Thanks to the SAPS-CSTI-Générique20 funding, the CO2NCRETE and PlayGrHyD projects will be able to be integrated into the mechanisms set up within the framework of the Science with and for Society label and benefit fully from them. The additional financial resources will make it possible to optimize the quality and dissemination of the planned mediation materials.

With the current environmental issues and climatic change, it is of major importance to design highly energy efficient buildings. Several programs have been developed in the past 50 years to model the transfer phenomena in building enclosure to assess the global energy consumption. However, the enclosures are always designed as plane by association of several layers of different properties. In other words, is it not possible to design enclosures with shapes and topology optimized to minimized the transfer? The issue of the project is to develop a numerical and experimental framework to advanced design of building enclosures with optimized shape and topology. The answer to this considerable issue relies in tackling the lack of the actual state-of-the art models and experimental facilities. A combined experimental-modelling approach will be developed: (1) an innovative model with transient transfer processes considering time and space varying boundary conditions (2) elaborating a fast optimization numerical strategy to retrieve the varying topology and shape of enclosures and (3) verifying the insights with a pioneering experimental demonstrator based on 3D printing and controlled facility.

This work aims to evaluate the impact of plasticity and the nature of grain boundaries on hydrogen-induced brittle fracture mechanisms in nickel base alloys. In this context, and using innovative multiscale numerical and experimental approaches, we will interrogate in the presence of hydrogen, the implication of the mechanisms of plasticity coupled with the nature of the grain boundaries on the processes leading to the decrease of mechanical properties of metallic materials. The purpose of the project is the establishment of a damage map associating the modes of fracture, the character of the grain boundaries and the hydrogen-plasticity interactions.

Hydrogen embrittlement (FPH) is a major cause of failures in the industry structures. This multi-physical phenomenon often leads to cracks initiation and propagation highly dependent on the environment. The severe failure but also the human and economic consequences that may result have been the source of many studies and publications on this topic since the first evidence of the phenomenon, a century ago. Despite many national and international projects on the HE, the mechanisms of hydrogen diffusion and trapping linked to the materials microstructure are relatively unexplored. In other words, if the mechanisms of embrittlement are now well identified, the kinetics associated with transport and segregation of the species (hydrogen) at the origin of the damage remain poorly apprehended. Unlike other defects, such as dislocations or vacancies, there is a clear misunderstanding of the grain boundaries effect on hydrogen diffusion and trapping. In the most general case of polycrystalline structures, the average behavior of the aggregate (grain and grain boundaries) and the deviation from it are key elements concerning the diffusion and trapping processes which affect partly the material durability.This scale transition stage is often neglected however it can have important consequences on the measurement of the diffusion coefficient and/or the trapping energy. We propose to develop electrochemical permeation tests (EP) and thermal desorption spectroscopy (TDS) of nickel alloys (single crystal and bi-crystrals and finally polycrystals). In parallel, we will proceed to the development of "robust" finite element codes and more "efficient" calculation means for the calculation of diffusion on 3D aggregates. For this work will serve as a guide to the development of scale transition model of non-stationary phenomena (diffusion process) coupled with the trapping process associated to the heterogeneities of time and space. This project is a "coupled" way of thinking through continuous exchange between the experiment and model development efforts with simple structures to disentangle the various phenomena associated with leading transport and trapping of hydrogen. Treatment results according to the different variabilities will allow us to build tools for a reflection support in the development of microstructures less inclined to hydrogen embrittlement depending on whether it is a function of diffusible or trapped hydrogen (grain boundaries, development of dipole dislocation structures…).

Energy flexible buildings can support the integration of renewable energy sources in the national energy mix by modulating their energy use. Modulating the heating energy use of new and existing buildings could provide 10 to 20 GW of flexible load in France according to the literature and demonstrator projects. Despite a large potential identified, a number of issues prevents the deployment of this technology: communication, privacy, cost-effectiveness, control and reliability of the response. This project focusses on the last two issues and will test indirect control strategies to maximise the flexibility potential and coordinate the response of energy flexible buildings. The advantages of indirect over direct control strategies are the ease of deployment and the respect of the users’ privacy. The use of an indirect controller will ensure that the objective of matching production and demand is achieved at the aggregated level, though allowing some degrees of freedom at the building scale (the signal sent can be interpreted differently by each end-user’s energy management system). However, the main challenge of indirect controller is to get a reliable estimation of the capacity available, in order to be able to trade the capacity on the electricity market. This lack of reliability in the response has been identified as a barrier to the development of indirect control strategies for demand response. In this project, indirect control strategies combined with a rule-based controller (RBC) at the building level will be simulated on different case studies, accounting for the diversity of buildings and users. This project is centred on the building energy use, but will consider the problem from a district perspective using an integrated and multidisciplinary modelling approach, in order to come up with robust and optimised solutions. The project is coordinated by LaSIE (La Rochelle), and partners from G2Elab (Grenoble) will bring their expertise in the modelling of electrical networks. The project is divided in three main parts: the first part is related to the development of the simulation platform, the second part to the evaluation of the control strategy on the Atlantech low carbon district, and the last part to the robustness and of the reliability of the controller developed. In the first part, the building models will be defined using building energy simulation tools and grey-box models will be developed to ensure a short computation time. The building typology of the Atlantech low carbon district will be used as a reference and different types of users (based on stochastic modelling) will be considered. In parallel, the LV electrical network and the local production systems will be developed. Steady-state and simple modelling techniques will be used to focus on the main problems that can arise from energy flexible buildings (e.g. peak demand, ramping, voltage stability). The last step of the platform development will be to validate the integrated model using measured data from the Atlantech district in La Rochelle. Based on this integrated model developed, indirect control strategies combined with RBC will be tested and analysed on the case-study to properly evaluate the performance at the grid and building levels. The objective of this part is to check that the proposed control strategy makes use of the flexibility potential and does not create any side-effects. Finally, the last part will focus on the reliability of the control proposed and will extend the work to more case-studies. The sensitivity of the controller will then be evaluated, by varying the response of the users, the types of building and the environment. The results of the project can be used to define control strategies that enable demand response for residential customers and also to provide tools for a reliable estimation of the shifting capacity under indirect control.