Heat-reflective 'cool roof' paint cuts summer power bills for vulnerable Seoul households

The Seoul Metropolitan Government said a pilot program applying heat-reflective "cool roof" paint to 152 buildings housing older adults, low-income families and other vulnerable residents produced clear results this summer, cutting August electricity bills by up to 40 percent compared with a year earlier and lowering rooftop surface temperatures by more than 10 degrees Celsius.

"I was worried about how we'd get through the summer heat, but after the cool roof coating, the house is a lot cooler, and my electricity bill dropped by 50,000 won ($36) compared with last summer. It even stopped the leaks," one resident said.

Another said the coating made the house "livable," adding that a leaking rooftop was also fixed and expressing hope the program would expand to reach more elderly residents and others in need.

The city launched the program in April by designating "cool roof priority districts" — aging, low-rise residential areas with poor insulation and limited access to home repairs, where vulnerable groups such as older adults, children, people with disabilities and low-income households live.

Cool roof paint, which reflects radiant heat when applied to rooftops or exterior walls, was found in a demonstration test on Seoul Housing & Communities Corp. apartments to lower rooftop surface temperatures by as much as 9.2 degrees Celsius and indoor temperatures by about 1.8 degrees Celsius.

By early June, the city had completed coating work at 152 sites covering 31,204 square meters, directly benefiting roughly 2,000 residents. Some buildings that also received waterproof coating alongside the cool roof paint saw long-standing roof leaks resolved.

The Seoul Metropolitan Council this month passed an amendment to the city's basic ordinance on carbon neutrality and green growth, expanding eligibility for such energy-efficiency support beyond vulnerable households on top floors to any building more than 10 years old.

Citing that change, the city said it plans to expand the program next year from coating individual buildings to covering entire priority districts, in an effort to ease the urban heat island effect. It will also work with the Seoul Institute to use heat-mapping data to designate new priority districts, including areas with cramped, low-cost housing, while continuing targeted support for vulnerable households outside those districts.

Recognizing that extreme heat hits vulnerable communities hardest, a city climate official said that next year’s application will wrap up before summer to ensure effective, timely relief for residents.

"As heat waves grow more severe, the burden falls that much heavier on climate-vulnerable communities," said Yoon Jae-sam, head of Seoul's Climate and Environment Headquarters.

"We will ensure the thermal paint project is run effectively — including completing construction before the heat hits again next year — to help alleviate the hardships of vulnerable residents as much as possible."

This article was published with the assistance of generative AI and edited by The Korea Times.