Built Environment 2050: Integrating Efficiency, Health, and Carbon Neutrality Across Buildings and Cities

Abstract

The built environment accounts for a substantial share of global energy demand, greenhouse gas emissions, and time spent indoors, positioning buildings and urban form at the center of climate mitigation and human well-being. This review synthesizes advances across building physics, systems engineering, and urban design to identify coordinated strategies that lower operational energy, reduce embodied carbon, improve indoor air quality and thermal comfort, and enhance resilience. We map evidence from laboratory studies, field monitoring, and city-scale modeling to show that demand reduction through envelopes, efficient and electrified HVAC, lighting, and controls remains the least-cost pathway in most contexts, particularly when sequenced with grid-interactive demand flexibility and onsite renewables. We highlight the convergence of materials science (low-carbon materials, phase change media), mechatronics (heat pumps, active façades), and data science (digital twins, AI-based controls), and we discuss trade-offs between air quality, ventilation energy, and filtration. Finally, we frame a research agenda around climate-appropriate design, performance verification, and equity-centered retrofits that deliver persistent emissions reductions and healthier indoor environments. Six original figures and three tables summarize trends, correlations, performance distributions, and adoption barriers for decision-makers and researchers.