The transition to a circular economy by 2050 values the use of building materials that are more respectful of the planet. It is in this context that the interest for new construction in earth masonry is increasing, justified by its low environmental impact and by the desire to keep the memory of local building typologies for landscape insertion and the tourist attractiveness of territories. The use of earth masonry as construction material remains limited by the difficulty of correctly evaluating the performance of the load-bearing structure under dynamic action, which can be prohibitive for questions of technical certification and insurability of a new construction in seismic zones. The goal of DYNATERRE project is to design specific test devices to obtain a better mechanical knowledge of earth masonry, to optimize the construction material conception and production improving thermo-hydro-mechanical properties, but also paying attention to environmental goals, and to understand the influence of conception choices on a set of parameters used to characterize the material behavior in building modeling for seismic design in accordance with the Eurocodes. The project is developed following a progression of knowledge of the structural response of masonry buildings at different scales: starting from the scale of raw materials, then of the composite material, going towards the structural element, to arrive at the global response of the building. The research institutes, partners of the project, have complementary skills on numerical and experimental approaches and they have been involving for several years in the development of geo-sourced masonry construction, in collaboration with the partner companies.

The BAYREB project proposes investigating the theoretical potential of Bayesian inference applied to the diagnostics of existing buildings before their refurbishment. The largest potential for energy savings in the building sector lies in the renovation of the existing building stock. As a result, an increasing amount of research is being dedicated to encourage decision makers. Guaranteeing the performance of a building after renovation would be an efficient incitation, but is still difficult to perform in practice. A necessary condition for a cost-effective refurbishment, adapted to each specific building, is to perform detailed diagnostics of its performance prior to picking solutions: for instance, to estimate which proportion of the energy consumption is caused by air leakage, by transfer through the envelope, or by a dysfunction of the heating systems. The solution for establishing such diagnostics is to implement inverse techniques, which are able to automatically learn from in-situ measurement data in order to construct a realistic representation of the characteristics of a building. The importance of the energy audit of existing buildings has already motivated several projects which underlined the difficulty of applying inverse methods for the identification of building properties. The overall observation of these projects is that a reliable energy audit requires a rigorous theoretical basis in order to explore its full capabilities. Moreover, previous works on the topic of building energy performance characterisation meet two main problems: - The most common inverse methods in engineering are deterministic and do not ensure finding the global optimum in the search space. Moreover, they often only offer point estimates of the sought properties: confidence intervals on identified parameters can only be obtained by a separate forward sensitivity analysis. - When applied to building physics, inverse methods always rely on a simplified modelling of the buildings (RC models) and may exceedingly overlook important influences on the energy performance: occupant behaviour, HVAC control strategies and coupled influences of heat, air and moisture. While always keeping in mind the realities of the energy performance monitoring of buildings, the BAYREB project will attempt to go closer to the fundamentals of inverse techniques, in order to apply them for this purpose. The novelty of the BAYREB proposal compared to previous projects is the specific choice of the Bayesian statistical framework, and fundamental research on the capabilities and limitations of inverse methods applied to building physics. The principle of Bayesian inference is to draw conclusions from incomplete observations of a system, and update knowledge as more data is available. Given a set of records (sensor data and inaccuracy), and some prior assumption on the model structure (expert knowledge), one can compute the probability of their causes (energy audit, envelope properties…) by means of conditional probability and the Bayes theorem. The particularity of Bayesian inference, as opposed to other inverse methods, is that it inherently performs an inverse propagation of uncertainty: missing data, sensor inaccuracy, or simplifying model assumptions, will have a direct effect on the assessment of building characteristics and their confidence intervals. A second advantage is the fact that it can be applied to any class of mathematical function, from white-box to black-box models, as it does not require the computation of sensitivity gradients. The ambition of the BAYREB project, compared to related work on building parameter identification, is therefore twofold: to address the problem in a fully stochastic manner which will account for all model and measurement uncertainty; and to not force end users to a given building simulation software.

The use of local materials is characteristic of most of millions of housing built before 1948 in France. These materials are not industrially processed and therefore lead to a significant decrease of grey energy consumption. However, due to lack of scientific knowledge, there is currently no clear recognized guidance for their set-up, or means of measurement to guarantee their performance. This lack commonly leads to apply renovation and construction methods which are unsuitable, and / or to prefer other building materials, environmentally less efficient, but benefiting from standardized testing procedure. In the best case, companies rely on their empirical knowledge of these buildings. Thus, the challenge of this proposal is to explore ways to measure and guarantee hygrothermal, mechanical and seismic performances of local materials and ensure their dissemination and development through an analysis of institutional conditions. To achieve this objective, we propose to identify and measure, through physico-mechanical modeling and experiments at different scales (laboratory, on site), the key parameters needed to describe the hydro-thermal behavior of buildings and seismic. In this context, we will study the impact of natural vegetable fibers additions on the behavior of the studied clay soils. The approach will be validated on the rammed earth and rough masonry constructions, which are the most representative of old buildings (before 1948). Ultimately, PRIMATERRE project will allow the development of design guidance and training modules.

Environmental issues in building sector are huge, particularly in the context of reducing greenhouse gas emissions. This concerns not only the construction phase, but also operation phase and end of life of buildings. Within this framework and following new RE2020 regulations, this project aims to investigate the multi-physical behaviour of raw earth building insulated with bio-based materials. PACS+ project will focus on different scientific issues: the in situ measurement (large scale) of thermal and hygric fields with non-destructive methods; a detailed understanding of hygric effects within porous materials with the help of modelling; the description of the coupled hygro-thermo-mechanical behaviour specifically at the interface between raw earth and bio-based materials; the evaluation of insulation effect on global performance from both energy and structural point of view. The originality of the current proposition is considering together the association of 2 materials –earth and bio-based insulating- and the relative effects between both. It is chosen to deal with the whole multi-physical effects that take place in such building panels. Another original point is to focus on real scale; the development of original non-destructive tools, at this scale, seems to be promising in the perspective of in situ diagnostic. That’s why, tools will be used on materials and panels at both scales for characterization, with a particular attention to the scale effects. On one hand, on a composite sample, the coupled hygro-thermo-mechanical behaviour will be characterized, interpreted and reproduced by suited models. On the other hand, on large scale panels, the influence of insulation on energy and structural performances will be evaluated both in transient phase and in steady state.

The rehabilitation of the existing buildings is a major stake to reduce of a factor the 4 gas emissions for purpose of greenhouse. So that this effort is authorized by all it is necessary to propose complete technical solutions (insulation, ventilation) and acceptable for the professionals. These solutions must bring answers to the energy reductions but also to the comfort of the occupants and the durability of the solution suggested. At the time of rehabilitations, the principal risk, badly apprehended at the present time as well in the practices as in the regulation, lies in a slow and irreversible degradation of certain components sensible to moisture (beams out of wooden, stones tender, old coatings, etc). This degradation can, in certain cases, to lead to the collapse of all or part of the building. Moisture was indeed always the enemy number one of the building. Moulds, rot of wood, corrosion of metals are among the current effects of the dangerous connections that maintains water with materials and the works. To bring viable solutions, our project falls under a step of energy restoration “total” of the park of existing buildings, by distinguishing the constructive times and modes (mainly “built old” on a side, “modern frame” of the other) and while seeking to couple the dependent aspects: - with the thermal improvement of the envelope (current walls and connections), - with the hydrous transfers through the envelope, - ventilation and the permeability to the air, - the consequences of the effects of moisture on the emissions of materials and the risks of moulds. This study proposes to produce a guide of assistance to the rehabilitation of the existing buildings by proposing adapted solutions. This guide will be accessible by the professionals from the building. To validate these solutions, a tool articulating the models and modules of simulations existing able to predict the power consumptions, the comfort of the occupants and the risks of pathologies related to moisture after restoration will be developed. This tool will be validated by in situ measurements before and after restoration on real and occupied buildings and by measurements on an experimental cell to build. The experimental cell will allow experiments in artificial climatic conditions, for better including/understanding the phenomena of transfers and in real climatic conditions. The data input being essential to simulations, a list of the characteristics necessary to the models will be carried out on the basis of element existing and supplemented if necessary by measurements directly on the products. The guide will be produced starting from the results of measurement of this study and will be supplemented by simulations of configurations suggested during the analysis of the existing built park. Thus the building owner or the project superintendent will have at his disposal a guide proposing of the checked and validated solutions of rehabilitation. If the guide is not sufficient, the tools developed in this study will make it possible to answer its request.