Urban Heat Island (UHI) mitigation in hot-arid environments requires integrated passive cooling strategies that extend beyond isolated interventions. This study evaluates the combined effects of cool pavements, green walls, shade trees, and cool roofs at the neighborhood scale in Al Ain City, UAE, using ENVI-met microclimate simulations calibrated and validated with field measurements. Unlike previous studies that focus on single strategies or building-level analysis, this research provides a comprehensive urban-scale assessment grounded in surface energy balance theory and urban canopy layer processes. The study integrates radiative, convective, and evaporative mechanisms and evaluates their influence on pedestrian-level thermal comfort using Mean Radiant Temperature (MRT) and Physiological Equivalent Temperature (PET) indices. Results reveal that the integrated application of these strategies reduces pedestrian-level air temperature by up to 3.5 degrees C, peak surface temperature by approximately 10-12 degrees C, and mean radiant temperature by up to 10-12 degrees C during peak summer afternoon conditions. These outcomes confirm the superior performance of multi-layered horizontal, vertical, and rooftop interventions in enhancing outdoor thermal comfort and mitigating urban heat accumulation. The findings advance knowledge on passive microclimate design and provide a transferable, performance-based framework to inform sustainable neighborhood planning and climate adaptation strategies in arid regions.