Wood is considered a very environmentally friendly building material because it can still store CO₂ after felling and bind it for between 40 and 100 years - as long as it does not rot or burn. When using native wood, both the transport routes and the energy required to provide as well as process it are less than, for example, tropical wood or the production of other building materials, which makes its environmental balance far better. If forests are intact and sustainably managed, wood is also sustainable as a source of energy and as a building material - however, burning wood without appropriate filtration produces particulates and leads to bad air.
Advantages of wood as a building material
The advantage of timber construction is that the building material is highly insulating and stores heat, even with a low wall thickness, which makes it very suitable for energy-optimised buildings. The building material also has only a low dead weight, but a high load-bearing capacity and high compressive and tensile strength. It is essential that the material is dry before it is used, as this usually means that it does not need to be chemically treated when used in the interior. On the other hand, freshly processed wood, for example, can suffer from mould growth within a short time without sufficient ventilation.
Wooden floors can also be helpful in regulating humidity and the indoor climate - as long as they are not sealed with varnish, but merely treated with wax or oil. At a relative humidity of over 30 percent, it absorbs some of this moisture; if the humidity drops, it is released back into the room. Thus, untreated wood can contribute to a pleasant indoor climate.
Wood emits VOCs into the air - harmful or harmless or even healthy?
Untreated wood can emit VOCs, i.e. various chemicals, into the indoor air over time, which are responsible for the typical smell of wood, for example.
The gaseous substances emitted by wood are mainly monoterpenes (e.g. α- and ß-pinene), aldehydes (pentanal and hexanal) and acetic acid. However, the concentration of VOCs in air, which can be caused by wooden furnishings, can be considerable, as the graph shows. Due to this VOC contamination of indoor air by both building materials and furnishings made of wood, the question arises as to the possible hazard potential of the VOCs released into the air by wood.
However, the all-clear can be given. Scientists at the Fraunhofer Institute for Wood Research in Braunschweig, together with the Institute for Environmental Medicine and Hospital Hygiene at the University of Freiburg, exposed volunteers to significantly increased wood VOC concentrations in a large test chamber in various test series in order to test the thesis of potential harmfulness. Freshly dried pine wood and freshly manufactured pine chipboard were used for the test, as these have been proven to be highly VOC-laden. In ten long-term test series with up to 25 persons each, no adverse health effects could be detected, neither in health parameters nor in mood disorders. In further studies, human lung cell cultures were exposed to significantly increased VOC concentrations, in which no adverse health effects could be detected either.
Treated wood can release formaldehyde into the air
The scientists' statements apply exclusively to untreated wood. If the wood has been treated with artificial wood preservatives such as varnishes or paints, or if certain glues have been used - e.g. for chipboard, furniture and other composite wood products - solvents such as formaldehyde and other chemicals can also outgas over a longer period of time and be released into the indoor air.
Whether the VOCs and other gases emitted by wood into the indoor air are healthy or even beneficial to health cannot yet be clearly proven. However, according to the current state of knowledge, there is no risk to health from wooden furniture, wooden floors and other wooden furnishings, as long as they have been processed properly and without the use of harmful chemicals. Wood can therefore be quite healthy, because it helps to regulate and stabilise the indoor climate - temperature and humidity.
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