Thermal performance of south-facing envelopes in solar enrichment zone of Qinghai–Tibet plateau: Field measurements of multiple dwellings in winter and transition seasons

Utilizing solar energy is essential for achieving zero carbon emissions in buildings, especially in solar enrichment zone, such as the Qinghai-Tibet Plateau. Given a climate characterized by low temperatures and high solar radiation, the thermal performance of south-facing envelopes is crucial for the collection and utilization of solar radiation, necessitating detailed field investigations. This study conducted field measurements on three typical dwellings in Litang County and Ngari Prefecture during winter and transition seasons. Transparent envelopes had heat gains of 20.7 MJ⋅m^-2 but lost 26.4 MJ⋅m^-2, with indoor temperature fluctuation of 17.2 °C. Opaque envelopes gained 132.3 W⋅m^-2 from solar radiation and lost 99.3 W⋅m^-2 through convection, storing 2.5 MJ⋅m^-2 with over 85 % lost to the outdoor environment. This research revealed the dynamic thermal characteristics of heat collection, storage, and insulation performance of south-facing envelopes in local climate, indicated that the existing thermal performance is not yet sufficient to cope with the low temperature and high radiation climate. This work can provide reference for the development of solar utilization envelopes for the Qinghai-Tibet Plateau.