Geoffrey Promis

Impact of combined moisture buffering capacity of a hemp concrete building envelope and interior objects on the hygrothermal performance in a room

In this article, a hygrothermal building model, taking into account the building envelope, indoor heat and moisture sources, indoor environment and moisture buffering capacity of interior objects, is presented and validated with the test cases found in the literature. The model is used to study the impact of hemp concrete and the moisture buffer capacity of the interior elements on the prediction of the hygrothermal comfort in the building. The numerical results show that the use of hemp concrete in buildings can ensure good hygrothermal comfort. Besides, taking into account the effect of moisture buffering of indoor objects increases the building performance. Our results also suggest that neglecting moisture transfer through the envelope increases significantly the predicted percentage of dissatisfied indices and reduces the acceptability of indoor air quality during the occupied period. This study also confirmed that the combined relative humidity-sensitive ventilation system and moisture buffering capacity of building envelope and of interior objects is a very efficient way to reduce the heating energy consumption.

SENSITIVE ANALYSIS OF HARMONICS ON THE ASSESSMENT OF THERMAL DIFFUSIVITY OF BUILDING MATERIALS OF A PERIODIC STATE

Thermal efficiency of buildings requires a perfect knowledge of the thermal properties of materials which compose building envelope. To this end, the use of reliable testing methods for thermal diffusivity measurements of buildings materials is fundamental. Currently, periodic methods are based on the exploitation of fundamental harmonic, resulting from Fourier series decomposition. The objective of this paper is to demonstrate that fundamental is necessary and sufficient in order to characterize the thermal diffusivity. For those purposes, a sensitive analysis of harmonic contributions from Fourier series is supported by a substantial experimental campaign. Moreover, some dissymmetrical tests were carried out in order to highlight the preponderant influence of fundamental, compared to other harmonics. The analysis of contributions of harmonics shows that the evolution of thermal diffusivity is very slightly dependent on the number of harmonics. Then, the exploitation of fundamental is necessary and sufficient, and the characterization test protocol is validated by experimental results and by the comparison with commonly accepted values for these kinds of materials.