Since 2023, the city of Seoul has been creating gardens in leftover spaces such as roadsides and alleyways
A total of 1,315 sites covering 910,000㎡ … 45% involved removing artificial pavement and converting to green space
The effect on reducing urban heat is clear … Mayor Oh Se-hoon “Realizing a ‘walking shade zone’ in everyday life”

Around 2 p.m. on the 5th, the second consecutive day that a severe heatwave warning was in effect for Seoul, three to four citizens were sitting on a bench in the shade of trees in the downtown garden in front of Seoul City Hall. Park (53) said, “I sat for a moment because it was so hot the moment I came out of the subway station,” adding, “It feels less hot here because there is shade.”

Choi (28), an office worker who was sitting on a bench under the trees looking out at Seoul Plaza, also said, “I sat down after seeing others sit, and maybe because there is shade here, I do not feel that it is so hot.”

The daytime high in Seoul that day reached 39.2 degrees. Even though a facilities manager was spraying water on the sun-drenched surface of Seoul Plaza to cool it, the surface temperature measured by thermometer quickly rose to 36 degrees. By contrast, the temperature under the wooden bench right next to the plaza read 34 degrees.

As record heat continues nationwide, green spaces created throughout the city are serving as heatwave refuges for Seoul residents. Taking into account the characteristics of the city center where securing large green areas is difficult, since 2023 the Seoul Metropolitan Government has been promoting the ‘Garden City Seoul’ initiative, which turns leftover spaces such as roadsides, alleyways, traffic islands, beneath street trees, and rooftops into gardens. From 2024 to this year alone, 1,315 urban gardens have been created across Seoul, covering a total area of 910,000㎡.

A Seoul City official said on the 6th, “Forty-five percent of all urban gardens (410,000㎡) were created after removing artificial pavement such as cement and asphalt or by converting neglected spaces into green areas.” In places where artificial pavement was removed, a variety of trees, flowers, and grasses were planted. This reduces impervious surfaces (paved surfaces that prevent rainwater from soaking into the ground), which easily heat up under sunlight.

Green spaces created on upper building levels are also lowering urban heat. A survey by the city of the post-greening surface temperatures of 67 buildings where rooftop greening had been completed found an average of 31.1 degrees, which was 2.4 degrees lower than the average surface temperature of nearby non-greened buildings (33.5 degrees). Among all buildings, the largest temperature difference was observed at Dongbu Municipal Hospital in Dongdaemun District, where the measured surface temperature after rooftop greening was 34.2 degrees. The adjacent non-greened area, by contrast, recorded 43.1 degrees, a difference of nearly 9 degrees.

The city plans to continue the Garden City initiative while also strengthening efforts to secure a ‘walking shade zone’. By expanding gardens, street trees, and neighborhood green spaces, it aims to ensure that shade naturally continues along the routes people take. Recent overseas studies indicate that, in addition to the total amount of urban greenery, securing shade in the spaces where people actually walk is a key factor in reducing exposure to extreme heat.

Seoul Mayor Oh Se-hoon said, “The next stage of Garden City Seoul is to realize a ‘walking shade zone’ so that from the moment residents step out of their homes until they reach their destinations, they can enjoy greenery and shade in daily life,” adding, “We will densely connect small gardens, street trees, and urban green corridors to build a green city that is resilient to heatwaves and that residents can tangibly feel.”