Abstract
The building and construction sectors significantly contribute to global climate change through both the embodied carbon of construction materials and operational energy use, stressing the need for more sustainable, circular practices. Insulation materials are central to this transition, as they not only reduce energy demand but also offer opportunities for low-impact material innovation through bio-based inputs, recycled content, or reuse strategies. This study examines how the environmental impact of a wood-fibre insulation board can be optimised by substituting virgin ingredients with bio-based or recycled materials and by applying circular design principles. The work is part of the Horizon Europe-funded EASI ZERo project, which aims to develop and validate low-impact building envelope components for efficient renovation and the design of zero-energy buildings. Using life cycle assessment (LCA), a consolidated wood-fibre board made from virgin ingredients is compared with laboratory-tested production options that replace the fossil-based bicomponent binder with bio-based or recycled alternatives, as well as with variants that substitute virgin wood fibres with recycled fibres. Results indicate that increasing bio-based and recycled content can reduce embodied carbon from 0.61 to 0.52 kg CO 2 eq., while circular end-of-life strategies further lower overall climate impacts. The findings emphasise that in-depth knowledge of product design and the integration of multiple circular strategies are essential for reducing the carbon footprint and promoting circularity in construction.