Effects of Building Height and Window-to-Wall Ratio on Cooling Demand, Passive Comfort, and Peak Demand in a Composite Climate: EnergyPlus Simulations and an Exploratory Surrogate Model

Rapid vertical growth in Tier-2 Indian cities is reshaping residential forms and may affect cooling demand, passive comfort, overheating severity, and peak electricity demand. This study examines the influence of building height and window-to-wall ratio (WWR) on residential thermal performance in Patna, India, a composite-climate context. Five archetypes–detached house, row-house, low-rise apartment, mid-rise apartment, and high-rise apartment–were simulated in DesignBuilder/EnergyPlus Version 23.1.0 under 20%, 30%, and 40% WWR scenarios. Passive and active operation modes were evaluated through 30 annual simulations, generating 262,800 hourly records. External shading was excluded, and occupancy and ventilation assumptions were standardized to create a controlled benchmark design. Performance was assessed using annual cooling energy demand (ACED), all-hour and occupied-hour passive comfort percentage, adaptive degree-hours (ADH), and peak demand indicators. At 20% WWR, ACED increased from 33.13 kWh/m2·yr in the low-rise archetype to 42.79 kWh/m2·yr in the high-rise archetype, while all-hour passive comfort decreased from 68.16% to 49.28%. The row-house archetype performed best due to reduced exposed envelope area. A second-order surrogate model provided exploratory scenario-level approximation across 15 archetype–WWR cases. The findings support further investigation of morphology-sensitive residential envelope guidance within bounded composite-climate benchmark conditions.