Seoul is building a citywide network of shaded walking routes it’s calling the “right to shade,” starting with a pilot covering 10 high-traffic streets through 2027 before expanding citywide in 2028. The push comes after Korean health data found that 31.4% of the 815 heat-related illness cases reported in Seoul between 2023 and 2025 happened on ordinary streets, not indoors or at outdoor events.
The plan combines more street trees where space allows with awnings, canopies, and small shelters elsewhere, designed to connect residential areas to subway stations, schools, markets, and hospitals rather than just shading isolated plazas. City officials have explicitly framed extreme heat as a disaster-level public safety issue rather than a seasonal inconvenience.
A Different Approach: Cooling Without Electricity
Separately, researchers at Spain’s CSIC national research council have developed a nanostructured material that cools sun-exposed surfaces by up to 12.9°C with no electricity at all, using a polymer engineered to radiate heat directly into the infrared window where it escapes into space rather than getting trapped near the surface. Outdoor testing in Madrid recorded that reduction under peak midday sun, on a material intended for eventual use on building roofs and facades.
Why These Two Stories Point the Same Direction
Both approaches treat heat as an infrastructure problem to be engineered around rather than something to simply endure, but they operate at very different scales and costs. Seoul’s shade network is a public infrastructure investment available to anyone walking the covered routes, while passive-cooling materials are still in the research and early-deployment stage and will likely reach expensive new construction and high-end retrofits well before they reach older, lower-cost housing stock. Which kind of cooling reaches ordinary neighborhoods first, publicly funded shade or gradually commercialized cooling materials, will matter a lot as extreme heat becomes a bigger part of more cities’ summers.
Seoul Mayor Oh Se-hoon unveiled the policy at a City Hall press briefing, saying “heat waves are no longer a temporary discomfort” but have “become an everyday disaster threatening the lives and safety of citizens.” City data backing the plan found Seoul’s pedestrian routes are exposed to direct sunlight for an average of four hours and 21 minutes a day, with more than a quarter of routes exposed for six hours or more.
