Development of sound absorbers from renewable raw materials: Challenges and first steps

About 40% of the global CO2 emissions are currently generated in the building sector, 70% of the raw material extraction in Germany is used for construction and 50% of the total waste is produced by the construction sector. These figures indicate that the goal of reducing grey energy in construction, using sustainably produced materials and making these products recyclable, is becoming increasingly urgent. The currently used sound absorbers are largely made from materials that are not sustainable. Many absorbers are made from polyester fleece, glass-, mineral-, and rock-wool or other material from oil or have high energy demand for production and thus have a high CO2 footprint. Others like wood wool absorbers are bonded with cement or magnesite, also resulting in a high GWP.Future sound absorbers need to be manufactured from renewable raw materials, preferably made from waste or from by-products of other renewable production chains. First prototypes for such absorbers have been produced, and first measurement results of various materials like wood foam, citin absorber, sea gras absorber and others will be presented. This contribution aims for a discussion on how room acoustics solutions can be more sustainable, as further research is needed.