Determining the effects of modification with natural tannin and climatic conditions on thermal transmittance in some types of wood

Abstract

This study determined the thermal conductivity (λ) and transmittance coefficients (U) of Scots pine, chestnut and oak wood—widely preferred in the woodworking industry—modified with a natural tannin solution. The 150 samples were prepared with dimensions of 20 mm × 295 mm × 295 mm in accordance with TS EN ISO 13788 (TS EN ISO 13788 (2012) hydrothermal performance of building components and building elements internal surface temperature to avoid critical surface humidity and interstitial condensation—Calculation methods. https://www.iso.org/standard/51615.html Accessed 10 November 2020) standards. Experimental samples were dipped in a natural tannin solution for 3 or 6 h, and a natural tannin solution was applied by a 3- or 6-layer brushing process. These four groups were modified with the tannin-based wood preservative, and unprocessed (control) samples were conditioned (alternating) between a temperature and humidity of 20 °C/65%, 40 °C/35% and 10 °C/50%, respectively. Samples were tested with a heat transfer device based on each wood type, climatic condition and process type. These samples were used to measure the thermal conductivity coefficient, λ, and thermal transmittance coefficient, U. The study found that the type of wood, modification process and climatic condition variables and their interactions were found to be significant. The lowest thermal conductivity (λ) and transmittance coefficients (U) were measured to be 0.1049 W/mK and 5.914 W/m²K for Scots pine brushed with 6 layers of tannin, respectively.