An Analysis of the Ecological Features of Stilted Building in Yanzibian , Southern Shaanxi , China

Silted building is one of the most characteristic traditional residential building types. In the historical process of social transition, silted building has powerful ecological adaptability. Nowadays, there are only a limited number of silted buildings in the Southern Shaanxi region. Thus, this paper is aimed to acquire the first hand data by a field survey on the silted buildings in Yanzibian in Hanzhong, Southern Shaanxi region. Through an analysis of its building idea and technique, the paper interprets the ecological features of silted building in terms of aesthetic consciousness, selection of site, pattern, material usage and building technique, etc. The research result is aimed to provide a lot of referential influences and value for residential buildings and construction of new rural areas in the future and to provide enlightenment for design of ecological buildings.


Introduction
Building is the carrier of culture.Through the ontology of building, we are able to know about its cultural transition, belief and worship as well as the local customs.Also, we can have an idea about how the building adapts to the survival environment.All this can be embodied thoroughly in building.This paper interprets and perceives the ecological features of silted building by studying the mountainous form of silted buildings in Yanzibian in Hanzhong, Southern Shaanxi.

Overview
Southern Shaanxi refers to the area in the southern part of Shaanxi Province and contains the three areas of Hanzhong, Ankang and Shangluo ranging from the west to the east.Yanzibian is located in the western part of Ningqiang County in Hanzhong City, Shaanxi Province.It is neighboring to Sichuan Province and Gansu Province and is connected to Yangpingguan Town and Anle River.As it is located in the intersection between the two rivers of Jialing River and Anle River, Yanzibian is one of the four ancient ferries in Ningqiang County.Yanzibian is named as its form is similar to a swallow that soars with lifted wings.In Yanzibian, beautiful mountains and clear waters are everywhere and the scenery is as beautiful as a picture (See Figure 1).Until now, at the mouth of the shore of Yanzibian stand tall and upright only a few silted buildings.
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Selecti
To comply farming cu thought th According between h ancient pe the though nature as a that the da exchange w Selection comprehen practice fo effect on a the ancien and man".the sphere site, patter disaster an should be is suppose rosefinch a can be fou   wall, wall itself does not have the effect of moisture proof and it becomes softened once it is mixed with water.In the construction of the wall, grait is used as the basic damp-proof course and the wall space is often smeared by cob in a well-distributed way, which has a good antiseptic moisture-proof effect.The third merit is the microclimate adjustment effect.The summer in Yanzibian is hot and the sunshine duration is relatively adequate.Sunshine leads to increased temperature of the outer wall.Thus, weaved thin bamboo is added in the process of building a wall.A lot of air is left in the thin bamboo stalk, which forms an air insulating layer and which makes the wall have good functions of heat preservation and heat insulation.The four and the last merit is the force reduction and anti-shake.Since bamboo reinforcement is added in the wall, this strengthens the toughness of the wall.When an earthquake occurs, the wall is pressed by the bamboo cane and is absorbed in a disperse way.This weakens the effect of the force on the front wall.

The Structure of the Roof
The root of silted building in the local area adopts the basic "bone" pattern of sloping root (See Figure 5).The pattern of sloping root has realistic meaning in embodying the ecological features of traditional residential houses in Southern Shaanxi.
Figure 5. Silted building and sloping root in Yanzibian On one hand, the sloping roof of Southern Shaanxi is usually constituted by tiling and cant strip.Between the two layers of tile is naturally one layer of air interlayer which has the performance of strengthening thermal insulation and heat insulation.Since the slope of the root is large and is convenient for drainage of water, it has a perfect effect of insulating rainwater.On the other hand, since the temperature difference in the summer in Yanzibian is great, the high root can play a good role of transitional space.The eave overhangs far.This is not only aimed to speed up drainage of water, but also the far-reaching overhanging eave helps to make the room in a low temperature of shadow for a long time and reduce the possibility that the sunshine directly radiates the wall.This also can prevent the rainwater from soaking the base layer of the wall when it drips, which reduces the direct damage of rainwater to the wall.

The Structure of the Ground
Construction of the ground of silted building is relatively simple.Its foundation part is usually constructed with rock or grait.The first layer of ground is pieced together by board, having perfect performance of heat preservation, thermal insulation and humidity resistance.On the second layer and the third layer of ground, the lower layer is laid with board, the middle layer is mingled with two layers of tiles which have the effect of consolidation, and the top layer is laid with a layer of board.Some houses are laid with fabricated board.Under the ground is keel and on the keel is supported with board.In order to make it ventilated and moisture proof, each board with have a crack less than 1cm in advance.In the rainy season of summer, the board can be torn down to store in order to prevent the board from going mouldy.

Parvis -The Effect of Filtering
The space of parvis is the result that people gradually improve and develop the residential buildings to respond to the local moisture and rainy natural environment.As the old saying goes, "A good and wealth parvis in a building is mostly upright, foursquare and neat.And in a good parvis, the parvis usually has the meaning of storage.What the parvis stresses is uprightness and foursquareness flourish the parvis.Such natural Yin and Yang rhythm is not necessary to pursue continuously" (Ruoguan Daoren, 1995, p112).
Its ecological presentation: 1) Lighting and ventilation.As the distance between buildings in the courtyard of a traditional residential house is relatively short, lighting and ventilation in the courtyard is not smooth and the parvis has a good effect of adjustment.2) Collection and excretion.The so-called "Four water running to the hall" has the meaning of draining off rainwater to the parvis through the eave hanged from the parvis, which also has the meaning that rich water should be kept in one's own field.As for the silted building, an open parvis can bring in clean air from a high altitude.One part of air discharged from the room is drained out to the courtyard through the drainage ditch of the parvis under the effect of gravity.Another part of light air will escape from the parvis.Air inside and outside the room is continuously exchanged, which has the effect of purifying the air.3) In addition, the parvis is an open space where privacy is relatively weak, which forms a transitional space for the inside and outside environment of the room.

"Guobai" -The Effect of Moisture Protection
In the traditional Chinese architecture, "Guobai" is a method to deal with the vision of space.As a matter of fact, it reflects a phenomenon of an architecture group in spatial combination and is application of the aesthetic experience of the ancients.It can be said that, "Guobai" takes advantage of the skillful distance between the door and the scenery and uses the method of mingled scenery and enframed scenery to let a close view and the distant view to fall into the vision of a viewer.The feeling of the view should not be complete, but should be comfortable, so as to satisfy the aesthetic need of the ancients.Here, "Bai" refers to the light of the sky, so that not only the viewer can view the ridge of another building at the opposite, but also a thin of sky is required to remain in the vision to attain "balance of Yin and Yang".This thin of sky, similarly, relates to the lighting and sun adoption in the room and has certain effect of moisture protection and damp protection (See Figure 6).Appropriate control and adjustment of the distance between different buildings can effective prevent the phenomenon of "extensive moisture" on the land in the parvis in the house.It is necessary to adjust or control the height of "Guobai" according to the climate feature, architectural direction and elevation of the residential buildings so as to attain conversion and balance of Yin and Yang and to promote better improvement of the light environment and heat environment in the parvis.

Concluding Remarks
Ecological environment plays a restrictive role in the development of human kind, while development of human kind is a process that continuously adapts to and modifies the environment to satisfy the demand of human kind.This is exactly an interactive mode between man and the nature.Whether in terms of aesthetics, selection of site, selection of materials and design or in terms of building, the silted buildings in Yanzibian in Hanzhong of Southern Shaanxi imply abundant ecological wisdom.The characteristics are delicate, pretty and simple aesthetics, pattern next to the mountains, local use of materials, wonderful art and excelling nature in design and building adjusting measures to local conditions.All these characteristics are the result of long term co-existence and co-survival of local people with the ecological environment that they depend on.This promotes silted building to play a harmonious and organic role in the ecological environment system.If these ecological features can be protected, developed and used, it is believed that this will be of great benefit to ecological residential housing and new rural construction in the future.And this will create ecological home that is more appropriate for human kind to reside in.

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