The ‘Hybrid Composites' Project (HC) has developed new collaborative models, digital techniques and design methods for additive manufacturing (AM) with biocomposites in a way that can support the development of practice, business models and smart technology towards a more sustainable built environment and a circular economy. HC focused on design for AM production with cellulose-based materials for applications in full-scale building construction, and was implemented in a series of demonstrators with increasing complexity. The goals has been to in an integrated way decrease construction costs, time, weight, structural complexity, assembly time on site and climate impact, and at the same time increase the possibility for customised design as compared to conventional timber construction. The house prototype C-Hiva is the final demonstrator, which shows how building elements produced through AM can be combined with conventional timber construction. The prototype was also a contribution from Chalmers ACE and Team Sweden in the competition ‘Solar Decathlon Europe 2021/2022, which took place in Wuppertal, Germany, in June 2022 (www.sde21.eu). The HC project has developed prefabricated light-weigh construction through new design methods, simulation and integrated BIM processes in a collaboration between Chalmers ACE, RISE and Stora Enso.