Ondol is a Korean traditional heating method that will make hot smoke heat the entire room bypassing the gudeuljang, a flat stone used for the Korean floor heating system. After hot smoke heats up, it goes out through the chimney which is located at the edge of gudeuljang, and these processes are repeated.

▲ Heating method

The shape of the barrels made of ondol rooms began to appear at the end of the Goryeo Dynasty. It was mainly used by the wealthy people and in the rooms of the sick or the elderly. It had a great influence on the lifestyle of Korean people. Since the floor was heated, the ondol became an important cause for Koreans to live on the floor. This also affects all indoor furniture's size, location of doors, and handles attached to the furniture suitable for sitting down. Also, people used to put food on the floor to heat them.

Ondol heats the floor evenly, so it does not get damp and is resistant to fire. Once heated, gudeuljang keeps the floor warm for a long time, making it perfect for a cold winter. The combination of ondol and hanji, which traps and releases moisture, creates a comfortable indoor ecosystem regardless of the harsh winter weather outside. It also saves space and money as there is no need for a separate heating device. However, they need a high level of technique to install. Also, they took quite a long time to heat the entire room and hared to control the fine temperature.

In modern times, there has also been a change in the form of ondol. It is more widely used as a mixture of modern and traditional methods. Instead of using traditional fuels. it uses various types of energy such as oil and gas to improve thermal efficiency and convenience. Also, hot water pipes, as well as oil and gas, are used to heat the floor. Underfloor heating systems using warm water between floor joists and electric radiant heating systems under hardwood floors bring indescribable warmth and comfort for indoor barefoot cultures all over the world.

▲ Modern heating method

By Wooin Gil