Hygrothermal properties of light earth insulation materials: evaluation of uncertainties and consequences
Hygrothermal simulation of bio-based materials requires heat or moisture storage and transfer properties. Even if their determination is defined in numerous standards, characterization implies uncertainties. In this work, we aim to evaluate the uncertainties in the determination of heat and moisture storage properties of light earth insulation materials and of their constitutive raw materials (hemp shiv and earth). Heat thermal capacity is evaluated by Differential Scanning Calorimetry (DSC). Sorption isotherm is evaluated by gravimetric methods. Attention is paid on protocols and methods, on the measurement repeatability or on the influence of drying temperature and relative humidity. Results show that uncertainties up to 10 % are noted for heat capacity, while they may rise up to 100 % for sorption isotherm. These values are compared to uncertainties due to material variability. In addition, a discussion is proposed regarding the validity of mixing law. Last, the consequences of all uncertainties are evaluated on the prediction of hygrothermal behavior of an existing wall insulated with light earth insulation materials.