Indoor Air Quality and emissions from building materials have been over the last decades a major challenge for scientists, industry and consumers. Traditional construction materials contribute to contaminants such as VOCs, formaldehyde, particulates and fibres. However, new eco-innovative building materials are able to provide a healthier indoor environment both by substituting source of contamination and by elimination of contaminants arisen from other indoor sources.Within OSIRYS proposal a holistic solution for facades and interior partitions will be developed ready to be applied in building retroffiting and new construction by means of the development of forest based biocomposites with different functionalities able to meet the strictest requisites of the Building Code and improve indoor air quality by VOC and microorganisms elimination, increase thermal and acoustic insulation and control breathability of the construction systems.Thermoset epoxy resin based in forest wastes and thermoplastic lignin-base polymer will be reinforced with natural fibres such as wood, flax, hemp, etc. Besides, cork granules will be used for insulation performance. Special attention will be put on additives, especially fire retardants, to meet cost/processability/performance ratio. However, it is expected that biomass feedstock in each building element will be >75%, what allows to reduce embodied energy on building materials by more than 25%.Research activities will include: development and testing of the new eco-innovative materials; design and engineering to ensure the technical viability, aesthetical aspect and ease to incorporate the system in building retrofit actions; LCA; evaluation of the reuse and recycling; study on the adequateness to the requirements of the Building Code; demonstration activities by applying the final system in a test building and in two new buildings in Spain and Sweden to make validation in two different climates and cost effectiveness assessment.