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29 may 2019

“Transparent” wood as an eco-friendly building material

A Swedish scientific team has developed an experimental translucent wood that absorbs, stores and releases heat. Designed to be fully biodegradable in the long term, this composite wood could be used in the construction of eco-efficient buildings.

This “transparent” wood designed by the team of researchers from KTH Royal Institute of Technology in Stockholm1is multifunctional: in addition to its optical and thermal properties, the material can bear heavy loads, which bodes well for its use in the design and construction of eco-friendly houses and buildings.


It took three years to design a wood of this kind, balsa to be precise. The scientists first of all had to remove the ligninfrom its cell walls to give it a transparent appearance. Allowing light to pass through, it became of interest in terms of controlling light diffusion. The researchers then injected acrylic3into the walls of the now porous wood to protect it from humidity. They also added a polymer4, polyethylene glycol (PEG5), capable of storing heat.


This is where the major innovation lies: the wood treated in this way is capable not only of brightening and heating houses during the day, just like glass or even metal, but also of using the energy accumulated during the day to enhance the interior space when the sun goes down. The next aim pinpointed by the researchers is further improving its storage capacity to make it even more energy-efficient.


“The PEG and wood are both bio-based and biodegradable,” states Lars Berglund from the Swedish institute behind this research program. However, he notes that “the only part that is not biodegradable is the acrylic, but this could be replaced by another bio-based polymer.” 


There are already plans to industrialize this technological advance. The researchers believe that this translucent wood could be available for niche interior design applications within five years. 


1 “Biokomposter” program, KTH Royal Institute of Technology, Stockholm.

2 Lignin is one of the main components of wood, along with cellulose.

3 Acrylic is a polymer used to manufacture synthetic products (resins), and by extension denotes artificial textile fibers.

4 Polymer: a macro-molecule resulting from the combination of several molecules

5 Known as a “phase change material,” PEG is a solid that melts at a temperature of 27°C and stores energy during the process. The temperature may be adjusted by using different types of PEG. 

Source: Enerzine, Du bois transparent qui absorbe, stocke et libère la chaleur !, April 2019.



© Gerard Lacz/Rex Feature/REX/SIPA