The primary purpose of heating systems is to raise the temperature of an enclosed space for added comfort of the occupants. The system regulates ambient temperature, thus additionally maintains the electrical structural and mechanical building systems. The heating system has seen a very dramatic history, from hot smoke-heated floors in ancient Asia to modern heating systems. The following highlights the significant systems that formed the basis for modern heating systems in Asia.
Kang and Dikang
Baked earth and raised surfaces, treated by fire, have been discovered to be in use in ancient China, dating back from 5300 to 4300 B.C. The process of baking the earth, known as zhi, gave rise to the kang and dikang.
Kangoriginally stood for “to dry”. It later was used to refer to a raised heated and seating surface. The original kang designs, traced back to the 11th century B.C consisted of a raised surface in the living and sleeping areas. In most cases, especially in the colder regions, the kang, taking the form of a U shape or a bed-like surface, occupied more than half the room area. The primary source of fuel was charcoal and wood. From the main combustion area, the heat was conducted though flues built into the floor.
The dikang was used in the northeast Manchuria regions. A dikang is a kang that covers the entire floor. It consists of a fireplace, a chimney (for wood fueled systems) or without a chimney for the charcoal variant. The flues in the floor transmitted the heat around the room. The heat was then conducted to the room, and occupants, through various stones placed strategically around the room. The Manchurians preferred heated floors to a raised surface in the kang system, popular in the northern Chinese areas.
The Koreans developed a variation of the kang known as the ondol. The system consisted of two primary components: the heat source and the flues. The heat source was the primary kitchen stove. The flues would then transmit the heat around the building’s external wall and floor. Strategically placed stones would then radiate the heat from the flues to the room. The comfort associated with these rooms gave rise to a lifestyle where Koreans would remove shoes before getting into a room. They sat and slept on the heated floor.
The original designs of the ondol, 4th century B.C TO 11TH century A.D, consisted of L and I shaped heating systems. A complete set of an ondol consisted of an agungii, (a furnace located outside), a gorae, (the gas passages) and a guldik, (the chimney). The L shaped variant common in the cold northern regions, was primarily used by the lower class. Later on, from 700-1100A.D, it was adopted in the central regions of Korean peninsula by the middle and upper class people, who developed better designs. The shorter I shaped design was used at the warmer areas. However, the indoor placement presented a number of challenges. This included overheating and a lingering smell of food. To overcome these challenges, later designs, between 1000 and 1200 A.D, saw the placement of the actual heat source outside the rooms.
As from 2000, hot water heating systems have gradually been adopted throughout modern China. Although the central heating system, consisting of radiators and heating ducts is in use in some places, there are not popular due to the emanating air pollution. Many commercial and residential buildings are therefore, fitted with hot water systems from the onset. Most traditional buildings, however, still feature modern design kangs. The change, however, is the introduction of biomass as the main source of fuel. Experts have found a change in the fuel and renovations to be more economically viable than replacing the entire heating systems.
The traditional ondol design was replaced by a modified design after the Korean War in 1953. The furnace was adapted for use with coal, as the Korean government sought to reduce on deforestation. The modern design featured energy efficient features such as floor insulation, cast concrete block and a heat release system. As from 1975, however, more and more residents and property owners abandoned the systems to settle on hot water radiant floor heating systems. Attempts to introduce the western lifestyle radiators have proven to be unsuccessful over the years. This is because people still prefer the warm floor associated with hot water radiant heating system.