Thermal properties of wood and wood panel products for use in buildings

This report provides a review and evaluation of currently available information on the thermal conductivity and specific heat of wood building materials. We derived a linear equation for thermal conductivity of solid wood as a function of density and moisture content from data in the literature and used this to provide estimated conductivity values for various types of hardwoods and softwoods. Far fewer data exist for the thermal conductivity of wood panel products. Current design values appear to be based on the premise that the conductivity of plywood is the same as that of solid wood of the same species, but the few reported results from the measurements indicate a lower conductivity. More definite information exists on the conductivity of conventional particleboard and fiberboard, but additional conductivity measurements of plywood and some of the most commonly used flakeboards, such as oriented strandboard (OSB), are needed. Additional measurements of the specific heat are needed for all wood panel products. We discuss the special problems of measuring thermal properties of wood products with high moisture contents and the practical relevance of such data to building design and performance, and we conclude that thermal properties above fiber saturation are of little practical significance. The report contains the authors' recommendations for design values for thermal properties and for further research and additional measurements, as well as a bibliography. 33 refs., 14 figs., 10 tabs.