Despite centuries of demonstrated climate resilience, a systematic scientific quantification of traditional adobe's intrinsic thermal performance-isolated from the effects of bioclimatic design-remains limited. This study addresses this gap through field monitoring of a traditional adobe dwelling in a cold desert climate (BWk, Laghouat, Algeria), conducted in accordance with ASHRAE Standard 55, combined with a validated EnergyPlus simulation. A methodological approach examined a Lealli (elevated mixed-use) dwelling with a suboptimal thermal layout to isolate material-specific performance. Under extreme conditions (winter: - 3.3 degrees C to 15 degrees C; summer: up to 40 degrees C), the 0.57-0.65 m adobe walls reduced indoor temperature amplitude by 74%, stabilized relative humidity at 41-45.3% (an 80% reduction in variation), and provided a 9-hour thermal lag during summer. This performance maintained 83-92% of monitoring period occupied hours within ASHRAE comfort limits without mechanical cooling. Occupant surveys indicated thermal neutrality (MTS = 0, indicative PPD = 5%, at 29-30 degrees C)-aligning with adaptive comfort models for naturally ventilated buildings. The material thermal inertia remained consistent across seasons (specific heat: 987J/kg.K, density: 2567.6 kg/m3; thermal conductivity: 0.89 W/m.K), confirming performance is inherently governed by material properties. While winter indoor conditions (8.92-12.52 degrees C) required supplemental heating, the adobe provided significant thermal regulation with 84% humidity stability (54-63%), a 0.16 decrement factor, and a 9-hour thermal lag. Annual free-running simulation yields 40.2% thermally comfortable hours across the full year, rising to 69.2% during summer. Parametric energy simulation further demonstrates a 29.9% total energy saving over hollow brick, driven by a 55.1% cooling reduction and 27.8% heating reduction. The documented passive cooling and heating energy reduction capacities positions adobe as a low-carbon solution, providing evidence-based benchmarks for its integration into contemporary sustainable buildings in cold desert regions.