Heating load reduction characteristics of passive solar buildings in Tibet, China

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.