Bring nature into your home with wood! With knots – places where a side branch grew on the tree – and grains as an expression of the natural look, and the warm appearance of the material.
Wood is a natural composite material, with cellulose fibres embedded in a matrix of lignin and hemicellulose – all three components composed of natural polymers. Lignin is the glue that holds the cellulose fibres together. Plant a tree, add extra nutrients if necessary, let nature take its course and voilà … It grows naturally into a wood-producing organism. Usually the tree trunk is the source of the wood.
Outdoors, trees provide a natural means of cooling. After all, the leaves take away direct solar radiation and therefore heat. The leaves also evaporate water, and this evaporation requires heat which is extracted from the environment, thereby cooling it. With lots of trees around your house, you can sit in the garden and enjoy the coolness of a hot summer, and benefit from it indoors as well.
Traditionally, wood has been widely used because of its abundant occurrence in the neighbourhood. Go to the woods, chop down a tree, work it with a saw to the right size and you have the wood available. This makes wood a sustainable raw material for construction. Properties such as stiffness and (compressive) strength are useful for wooden beams to be able to bear a mechanical load well. Wood cells consist of elongated cellulose chains in the longitudinal direction of the trunk, which explains the anisotropic character of wood: in this longitudinal direction wood is much stronger than in the transverse direction.
Moisture plays an important role in the use of wood. For example, wood rot occurs when fungi chemically break down the cellulose or lignin under damp conditions, as a result of which the wood loses its mechanical properties. Wood rot can be prevented by protecting the wood with a covering layer of paint, or by ensuring that no moisture can get in contact with the wood. The ‘warping’ – deforming, actually – of wood also has to do with moisture. By absorbing moisture, the wood can expand, and by releasing moisture, the wood shrinks. That’s the reason why it is easier to open a door or window in summer than in rainy seasons such as autumn or winter when the door or window often sticks …
Wood is a sustainable material, and this is because it is constantly renewable. After all, trees are part of the short carbon cycle: through photosynthesis, carbon dioxide (CO2) from the air is absorbed and eventually converted into carbon-based, natural polymers that are stored in the trunk. Ergo, the tree grows. If such a tree is chopped down after a few decades, the wood can be used as a building material for many decades to come – for example, in a home throughout its service life. Or, of course, it can be used to make a long-lasting book – also a sustainable storage of carbon dioxide.
Even after its practical use, the wood is still useful: you can burn it to generate heat and energy – another ancient application of wood. This does not release more CO2 than is absorbed by the tree during its growth. The cycle is complete when the CO2 released is used for the growth of a new tree.
Wood from the distant past can still be found in the soil in all kinds of forms: as peat, as coal, but also as petrified wood – where you can ask yourself: is it stone or wood? Petrified wood can be considered best as a fossil of a tree from millions of years ago. This fossil is created when a fallen tree is buried in a layer of sediment and deprived of oxygen. The organic components of the wood such as lignin and cellulose decay and are replaced by minerals from the water seeping through the sediment. This process, which takes many millions of years, preserves the original structure of the wood. Chemically, however, we are dealing with ceramics, for example in the form of silicates. Petrified wood therefore has the structure of an organic material (wood), but consists of inorganic material (stone).