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In this paper, the thermal performance of a sandwich ventilation wall was studied based on the hot and cold box. The model consists of two types of cover plates: wall thermal insulation set and non-set. We tested the surface temperature, air temperature and the heat flux density of air interlayer in three different forms of airflow within the wall. The experiment results show that introducing fresh air from the outside in cold areas in winter will not affect the thermal insulation performance of the wall if the hole openings are reasonably organized. Compared with the traditional exterior wall, the air flow rate and pressure increase in the structure of the air layer can improve the thermal performance of the sandwich wall. By com-paring the two kinds of wall heat transfer coefficienies of the non-thermal insulation cover plate and the thermal insulation cover plate, it is found that the thermal insulation design of the cover plate can further improve the thermal performance of the sandwich wall by 12.3%. [ABSTRACT FROM AUTHOR]

• Adobe Yaokang for traditional heating in cold climates was presented. • A quantitatively analysis of the thermal performance of Yaokang was conducted. • Effect of Yaokang heating on indoor air quality were analyzed. • A mathematic model based on thermodynamics equilibrium of Yaokang was proposed. As a traditional heating system, Yaokang are widely used in cave dwellings in rural China. Yaokang are built by local craftsmen, according to traditional construction methods. To study the thermal environment of Yaodong dwellings with Yaokang heating and the effect of the burning of Yaokang on the health of residents, the thermal performance of Yaokang and the indoor air quality with Yaokang heating were quantitatively analyzed. The results showed that Yaokang has an excellent thermal storage capacity, and can supply heat to the room for a long period, even after the burning has stopped, with a thermal efficiency of 67.7%. Meanwhile, the concentrations of CO, particulate matter (PM2.5), CO 2 , and volatile organic compounds (VOCs) in the indoor air were generally within the ranges of good air quality or light pollution. Finally, based on the theory of thermodynamics, a mathematical model of Yaokang heating process was established, and verified using experimental data. Based on the model, optimization of the thermal characteristics of Yaokang and effective regeneration designs for the Yaodong can be obtained. This study can also provide basic data and theoretical support for the protection and inheritance of vernacular buildings. [ABSTRACT FROM AUTHOR]