Studies On Summer Thermal Insulation Design Mechanisms And Methods Of Non-transparent Building Envelope Based On Regional Climate Difference

China has a vast area and high temperature in summer affected by monsoon.Thermal insulation in summer has always been one of the main contents of building thermal engineering.The temperature difference between indoor and outdoor is smaller in summer.The ratio of solar radiation in outdoor thermal loads is high.The existing research on thermal insulation of building envelope focuses on the shading of transparent envelope.Under the action of indoor and outdoor air temperature and intermittent solar radiation,the heat transfer process of a non-transparent envelope with a certain heat accumulation is more complicated.The poor thermal insulation effect of non-transparent envelope is an important reason to affect the indoor thermal environment of building in summer.Because there are obvious differences in the action mechanism and insulation methods of temperature and radiation,it is the basic work to improve the thermal insulation performance of buildings to carry out the research on thermal insulation design based on regional climate difference.Among them,the outdoor calculation parameters needed to satisfy the heat transfer analysis of non-transparent envelope,the influence of different climatic actions and materials,the structure on the thermal reaction characteristics of the envelope,and the radiation control judgment,design target determination and construction design in the design are all the problems to be solved in the thermal insulation design of non-transparent envelope.This study starts with the requirements of thermal insulation design in different regions and the hourly outdoor temperature and radiation parameters required for the study.According to the weather data of the ChinaMeteorological Administration for 30years,through the analysis of the trend of outdoor temperature change and its influence on the climate zones,the Degree-Day is used to subdivided the zones in the existing first-levelzones to distinguish the thermal insulation design requirements of different towns.In view of the fact that there is no vertical solar radiation observation at conventional meteorological stations,the measured data from self-built radiation observation stations are used.The distribution of hemispherical diffuse solar radiation and the influencing factors of vertical diffuse solar radiation are analyzed.Based on the angle between the normal of vertical surface???and the direction of solar radiation and the clear sky index?K_t?,a calculation model of diffuse solar radiation from vertical surface is proposed.Compared with the existing model,the input parameters are reduced and the calculation accuracy is improved.The outdoor weather data for thermal insulation design in 145 major towns in China and 4 outdoor weather data for extreme weather conditions in summer were generated.The method of generating outdoor calculation parameters for thermal insulation design is improved,and the design parameters are provided for thermal insulation design and research.Through the analysis of the characteristics of temperature and radiation action and its correlation,the difference of thermal reaction of the envelop under climate action analyzed.The 6 common building thermal-insulation materials and structural materials with the monotonicity of physical parameters are selected.The maximum and minimum temperature of the wave front and back surface and the time when the extreme value appears are calculated by using KValue software.The effects of material thickness,thermal inertia index and thermal resistance on the thermal reaction characteristics of uniform flat wall were analyzed,and the effects of material,thickness and position of high thermal resistance layer and structural layer on the thermal response characteristics of composite flat wall were also analyzed.The mechanisms of thermal insulation of non-transparent envelop is expounded from two aspects of climate action and building envelop,which provides theoretical support for thermal insulation design under different climatic conditions.Based on the comparison of the mechanism of temperature and solar radiation,and the purpose of temperature and radiation classification,it is suggested that the ratio of external heating by radiation and maximum heating generated by outdoor temperature and radiation?ATR?should be used as the index of radiation intensity.It is put forward that the heat flux?Q?120 Wh/m² or maximum temperature increment??_max·i?1K on the interior surface of the non-transparent envelope caused by the radiation is considered as the judging condition for taking the radiation control measures.The results of radiation control in 145 major towns are given.From the point of indoor thermal environment demand,this paper analyzes the thermal insulation design objectives of non-translucent envelope of various climatic types,and puts forward the requirements of thermal insulation design with the control index of"hourly internal surface temperature"as the control index of the design day.Based on the analysis of thermal reaction characteristics of materials and structures,the thermal insulation structure of typical non-transparent envelop with"strong radiation-large temperature range"and"weak radiation-small temperature range"climate conditions under three indoor operation modes is analyzed,and the recommended structure meets the requirements of thermal insulation design is given.Through the comparison with the current thermal insulation and energy efficiency design standards,the design objectives of the non-translucent envelope proposed in this study promotes the thermal insulation design requirements of different periods of time.It can effectively reduce the thermal effect of the non-translucent envelope in natural ventilation mode and improve the indoor thermal environment level.