Influence of temperature and moisture content on the thermal conductivity of wood-based fibreboards

Temperature and moisture content are important parameters affecting thermal properties of wood and wood-based materials. Quantitative data are required to better characterize the thermal performance of fibreboards. The aim of this work was to assess thermal conductivity of insulation fibreboards at different temperatures (ranging from −10 to +60 °C at 10 °C increments) and moisture contents (gravimetrically determined after conditioning at 15, 50, 85 % RH). Thermal measurements were done conducted with at stationary boundary conditions. The relationship between thermal conductivity, temperature and MC of samples was found by fitting data to a second order polynomial function. Moisture behavior was characterized by applying the Hailwood–Horrobin (H–H) sorption model. The single-hydrate model was used with the equilibrium moisture data at each conditioned climate step, starting at 10 % RH, up to 90 % RH, at 10 % RH increments. Total sorption as a composite of hydrated and dissolved water sorption was quantified for adsorption as well as desorption. Modelled data were in close agreement with the experimental data. Accurate datasets on the thermal behaviour of insulation materials are crucial in numerical modelling approaches, which will improve the proper design of building envelopes.