Characterization of the coupled hygrothermal behavior of unfired clay masonries: Numerical and experimental aspects

Abstract Numerical and experimental methodologies are presented in order to evaluate thermal and moisture buffering properties of hygroscopic masonry walls composed of unfired clay bricks. An original full-scale instrumented wall is subjected to various transient scenarios on both faces, using a double climatic chamber device. This equipment allows a separated thermodynamic balance in the two rooms for the determination of heat and mass flows through the wall. The development of a coupled heat and mass transfer process implemented in the Cast3M finite element software is outlined as well. The material's input parameters for the model are first identified on samples at a decimeter scale. Among them, a continuous dependence law governing vapor permeability vs. moisture content is established, by exploiting the kinetics of sorption steps in both cubic and half-brick samples. Based on these experimental characterizations, all parameters are introduced for the simulation of a full-scale wall through different scenarios of hydric loading. Comparisons drawn between simulation and the experimental evolutions of moisture and temperature show a good accuracy at this scale. The moisture balance quantities derived in both cells are also verified, proving the model's effectiveness in terms of mass transfer simulation. Finally, the thermal effect of sorption heat is also discussed, experimentally as well as numerically. For realistic scenarios, it is shown to be limited to about 0.5 K.

[1]  Peder Wolkoff,et al.  The dichotomy of relative humidity on indoor air quality. , 2007, Environment international.

[2]  Carey J. Simonson,et al.  Moisture buffering capacity of hygroscopic building materials: Experimental facilities and energy impact , 2006 .

[3]  J. Fourier.  Théorie analytique de la chaleur , 2009 .

[4]  Jean-Emmanuel Aubert,et al.  Effects of the anisotropy of extruded earth bricks on their hygrothermal properties , 2014 .

[5]  Monika Woloszyn,et al.  Influence of sorption isotherm hysteresis effect on indoor climate and energy demand for heating , 2011 .

[6]  J. E. Oti,et al.  Engineering properties of unfired clay masonry bricks , 2009 .

[7]  Peter Walker,et al.  Building houses with local materials: means to drastically reduce the environmental impact of construction , 2001 .

[8]  Christophe Petit,et al.  Modeling of the sorption hysteresis for wood , 2009, Wood Science and Technology.

[9]  C. Simonson,et al.  The effect of structures on indoor humidity--possibility to improve comfort and perceived air quality. , 2002, Indoor air.

[10]  J. Aubert,et al.  Hygrothermal properties of earth bricks , 2014 .

[11]  Tim Padfield.  The role of absorbent building materials in moderating changes of relative humidity: Ph.D.thesis , 1999 .

[12]  Fraunhofer-Institut für Bauphysik,et al.  Simultaneous heat and moisture transport in building components: One- and two-dimensional calculation using simple parameters , 1995 .

[13]  S. Merakeb.  Modélisation des structures en bois en environnement variable , 2006 .

[14]  David Allinson,et al.  Hygrothermal analysis of a stabilised rammed earth test building in the UK , 2010 .

[15]  S. Gustafsson.  Transient plane source techniques for thermal conductivity and thermal diffusivity measurements of solid materials , 1991 .

[16]  A. Fick.  On liquid diffusion , 1995 .

[17]  P. Fanger,et al.  Upper limits for indoor air humidity to avoid uncomfortably humid skin , 1998 .

[18]  John A. Nelder,et al.  A Simplex Method for Function Minimization , 1965, Comput. J..

[19]  Monika Woloszyn,et al.  The effect of combining a relative-humidity-sensitive ventilation system with the moisture-buffering capacity of materials on indoor climate and energy efficiency of buildings , 2009 .

[20]  P. Fanger,et al.  Impact of Temperature and Humidity on the Perception of Indoor Air Quality , 1998 .

[21]  A. Shea,et al.  Conditions affecting the moisture buffering measurement performed on compressed earth blocks , 2014 .

[22]  Shinichi Tanabe,et al.  Effect of humidity on human comfort and productivity after step changes from warm and humid environment , 2007 .

[23]  Adewale Dosunmu,et al.  Determination of Moisture Adsorption Isotherm of Shale from Agbada Formation Using GAB Model , 2012 .

[24]  Jacques Miriel,et al.  Study of thermal behaviour of clay wall facing south , 2006 .

[25]  Tuan Anh Nguyen,et al.  Approches expérimentales et numériques pour l'étude des transferts hygroscopiques dans le bois , 2014 .

[26]  R. Dent,et al.  A Multilayer Theory for Gas Sorption , 1977 .

[27]  Andrew C. Heath,et al.  An inverse modelling approach to estimate the hygric parameters of clay-based masonry during a Moisture Buffer Value test , 2014 .

[28]  S. Rossignol,et al.  Experimental evaluation of hydric performances of masonry walls made of earth bricks, geopolymer and wooden frame , 2015 .

[29]  M. R. Hall,et al.  Hygrothermal behaviour and relative humidity buffering of unfired and hydrated lime-stabilised clay composites in a Mediterranean climate , 2013 .

[30]  P. Fanger,et al.  Upper limits of air humidity for preventing warm respiratory discomfort , 1998 .

[31]  Paul Fazio,et al.  An investigation of moisture buffering performance of wood paneling at room level and its buffering effect on a test room , 2012 .

[32]  Monika Woloszyn,et al.  Modelling of hysteresis influence on mass transfer in building materials , 2009 .

[33]  A. Shea,et al.  The moisture buffering capacity of unfired clay masonry , 2014 .

[34]  Kenichi Hasegawa,et al.  Assessing the moisture buffering performance of hygroscopic material by using experimental method , 2012 .

[35]  Jaakko Paasi,et al.  Performance of ESD protective materials at low relative humidity , 2001 .

[36]  Dalel Medjelekh.  Caractérisation multi-échelle du comportement thermo hybride des enveloppes hygroscopiques , 2015 .

[37]  Monika Woloszyn,et al.  Identification of the hygrothermal properties of a building envelope material by the covariance matrix adaptation evolution strategy , 2016 .

[38]  Björn Johannesson,et al.  A two-phase moisture transport model accounting for sorption hysteresis in layered porous building constructions , 2009 .