Phase change materials for building‑sector thermal regulation

A review of PCM classes, latent‑heat storage mechanisms, integration strategies in cementitious and masonry systems, and constraints governing structural and thermal performance.

The article argues that PCMs can enhance passive thermal management by storing and releasing latent heat near the phase-transition temperature, provided integration methods preserve mechanical integrity and durability.

PCM classification (organic/inorganic/eutectic)

Latent‑heat storage and release

Integration in concrete, mortars, and bricks

Background and objective

The review positions buildings as major energy consumers and highlights increasing heat-wave intensity as a driver for passive thermal regulation strategies. PCMs are presented as materials capable of absorbing or releasing heat during phase transition, thereby modulating indoor temperature swings and reducing dependence on active cooling/heating systems. The article focuses on PCM characteristics, types, and the practical considerations involved in construction-sector deployment.

PCM classification and latent-heat mechanism

PCMs are categorized into three broad types based on composition and phase-transition behavior: organic PCMs, inorganic PCMs, and eutectic PCMs. Organic PCMs are described as chemically stable and non-corrosive but with relatively lower thermal conductivity. Inorganic PCMs are associated with higher thermal conductivity and latent heat capacity but may be prone to supercooling and phase-separation issues. Eutectic PCMs are described as mixtures designed to melt and solidify at a single effective temperature, combining desirable attributes of constituents to improve performance and mitigate supercooling.

Organic PCMs (composition and constraints)

Stated attributes Chemically stable, non‑corrosive

Constraint Lower thermal conductivity relative to inorganic systems

Core function: Provides latent-heat buffering with comparatively limited heat-transfer rate.

Inorganic PCMs (thermal capacity and risks)

Stated attributes Higher thermal conductivity and latent-heat capacity

Constraints Supercooling and phase separation can hinder solidification near freezing point

Core function: Supports high storage density but requires stabilization and compatibility controls.

Eutectic PCMs (single transition temperature)

Concept Mixtures melt/solidify at a defined temperature point

Functional intent Combine beneficial properties while reducing supercooling

Core function: Provides tunable transition temperature for envelope-specific setpoints.

Phase transition evidence (DSC exemplar)

Method referenced: Differential scanning calorimetry (DSC)

Anchor (reported) Paraffin wax melting point ~53 °C (DSC peak)

Core function Ties PCM function to measurable latent heat and transition temperature.

Integration routes into cementitious and masonry systems

The review outlines multiple PCM integration strategies, including direct incorporation into mixes, impregnation into porous substrates, encapsulation (microencapsulation or macroencapsulation), and engineered placement such as grooved brick concepts. Selection of integration method is framed as a multi-objective optimization: maximizing latent-heat benefit while limiting adverse impacts on strength, density, and durability. The article further notes that PCM dosage and placement location can alter both the magnitude and timing of heat absorption/release, thereby influencing indoor thermal comfort.

Application domains: walls, mortars, and bricks

PCM deployment is discussed for wall systems (including layering approaches in walls/concrete/mortars) and for masonry units (PCM-infused bricks). PCM layers are described as functioning by absorbing heat during high-temperature periods and releasing it during cooler periods, shifting heat-flux timing. For bricks, the review reports that PCM incorporation can reduce variation in indoor heat transfer and introduce a meaningful time delay in heat transmission, thereby supporting diurnal thermal smoothing.

Wall/mortar integration (layering concept)

Approach PCM layers applied to external or internal wall regions

Design note Thickness and placement affect storage benefit and thermal resistance

Core function: Attenuates temperature excursions through latent-heat buffering at the envelope.

PCM in bricks (reported performance anchors)

Reported dosage 20% PCM in a brick system (context-specific)

Reported transition point Melting point ~32 °C (PCM used in cited brick context)

Core function: Targets transition temperature near comfort-relevant ranges for envelope moderation.

Integration techniques taxonomy

Methods listed Direct incorporation, impregnation, encapsulation, grooved bricks, 3D printing

Core function: Provides a menu of integration pathways with different stability and performance trade-offs.

Mechanical/durability interaction (limitation framing)

Stated concern Increased PCM dosage can reduce compressive strength and density in certain systems

Core function Specifies the principal constraint that bounds PCM adoption in structural materials.

Governing constraints, evaluation methods, and boundary conditions

The latent-heat advantage is maximized when PCM transition temperature aligns with the envelope’s operational temperature range. The review emphasizes that placement (external vs internal layers) and thickness influence both thermal buffering and added thermal resistance, which can diminish the effective heat absorption/release rate.

Heat-transfer benefit depends on transition temperature and placement

The article highlights that increasing PCM dosage may improve thermal storage but can degrade compressive strength and density, particularly when PCM interacts with binder systems or interrupts load-bearing microstructure. Consequently, structural application requires balancing thermal benefit with mechanical feasibility.

Dosage sensitivity and mechanical-property trade-offs

PCM–binder interactions and the method of incorporation (e.g., encapsulated vs directly mixed) govern durability. The review notes that high dosages may hamper bonding and adversely affect mechanical and durability properties.

Microstructure and compatibility challenges (cementitious systems)

The review enumerates a multi-tier evaluation approach: laboratory thermal analysis (e.g., DSC, DTA, TPS), mechanical characterization (e.g., compressive strength, density), controlled environmental chamber testing, and heat-flux measurement. Infrared thermography is described as useful for visualizing heat-flow patterns and identifying non-uniform PCM distribution.