Investigation And Analysis Of Thermal Insulation Performance Of Rural Residential Building Envelopes In Hunan Area

With the rapid development of society and economy, building energy conservation has become an important part of sustainable development in our country. As rural residential buildings have been constructed at an annual rate of 500-700 million m2, its energy consumption is continuously increasing. With the development of the new urbanization, the thermal comfort requirements of the residential environment are higher. Consequently, most people use air-conditioners and electrical fans to make their lives more comfortable, but resulting in consuming more energy. However, envelopes in rural area are normally not well insulated or even not insulated, causing a greater energy waste. Thus, it is extremely important to study the thermal insulation system that is suitable to apply to rural residential buildings in Hunan area.In this paper, a field investigation about 370 rural residents has been firstly carried out in Hunan region to figure out the existed problem in rural building envelopes. Through the survey, the results show that 63.2% of the investigated buildings has t wo stories and the building area is more than 100 m2. In this area, 240-mm clay brick wall is generally used for external wall, which accounts for 75.7% of the dwellings. Typically, most buildings are built with pitched roof, single-layer aluminum alloy window, the proportion reaching 55.1%, and the window wall ratiois significantly larger. As a matter of fact, it can be found that there are few thermal insulation technologies had been applied to envelopes in Hunan rural regions and the window wall ratio is obviously too high. Other problems such as unreasonable planning, lack of technical support and weak awareness of energy conservation are believed as important factors that cause building energy inefficient.Then, a simulation was performed to study influ ence of different thermal insulation materials on energy consumption. Thus, several standard buildings was built and simulated by utilizing Design Builder. The simulation results states that external walls occupy the largest proportion of the total energy c onsumption of building envelope, the ratio is 50.6%-56.1%(The external wall of slope roof forms of residential is 56.1% and the flat roof forms of residential is 50.6%.). Furthermore, through the sensitivity analysis, this paper focus on the thermal insul ation of the external wall. According to the simulation and comparative analysis results, it can be concluded that extruded polystyrene board(XPS) board shows the maximum energy savings of about 21.4%, which is considered as the best thermal insulation ma terial in Hunan rural areas.Next, the optimal insulation thickness of external wall was analyzed and results were presented. When the thermal insulation thickness reaches 20 mm, the annual total cooling consumption indicators tends to be stable, and when t he thermal insulation layer thickness reaches 40 mm, the total cold heat indexes will also tend to be stable. At the same time, comprehensively considering the expenditure on heating, cooling and insulation materials, when thermal insulation thickness of the external wall reaches 30 mm the total cost is the lowest in a building life cycle. Therefore, the optimum thickness of the external wall of the rural residential buildings is about 30 mm in Hunan province.In summary, the results, as demonstrated in thi s thesis, show that the application of thermal insulation technology to rural residential building envelopes could be an effective and economic way that can greatly increase the efficiency of the building energy saving. Meanwhile, it can provide certain th eoretical and applicable foundation for energy-saving retrofitting of the existing residential buildings, and play a positive role for the future development of rural residential energy-saving technology as well.