Thermal Conductivity

The thermal conductivity λ increases approximately linearly with increasing density and moisture content. It is higher in the fiber direction than perpendicular to the fibers.

In EN 12524 specified thermal conductivity (design value) to 0.13 W / (mK) and 0.18 W / (mK) for wood density of about 500 kg / m³ respectively about 800 kg / m³. This standard can also be tabulated values for other wood based products are found and conversion factors for the effect of moisture.

Heat capacity

Wood has a relatively high specific heat capacity. It stated in EN 12524 for 1500-1700 J / (kgK). This can be compared with the corresponding value of concrete, 1000 J / (kgK).

The amount of wood is limited in modern houses and the possibility of using wood to offset climate variability is limited. Wooden house with stud frame usually contrary deemed to have small thermal inertia and can therefore be fitted with days varying temperature regulation.

Temperature Fluctuations

The wood thermal expansion coefficient is comparatively small. It has minor impact at temperatures above 0 ° C, because the movements caused by changes in moisture content is completely dominant. At temperatures below 0 ° C, the differences in temperature at different depths in the wood cause tension that can provide cracks, such as frost damage to growing trees. The thermal expansion coefficient of pine and spruce parallel grain is about 0.4 to 0.5 x 10-5 and perpendicular to the fiber direction 3.4 to 5.8 x 10 -5. Eurocode 1, EN 1991-1-5, gives linear thermal expansion coefficients that can be used to determine the load effects caused by temperature. The wood is the 5 x 10 -6 / ° C along the fibers and 30-70.x10 -6 / ° C perpendicular to the fibers.


 
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