Plant based insulation as carbon sink? : life cycle assessment of biochar based building Insulation material

The building industry is responsible for about one third of the global greenhouse gas emissions and drastic measures are needed to reduce its environmental footprint. But what if the carbon footprint could not only be reduced, but if buildings could even serve as carbon sinks to fight climate change? The interdisciplinary CarNE research project developed a novel type of building materials based on biochar from plant-based wastes and side streams. With a multicriteria decision analysis (MCDA), we assessed 37 biomass streams available in Central Europe that could potentially be suitable for the production of biochar insulation materials. With the MCDA, biomass streams such as bran, forest wood bark, and wastes from coffee roasting were evaluated against nine sustainability criteria, six socio-economic criteria, and five technical criteria. For the most promising biomass streams, material samples and first scale-ups in the form of insulation boards were developed. In collaboration with project partners from Zurich University of Applied Sciences ZHAW and Empa, a cradle-to-grave life cycle assessment of the new product system from different biomass streams was performed and compared to conventional building insulation materials. Impact assessment was made with the Environmental Footprint methodology and a special focus was laid on the evaluation of the biochar-based products’ potential to remove carbon dioxide from the atmosphere and store it long-term in the building stock. Depending on their specific properties, the biochar materials could be reused in agriculture to increase soil fertility once the buildings have been deconstructed. The results presented at the LCM 2023 will reveal if biochar-based building insulation materials outperform conventional insulation materials and if they have potential to contribute to a net zero building industry.