The urban heat island (UHI) effect—whereby metropolitan areas experience temperatures 2–8°C above surrounding rural zones—has intensified under accelerating urbanization and climate change. By 2025, over 60% of the global population resides in cities, and projections suggest this figure will exceed 68% by 2050. Conventional cooling strategies, predominantly mechanical air conditioning, account for approximately 15% of global electricity consumption in the built environment, creating a feedback loop that amplifies both energy demand and waste heat emission. Against this backdrop, passive cooling materials have emerged as a critical frontier in sustainable building science.
Phase-change materials (PCMs) offer a thermodynamically elegant solution: by absorbing and releasing latent heat during solid-liquid transitions, they buffer interior temperatures without active energy input. However, first-generation PCM systems suffered from leakage, low thermal conductivity (typically 0.1–0.3 W/m·K), cycling degradation, and poor integration with existing building materials. These limitations catalyzed a turn toward biological inspiration—studying how organisms such as desert beetles, polar fish, and thermophilic plants manage thermal extremes through hierarchical microstructures and composite architectures.
The convergence of biomimicry and PCM engineering has yielded a new class of composites: materials that replicate nature's strategies for thermal buffering through porous scaffolds mimicking bone microstructure, encapsulation shells derived from crustacean chitin, and shape-stabilized matrices inspired by plant cell walls. This review systematically examines the trajectory, achievements, and unresolved challenges of this interdisciplinary field over the past decade.
The following table summarizes the eight most influential publications identified through systematic screening, ranked by citation impact and methodological contribution to the field.
| Author(s) | Year | Focus Area | Key Finding | Methodology |
|---|
A decade of accelerating progress, from foundational encapsulation studies to sophisticated biomimetic composite systems tested in real urban environments.
Three persistent tensions shape ongoing research directions, reflecting deeper trade-offs between performance, scalability, and sustainability.
Analysis of methodological approaches across the 47 reviewed publications reveals a clear shift from purely laboratory-based characterization toward integrated computational-experimental frameworks.
Key quantitative findings distilled from the reviewed literature, representing consensus values or notable outlier achievements.