Enhancing thermal performance of cross-laminated timber using phase change materials for energy efficient building envelopes

초록

The urgency of climate change has placed energy efficiency and low-carbon construction at the forefront of building energy research. Enhancing the thermal performance of building materials is a key strategy for reducing energy demand. Cross-laminated timber (CLT) is increasingly adopted as a sustainable structural material; however, its low thermal inertia limits its ability to moderate indoor temperature fluctuations. This study integrates phase change materials (PCMs) directly into timber to enhance thermal storage capacity at the material level. Unlike conventional approaches that apply PCMs as separate layers or surface-added components, PCM was embedded within the porous structure of wood to directly impart intrinsic thermal functionality. A paraffin-based PCM, n-heptadecane, with a phase transition temperature of 22.5 °C was introduced into wood via vacuum impregnation, and its thermal and physical properties were evaluated through thermogravimetric and calorimetric analyses. After 48 h of natural drying, the specimens exhibited high PCM retention and increased latent heat with minimal leakage. These enhanced wood elements were incorporated into the core layers of CLT panels. While maintaining thermal conductivity comparable to conventional CLT (0.126 W/m·K), the panels demonstrated a 44.21% increase in specific heat near the PCM phase transition temperature. Building energy simulations showed an annual energy reduction of up to 11.76% when standard walls were replaced with 125 mm PCM-integrated CLT panels, whereas the 150 mm panel showed the greatest total reduction compared with the masonry baseline. These results demonstrate that PCM-integrated CLT can enhance thermal inertia, providing a structurally integrated and scalable approach for improving the energy performance of timber-based building envelopes. © 2026 Elsevier Ltd.

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