Integrating prefabricated straw bale panels into timber framed housing in cold climate urban contexts

This research addresses the integration of straw-bale construction systems into multi-story timber-framed housing in Nordic urban contexts, with a specific focus on Finland. Given the increasing need for low-carbon construction alternatives, particularly in cold-climate regions, exploring renewable and bio-based materials is of both environmental and architectural importance. The objective is to examine the feasibility of using prefabricated straw-bale panels in combination with a post-and-beam timber structure to meet basic fire safety and spatial adaptability criteria. This study contributes a conceptual hybrid design model that incorporates straw as an external infill material, aiming to extend material diversity in sustainable architecture. Employing a research-by-design methodology, the Viinikanlahti project is grounded in a real urban development site in Tampere, and engages with zoning constraints, design principles, and literature-based regulatory parameters. Key findings are as follows: (1) Precedent literature indicates that clay-rendered straw-bale panels may meet P2 fire classification requirements under prescribed detailing conditions. (2) The adoption of a post-and-beam timber framework facilitates programmatic flexibility by enabling interior transformations independent of the primary load-bearing system. (3) While no LCA was performed in this study, existing environmental assessments suggest that straw-based assemblies possess favorable embodied carbon metrics owing to low processing energy and end-of-life biodegradability. For stakeholders such as housing authorities, municipal planners, and ecological developers, this study offers a speculative yet contextually grounded model that highlights the architectural potential and regulatory questions surrounding bio-based materials in Nordic mid-rise housing.