The Study On The Natural Ventilation Design Of Rural Residential Houses In The North Of Hunan Province

With the rapid development of Chinese economy and the improvement of people's living standard, energy-saving of residential houses turned into the important part of sustainable development. Because of the large building area, the energy consumption growth of rural residential houses should be paid more attention. Based on the undeveloped countryside economy, the emphasis of the energy-saving in rural residential houses should be the utilization of passive technologies in order to reduce the energy consumption and the increase of energy demand. Design is the key in the utilization of passive technologies, but the design of rural residential houses are rough and worth to be improved.Based on the approaches and barriers of sustainable building, one of the important barrier was proposed, which is that the research findings are hard to be ultilized by designers. With the analysis on the status of Chinese sustainable building, the focuses are proposed including equipment, materials and technologies, design and education, especially the design. Combined with the development of the status of Chinese building design and the architectural semiotics, "quantitative symbol" is proposed as a new design methodology that integrated with the traditional figurative thinking and quantitative thinking. Furthermore, the possibility of the new design method by using in the rural residential houses is analyzed.The investigation of energy consumption was carried out in 128 houses located in the north of Hunan, and the measurement of indoor environment was implemented in a traditional folk house and a modern house in Zhangguying Villiage. The results show that the energy consumption of rural residential houses in the north of Hunan is only 2/3 of the urban houses and the power consumption is only 2/5 because of undeveloped economy. From the analysis of the indoor environment, it was known that the traditional folk house got the comfortable indoor thermal environment and natural ventilation by shading, envelop insulation, site selection and other passive technologies. As a comparison, the modern house got the uncomfortable indoor thermal environment because of lacking passive technologies. But shading also reduced the indoor lighting environment in the traditional folk house. So, the research on the rural residential house should focus on the passive technologies with low energy consumption and costs. The utilization of passive technologies should consider the different demands in different season. When the demands are conflict, the demands in summer should be considered first. Natural ventilation is one of the important passive technologies for passive cooling in summer and worth to be studied carefully.With the specific study object, the natural ventilation effects of varies condition in three site selection models, including site selection model with undulating topography, site selection model with plants and site selection model with road, were simulated by the computational fluid dynamics (CFD) software in order to get the optimal site selection models and the corresponding "quantitative symbols". The results show:With undulating topography, the suitable space between the building and the hill is 12m despite the height of hills; With the plants, the suitable space between the building and the plants is 12m and the range should extend 4m from the west and east outside walls; With the road, when the space is 12m between north and south buildings, the north building can get the best natural ventilation effect in summer. Then, other technologies should be adopted for defending the cold wind in winter.Then, the natural ventilation effects of varies condition in three plane design models, including interior door design model, accessary space design model and patio design model, were simulated by the CFD software in order to get the optimal plane design models and the corresponding "quantitative symbols". In the interior door design, the oppositive open mode is useful to improve the natural ventilation in the north rooms; In the accessary space design, the space placed on the north or south side and extruding inward can not only improve the natural ventilation but also saving the land; In the patio design, when the depth is 2m, all of the indoor spaces of the building can get the best natural ventilation effect.In order to compare the simulation results, wind tunnel experiment was carried out for testing the site selection model with undulating topography in 10 conditions with different spaces and flow angel. The results of coefficient of wind-pressure comparison show that the average error is less than 15% and the single measure point error is less than 20%. For the simulation results using in the design and engineering, the simulation accuracy is acceptable and the simulation results can be used in the natural ventilation design of rural residence houses in the north of Hunan.In order to use the best models that proposed above in the design process, the characters of rural residence houses in the north of Hunan were summarized and the iterative design process were suggested including site selection, surrounding environment, orientation, plane design and detail adjustment. Then, evaluation criterions and weight coefficient for natural ventilation design of rural residence houses were determined by the analytic hierarchy process and expert panel.The main innovations of this dissertation are shown as follow:(1) Based on the status of the development of Chinese sustainable building and the building design, the "quantitative symbol" was proposed for the first time integrated with the architectural semiotics.(2) Energy consumption and indoor environment of the rural residential house, including the traditional folk house and the modern house, in the north of Hunan were investigated for the first time. Based on the investigation results, the characters of energy consumption on rural residential houses were analyzed and the indoor environment of the traditional folk houses and modern houses were compared in order to get the strengths and weaknesses of the passive technologies design.(3) The natural ventilation effects of varies condition in site selection model with undulating topography, plants and road were simulated by the CFD software. Then,3 best site selection models and the corresponding "quantitative symbols" were summarized.(4) The natural ventilation effects of varies condition in interior door design, accessary space design and patio design were simulated by the CFD software. Then,3 best plane design models and the corresponding "quantitative symbols" were summarized.(5) Based on the characters of rural residential houses and design, existing building design process and evaluation methods, the new natural ventilation design process and evaluation system were suggested.