Eugene planners adopt new method for calculating housing density; low-density average reported at 6.7 units/acre

Heather O'Donnell, senior planner for the City of Eugene, told the Envision Eugene technical advisory committee on Oct. 16 that staff has revised the methodology used to calculate housing density for the city's growth monitoring and Buildable Lands Inventory work.

O'Donnell said the new approach sums the total number of units and the total number of buildable acres across development sites, then divides units by acres, rather than averaging per-project densities. "We have come up with a better way to refine the actual densities that we're seeing from development permits," she said, adding that the change is intended to reflect the scale of projects more accurately.

The change matters for Eugene's long-range planning because density assumptions feed capacity estimates used in Urban Growth Boundary (UGB) and housing-supply work. "If you give equal weight to a single-unit lot and a 300-unit project, you misrepresent what the city is building," O'Donnell said.

Using the updated method, staff reported 4,570 units across 606 acres in land designated low-density residential, yielding an average of 6.7 units per acre. Staff also reported average densities of 5.6 units per acre for single-unit detached projects and 11.8 units per acre for townhouse projects. Developments on vacant land averaged 8.9 units per acre under the new calculation, O'Donnell said.

O'Donnell and Elena (associate planner) walked committee members…