Hygrothermal study of a wall built with prefabricated rapeseed concrete blocks
Résumé
45% of annual energy consumption is due to the building sector, which is the most energy-intensive sector in the world. This sector is responsible for 23% of greenhouse gas emissions. The RT2020 provides a strategy to reduce energy consumption, and one of its solutions is to use low-energy building materials and develop local industries. So Bio based materials are increasingly being used as construction elements in the building envelope due to their low environmental impact and hygrothermal performance. Their use would lead to a reduction in greenhouse gas emissions and would address the issue of depletion of natural resources.
There are several types of bio-based materials. In this study, we are interested in studying rapeseed concrete. This material has
good thermal and hygric performance.
In order to carry out the numerical simulation, several material parameters are required. A large experimental campaign on hygrothermal characteristics is carried out. The parameters calculated are thermal conductivity with values of 0.08 W/m.k, sorption curves, water vapor diffusion, capillarity and porosity.
The aim of this study is to investigate the influence of the dynamic temperature and humidity cycle, as well as the influence of
the different climates on the wall made of precast blocks of rapeseed concrete.
This numerical simulation of heat and moisture transfer is carried out on the WUFI 2D software. In the first place, the wall alone is studied. In the second part, a coating will be applied on both sides of the wall in order to compare the results of the two cases studied. The evolution of temperature, the water content and mould for 1 year will be studied in different depths of the wall in the two cases considered. The performance of the wall will be highlighted thanks to the addition of a coating.
This study shows that coating in the two sides protect the wall from the condensation risks and mod growth having a great influence on rate of dryness. In addition, different climates were tested affecting the hygrothermal performance of the wall. To complete the study, these types of walls should be compared with an experimental hygrothermal study.