Previously, I gave an overview of the ondol heating system of the traditional Korean home, the hanok. To recap, ondol is a form of radiant floor heating similar to the Roman hypocaust. It utilizes the heat of a fire that passes beneath a raised stone floor in order to create a comfortable place to sit, eat, and sleep, which is especially necessary because most activities traditionally occurred on the floor.
Restored upper class home at Namsangol Hanok Village with doors open facing courtyard.
Ondol was created because winters on the peninsula can be extreme, but summers are just as worse. High levels of humidity are notorious for making Korean summers almost unbearable. As a result, hanok were designed to allow maximum natural ventilation. Although there are regional variants, a typical floor plan was L or I-shaped with adjoining rooms commonly consisting of at least two walls with paper screen doors facing each other. Homes would be oriented with these walls facing prevailing winds in order to experience cross ventilation.
View through a hanok illustrating its openness to allow cross ventilation and views.
However, in The Green Studio Handbook by Alison Kwok and Walter Grondzik, it is noted that cross ventilation is dependent upon 1) differences in temperatures indoors and outdoors and 2) outdoor airflow rate, a.k.a wind. From my experience in Korea this summer, I know that summer breezes are weak. The air was generally stagnant, muggy, and very uncomfortable due to the humidity. So how do hanoks optimize cross ventilation and the comfort of those inside them? Paper screen doors open directly to the outdoors in order to allow air movement at the occupant level and increase human comfort. Some key rooms are also raised off of the ground, thus creating a Venturi Effect, where the decrease in pressure at the lower level aids in increasing air movement in the room above because of pressure differences and a wooden floor with visibly open joints. In other words, the air being pushed beneath the floor sucks in air from the room above through the floor and moves it by creating differences in pressure.
Raised portion of a hanok at Changdeokgung, one of the five palaces in Seoul, allowing maximum ventilation.
The hanok is a structure that responds to the climatic extremes of the Korean peninsula. It is designed to increase the efficiency of moving air by creating a very porous structure in the summer. It is also designed to effectively distribute heat through the radiant heat of ondol in the winter. With these lessons in hand, Korea has the tools to incorporate more sustainable methods in its architecture. Looking to tradition will prove to be invaluable for a nation struggling to create continuity between the past and the future.