Analysis Of Solution Multiplicity And Potential Of Natural Ventilation In Buildings

Natural ventilation had ever been neglected since the development of air conditioning. But recently, with the energy crisis and the using of closed air conditioning system, several problems related to indoor air quality and human health arose. Furthermore, meeting with the demand of sustainable development, natural ventilation has been attracted more and more interests from scientists and other related researchers or engineers again. Good application of natural ventilation is necessary because it can reduce initial construction costs and operating costs for residential buildings while maintaining ventilation rates consistent with the requirement of acceptable indoor air quality. However, it is much more complicated to utilize natural ventilation in modern buildings than before in traditional buildings. The reason for this lies on one hand that people have higher requirement on indoor air environment while building style and functions are more complicated, on the other hand, the indoor thermal comfort requirement of residents is higher. But as natural ventilation is affected by weather violently, if natural ventilation can be employed is not a question as simple as before. Therefore, this thesis focuses on the basic mechanics study of natural ventilation and its application potential in China, which is very important for the development of natural ventilation technology, building sustainable development, as well as good human living environment.The background and practical meaning of natural ventilation was firstly presented. Then the state of study on natural ventilation theory, potential analysis methods and its application was reviewed.For complex multi-zone buildings, the multiple solutions phenomena and flow multiplicity have received more and more attentions. The theoretical analysis was employed for studying flow variety and airflow in a two-zone model with different zone height. Then MIX program was used to compare the results and Fluent software was implemented to simulate and model. There were good agreements between the analysis data and simulation results. The results showed that multiple solutions and unstable solution existed with different height of zones and the simulation data can provide theoretical support for fireproofing and building design.A questionnaire investigation on 165 apartments' natural ventilation and thermal environment was carried out in 9 cities, Hunan province. Also some field experiments...