Ondol

The ondol is the system of traditional heating by the ground in Korea.

according to Joo Nam-Chull Professor emeritus of architecture at the Korea University Ondol is a process of domestic heating single in the world.

Since antiquity, the Koreans use a single system of heating called “ondol” which largely influenced several aspects of the Korean culture. To include/understand its principles and its structures is necessary to fully appreciate the ingeniousness of this innovating system.

The ondol, known under the term of “gudeul”, is a system of innovative heating whose strutures are integrated in the ground of the building. Four during the seasons being quite distinct in Korea, it is very hot in summer and extremely cold in winter. Korean architecture thus always preserved a room with heating at ondol and a living room with wood floor without heating.

In the rooms with ondol, the installation of the heating system under the ground allows a diffusion of heat by convection in the whole of the part. Thus, the air heated with the floor rises towards the ceiling, pushing the cold air towards the ground. This last heats it and raises it in the air (cycle of convection), thus heating the whole of the room. Moreover, the ground heating only the lower part of our body, our head is kept with the expenses, thus creating a pleasant temperature to live and sleep. Effective heating, the ondol has other merits such as the absence of gas emission or moisture in the room. Effective and hygienic, there is finally no fire hazard.

The system

The system is composed of three parts: a furnace where proceeds combustion for the production of heat, the conduits for the transmission of the air heated and smoke and a chimney for the evacuation of smoke towards outside. In the traditional system, firewood were used. In the peasants, one burned branches of trees or cereal stems. There exist two types of furnaces, the direct furnace and the furnace of kitchen. The first is a heating for the rooms, located in bottom and in the center of the wall external shortest of the part, for a maximum effectiveness.

The second is a furnace with double function: cooking and heating. Cross-pieces are installed on the furnace in order to suspend the pots. The furnace releases heat for cooking and the heated air passes by the conduits to the room been next to the kitchen to be able to heat more pots.

These two types of furnaces are manufactured out of clay and stone. Only certain houses of the rich classes used bricks, while in the palates, it was the single material of manufacture. In the furnace, fire is lit by a passage called “mouth of the hearth”, where the conduits are attached. Lines of strips constitute these conduits planned for the passage of the air and smoke. On these strips the floor, heated by radiant heat starting from the conduits rests.

A harmony enters the functional one and esthetics

There exist two types of chimneys: an contiguous chimney installed on the wall of the structure and a separate chimney on foot of the house. Certain contiguous chimneys are built on the surrounding wall of the buildings. For the chimneys on foot, the conduits can often be long and hidden under ground. Built with various materials, such as wood, vase, stones, bricks black and red, these chimneys are also decorated, thus playing a considerable part in the Korean garden.

The chimney is surmounted by a lid in the shape of house which evacuates smoke by its windows. In the thatched cottages, the lids were out of red terra cotta whose smoke was evacuated by holes.

The typical example of the chimney on foot is the Amisan chimney, behind the Gyotaejeon Hall of the Palate of Gyeongbokgung. Of hexagonal form, it is built out of red bricks and is decorated with various reasons. The upper part is surmounted of several completely remarkable lids of beauty. The chimney behind the Jagyeongjeon Hall of the same palate is built outside the building, in order to be used at the same time of chimney and fence. Surface is decorated by the ten symbols with longevity, with a line of lids which seems to form only one of them.

The design of the ondol differs according to the areas. In the province of Hamgyeong-C, in the North-East of the current North Korea, no wall separates the kitchen and the being next to room, the cross-pieces for the pots being installed on the same level as the floor of the room. Consequently, the furnaces are appreciably broader than in other areas. On the island of Jeju where the temperature is softer, the furnace of kitchen was worked so that heat does not penetrate in the room.

Origin and development

To when does go back the heating with ondol? The first ondols appeared with the iron age (of 300 av. J. - C. with 1 a. J. - C.) although the exact date is still ignored. L-shaped conduits were exhumed on the Sejuk-laughed site with Yeongbyeon-gun, in the province of Pyeongan-C, like on the ruins of Seodun-dong, in Suwon. The shape of L is transmitted to the period of the Three Kingdoms (of 57 av. J. - C. with 668 a. J. - C.). The inhabitants of Goguryeo built L-shaped conduits under the walls of north and the east. The furnace was installed in the south of the conduits is, and the chimney, outside the room, in the northern west of the conduits. The L-shaped conduits appear in the “Old story of Tang” and the “new History of Tang” under the term of “janggaeng”, which means long tunnel.

Conduits in straight line were discovered on the sites of the hearths of the fortress Busosan, constuite for the period of Baekjae (of 18 av. J. - C. with 660 a. J. - C.). This discovery confirms the effective use of the two shapes of conduits for the period of the Three Kingdoms. However, no conduit was exhumed on the sites of Silla (of 57 av. J. - C. with 935 a. J. - C.), which reigned in the méridonale part of the Korean peninsula, which makes it possible with difficulty to know if the ondol were used for this period.

Although the remainders of ondol were not discovered for the period of Silla Unifié (668-935), it is considered that the system was transmitted from generation to generation in the Korean peninsula since the periods of Goguryeo and Baekjae. For the period of Goryeo (918-1392), the conduits of warming of the ground cover the whole of the room. This change occurs at the latest at the 13th century. For this period, this type of room is called “uksil”, meaning hot room, term which appears in the documents of the beginning of the Kingdom of Joseon.

The traditional heating used during the Kingdom of Joseon (1392-1910) and the Japanese occupation (1910-1945) knows changes during the Sixties. Coal is used as fuel and the structure of the furnaces is modified. Later, the boiler is introduced to heat water and to make it circulate through the pipes. It was then the turn of the electric heating. More recently, the gas of pétrol liquefied was used and with the distribution of warm water in each hearth, the heating on a great zone (translated into Korean by local heating) becomes possible. Thus each hearth, that it is a house, multifamily apartments or large buildings, can from now on profit from a heating with pipes under the ground.

The ondol is present under the ground of any residential space and even of any Korean architectural structure. At the time of the Joseon dynasty, girls and boys could not be together, there was then in each house, a space with ondol for each one. This tradition is maintained until today because except for the living rooms in floor, the rooms always use the heating system on the ground, but this time by warm water circulation.

A lifestyle related to the ground

The ondol encourages the Koreans to sit down directly on the ground. At the time where the conduits were installed L-shaped, there were at the same time zones hot and cold in the same room. Chairs were laid out on the cold part. However, starting from the medium of the Kingdom of Goryeo, the Koreans did not use practically any more the chairs and asseoient themselves directly on the ground. This lifestyle involved a diversification of space. Thus, during the Joseon dynasty, the room of the women were used of living room, dining room the day, and as room to lay down the evening. The same room thus fulfilled three functions.

A room with ondol requires insulation while the living room without ondol request an opening. These two requirements could be satisfied thanks to the original fitting with the doors and the Korean windows, allowing a space isolated and opened at the same time.

The ondol, single heating system, and in particular its L-shaped conduits, largely influenced Chinese architecture, giving the construction of “kang” in Siheyuan (enclosed rectangular) of Beijing. In this kind of habitat, the conduits are arranged in straight line under part of the ground, the furnace is in the room while the chimney is outside the part.

In the United States, Frank Lloyd Wright (1867-1959), fascinated by the ondol, creates the heating on radiant surface (panel heating). When designing Imperial hotel of Tokyo in 1916, Wright develops the heating on radiant surface based on the principles of the ondol. The Japanese were strong interested parties by Ondol but they could not generalize it because of the seismic risks.

Joo Nam-Chull Professor emeritus of architecture at the University Korea (12.03.07)

According to the official agency North-Korean KCNA, " the system of ondol is indeed a tradition of the Korean people. Vestiges of ondol were found in sites of dwellings dating from the time of the kingdoms of Koguryo and of Palhae and them files of the kingdom of Koryo prove that the ancestors of the Korean people lived in houses heated according to the technique of ondol" (source: ).

According to the same source, " the system of ondol, which envisages the underfloor heating initially of a part, gradually developed today in system of central heating of all housing. Already at the time of the Koryo, all the surface of the ground was heated by the system of ondol".

This heating system developed since 1945 in North Korea and South Korea.

Category: Korean culture

Random links: