Evaluation of structural and thermal performance of polystyrene integrated cross laminated timber panels

This study aims to evaluate the structural and thermal performance of Polystyrene-Integrated CLT (P-CLT) panels, a hybrid system formed by integrating expanded (EPS) and extruded (XPS) polystyrene foam into the middle layer of cross-laminated timber (CLT) panels. Six P-CLT and CLT panels (54 × 1200 × 2400 mm) were tested for lateral load performance, and nine specimens (54 × 300 × 300 mm) were used for thermal conductivity measurements. P-CLT panels increased thermal insulation performance while maintaining load-bearing capacity, reducing thermal conductivity by 16.1% (EPS) and 19.9% (XPS). In lateral load tests, CLT panels reached 72.02 kN, while EPS- and XPS-integrated panels were 36% and 7% lower, respectively. Both hybrid panel types showed 47-50% higher displacement, indicating more ductile behavior. Stiffness was highest for CLT panels (3.44 kN/mm), while EPS and XPS panels measured 1.35 and 1.09 kN/mm, consistent with previous studies. Energy simulations showed that P-CLT panels, particularly with XPS, reduced heating energy demand by 9-12%, while uninsulated CLT systems increased demand by up to 46%. The P-CLT system provides a cost-effective sustainable solution for construction and renovation, representing one of the first experimental and simulation-based assessments of combined structural and thermal performance in hybrid CLT panels.