Bio-based building materials: A prediction of insulating properties for a wide range of agricultural by-products

Sustainable construction is a key solution in the light of today's climate and energy challenges. Indeed, the use of plant-based aggregates in the construction sector helps to improve both energy and environmental efficiency. However, the use of bio-based aggregates as loose-fill insulation remains limited despite the wide availability of raw materials (agricultural by-products or wild plants) and their easy implementation. One of the problems is the diversity of resources that complicates both characterization procedures as well as the understanding and prediction processes of bio-material behaviors. One way to overcome these obstacles is to offer a unified method which is applicable to a wide range of plant-based aggregates. This is the purpose of the following study with the prediction of the thermal conductivity of bulk aggregates. This paper initially focuses on the particle scale in order to identify commonalities across a wide range of aggregates. Based on a multi-scale study, then distinguishes two different types of particulate morphologies. Particulate values of thermal conductivity - unavailable in the literature - can thus be provided over the full range of temperature and relative humidity conditions. A linear relationship between thermal conductivity and density is suggested at the particle scale while this type of relationship was previously known at the material scale. This work will also demonstrate the possibility of anticipating and offering equivalent insulation performances depending on the local resource available for loose-fill insulation cases.