Recent advances in nearly zero energy commercial and residential buildings: Innovations, challenges, and climate-specific solutions

Nearly Zero Energy Buildings (NZEBs) are pivotal in addressing the escalating energy and environmental challenges of hot climates, where extreme cooling demands and reliance on fossil fuels intensify carbon footprints. This study brides a critical research gap by exploring and synthesizing NZEB strategies specifically for the under-represented and extreme context of hot-arid regions, with a focused application on Iraq. Passive design approaches such as solar shading optimization, natural ventilation, and phase-change materials (PCMs) are synergized with active technologies, including high-efficiency HVAC systems, hybrid energy storage (battery, thermal, hydrogen), and AI-driven smart energy management systems (EMS). A multi-objective optimization framework is developed to balance energy efficiency, cost, and thermal comfort, validated through case studies of retrofitted buildings in Iraq. Results demonstrate 30%–50% energy savings via hybrid systems, emphasizing the effectiveness of climate-responsive materials and load-shifting techniques. Critical challenges, such as extreme temperatures, dust degradation, water scarcity, and policy gaps, are analyzed, with recommendations for region-specific standards and financial incentives. Future directions prioritize advanced materials high-albedo coatings, aerogel insulation, decentralized renewable microgrids, and bioclimatic designs rooted in traditional Iraqi architecture. By integrating cutting-edge technologies with adaptive policy frameworks, this research underscores the viability of NZEBs in achieving energy autonomy and resilience in hot climates, offering a roadmap for sustainable urbanization aligned with global decarbonization goals.