Study On The Indoor Thermal Comfort Of Naturally Ventilation Houses At Countryside

With the development of domestic economy and people's living condition in China, occupants seek to ask for more from indoor thermal environment. When air-conditioning system comes to thousands of houses, however, there are plenty of families can not afford it in China, especially in those rural houses. Could natural ventilation houses in countryside satisfy occupants'thermal comfort?Both the two criteria contain Fanger's PMV-PPD model, which is based on the extensive experiments at well-controlled, extensive and rigorous laboratory environments. This approach seeks to capture people's responses to the thermal environment in terms of heat balance between people and environment. Many researchers found the discrepancy between PMV-PPD model and occupants' actual thermal sensation through field study. They claim that indoor thermal environment at natural ventilation buildings is influenced significantly by the outdoor climate, and the regression of neutral temperature on outdoor temperature is provided. ASHRAE sponsored such study too and attach the result into its criteria, which is 5.3 of ASHRAE 55-2004. Could this standard be applied in the natural ventilation buildings in countryside in China?At the time of China has been propelling the New Socialist Countryside Building Campaign, many creative measures to improve people's houses are on the way. The writer organized a series of study, holding the two questions above. The team has studied the thermal environment in newly built houses in summer and winter at the Town of Xiao Yudong in Sichuan Province, and also the thermal sensation has been investigated at the same time. The PMV approach and TSV approach matches well when telling that local indoor thermal comfort in summer is good while it is terrible in winter. People have to use furnace to keep warm. Although most people feel cool in winter, the houses still able to sustain a temperature difference of 4℃between the indoor and outdoor temperature. The discrepancy between PMV and TSV approaches occurs most in winter when the indoor temperature is too low. The PMV model overestimates people's cold discomfort in winter.Then the writer tries to figure out the thermal comfort by the adaptive comfort standard in ASHRAE 55-2004. as well as the Fanger's PMVe approach expanded from PMV model, and the Yao Runming's aPMV model. It comes out that the adaptive comfort standard in ASHRAE 55-2004 is too limited in the ranges of occupants' clothing insulation, metabolic rate, and outdoor climate, while local people's habituation and climate don't fit well, so the neural temperature and acceptable indoor temperature ranges provided by the standard go even wilder than the results of PMV model do. Surprisingly Fanger's PMVe model shows wonderful ability when applying to the naturally ventilation buildings, as long as the expectation coefficiente is suitable. Yao's aPMV approach works effectively to adjust PMV to TSV at hot days in summer and cold days in winter, while in the neural days, the method is not so reliable. So the writer concludes that the so called adaptive comfort model which is only focused on the regression of neutral temperature on outdoor climate has too many limits in field study; Fanger's PMVe approach works well in naturally ventilation buildings and the future research on thermal comfort should be based on Fanger's PMV/PMVe approach, complied with actual thermal sensation investigation; it is an optional method to use Yao's aPMV approach when the thermal comfort is terrible.