China's Tibet autonomous region has abundant solar energy resources, cold winters, and cool summers. These are ideal conditions for the application of passive solar heating methods. However, differences in climatic conditions and building types can significantly affect passive solar technology's feasibility, which makes it challenging to promote passive solar buildings in Tibet. In this study, the suitability zone for passive solar technology is categorized based on the sub-zoning indicators for Tibet. By modeling between direct gain windows, Trombe walls, and attached sunspaces, the effect of indoor thermal environments and the capacity for heating load reduction is compared for different passive solar technologies. The climate-difference impact analysis shows that the Ⅰ-B-1 zone is better suited for passive solar technology than other climate zones. More specifically, this zone has an average energy-saving rate difference of up to 28.61% compared to the Ⅱ-A-1 zone. The analysis of the impact of building type differences indicates that residential buildings have higher Trombe wall-to-wall ratio limits and more significant potential for energy savings than office buildings. The study also clarifies the implications of Tibet's climate conditions and building type differences on the effectiveness of passive solar technology. Moreover, it recommends appropriate passive solar technology adoption methods for every climate zone. This study can be used as a reference and engineering guide to improving the indoor thermal environment of Tibetan buildings, tailored to the highly variable local conditions.

The hypoxic environment at high altitudes causes various sleep disorders. Diffuse oxygen enrichment is an effective way to alleviate sleep disorders and improve the built environment in high altitude areas. In this study, a novel point source local diffuse oxygen supply method was proposed to improve the sleeping oxygen environment. The oxygen supply performance was investigated by the computational fluid dynamics (CFD) method including the oxygen concentration and air velocity distributions. A sleeping experiment was conducted on the plateau to validate the CFD model. The occupied zone including the inhalation zone and the active zone was defined. The results showed that the oxygen concentration showed a rapid rise, then decreased slowly, and finally tended to be stable. The oxygen concentration after stabilization was remarkably influenced by indoor ventilation rate. The sleeping environment’s improvement was examined considering the oxygen enrichment efficiency, uniformity, stability and human comfort demand. The optimal strategies were recommended with a ventilation rate of 1 air change per hour, supplied oxygen concentration of 90%, and jet distance of 0.50 m. The study contributes to improving the oxygen environment and human sleep quality in an effective and energy-saving approach to the sustainable development of buildings in high altitude areas.

Diffuse oxygen supply is an important means to improve the indoor oxygen environment of buildings and ensure physiological and psychological health of immigrants in plateau areas. Existing research on oxygen enrichment strategies at high altitudes has mainly focused on confined spaces under mechanical ventilation, with few studies on the distribution of indoor oxygen concentration under natural ventilation in actual buildings. This study used a verified computational fluid dynamics (CFD) method to investigate the indoor oxygen distribution with practical consideration of natural ventilation at high altitudes. The results showed that the oxygen distribution under wind-driven natural ventilation was more nonuniform than that under buoyancy-driven natural ventilation, with the ratio of local oxygen concentration to overall-mean oxygen concentration, the k value, between 0.8 and 1.3 under wind-driven natural ventilation and between 0.9 and 1.1 under buoyancy-driven natural ventilation. The effects of meteorological condition and oxygen source position on indoor spatial oxygen distribution characteristics were explored with careful examination in human occupied zone under lying, sitting and standing postures. The results can provide implications for effective and energy saving design of indoor oxygen supply system in plateau buildings.