[RAS Korea] Ondol: Korea's unique floor heating

A traditional kitchen is in use to power ondol floor heating, in Sajik Village, Jangsu County, North Jeolla Province. / Korea Times file

By Steven L. Shields
royalasiatickorea@gmail.com

When asked about what living in Korea might be like, one of the first answers is always: the warm floors. Korea's living spaces are not cluttered with radiators, common in the United States and other parts of the Western world well into the 20th century, and are still used today in many places. In the old days, the place of honor in the room was right at the "hot spot," closest to the firebox (agungi) just outside and beneath the floor. Most homes in Korea no longer have a hot spot since the modern ondol system circulates hot water evenly.

Although other regions anciently had some floor heating systems, none was quite like the ingenious energy-efficient method developed in Korea. Archaeologists have found evidence of ondol dating to the Bronze Age (circa 900 BCE). The system became widespread during the Three Kingdoms Era (57 BCE to 668 CE), with examples uncovered by researchers throughout the Korean Peninsula. Over the centuries, the ondol experienced little change in its basic principles and construction. Rather than use fire as the direct source of heat inside the house, the system employed channels under the floor, connected directly to the kitchen's cooking fires. This arrangement kept the fire outside of the living space. The hot smoke passed under the floor and out a chimney at the opposite side of the house. Larger houses installed more fireplaces (agungi) at strategic points.

A house in Hahoe Village in Andong, North Gyeongsang Province, has slots for ondol floor heating, June 27, 2012. / Korea Times photo by Jon Dunbar

One of the first, and perhaps most important, customs to learn in Korea is taking off shoes at the house entrance. What is the reason for this time-honored custom in Korea? The floor has been a living surface for sitting, dining and sleeping for millennia. In the West, one would never wear shoes while standing on a sofa or a bed ― those are living surfaces. Although modern furniture is commonplace these days, and "living" is rarely done directly on the floors, the custom of removing shoes prevails. There is no need to change. There is no need to bring dirt into the house.

Wood fires heated houses throughout Korea, but after the 1950-53 Korean War, with wood scarce, low-grade coal was pressed into cylindrical briquettes, called "yeontan." They provided a relatively cheap fuel source for heating and cooking, both on small and large scales. The fireboxes and flues often had to be modified to accommodate the different fuel sources. Unfortunately, the coal burned at a lower temperature than wood, so the country was invaded by toxic and sometimes lethal gases from the coal. Every winter, the newspapers would tell stories of people who died from carbon monoxide poisoning. With continued industrial development, coal- and wood-burning ondol houses have mostly been converted to pipes in the floor circulating hot water, fueled either by electricity or gas boilers. All modern construction in the country uses these systems.

Firewood, likely for ondol floor heating, in Hahoe Village in Andong, North Gyeongsang Province, June 27, 2012. / Korea Times photo by Jon Dunbar

Long before K-pop and the Korean wave, one of Korea's earliest technological creative exports was the ondol floor heating system. American architect Frank Lloyd Wright, famous for his striking linear style of houses and public buildings, was inspired by Korea's ondol heating system and incorporated the idea into some of his projects in the United States.

At 7:30 p.m. next Tuesday, April 13, Dr. Robert Fouser will give an online lecture on Wright and his ondol adoption in the 1950s. Visit raskb.com for the Zoom link.

Steven L. Shields, a retired cleric, is president of the Royal Asiatic Society Korea (www.raskb.com) and is a columnist for The Korea Times.

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