Study On Thermal Optimization Of Low Energy Consumption Residential Buildings In Tibetan District Of Sichuan Province

The issue of energy and environment is a great challenge facing all countries in the world today.The geographical environment of Tibetan district of Sichuan province is complicated,the climate is diverse,and the conventional energy is scarce,so the ecological environment there is fragile.If conventional energy is used to solve the problem of winter heating,energy waste and ecological environment destruction will be caused.Therefore,it is of great significance to study low energy consumption residential buildings in Tibetan district of Sichuan province.Firstly,through the field investigation and tests of the traditional residential buildings in the Tibetan district of Sichuan province,the passive experience in the site selection,shape design,orientation,layout and building materials was summarized,which provided direction for quantitative research on orientation,body shape and thermal design optimization of envelope structure;An experimental study was conducted on the indoor thermal comfort of residents in Tibetan district of Sichuan province by means of thermal sensory voting,which provided a basis for determining indoor thermal comfort standards for low-energy residential buildings without auxiliary heat sources and ultra-low energy residential buildings.Secondly,the synergistic process and laws of geographical and meteorological factors and building thermal design parameters on indoor temperature and heating demand are systematically studied.By quantitatively studying the coupling effect of geographic and meteorological elements on building orientation,the concept of the average temperature difference of the total orientation is proposed,and the optimization method of the building orientation based on the equation of the average temperature difference of the total orientation is given.A simple calculation method of the occlusion orientation is presented.By quantitatively studing the coupling effects of geographical and meteorological factors on building shape,an optimal design method of building shape based on the optimal depth equation is obtained.By quantitatively studying the coupling effect of the thermal performance of the envelope structure on indoor temperature and heating demand under the influence of multiple factors,the thermal design optimization method of the envelope structure based on the multi-factor relationship equation is obtained.Thirdly,by quantitatively studying the sensitivity of geographical and meteorological factors such as solar radiation,outdoor temperature and atmospheric pressure to the changes of indoor temperature,the equations of influence of solar radiation,outdoor temperature and atmospheric pressure on the changes of indoor temperature are obtained.A simple calculation formula for indoor temperature can be obtained by using the influence degree equation,then based on this calculation formula and indoor thermal comfort standards,the necessity criterion for auxiliary heat sources for low-energy residential buildings is obtained.Fourthly,by quantitatively studying the effects of meteorological elements such as solar radiation,outdoor temperature and thermal performance of enclosure structure on the heating demand,a linear equation for the influence of meteorological elements and thermal performance of the enclosure on the heating demand is obtained,then based on this linear equation,the thermal design optimization method and thermal design division of ultra-low energy residential buildings are obtained.Based on steady-state heat transfer calculation,with annual net income as dynamic economic evaluation index,the economic evaluation of the high-performance enclosure structure and the total heat exchange fresh air system is carried out.The economic feasibility zone division index of the high-performance enclosure structure based on the relationship between heating degree day and the solar radiation intensity is proposed for the first time,and the heating degree day were proposed as the economic feasibility zone division indicators for installing a full-heat-exchange fresh air system at this stage.The above work provides specific design methods and basic theoretical support for the thermal optimization of low-energy residential buildings and has important value and significance for the rapid development of low-energy buildings in Tibetan district of Sichuan province.