A single coat of paint brings relief from deadly summer heat in Gumi

GUMI, North Gyeongsang — Ten buildings at a public rental apartment complex in Gumi, North Gyeongsang, have been coated in heat-reflective paint, and the province says exterior wall temperatures there have since fallen by between 2.2 and 15.3 degrees Celsius (4 and 27.5 degrees Fahrenheit). Indoor temperatures dropped about 1.6 degrees Celsius.

The complex, Hwangsang 3 Jugong, holds 600 units of permanent rental housing run by the Korea Land and Housing Corporation. Most of the residents are older or in poor health, the people least equipped to cope with extreme heat.

On Tuesday, a resident in their 60s rested in a pavilion beside the complex playground and looked up at the buildings.

"Every year the heat has been rough, but they put on a single coat of paint, and it did get a bit cooler," the resident said.

Gumi city government paid for the work with 400 million won ($280,200) in 2024 through a national grant competition that funds support for people and areas most exposed to the climate crisis. The city says it is the first time the paint has been applied across a large apartment complex anywhere in the country. Residents helped choose the exterior design from the planning stage.

Heat-reflective paint is a functional coating that bounces sunlight and radiant heat away before it passes into a building. Applied to rooftops, the high-reflectance coatings reduce the heat a structure stores. That eases conditions during a heat wave and cuts the energy needed for cooling.

Testing by the Seoul Housing and Urban Development Corporation found that the paint lowered rooftop surface temperatures by up to 9.2 degrees Celsius and indoor temperatures by about 1.8 degrees Celsius. Summer cooling energy use fell by up to 40.8 percent, and by 26.4 percent on average.

"After they painted, I put my hand on the outside wall, and it was clearly cooler than before. The inside felt like it had come down too," Kim Jong-chul, aged 72, said. "It has been a big help in reducing the harm from the midsummer heat." Kim added: "At the public hearing they held for residents before the painting, they told us the effect lasts about five years. I would like them to repaint it regularly."

Hwang Myung-seok, North Gyeongsang's vice governor for administrative affairs, went to the complex's management office on Monday to hear from residents who have struggled through the heat.

"It is clearly different since they painted," one resident told him. Hwang said the province would analyze the results closely, then refine the program and widen it.

Other local governments are turning to the same material as heat waves and cold snaps grow more frequent. Nowon District in northern Seoul recently designated "cool roof" zones in the Gongneung 1 and Sanggye 2 neighborhoods, both dense with small older multifamily houses where the alleys trap air and indoor heat builds up in summer. The district picked the two areas to improve housing that does badly in heat waves and to ease cooling bills for households that can least afford them.

"We pushed this project forward to keep the harm to residents vulnerable to climate change as small as possible," a Gumi city official said. "We hope other places, not just Gumi, will use heat-reflective paint to support vulnerable groups and cut heating and cooling energy as they prepare for heat waves and cold snaps."

BY KIM JUNG-SEOK [cho.yongjun1@joongang.co.kr]