Commuters sit and stand inside a subway car in Seoul on Dec. 1, 2025. [YONHAP]

 

Every winter in Seoul, as commuters zip themselves into padded parkas and tightly wrap scarves for protection against the cold, similar complaints resurface online about subway seats that feel less like a place to rest and more like a heating pad set to high.

 

“The
eong-ddeu on the subway is crazy hot every time I get on.”  

 

The complaint appeared on X, formerly known as Twitter, on Feb. 15. Eong-ddeu, which literally means “hot bottom,” is Korean slang for heated seats.  

 


 

This winter was no exception. According to a source at Seoul Metro, hundreds of complaints poured in about overheated seats inside subway cars. In November alone, the operator received 109 complaints — 103 text messages and six phone calls. The number jumped to 304 in December and climbed to 532 in January. Seoul Metro operates subway lines No. 1 through 8.  

 

And it isn’t just the subway. Heated seating has quietly become part of the city’s streetscape as well. At bus stops across Seoul, benches warm themselves automatically when the outdoor temperature drops — a feature that often surprises first-time visitors to the city. Since the 2010s, the city has steadily expanded the program, buoyed by enthusiastic public feedback. 

 

As of 2025, 97.45 percent of bus stop benches in Seoul are equipped with heating functions, according to the Seoul Metropolitan Government.

 

Why does the capital invest so heavily in keeping public transportation warm? And how are those systems actually designed to work?

 


Not quite what you think

 

Commuters sit in a subway car on Seoul’s line No. 5 on June 2, 2025. [YONHAP]

 

On an online forum in early December, a user asked, “The eong-ddeu on subway seats is unbearable these days. Is it just me?” Dozens of comments followed. 

 

“I agree,” one person wrote. 

 

“I end up standing because it’s too hot.” 

 

Others countered that the warmth was unavoidable: if one person overheats, another will complain they’re freezing.

 

But here’s the twist — the seats themselves are not designed to be heated.  

 

“The heaters in subway cars are installed underneath the seats,” a source at Seoul Metro said, adding that it is part of the overall cabin heating system, not seat warmers. 

 

According to the source, temperature sensors automatically regulate the system, reducing heat when it gets too warm and increasing cooling during the summer.

 

Many riders point to stainless steel seats as the main culprit. After the 2003 Daegu subway fire, Seoul replaced seat materials with stainless steel by 2005 to reduce fire risk.

 

Complaints soon followed. Subway cars manufactured after 2007 switched to flame-retardant fabric and, more recently, to reinforced plastic seats after reports of bedbug infestations.

 

Disinfection workers sanitize a line No. 9 subway car at a depot in Gangseo District, western Seoul, amid concerns over bedbugs, on Nov. 9, 2023. [NEWS1]

 

Government guidelines set recommended indoor temperatures at 24 to 27 degrees Celsius (75 to 81 degrees Fahrenheit) in summer and 18 to 21 degrees in winter. Subway cars are generally maintained at 24 degrees in summer, while “mildly air-conditioned” cars are set at 25 degrees. 

 

When complaints come in, train operators may increase airflow, adjust heating or cooling intensity, or run full cooling systems in especially crowded sections. In unavoidable situations, operators make announcements asking for passengers’ understanding, explaining that both heating and cooling systems are already running at full capacity.

 

In other words, that intense warmth commuters feel isn’t intentional comfort — it’s collateral heat.

 

An office worker in his 30s who commutes through Jongno District said he notices it most when he’s wearing a thick winter parka. 

 

“Six or seven times out of ten, the seats feel hot,” he said. Stainless steel seats, he added, seem worse than newer plastic ones, which don’t retain heat as much.

 

Still, he shrugged it off. “It’s not unbearable,” he said. “I’d rather be too warm than cold in winter.”

 


Warmth as infrastructure

 

A similar approach is used at bus stops. The heated benches, first proposed by a private company in 2008 and later adopted by the Seoul city government through a competitive bidding process, operate automatically when the outdoor temperature drops below 18 degrees Celsius. The surface temperature stays between 36 and 38 degrees Celsius — roughly body temperature. Following positive feedback, the benches have been expanded nationwide.

 

A heating-and-cooling bench installed at a bus stop in Jangchung-dong, Jung District, central Seoul, in November 2024 [JUNG DISTRICT OFFICE]

 

Made of reinforced glass, the benches are built to withstand heavy use and harsh weather. In summer, an internal cooling system keeps the surface pleasantly cool. Inside, carbon-fiber heating elements generate warmth efficiently, using relatively low power while emitting far infrared radiation, which proponents say enhances heat transfer.  

 

The man who originally pitched the idea reportedly said he was inspired by a simple thought: Koreans believe that when you sit, you should be warm. That belief traces back to
ondol, Korea’s traditional underfloor heating system, which for centuries has defined the home as a place where heat rises gently from below. It also echoes an old principle from traditional Korean medicine known as
du-han-jok-yeol — literally, “cool head, warm feet.” The idea holds that keeping the lower body warm improves circulation and balance, helping heat descend from the upper body and preventing illness.

 


The cost of comfort?

 

The popularity of heated benches at bus stops has brought complications. While residents generally express satisfaction, local governments face mounting financial and administrative pressure. Installing a single heated bench costs between 3 million and 4 million won ($2,200 to $3,000), with monthly maintenance costs of about 40,000 won per unit.  

 

Once benches appear in one neighborhood, complaints soon follow from others asking why they were left out. Some critics argue that the money would be better spent on reducing bus intervals instead of warming seats.

 

Maintenance has become an issue as well. Last month, Kim Je-seon, head of Jung District in Daejeon, wrote on Facebook that an inspection of 59 heated benches in his district found malfunctions at seven locations. Residents, he said, were frustrated, but the benches fall under city jurisdiction, limiting how quickly fixes can be made. In response to similar concerns, Seoul’s Yangcheon District announced plans last December to build an integrated management system for heated bus stop benches.

 

A diagram illustrating airflow inside a subway car [SEOUL METROPOLITAN GOVERNMENT]

 

Temperature sensitivity does not end with winter. In summer, subway air conditioning brings a different set of complaints, prompting Seoul Metro to issue guidance for riders. The coolest spots in a subway car are near the priority seating areas at either end, where cold air circulates most efficiently, according to the operator. 

 

The warmest area tends to be the center of the car. 

 

Measurements show temperature differences of two to four degrees Celsius, depending on seat location, and up to six degrees when cars are crowded. Passengers are also recommended to check crowding information on the official Seoul Metro subway app or the TMAP navigation app.

 

Those who feel cold are advised to use mildly air-conditioned cars, which operate at temperatures about one degree warmer than standard cars. These designated cars vary by line: on lines No. 1, 3 and 4, they are the fourth and seventh cars; on lines No. 5 through 7, the fourth and fifth; and on line No. 8, the third and fourth. Line No. 2, the city’s busiest, does not offer mildly air-conditioned cars because of congestion.  

 

For winter complaints about excessive heat, Seoul Metro says reports can be submitted by phone or text message to its customer service line, 1577-1234, or through the Seoul Subway mobile application, which currently only accepts reports in Korean. 

BY CHO JUNG-WOO [[email protected]]