Review of bio-based wood fiber insulation for building envelopes: Characteristics and performance assessment

A sustainable future in the built environment is contingent on the reduction of energy consumption. Thermal insulation has been widely used as a means of reducing the operational energy usage of buildings, however current products dominating the market are non-renewable, fossil-based, and utilize energy intensive production methods. Wood fiber insulation (WFI), the most successfully commercialized natural insulation product, has been produced in European nations since the late 1900 ' s, however spread to other regions did not occur until recently. Limited global use has led to a narrow body of research that focuses largely on material development and use in cold climates. The investigation of WFI in building envelopes is insufficient, especially regarding its biological and hygroscopic nature, as well as its impact on the building envelope's performance. This paper aims to review WFI's hygrothermal and energetic performance. First, material property evaluation, such as thermal conductivity and moisture sorption, provides insight into the ability of WFI to be used in buildings while determining if there are special considerations when being used. An assessment of WFI within wall and roof assemblies allows for investigation under varying climatic conditions and within building systems. Finally, whole building monitoring allows for an understanding of how WFI acts within the building envelope with human occupation. Findings reveal WFI provides comparable thermal conductivity to conventional insulation materials, while being biologically derived and vapor open. Further research is required to harmonize testing methodologies, production processes, and additives used to better the impacts these have on WFI's properties.