Smart strategy for built environment optimization: In-situ test and orthogonal experiment in traditional ethnic dwellings

Maintaining indoor thermal comfort usually increases energy consumption from HVAC systems, making the development of passive retrofit strategies important. This study focuses on traditional dwellings in the cold high-altitude region of northwestern Sichuan, China, aiming to balance thermal performance improvement with the preservation of their architectural and cultural value. Field measurements, simulation modeling, standardized scoring, orthogonal experimental design, and simulation validation were integrated to evaluate passive retrofit strategies. The orthogonal experiment reduced the full-factorial design space from 8,748 possible combinations to 81 representative cases. The optimal strategy was identified as building form A, orientation S360, SEPS wall insulation, window construction 5, and WWR i. This strategy increased the proportion of thermally comfortable hours from 7.8 % in the baseline case to 24.0 %, corresponding to an increase of 16.2 percentage points. The study demonstrates that indoor thermal comfort in traditional dwellings in cold high-altitude regions can be substantially improved while preserving architectural appearance and cultural value. The findings provide a transferable methodological reference for traditional dwellings facing the dual challenge of heritage conservation and thermal performance improvement.