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The underground cave dwelling located in loess plateau of China is known for its use of natural and passive environment control systems for a comfortable indoor environment. However, it has not been proved by a detailed and quantitative analysis so far. This paper conducts qualitative and quantitative evaluations on the thermal performance of ancient cave dwellings. Firstly, the authors conducted a qualitative analysis on the passive strategies of vernacular underground cave dwellings by field investigations. The orientation of building, the presence of underground courtyard, use of biomass massive building envelope, etc. Formed the indoor environment. Secondly, a quantitative analysis was also carried out based on long-term remote monitoring experiments by recording thermal environment parameters in a selected building. The analysis results were very much in agreement with the inferences drawn from the qualitative analysis. Finally, in order to evaluate the whole annual thermal performance, numerical simulations on the Yaodong models was also conducted using the software Energyplus. The study provided positive results confirming that climate responsive strategies employed in underground cave dwellings were highly effective in providing methods and implications to create more comfortable indoor environments for rural residences. Image 1 • A vernacular underground cave dwelling presented for cold climates. • Climate responsive strategies of underground cave dwellings was obtained. • A long-term remote monitoring was carried out. • Annual thermal performance of the cave dwelling was evaluated. [ABSTRACT FROM AUTHOR]

Highlights: [•] An improved passive solar house suitable for cold area of China is presented. [•] The function of heat gain and solar irradiance is obtained by regression analysis. [•] The free running temperature prediction formula of passive solar house is obtained. [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]

Climate responsive strategies contained in traditional native dwellings can provide theoretical basis for the development of sustainable buildings. This study focused on a quantitative analysis of cliff-side cave dwellings located in cold region of China. Field measurements in summer and winter were carried out. Based on the monitoring data, thermal environment of the cave dwelling and thermal characteristics of the adobe massive building envelope were evaluated. Results showed that the cliff-side cave dwelling was well adapted to local environment for its good ability of thermal insulation under the natural conditions. Furthermore, in order to assess the whole annual thermal performance and thermal comfort level, numerical simulations on the cliff-side cave dwelling models was also performed using the software Energyplus. Results showed that 52.50% time of the year was comfortable of the living room. Meanwhile, some technical strategies of making full use of solar energy and natural ventilation was proposed in the end of this paper, which can provide technical support for the regeneration design of traditional residential buildings. • Cave dwellings with massive envelope adapt themselves to the local climate well. • 52.50% time of the year was comfortable of the cliff-side cave dwelling room. • Renewable energy using strategies on the vernacular cave dwelling were proposed. [ABSTRACT FROM AUTHOR]

Phase change materials (PCMs) are recognized as a promising passive energy retrofit technology for existing buildings, as they are applied to the internal and external surfaces of the building with less impact on the original structure. However, the effectiveness of PCMs varies from region to region. Taking the Central Plains of China as an example, this paper investigated the effect of phase change temperature and material thickness variation on the energy efficiency of PCM when it was arranged on 14 placements including furniture through EnergyPlus (E+). And further explored the applicability of coupling PCMs with natural ventilation (NV). The results showed that: for the Central Plains of China, PCMs arranged on the internal surface of building roofs were optimal, and the reduction rate of uncomfortable degree hours could reach 38%, 26%, 24% and 40% after integrating PCMs into the roof, floor, external wall and furniture. The uncomfortable degree hour reduction rate per unit mass of PCM was 0.052%/kg for the roof, and the value of furniture was very close to the external wall and floor, which achieved 0.033%/kg. In addition, the coupling of PCM with NV improved the energy efficiency of PCM by more than twice. [ABSTRACT FROM AUTHOR]

Clothing can absorb fine particulate pollutants from the atmosphere outdoors and then release them after entering the room in a form similar to three-handed smoke. In this study, the experimental site in Zhengzhou, a typical city with heavy pollution in central China, was used to investigate the adsorption and diffusion patterns of three different fabrics of polyester, polyester-cotton, and cotton clothing for fine particle pollutants, to guide people's behavior patterns and indoor air distribution, and to reduce indoor pollution exposure. The results showed that when garments of three different fabrics were exposed to moderate and heavy PM2.5 pollution for 1 h, 2 h, and 3 h, respectively, and then transferred to the diffusion chamber, polyester always released the highest PM2.5 concentration to indoor air during the same release cycle, followed by cotton and polyester-cotton. In addition, the concentration of indoor air pollutants will be periodically affected by the diffusion of fine particulate adsorbed by clothing fabrics. With the increase in outdoor pollution and exposure duration, the indoor PM2.5 concentration takes longer to stabilize at certain levels after the clothing is transferred to the indoor side. Finally, the comparison of natural ventilation experiments proved that it is not feasible to rely solely on natural ventilation to improve the influence of clothing pollution sources on indoor air quality. [ABSTRACT FROM AUTHOR]