it should use project densities for housing affordable to lower income households developed either locally or regionally to determine typical densities[6] . Using this adjustment factor may result in utilizing different capacity methodologies for above moderate-, moderate-, and lower income sites.

Current or planned availability and accessibility of sufficient water, sewer, and dry utilities The capacity methodology must be adjusted to account for any limitation as a result of availability and accessibility of sufficient water, sewer, and dry utilities (i.e., if the capacity of the site could be limited because a development would have to use a septic system, if there are any septic tank requirements or restrictions that constrain capacity, or limitations on water hook-ups). See Part A, Step 3 for more information on infrastructure requirements.

Example Capacity Calculation Here is an example of the actual capacity calculation for a particular site in the inventory. The methodology analysis must describe how each of these adjustments was generated per the analysis requirements above. The factors used below are based on the factors outlined in the statute. The percentages and how the factors are applied will vary depending on the unique circumstance in each jurisdiction.

6 In using this adjustment factor, because of the use of density bonus, it may be possible that trends demonstrate typical densities higher than the maximum allowable densities, especially for housing affordable to lower income households. On a case-by-case basis, it may be appropriate to utilize increased densities due to density bonuses when determining the adjustment factor in the capacity methodology.

Site Inventory Guidebook

Page 21

May 2020

Site Description
Size of site	2.5 acres
Zoning	Residential Mixed-Use
Allowable density	20–45 dwelling units per acre
RHNA affordability	Lower income
Existing Use	Nonvacant, single storefront
Infrastructure availability	Yes, no constraints
Environmental constraints	None known

Capacity Factors	Adjustment	Reasoning
Land Use Controls and Site Improvements	95%	For net acreage due to on-site improvements including sidewalks, utility easement
Realistic capacity of the site	55%	55% adjustment based on past development trends for residential redevelopment in the residential mixed-use zones, and programs to incentivize development in this zone.
Typical densities	95%	Affordable housing projects are built out to almost maximum density
Infrastructure availability	No adjustment	Not applicable, no constraint
Environmental constraints	No adjustment	No known site constraint

Realistic capacity utilizing factors = (2.5 X 45)( .95)(.55)(.95) = 56 units

Realistic Capacity = 56 Units