It's Cold! Turn on the Floor!

Photo Credit: Korea Times

Still considered a luxury in most of the world, Koreans have used ondol heated floors for centuries.

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Temperatures are dropping in Korea, and I've been running around Seoul trying to snatch up a new winter coat. Mt. Seoraksan, which we recently recommended for its beautiful fall foliage, has already welcomed the first snowflakes of the year.

Back in the U.S., my family is preparing to turn on the heater that (rather inefficiently) pumps hot air through the same ducts that serve the air conditioner in the summer. In Korea, however, my mornings have begun with the push of a button with a different function: to turn on the floor.

The unique heating system that warms the floors of Korea is called ondol, meaning warm stone. The original technology dates back centuries, but like everything in Korea, it's been modernized over time.

Original ondol systems were traditionally used for both cooking and heating. They can be seen in hanoks that have survived until today. In order to cook in olden times, Koreans lit fires under a stone hearth. The heat transferred to the stone floors in the house and kept them warm for hours after the fire was extinguished.

The technology is more advanced than it sounds and for having been created centuries ago, is quite amazing. It relies on an understanding of scientific principles of heat transfer – conduction, convection and radiation.

According to Koreabrand.net, ancient Koreans developed several complex devices to send flames horizontally under a floor, which included the agungi (furnace hole) hamsil (agungi without a stand over it) and flue entry. These ensure the flames were going in the right direction without getting extinguished too soon. The network of flues were also made so that flames and smoke could pass and heat the flat stone, called gudeul, over the flues and stay hot longer. Several holes were dug near the furnace, flues and chimney to keep the heat in and draw out only the cooled smoke.

Photo Credit: Mani Puris in Korea

In addition to warming the residents of a home, ondol helps to maintain the proper humidity and temperature levels in the room as the heat rises from the floor (as opposed to heating systems in other countries, where hot air may only be blown to upper areas of the room).

It also has therapeutic benefits. In ancient times the ondol system helped women recover quickly from childbirth and a similar heating system is seen in modern hospitals today. Laying on an ondol floor keeps all parts of the body warm and even promotes circulation during sleep.

Ondol is still a big part of Korean culture. In modern homes, ondol systems pump hot water through pipes under the floor, turning the entire floor into a radiant heat source. The hot water is provided either by a central boiler that serves an entire apartment block or by tankless, natural gas water heaters in individual apartments. Both methods are high efficient.

There are other benefits, beyond energy efficiency and the joy of stepping barefoot onto a warm floor. In dense cities like Seoul and Busan, where residents are always space conscious, heated floors free up space that would otherwise be used by wall-mounted radiators or fireplaces.

It's not uncommon today to see large families eschew chairs and beds in favor of relaxing on a warm floor. Many Korean hotels even offer bedless ondol options.

Photo Credit: Korea Brand

For me, there's nothing better than being greeted by a warm ondol floor after being beaten up by Seoul's freezing winds. I'll often bypass the bed or chair and opt to sleep or do work on the floor. Sometimes I even dry my clothes on the floor, as it almost acts as a flat drying board.

Personally, I'm not a fan of winter or the cold, but the ondol system in Korea makes this season much more bearable.

About the author by Donna Choi

Born and raised in the States, I came to Seoul in 2009 and have loved living and working in such a high-tech and connected city ever since. I enjoy collecting unique, cute gadgets/items (I have a bread-scented smartphone case!) and traveling around Korea. My personal mission while living in Korea: Try every type of Korean food known to exist.

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