One of the oldest building materials in the world can soon change drastically. Wood is a perfect insulator, durable and is also a renewable resource, which makes it appreciated by manufacturers around the world. However, despite its best features it is still opaque. What makes it necessary to use glass and other artificial materials to let natural light into the rooms – necessary for people to maintain mental health and to save artificial light.
Problems of modern buildings
Unfortunately, currently used glass is not a good insulator. Looking for an alternative to windows that lose heat in the winter and not protect against heat in the summer, a team of researchers from the KTH Royal Institute of Technology in Sweden has developed a chemical wood treatment process that makes it transparent and does not lose its most important properties.
We have prepared a material that is multi-functional – it can transmit light very well and also store heat. We have combined these two functions in one material – says Céline Montanari, one of the researchers working on the project.
Currently, around one-third of global energy consumption comes from the construction sector – largely due to heating, cooling and indoor lighting systems. Transparent wood is therefore presented as a potential replacement for energy-efficient constructions.
The woodworking process begins with the removal of lignin – a polymer that makes the wood stiff. The resulting element remains structurally strong and looks like matt glass. The team went a step further – filling the holes left after removal of lignin, with polyethylene glycol. It is a phase changing material that can be solid or liquid depending on the ambient temperature. As the temperature rises, it melts, and when it cools it becomes very durable. Wood cell walls provide structure for the polymer. As it progress through this focusing process, the solid acquires different levels of transparency – from a more matte appearance to almost a completely transparent one.
This material feature makes it not an ideal replacement for glass, however, it will be suitable as a skylight to increase the amount of natural light in the building. The more modified wood can be included in a given project, the smaller the energy footprint will be left behind.
100 grams of wood material with polyethylene glycol can absorb up to 8,000J of heat, which essentially corresponds to what a 1W bulb can produce in two hours – says Dr. Montanari. – Another advantage is that the material has the strength of wood and will not fall apart when impacted, so it is therefore much safer than glass.
Researchers are now looking to increase the thermal capacity of transparent wood to achieve even greater energy savings. They cooperate with various companies to establish plans related to the production of material on an industrial scale. It is assumed that a commercial product will appear on the market within 5 years.