Scientific guidelines
The actions developed under this theme concern the envelope and structural elements of buildings. The theme focuses on understanding the thermal, mechanical, and hydric responses of envelope and structural elements in new or existing buildings, particularly those incorporating unconventional and multifunctional materials.
Locks and a scientific approach to the problem
In line with studies already underway at LOCIE on the behavior of wall elements or structures incorporating unconventional low-energy or low-carbon building materials (development, modification, hygrothermal and mechanical characterization, coupling in porous media), the laboratory will also focus on multifunctional walls (mechanical and thermal) and their assemblies. One section will be devoted to the study of the multilayer materials required for these walls. There are many phenomena to be taken into account, including coupled mass and heat transfer, the mechanical and hygrothermal behavior of walls, energy collection and conversion integrated into building envelopes, the structural stability of buildings, structural dynamics, and the behavior of building materials. In addition to the complexity of the phenomena already mentioned, there are also phenomena related to assemblies and multifunctionality.
To achieve this, it is necessary to develop methods for inspecting and diagnosing the structure and energy efficiency of buildings. Methods based on dynamic experimental analysis and image correlations appear to be very promising. The challenges relate to multi-physical behavior and the difficulty of in-situ measurement, hence the need to reconstruct a valid model from minimally intrusive measurements. In this context, we will focus on the development of innovative metrology for moisture in building walls, such as the development of microwave sensors, or temperature and humidity sensors based on wireless technologies such as RFID.
Faced with the challenge of renovating old walls, the reliability of modeling must be improved. Indeed, insulating old walls (rammed earth, etc.) disrupts the hygrothermal balance and can impact the mechanical cohesion of the material. The impact of this disruption can be understood by studying the phenomena of mass and heat transfer coupled within the material, which are influenced by the environment (sunlight, wind, building users, heating, ventilation, etc.). Highly hygroscopic materials (e.g., bio-based insulation or other unconventional materials) can reduce the amplitude of variations in boundary conditions ("buffer effect"). However, this behavior remains complex, and more accurate modeling requires taking into account new phenomena that are neglected in standard models (volumetric heterogeneity, hygro-thermo-mechanical couplings, sorption kinetics, impact of binders on properties, etc.), both within a material and at interfaces.
This renovation challenge is fully in line with the goal of limiting the environmental impact of buildings. This effort sometimes requires repairing or strengthen the structure in place, from a mechanical point of view: for example, the protocol combining a stainless steel grid and mortar developed in the laboratory has yielded promising results and should be studied further. More generally, the use of low-carbon materials (raw earth, natural stabilizers or stabilizers derived from waste, etc.) is an interesting alternative to traditional construction methods. To this end, it is necessary to study their multi-physical behavior, including health aspects, while taking into account their impact on 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 developing approaches at very different spatial scales (from the basic component, through its integration into the envelope with variable boundary conditions, to coupling with energy needs at the building or regional level) and temporal scales (from daily variability in sunlight to climate change).
Permanent staff
The researchers associated with this theme represent 6.7 FTE EC (including 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%).
Resources mobilized
Actions are already underway to address most of these issues. For example, in the area of rammed earth, the MOPGA (rammed earth stabilization), ADEME-Olimp (rammed earth insulation), and ANR V-Batch (rammed earth structures) programs have just been launched, enabling the initiation or strengthening of 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 collaboration with the University of Science in Ho Chi Minh City, Vietnam, to continue. A new collaboration with a team specializing in mold identification will also be developed. This initiative, which has already begun as part of a SCUSI program in the Auvergne-Rhône-Alpes region, will also enable the development of cross-disciplinary projects within LOCIE itself. All these projects will rely on various experimental methods, either existing or currently being installed at LOCIE, which will need to be improved or adapted to the different projects (thermogravimetric analysis, double thermohygric chamber (RHBox), conductivity meter, structural platform, etc.). An MCF 60 has just been recruited to strengthen the diagnostic and mechanical repair aspects.
Partnerships and projects
PUCPR (Brazil), ENTPE –Lyon, Cethil – Lyon, CSTB –Grenoble, Ho Chi Minh City University of Science, Vietnam, UGA-Isterre, Politecnico di Milano, CEREMA BPE SCUSI team (Region), ANR V-Batch, OLIMP, SMART RENO, and industrial collaborations (EDF, Léon Grosse, Filiaterre, Patriarche Architecture).