Thermal Performance of a Prefabricated Wall System Based on Styroconcrete Incorporating Recycled Expanded Polystyrene: A Numerical Comparison with a Conventional Large-Panel Building System

This article investigates the thermal performance of a conventional W-70 large-panel building system and a modern prefabricated wall system incorporating recycled expanded polystyrene (EPS) regranulate. The study aims to compare the thermal performance of two prefabricated wall systems representing different construction technologies and to evaluate the combined influence of their structural and material solutions on heat losses and thermal bridging. Numerical simulations were performed using THERM 7.6 based on the finite element method (FEM). Three representative structural junctions were analysed: the external corner, the external wall-to-internal wall junction, and the floor slab-to-external wall junction. The evaluation included thermal transmittance (U-value), heat flow rate, thermal coupling coefficient, linear thermal transmittance (Ψ), minimum internal surface temperature, and the internal surface temperature factor (fRsi). The results demonstrated that the analysed prefabricated wall system exhibited lower heat losses and improved thermal performance than the conventional W-70 large-panel system. The observed differences reflect the combined effect of the wall build-up, material properties, insulation thickness, and structural junction geometry. The incorporation of recycled EPS regranulate constitutes one of the design features of the analysed wall system and may contribute to more sustainable use of construction materials through the utilisation of recycled polymer waste.