URBAN HEAT

Interventions that reduce heat exposure in built-up areas: street and corridor greening, urban forestry, cool and reflective surfaces, shade structures, and water-based cooling. A record enters this class when the operator's primary stated aim is lowering air or surface temperature, or reducing heat-related harm, in an urban environment.

One record. C4P-URB-0001, the Medellin Green Corridors: 30 road and stream corridors converted to multi-layer vegetation from 2016, USD 16.3 million (2016) capital, about USD 625,000 per year (2022) maintenance. Graded T2 for transferability and E3 for evidence. The city reports a fall in corridor air temperature from 31.6 C to 27.1 C between 2016 and 2019; every temperature figure is an operator measurement with no control sites and no published protocol.

A single record establishes nothing about the class. It establishes what one deployment cost, what its operator measured, and what happened to it across two changes of government. Cross-record comparison in this class becomes possible when further records are published.

No independent, peer-reviewed measurement of the Medellin corridors' cooling effect was located as of August 2026; the class currently contains no E1 or E2 evidence. Candidate records under research include deployments in Singapore, Seville and Phoenix, which were passed over for the seed record because their public documentation is thinner on costs or on post-transition history.