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Bio-based building materials such as hemp concrete have been used successfully in building construction due to their thermal and environmental properties. Since they are also hygroscopic, modeling their hygrothermal behavior is also relevant for appropriate building design. In this work, heat and moisture transfer is investigated numerically by accounting for hysteresis and phase change effects. Input physical properties and their dependency on temperature and moisture content were determined by laboratory experiments. To validate the model, two extended cyclical adsorption/desorption experiments were first performed on an instrumented hemp concrete sample. One of the tests was conducted according to the Nordtest protocol. In the third experiment, a hemp concrete wall was monitored under various boundary conditions. The comparison of numerical results with experimental data gave satisfactory results for all the experiments, regarding mean moisture variation, local temperature and relative humidity variations. Lastly, we conclude on the use of a hysteresis model for hygroscopic materials. [ABSTRACT FROM AUTHOR]

Abstract: The sustainable world''s economic growth and people''s life improvement greatly depend on the use of alternative products in the architecture and construction, such as industrial wastes conventionally called green materials. For this purpose, hemp concrete is more and more recommended by the eco-builders because hemp is a renewable plant, recyclable and does not degrade within time. It corresponds perfectly to the requirements of high environmental quality buildings. The objective of this article is to study transient hygrothermal behaviour of hemp concrete at whole building level. The physical model is one-dimensional and was implemented into the object-oriented simulation environment SPARK, using the finite difference technique with an implicit scheme. The numerical result showed that the use of hemp concrete wall in buildings can ensure good indoor air quality and energy savings in winter. Besides, the combined effect of moisture buffering with the adequate ventilation strategies increases hemp concrete building performance. Our results also suggest that taking into account the hygrothermal transfer at whole building level with heat and moisture production sources has significant effects on predictions. [Copyright &y& Elsevier]