Vernacular Underground Chinese Villages: the Yaodong

The Laoniuwan valley, in Shanxi Province, is located between a bend in the Yellow River and a rough yet green terrain of the Loess Plateau. For centuries this place represented the outer limit of imperial rule and there remain portions of the Great Wall, which rises and falls according to the ancient erosion gullies of the earth. Here the main long, narrow road circles sweeping mountains, flanks the terraced, green fields interspersed with traditional underground villages, thus composing a very unique natural and human landscape. The Laoniuwan village is a very ancient one: it developed under the Qing Dynasty (1644-1912), occupying a dominant position on an important landing along the Yellow River and inside the walls of the homonymous fortress, from the Ming era. Thus, it had played a strategic role for the defense of borders and for trade with the Tartars, on the Mongolian side of the river. Laoniuwan is a typical example of Chinese underground settlement, made of cave dwellings, known as yaodong (??), dug into soft stone of the loess hillsides. That's why the Plateau, is very fine and loamy, and is highly fertile, easy to farm and dig. Despite the easy erodibility, the Plateau' terrains have the characteristic of being pseudo coherent, i.e. they can be excavated and the cavities are more or less self-sustaining. Thanks to this property, cave houses in Loess Plateau represented an insulated shelters from the semi-arid climate, cold in winter and hot in summer. Thus yaodongs have been existed for thousands of years, providing good living conditions with less expense on the energy, and even today, in China, there are perhaps 20-30 million people still living there. Generally, a yaodong is a kind of artificial cave, made by earth subtraction, and adapted into living space by closing the entrance with walls made of fired bricks, earthen bricks, stones, wood, depending on the different sites. While Laoniuwan's ones represent a very local type, a kind of hoop yaodong, having a chamber partially above ground connecting together 3 or 5 underground rooms. Thus the chamber has three stone and/or earthen bricks walls, with an arched structure on the main one allowing the sun to further penetrate inside the caves. A wooden and straw roof protects the above ground structure, covered by at least two meters of soil mud to ensure the thermal insulation of the caves. In that sense Laoniuwan's type uses and optimizes local materials constituting the very expression of local geo-climatic conditions and traditional uses. As for many traditional Chinese rural villages, in recent years, many of the residents have moved to big cities, looking for a work or more modern living conditions. However, Laoniuwan has been tried to not losing its vitality by attracting tourism, even if some problems still restrict its sustainable development. Since 2016, through a series of projects, this multidisciplinary research group, on a comparative basis between Italy and China, has dealt with the evaluation of best practices in the field of conservation, sustainable use and enhancement of underground heritage, such as cave dwellings. The research is still ongoing and the paper will introduce some project premises by analyzing the Laoniuwan village case.