Thermal Insulation Properties of Cross-laminated Timber Panels with Different Geometric Interlayers in Various Temperature Environments

Abstract

Three-layer cross-laminated timber (CLT) panels were produced using Scots pine (Pinus sylvestris L.) for the outer layers and poplar (Populus) for the middle layer. Circular, rectangular, and trapezoidal geometric corrugates were applied to the middle layer; the aim was to determine the air-dry density, moisture content, thermal conductivity (λ), and thermal transmittance (U) values of the resulting panels under three different climatic conditions. The moisture content of the geometric corrugated CLT panels was higher than that of the control group. In contrast, the air-dry density values were approximately 15% lower than those of the control group. The lowest value of the thermal conductivity coefficient was obtained for the circular- corrugated panel at an average of 0.099 W/m·K, while this value was measured at 0.108 W/m·K for the control group. Similarly, the thermal transmittance coefficient also showed the lowest value, 2.026 W/m²·K, in the circular- corrugated panel. Both the corrugate geometry and ambient temperature had statistically significant effects on the heat conduction and thermal transmittance coefficients. However, the combined effect of corrugate geometry and ambient temperature was not statistically significant. Circular grooving improved the thermal performance of CLT panels, which were judged to be suitable for structural applications requiring thermal insulation.