Optimization Of Indoor Thermal Environment In Winter For Traditional Tibetan Dwellings In The Sichuan Northwestern Plateau

The indoor thermal environment has an important impact on human health and comfort,and the poor indoor thermal environment is not conducive to human health.The indoor thermal environment is mainly affected by outdoor weather parameters such as outdoor air temperature and humidity,wind speed and solar radiation.The Sichuan Northwestern Plateau,which is part of the Qinghai-Tibet Plateau,located in the Ganzi Tibetan Autonomous Prefecture and the Aba Tibetan Autonomous Prefecture.The average annual temperature in the region is low.Between 1961 and 2010,the average regional temperature was only 8.2℃,and the annual average temperature of Songpan and Ganzi was around6℃.According to previous research,the indoor thermal environment in the Sichuan Northwestern Plateau traditional dwelling is poor,which can not meet the requirements of human comfort and health.It is necessary to pay attention to the indoor thermal environment in winter of traditional Tibetan dwellings in the Sichuan Northwestern Plateau.So,it’s critical to explore optimization strategies for improving the indoor thermal environment in winter for this region.To put forward the optimization strategy for improving the indoor thermal environment,a field research and a series of numerical simulation studies have been did.During January2018,a field research has been did in the Qiongshan Village,located in Danba County,Ganzi Tibetan Autonomous Prefecture.The investigation include the questionnaire survey for local residents’thermal sensitive and heat expectations,and a series of field measurement in a typical residential building,including the air temperature,the air humidity and the wall temperature.Based on the survey results,a thermal comfort evaluation has been did.And moreover,a numerical simulation method was used to discuss the optimization strategies by the building energy simulation tool EnergyPlus.Finally,an optimization has been put forward and evaluated.The questionnaire survey results show that most local residents feel neutral,while the number of residents who are dissatisfied with the current thermal environment is only 2%of the respondents.And 60%of respondents expect the thermal environment become warmer.The measurement results show that during the test period,the outdoor mean air temperature is 4.75°C,the indoor mean air temperature is 5.93°C without any heating equipment,and intermittent heating,indoor mean air temperature is 9.04°C.Moreover,according to the aPMV indicator,the acceptable indoor temperature range is 9.75°C-22.31°C in the most of the time during the test period.So,there are some problems that indoor air temperature is low and thermal comfort is poor for traditional dwellings in this region.The good thermal performance of the building envelope can resist the influence of outdoor climate on the indoor thermal environment effectively.On the other hand,there are abundant solar radiation resources,which can raise indoor air temperature effectively.Therefore,the optimization strategy is proposed from these two aspects.According to numerical simulation results,when the heat transfer coefficient of the building exterior wall is greater than 0.1W/m~2·K,it has a parabolic relationship with the indoor temperature in winter.And when the heat transfer coefficient of the building exterior wall is 0.15W/m~2·K,the indoor temperature in winter can be increased by up to 3°C.When the roof heat transfer coefficient is 0.10 W/m~2·K,the indoor temperature in winter is increased by about 3°C.The solar radiation absorption coefficient of the roof has a linear relationship with the indoor temperature throughout the year.When the value is 0.86,the indoor temperature can be increased by about 0.8°C.Furthermore,additional sunroom can increase the indoor air temperature of adjacent room effectively.The indoor temperature can be raised by 4~10℃,and the indoor air temperature in winter can reach up to 20℃.After optimization,the indoor air temperature in winter can be increased by 18°C,while the index of heat loss of building is 7.75 W/m~2.In addition,some optimization strategies and building construction suggestions for improving the indoor thermal environment during winter are put forward.And the results of this paper can provide a reference for the traditional Tibetan dwellings in the Sichuan Northwestern Plateau to improve the indoor thermal environment in winter.