The project comprises 80 passive solar houses and 20 houses with combined passive and active solar heating in the Qinghai–Tibet Plateau region. The indoor thermal environment and the performance of the solar collection components are discussed through field testing during the coldest part and the transition part of the heating period. Moreover, the fractional energy savings, thermal efficiency, and fraction of the combined passive and active solar heating are analyzed. The results indicate that an auxiliary heat source should be used as a supplement. By comparing the heating of a passive solar house with a vernacular house, the energy savings of the passive solar house in the demonstration project were found to be approximately 62% during the study period. The thermal efficiency of the active solar heating system is 84.5%, and the solar energy utilization is 38.2%. The monthly average heat load index is 15.2 W m^–2.