Close to the Ailao Mountains in southwest China's Yunnan Province live Huayao Dai people, a branch of Dai ethnic group. Their houses are built of natural materials with soil as the main ingredient in construction. The four sides of the houses are rammed with clay. The soil on the roof alone is 20 cm thick. Such green houses absorb and dissipate heat slowly and can automatically adjust the temperature difference between day and night.

(All photos taken by CGTN's Zhao Ying.)

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