A yaodong (Chinese: 窰洞; pinyin: yáodòng) or "house cave" is a particular form of earth shelter dwelling common in the Loess Plateau in China's north. They are generally carved out of a hillside or excavated horizontally from a central "sunken courtyard".
The earth that surrounds the indoor space serves as an effective insulator keeping the inside of the structure warm in cold seasons and cool in hot seasons. Consequently, very little heating is required in winter, and in summer, it is as cool as an air-conditioned room.
The history of yaodongs goes back centuries, and they continue to be used. In 2006, an estimated 40 million people in northern China lived in yaodongs.
In the last decade, yaodongs have been brought to the attention of scientists and researchers. These traditional dwellings have been regarded as an example of sustainable design.