The actions developed in this theme concern the building envelope and structural elements of the building. The theme focuses on understanding the thermal, mechanical and hydric responses of the envelope and structural elements of a new or existing building, including in particular non-conventional and multifunctional materials.
Locks and scientific approach to the problem
In the continuity of the studies already undertaken at LOCIE on the behaviour of wall elements or structures comprising non-conventional low-gray energy or low-carbon building materials (elaboration, modification, hygrothermal and mechanical characterizations, coupling in porous media), the laboratory will also focus on multifunctional walls (mechanical and thermal) and their assemblies. A section will be devoted to the study of the multilayer materials required for these walls. The phenomena to be taken into account are numerous and concern the coupled mass and heat transfers, the mechanical and hygrothermal behaviour of the walls, the collection and conversion of energy integrated into the envelopes, the structural stability of the building, the dynamics of the structures and the behaviour of the construction materials. To the complexity of the phenomena already mentioned will be added phenomena related to assemblies and multifunctionality.
For this purpose, it is necessary to develop methods of auscultation, structural and energy diagnosis of buildings. Methods based on dynamic experimental analysis and image correlation seem very promising. The challenges are related to the multi-physical behaviour and the difficulty of in-situ measurements, and therefore the need to reconstitute a valid model from minimally intrusive measurements. The development of innovative metrology for humidity in building walls, such as the development of microwave sensors, or temperature and humidity sensors based on wireless technologies such as RFID, will be considered in this context.
Faced with the challenge of rehabilitating old walls, the reliability of modelling must be improved. Indeed, the insulation of old walls (adobe, etc.) disturbs the hygrothermal balance and can impact the mechanical cohesion of the material. The impact of this disturbance can be understood by studying the phenomena of coupled mass and heat transfers within the material, influenced by the environment (sunshine, wind, building users, heating, ventilation, etc.). Highly hygroscopic materials (e.g. bio-sourced insulation, or other non-conventional materials) allow to reduce the amplitude of boundary condition variations ("buffer effect"). However, this behaviour remains complex and more accurate modelling requires taking into account new phenomena, neglected in standard models (volume heterogeneity, hygro-thermo-mechanical couplings, sorption kinetics, impact of binders on properties, etc.), within a material, but also at the interfaces
This renovation challenge is fully in line with the limitation of the environmental impact of buildings. This effort sometimes requires repairing or strengthen the structure The protocol combining a stainless steel grid and a mortar developed in the laboratory, for example, has given promising results and its study should be continued. More generally, the use of low-carbon materials (raw earth, natural or waste stabilizers...) is an interesting alternative to traditional constructions. For that it is necessary to study their multi-physical behavior, including sanitary, by taking into account their impact on the indoor air quality.
The envelope of a building, whether new or renovated, can not only protect the interior space, but also meet certain energy needs (heating, cooling, electricity, etc.). This requires the implementation of coupled physical models of these multifunctional walls, and the development of approaches at very different spatial scales (from the elementary component, through its integration in the envelope with variable boundary conditions, to the coupling with energy needs at the building or territorial scale) and temporal scales (from daily sunshine variability to climate change).
Researchers attached to this theme represent 6.7 EC eq (of which 2.30 Pr and 5.20 MCF), or 3.35 FTE_R.
N.Prime (MCf, 100%), O. Plé (Pr, 100%), M. Woloszyn (Pr, 50%), C. Ménézo (Pr, 30%), J.P. Plassiard (MCf, 100%), A-C Grillet (MCf, 100%), S. Rouchier (MCf, 20%), A. Agbossou (Pr, 50%), A-L Perrier (MCf, 50%), M. Pailha (MCf, 50%), A. Lushnikova (MCf, 100%).
Action is already underway on most issues. For example, on adobe, the MOPGA (adobe stabilisation), ADEME-Olimp (adobe insulation) and ANR V-Batch (adobe structure) programmes have just begun, making it possible to start or strengthen collaborations with the Politecnico di Milano, ENTPE and the ISTerre laboratory at USMB. With regard to the study of bio-based materials and their impact on the indoor environment, this will enable the collaboration with the University of Sciences of Ho Chi Minh City in Vietnam to be continued. It will also be necessary to develop a new collaboration with a team specialized in the identification of moulds. This action, which has already started within the framework of a SCUSI programme in the Auvergne-Rhône Alpes region, also allows the development of transversal projects within the LOCIE. All these projects will be based on different experimental means, existing or being installed at the LOCIE, which will have to be improved or adapted to the different projects (thermogravimetric analysis, double thermohygrid chamber (RHBox), conductivity meter, structure platform...). An MCF 60 has just been recruited to reinforce the diagnostic and mechanical repair aspects.
Partnerships and projects
PUCPR (Brazil), ENTPE -Lyon, Cethil - Lyon, CSTB -Grenoble, University of Sciences of Ho Chi Minh City Vietnam, UGA-Isterre, Politecnico di milano, CEREMA team BPE SCUSI (Region) , ANR V-Batch, OLIMP, SMART RENO and industrial collaborations (EDF, Léon Grosse, Filiaterre, Patriarche Architecture).