A new transparent wood becomes cloudier (right) upon the release of stored heat. Image: American Chemical Society
The creation of a new transparent wood could make buildings of the future more sustainable, and the material could also be used for heating.
Soon, our cities and suburbs could see the return of wood as the backbone of architecture, in the same way we may think of concrete and glass today. That’s according to new findings presented by a team of researchers from Sweden at the recent spring meeting of the American Chemical Society.
The team revealed it has forged a new kind of transparent wood that not only transmits light, but also absorbs and releases heat in what could provide major savings on energy costs.
Rather than being weak, this new wood can bear heavy loads and is biodegradable, making it ideal for eco-friendly homes. While it is possible to see through the wood, it is opaque enough to allow for privacy if used as a major building material.
The KTH Royal Institute of Technology in Stockholm team said the wood was altered by removing a light-absorbing component called lignin found in the cell walls of balsa wood. To reduce light scattering, they incorporated acrylic into the porous wood scaffold.
Then, a polymer called polyethylene glycol (PEG) was added to the de-lignified wood. “We chose PEG because of its ability to store heat, but also because of its high affinity for wood,” said Céline Montanari of the team. “In Stockholm, there’s a really old ship called Vasa, and the scientists used PEG to stabilise the wood. So we knew that PEG can go really deep into the wood cells.”
Known as a ‘phase-change material’, PEG is a solid that melts at just 27 degrees Celsius, but which stores energy in the process. However, its melting temperature can be changed using different types of PEGs.
“During a sunny day, the material will absorb heat before it reaches the indoor space, and the indoors will be cooler than outside,” Montanari explained. “And at night, the reverse occurs – the PEG becomes solid and releases heat indoors so that you can maintain a constant temperature in the house.”
The super wood also incorporated acrylic into it to protect it from humidity, making it the only non-biodegradable component of the process. However, lead investigator Lars Berglund said this could eventually be replaced in manufacturing by a bio-based polymer.
The team’s focus is now to scale up production of the transparent wood, believing it could be available for niche applications in interior design in as little as five years.
