Cool-roof paint cuts electricity bills 40%, brings relief to vulnerable households in Seoul

"I was worried about how I'd get through the summer heat, but after the cool-roof coating was applied, the inside of my home became so much cooler — and my electricity bill dropped by 50,000 won ($37) compared to last summer." That is how a resident in her 50s, identified only as A, described the impact of recently having heat-reflective paint applied to her home.

As climate change drives increasingly severe summer heat each year, the Seoul Metropolitan Government confirmed that its heat-reflective paint program — which supported applications at 152 aging or low-income residential buildings — has produced positive results like those experienced by A. The city plans to expand the "heat-reflective paint (cool-roof) application support project" next year to protect climate-vulnerable residents and reduce gaps in heat-wave coverage.

The city announced Sunday that it had designated "Seoul-type heat-reflective paint (cool-roof) specialized zones" in April and launched the support program. Heat-reflective paint deflects radiant heat and can be applied to rooftops or exterior walls to prevent heat from seeping into a building's interior. It also releases absorbed heat, helping suppress surface temperature rises on roofs. Demand has been rising in anticipation of hotter summers: one paint industry source said sales of heat-reflective paint this summer surged more than 60 percent compared with the same period last year.

A field evaluation conducted on apartments managed by the Seoul Housing & Communities Corporation showed that rooftop surface temperatures fell by as much as 9.2 degrees Celsius and indoor temperatures dropped by about 1.8 degrees Celsius.

The Seoul-type heat-reflective paint specialized zones are areas densely populated by vulnerable groups — including the elderly, children, people with disabilities and low-income households — living in aging, low-rise residential buildings with poor thermal efficiency that fall outside the reach of home-repair programs. By early June, the city had completed heat-reflective paint applications at 152 residential and welfare facilities within the specialized zones, covering 31,204 square meters.

The project benefited more than 2,000 residents living in the treated buildings. Electricity bills fell by up to 40 percent compared with the same month last year, and rooftop surface temperatures dropped by more than 10 degrees Celsius, easing cooling costs and improving living conditions. Some residents also reported that applying the heat-reflective paint alongside waterproof coating resolved roof-leakage problems in aging buildings.

The Seoul Metropolitan Council, in agreement with the city's climate-crisis response policy, passed an amendment Friday to the city's basic ordinance on carbon neutrality and green growth for climate-crisis response. The amendment expands eligibility for energy-performance improvement support — including heat-reflective paint — from "vulnerable residents on the top floors" to all "aging housing more than 10 years old since receiving occupancy approval."

Working with the Seoul Institute, the city plans to use scientifically measured and analyzed heat-wave maps to designate new specialized zones in areas with vulnerable populations such as single-room rental districts and aging residential neighborhoods. Even outside those zones, the city said it will provide targeted support to top-floor vulnerable households and welfare facilities to eliminate gaps in heat-wave protection.

"We will continue to run the heat-reflective paint program with substance next year so that we can ease, even if only a little, the hardships faced by vulnerable residents," said Yoon Jae-sam, head of the Seoul Metropolitan Government's Climate and Environment Bureau.