Shan Pavilion at the Zhan Garden in Nanjing was the earliest air-conditioning architecture in the world and could be used to keep warm in winter. [Photo/IC]

Ground heating system

Kitchen range made with sun dried mud bricks were also found in Han Dynasty ruins which was equipped with discharge flue. In addition, a fireplace was found beside the wash bath at the ruins of Xianyang Palace dating from the Qin Dynasty.

During the Ming (1368-1644) and Qing (1644-1912）dynasties, a ground heating system was used indoors, which was built by concreting circular flue underground. The charcoal fire smoke would flow through channels to the whole room and raise the temperature indoors. The ground heating system enabled the room heat up evenly and mildly. As the fiery pit and smoke jack was set outdoors, the heating method was safe, clean and practical.

The ground heating system wasn't invented by Ming and Qing dynasty people. It emerged as early as Wei and Jin dynasties (AD 220-420). The historical record shows that the northeast part of China had used fire pits to keep warm during that time, which functioned similarly as a ground heating system.