Why do 40 million people in China live in caves?

On the 635,000-square-kilometer Loess Plateau, traditional houses are still loved by local people, and about 40 million people live in such caves. This unique earth architecture has attracted the interest of more and more domestic and foreign architectural experts.

Cave dwelling refers to an arched cave dwelling house excavated at the edge of the earth cliff on the Loess Plateau, which is generally 3 meters wide and 7 to 8 meters deep. There are many types of caves, such as loess caves built by cliffs, caves built by adobe clods, caves built by quarrying on the spot, sunken caves with holes in the wall after digging a pit on the flat ground, semi-underground caves with composite soil, etc.

According to textual research, as early as 6,000 years ago, during the period of caves and semi-caves in banpo village, Xi 'an, there was a prototype of caves. Cave dwelling is a creation of our ancestors to develop underground space. After 50 years of investigation and study, experts found that caves are beneficial to longevity and health: firstly, the temperature of caves is between 10-22℃ and the relative humidity is between 30-75%, which is the most suitable living environment for people; Second, living in caves for a long time, the external climate and radioactive substances in the atmosphere have little influence on people, and the prevalence of asthma, bronchitis, rheumatism and skin diseases is obviously reduced.

Because the earth caves are not strong and beautiful, farmers who have become rich in recent years are more willing to build stone caves. Among the 6.5438+0.48 million agricultural population in Yan 'an, there were more than 600,000 holes in the newly-built stone kiln during 6.5438+00 years, and more than half of the farmers moved into new houses. There are still cave dwellings for urban and rural residents in Yan 'an 1/4, with about 50,000 households. Lanzhou municipal government allocated 200,000 yuan to start the experiment of cave renovation in Baita Mountain in the suburbs. Take steep gullies with no open value as construction land, and build caves with a total area of 1.500 square meters and 50 holes. This kind of terraced cave has an area of 34 square meters per hole, low cost, energy and land saving and good seismic performance. It not only solved the problems of dark, damp and poor ventilation in the old cave, but also maintained the inherent advantages of the cave, which was well received by the Ministry of Urban and Rural Development and experts and scholars at home and abroad.