Imagery
Wando & Jeonju Trip: 2005
This is the rear of the building, and you can see (although it will probably be more visible in the larger version; click on the photo to see it) the fire holes outside of each room and the chimney for the smoke. Basically, fires are lit in the holes and a system of flues circulates the hot air throughout the entire floor of the building. It gets nice and warm at night.