Seongjeonggak Hall in Changdeokgung Palace, although built after the Japanese Invasion in 1592, displays the architectural style and structure of Early Joseon period. It did not include ondol (Korean floor heating system) and contained Early Joseon style window frames. Later, King Jeongjo installed ondol as he repaired the building into a more convenient office. The initial construction of Seongjeonggak Hall was based on the architectural ideology of the Early Joseon Period, which divided up the space according to the season. Thus, the initial structure of the building consisted of a joint of a one-story building and a two-story building with the top floor of the latter specialized for hot and humid season. The two-story building was called ‘chimnu(寢樓)’, and its top floor was called ‘nu-chimsil(樓寢室)’