Buildings account for over 35% of Iran′s energy use, yet insulation performance is climate dependent and may involve trade-offs between energy demand, indoor humidity exposure, and thermal comfort. This study quantifies how climate-adapted thermal and moisture insulation strategies perform differently under two contrasting Iranian cities (humid Rasht vs. hot-dry Yazd). We test the hypothesis that climate-tailored envelope packages outperform a uniform approach when evaluated jointly for energy, indoor humidity screening metrics, and PMV/PPD comfort outcomes, while acknowledging climate-specific trade-offs. Using EnergyPlus with 20-year city-specific weather data, we simulated a prototypical detached residence and compared climate-adapted wall assemblies (Rasht: mineral wool with an interior vapor-control layer; Yazd: continuous XPS) and two glazing options (conventional vs. Low-E, via Simple Glazing System). Model predictions were validated against field data (monthly energy within 10%). Results show that Rasht is heating dominated, whereas Yazd is cooling dominated in summer. In Rasht, the optimized wall reduced indoor RH exceedance above 70% from 312 to 0 h/year (screening indicator of high-humidity exposure) and shifted winter PMV from ~−1 to near neutral. In Yazd, Low-E glazing reduced cooling energy by ~12% and improved summer comfort from PMV > +1 to near neutral (PPD < 10%). Overall, the comparative results indicate that climate-adapted insulation strategies can improve performance, but the dominant mechanisms and optimal measures differ by climate, supporting climate-indexed envelope guidance for Iranian practice.
