Aalto University – Lumir developed bio-based acoustic coating

The acoustic material, developed by Aalto University researchers in partnership with the company Lumir, is a fibre mass made out of wood cellulose.

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Aalto University
Aalto University - Lumir developed bio-based acoustic coating

Achieving adequate acoustics while maintaining the aesthetics of the space and reducing the visual aspects of acoustic materials and elements is a big challenge. Latest acoustic coating can address this issue. This type of coating can be sprayed on other sound absorbing structures to make it more effective on a wide frequency range. In addition, the coating acts as a carbon sink during its operating life, thus reducing the carbon footprint of the building. Over the past years, the study and development of acoustic eco-materials has received much attention. In this regard a cellulose-based material was successfully tested in a protected building owned by Aalto University.

The acoustic material, developed by Aalto University researchers in partnership with the company Lumir is a fibre mass made out of wood cellulose. When sprayed onto a surface, it forms a porous, sound-absorbing layer that follows the underlying shape.

The researchers recently demonstrated the new material in the reading room of an Aalto University building in Helsinki’s Töölö neighbourhood. It was used to be the main building of the Aalto University School of Business and is now protected by the Finnish National Board of Antiquities, With the new acoustic material, the reverberation in the room was easily attenuated while complying with the regulations.

Tapio Lokki, a professor of acoustics at Aalto University, says that the coating significantly improved the acoustics of the room. He further explains, ‘Two walls of the Töölö reading room were coated. On one wall, the mass was sprayed over glass wool, and on the other, it was sprayed on its own. With these easy steps, the acoustics of the space improved significantly without changing the appearance of the walls. The noise level in the room was significantly reduced, and the end result will sound even better once furniture and people come in.’

Features of the material;

  • The material can be used to coat a larger area than can be covered with acoustic panels
  • Producing the new material doesn’t consume much energy
  • More carbon dioxide is captured in the material than is released throughout the entire production process

Lokki and his team are now studying whether cellulose fibres from hardwood or softwood trees provide better acoustic performance in this material. ‘In our research, we have found that the origin of the fibres also seems to have an impact on acoustics,’ he says. ‘Interdisciplinarity is useful in this work, and we’ve also involved chemists led by Professor Jaana Vapaavuori.’

The collaboration between Aalto University and Lumir began five years ago. Master’s and doctoral students at Aalto have been studying how biomaterials can be used in acoustics. ‘Jose Cucharero is currently doing research for his doctoral dissertation while also working at Lumir,’ says Lokki.

Tuomas Hänninen, Lumir’s Director of Research and Development and one of Cucharero’s dissertation advisors, also praises the fruitful collaboration.‘Based on its results alone, we have developed a cellulose-based, carbon negative acoustic panel. We’re also working on an acoustic panel made out of 100% cellulose,’ he says.

The research has been quickly applied to product development and is a great move towards achieving carbon neutrality.