The challenge
LEED v5 credit LTc3, Compact and Connected Development, is worth six points and is among the most data-intensive in the rating system to evidence. Documenting it by hand means digitising a site boundary in GIS software, generating the 400 m study buffer, counting and classifying every rooftop inside it from aerial imagery, then cross-referencing each nearby transit route's published weekday and weekend timetable stop by stop. A senior sustainability analyst is typically given a full working day to produce it — for one credit, on one project.
Our approach
Built a density engine that geocodes the project address, takes a site boundary traced directly on live satellite imagery, generates the regulatory buffer automatically, and extracts every building footprint inside it from the open Overture Maps dataset — with footprint area, floor count and use type estimated per building.
Built a companion transit scorer that discovers qualifying stops inside the walking-distance buffer around each functional entry, aggregates route-level weekday and weekend trip counts from agency data, and scores each entry against the minimum-service thresholds.
Put an explicit auditor-verification step between the machine and the submission: the automated count is shown beside a manual count field, every extracted building sits in an editable ledger, and a justification note is recorded. Nothing proceeds on the software's word alone.
Outcome
Two consecutive runs against the same urban infill site returned a 137.26-acre buildable buffer, 385,389 m² of built floor area and a combined density of 30,223 sq ft/acre — one point via the combined-density pathway. The transit module returned 222 weekday and 200 weekend trips at the main entrance, three points under the minimum-service thresholds. A co-founder has since applied the toolset on live certification projects in his own practice, producing the documentation submitted to the certifying body.