Nearwise Catchment Analysis — Calculation Audit Report

Calculation

Method and limitations

Overture Maps provides the deduplicated roof-footprint inventory. OpenStreetMap supplies building-use classifications. Structures below 20 m² are excluded. Remaining unclassified footprints receive low, base and high screening factors of 0.35, 0.65 and 0.90. These are scenarios, not official household counts.

Data lineage

Overture Maps Buildings release 2026-07-22.0; OpenStreetMap contributors; WGS 84 coordinates. Output is preliminary feasibility evidence and is not cadastral, census or investment advice.