Next-Generation Bio-Based Phase Change Materials for Integrated Thermal Energy Storage in Net-Zero and Climate-Responsive Buildings: A Comprehensive Review

Abstract

Introduction: Buildings are rapidly transitioning toward decarbonization, electrification, and climate-adaptive performance, increasing the demand for compact, controllable, and code-compliant thermal energy storage (TES). Latent TES using phase change materials (PCMs) offers high energy density near comfort temperatures, yet widespread adoption remains limited due to low thermal conductivity in organic/bio-based PCMs, reliability challenges in salt hydrates, and insufficient evidence on composite safety, durability, and life-cycle impacts.

Objectives: This review aims to synthesize two decades of progress on next-generation bio-based PCMs and provide an integrated framework that treats PCMs as actively scheduled thermal batteries within building envelopes, air-side/hydronic loops, and dedicated TES tanks. The objective is to map material families, composite/encapsulation strategies, integration pathways, and operational horizons while producing practice-ready guidance for sizing, placement, safety, and supervisory control.

Methods: The review aligns thermophysical operating windows of PCMs with building comfort and system setpoints (≈20–30 °C for envelopes/radiant systems; 5–18 °C for air-side pre-cooling). An impact-by-likelihood assessment is used to prioritize material and system constraints, link them to mitigation strategies, and define acceptance criteria. Comparative evaluation includes latent capacity, thermal conductivity, durability, system-level integration performance, and control effectiveness across experimental, field, and simulation studies.

Results: Bio-based PCMs can achieve latent capacities comparable to petro-organic PCMs while offering improved circularity when conductivity is enhanced through recyclable pathways. Practical performance targets include in-situ latent heat ≥90–120 kJ kg⁻¹, effective thermal conductivity ≥2 W m⁻¹ K⁻¹, and <5% degradation after ≥10,000 cycles. When integrated into lightweight building envelopes, PCMs reduce peak sensible loads by ~15–30% and provide 2–4 K swing attenuation. Air-side/hydronic modules and coil-sleeve tank configurations reduce compressor cycling and increase thermal availability when melting points and heat-exchange geometries are properly matched. Forecast-aware supervisory control (e.g., MPC, digital twins) reliably converts latent capacity into peak-shaving and cost savings, given proper commissioning and enforcement of thermal comfort, fire/IAQ, and composite-integrity constraints.

Conclusions: Bio-based PCMs, when specified at the composite level, co-designed with predictive operation, and supported by evidence of durability, safety, and circularity, can deliver measurable energy, carbon, and resilience benefits in grid-interactive and climate-responsive buildings. A structured deployment roadmap—including pre-screening, simulation-aided sizing, composite procurement specifications, commissioning tests, and M&V with LCA/EPD documentation—enables reliable large-scale implementation of next-generation PCM-based TES technologies.