@article {1794, title = { Assessment of hygrothermal behavior of newly straw-rape concrete material in various conditions }, journal = { HEAT AND MASS TRANSFER }, volume = {55}, year = {2019}, pages = {2785-2796}, abstract = {

This article focuses on study of hygrothermal behavior of building made of new bio-concrete based on straw-rape. The assessment was conducted using a numerical study, performed using a coupled heat and mass transfer model which takes into account the temperature dependence of the moisture retention curve. The model consists on coupling of envelope model with mono-zone building ambient air model which takes into account ventilation, occupants production and internal inertia in term of thermal and moisture buffering. The model of building envelope was validated by comparison against experimental data carried out on real scale wall. The results reveal that considering moisture retention curve as a temperature-dependent property leads to better prediction of the relative humidity variation in the material, whereas it has weak influence on temperature variations. However, the overall isothermal model may be enough to predict the temperature and relative humidity variations of the indoor ambient air of building. Results have showed good contribution of the internal thermal inertia to reduce temperature variation of the ambient air of building. In addition, simulations highlighted strong capacity, of the straw-rape concrete, to damp the high variations of outdoor relative humidity for all considered climates, especially in desert climate. This effect conduces to avoid accumulation of moisture in the material thus it may rise the life service of the wall.

}, url = {https://hal.archives-ouvertes.fr/hal-02350660}, author = {M. RAHIM and R. DJEDJIG and O. DOUZANE and T. LANGLET and M. EL-GANAOUI} } @article {1669, title = { Experimental study of green walls impacts on buildings in summer and winter under an oceanic climate }, journal = { ENERGY AND BUILDINGS }, volume = {150}, year = {2017}, pages = {403-411}, abstract = {

This article presents the results obtained an experiment carried out to measure the thermal impacts of green walls on buildings. The experiment deals with full monitoring of a green wall set up on a scaled down experimental mockup of buildings located in La Rochelle city. Results underline the positive effect of green walls in summer and show moderate reduction of heat losses in winter. The distinction made between measured heat gains and heat losses through the compared facades helps to apprehend the energy impact of the envelopes greening. Besides, we analyzed through experimental observations the dynamic behavior of the green wall system, and we highlighted the importance of such an experimental model to take into account the vertical hygrothermal effects. The primary objective is better understanding of the thermohydric behavior and the energy impact of green walls by direct comparison between data recorded simultaneously on different configurations of buildings and streets with and without use green walls. Measurements of temperature, humidity and heat fluxes through facades with and without greening provide valuable data to assess performances of this technique, to analyze the thermal effects, and finally this gives data for further numerical studies.

}, url = {https://hal.univ-lorraine.fr/hal-01690569}, author = {R. DJEDJIG and R. BELARBI and E. BOZONNET} } @article {1705, title = { Thermal effects of an innovative green wall on building energy performance }, journal = { MECHANICS \& INDUSTRY }, volume = {18}, year = {2017}, abstract = {

Green walls and green roofs are innovative construction technologies involving the use environmentally friendly materials. In addition to their aesthetical and environmental benefits, green walls have significant thermal effects on buildings and heat islands within high-density urban areas. In this paper, we study the impact of an innovative green wall system on building energy performance. These green walls have specific composition and particular geometry that can lead to higher thermal performances and therefore more significant impact on building energy performance. The development, validation and prior integration of a hygrothermal green wall model in a transient building simulation tool make possible the assessment of the energy performance of buildings when covered by green walls. The used model was adapted to be the particular forms and composition of the studied green walls. In parallel, this type of green walls has been installed on a one tenth building mockup to be experimented. The aim of the experiment is to measure the thermal effects and to calibrate some parameters of the numerical model. The results highlight the thermal benefits of this kind of green walls in summer condition. They reduce annual energy demand of building up to 37\% for hot climates.

}, url = {https://hal.archives-ouvertes.fr/hal-02113149/}, author = {R. DJEDJIG and M. EL-GANAOUI and R. BELARBI and R. BENNACER} } @article {1603, title = { Hygrothermal behavior modeling of the hygroscopic envelopes of buildings: A dynamic co-simulation approach }, journal = { BUILDING SIMULATION }, volume = {9}, year = {2016}, pages = {501-512}, abstract = {

High levels of humidity in buildings lead to building pathologies. Moisture also has an impact on the indoor air quality and the hygrothermal comfort of the building\&$\#$39;s occupants. To better assess these pathologies, it is necessary to take into account the heat and moisture transfer between the building envelope and its indoor ambience. In this work, a new methodology was developed to predict the overall behavior of buildings, which combines two simulation tools: COMSOL Multiphysics (c) and TRNSYS. The first software is used for the modeling of heat, air and moisture transfer in multilayer porous walls (HAM model: Heat, Air and Moisture transfer), and the second is used to simulate the hygrothermal behavior of the building (BES model: Building Energy Simulation). The combined software applications dynamically solve the mass and energy conservation equations of the two physical models. The HAM-BES coupling efficiency was verified. In this paper, the use of a coupled (HAM-BES) co-simulation for the prediction of the hygrothermal behavior of building envelopes is discussed. Furthermore, the effect of the 2D HAM modeling on relative humidity variations within the building ambience is shown. The results confirm the importance of the HAM modeling in the envelope on the hygrothermal behavior and energy demand of buildings.

}, url = {https://hal.archives-ouvertes.fr/hal-01726570}, author = {M.Y. FERROUKHI and R. DJEDJIG and K. LIMAM and R. BELARBI} } @article {1629, title = { Modeling green wall interactions with street canyons for building energy simulation in urban context }, journal = { URBAN CLIMATE }, volume = {16}, year = {2016}, pages = {75-85}, abstract = {

A hygrothermal model of green walls and a model of mass flows in street canyons have been proposed and implemented in a building simulation program (TRNSYS). The coupled models allow the study of the hygrothermal interaction of green walls at the interface of the detailed building model and the urban microclimate of the street. Its use highlights the effects on both urban microclimate and buildings energy loads, especially in the summer period. While reducing anthropogenic heat release, green walls set up on west or east facades mitigate the street air temperature and reduce building cooling loads depending on streets\&$\#$39; aspect ratio. Some of the canyon model parameters were calibrated through numerical comparison with experimental data on a reduced scale mockup. This mockup has been designed specifically to assess the green walls hygrothermal impact and to evaluate the developed numerical tools. This experimental calibration made simulating the green walls interactions with street canyons of different aspect ratios possible. The experimental and numerical results obtained with green facades underline the advantage of this modeling approach for the design of passive cooling for buildings and mitigation of excessive thermal conditions within street canyons in dense cities in warm climates.

}, url = {https://hal.univ-lorraine.fr/hal-01688277}, author = {R. DJEDJIG and E. BOZONNET and R. BELARBI} } @article {1590, title = { Analysis of thermal effects of vegetated envelopes: Integration of a validated model in a building energy simulation program }, journal = { ENERGY AND BUILDINGS }, volume = {86}, year = {2015}, pages = {93-103}, abstract = {

In this paper, a newly developed heat and moisture transfer model for green envelopes is integrated in a transient building simulation program (TRNSYS) in order to investigate its dynamic performances coupled with a multizone building code. On the one hand we focus on the understanding of the coupled heat and mass transfers between green envelopes and the building; and on the other hand we study the model accuracy to assess the vegetation impacts together with building design. At first, the model reliability is verified through experimental comparisons during a summer period. Then, the developed simulation tool is used to assess the impacts of green walls on building energy performance. Since this model involves different hygrothermal transfer phenomena, the detailed numerical model results are analyzed to determine the weight of each phenomenon: evapotranspiration, shading effect and additional thermal resistance of green roof or wall. The results highlight the thermal benefits in summer and winter, especially for the west walls. The analysis of the different transfer mechanisms show that the foliage shading reduces the surface temperature variation whereas the evapotranspiration ensures the passive cooling when the water availability is sufficient.

}, url = {https://hal.univ-lorraine.fr/hal-01598429}, author = {R. DJEDJIG and E. BOZONNET and R. BELARBI} }