How do Koreans traditionally heat their homes?

Ondol in Korean traditional architecture, is underfloor heating similar to a Kang bed-stove that uses direct heat transfer from wood smoke to heat the underside of a thick masonry floor. In modern usage it refers to any type of underfloor heating, or to a hotel or a sleeping room in Korean style.

The main components of the traditional ondol are an agungi (firebox or stove) accessible from an adjoining room, a raised masonry floor underlain by horizontal smoke passages, and a vertical, freestanding chimney on the opposite exterior wall providing a draft.

The heated floor, supported by stone piers or baffles to distribute the smoke, is covered by stone slabs, clay and an impervious layer such as oiled paper. Ondol is that it can maintain heat for an extended period. In a traditional Korean house, people usually extinguish the fire before going to sleep at night, since it can stay warm until the morning.

The advantage of the Ondol is that the Ondol but these systems must be checked each year for safety issues. However, asphyxiation can occur due to lack of air circulation and ventilation hazards.

The Ondol does has some disadvantages. However, any leaks in the floor would allow black smoke to seep into the room. This would be the same pathway that the deadly carbon monoxide would get into the living quarters, putting the occupants at risk. Ondol has been linked to asphyxiation when the ventilation is inadequate.