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Abstract

This work presents an alternative view on the numerical simulation of diffusion processes applied to the heat and moisture transfer through multilayered porous building materials. Traditionally, by using the finite-difference approach, the discretization follows the Method Of Lines (MOL), when the problem is first discretized in space to obtain a large system of coupled Ordinary Differential Equations (ODEs). This paper proposes to change this viewpoint. First, we discretize in time to obtain a small system of coupled ODEs, which means instead of having a Cauchy (Initial Value) Problem (IVP), we have a Boundary Value Problem (BVP). Fortunately, BVPs can be solved efficiently today using adaptive collocation finite-difference methods of high order. To demonstrate the benefits of this new approach, three case studies are presented. The first one considers nonlinear heat and moisture transfer through one material layer. The second case includes the rain effect, while the last one considers two material layers. Results show how the nonlinearities and the interface between materials are easily treated, by reasonably using a fourth-order adaptative method. In our numerical simulations, we use adaptive methods of the fourth order which in most practical situations is more than enough.

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... An absolute error ε 2 of 5.21 Pa and 0.29 • C and a relative error error ε 2,,r of 0.08 and 0.04 are obtained between the experimental data and the interpolated initial profiles of vapor pressure and temperature, respectively. Some complementary information on the experimental design is given in [14]. ...
... If the reliability of the proposed model is very satisfactory, most approaches from the literature do not consider the air transport equation (2.14c). For instance, in [14] the reliability is proven for the same case study but considering a model with only heat and moisture transport by diffusion processes. A natural question raises on the importance of considering air transport to better represent the whole physical phenomenon. ...
... A natural question raises on the importance of considering air transport to better represent the whole physical phenomenon. To answer this question, the numerical predictions from the model in [14], denoted as HM (Heat and Moisture) model are compared to the one obtained with the proposed model, denoted as HAM (Heat, Air and Moisture) model. Figure 12 shows the probability density function of the relative error for each model between the numerical predictions and the experimental observations. ...
... An absolute error ε 2 of 5.21 Pa and 0.29 • C and a relative error error ε 2,,r of 0.08 and 0.04 are obtained between the experimental data and the interpolated initial profiles of vapor pressure and temperature, respectively. Some complementary information on the experimental design is given in [14]. ...
... If the reliability of the proposed model is very satisfactory, most approaches from the literature do not consider the air transport equation (2.14c). For instance, in [14] the reliability is proven for the same case study but considering a model with only heat and moisture transport by diffusion processes. A natural question raises on the importance of considering air transport to better represent the whole physical phenomenon. ...
... A natural question raises on the importance of considering air transport to better represent the whole physical phenomenon. To answer this question, the numerical predictions from the model in [14], denoted as HM (Heat and Moisture) model are compared to the one obtained with the proposed model, denoted as HAM (Heat, Air and Moisture) model. Figure 12 shows the probability density function of the relative error for each model between the numerical predictions and the experimental observations. ...
Preprint
This work presents a detailed mathematical model combined with an innovative efficient numerical model to predict heat, air and moisture transfer through porous building materials. The model considers the transient effects of air transport and its impact on the heat and moisture transfer. The achievement of the mathematical model is detailed in the continuity of Luikov's work. A system composed of two advection-diffusion differential equations plus one exclusively diffusion equation is derived. The main issue to take into account the transient air transfer arises in the very small characteristic time of the transfer, implying very fine discretisation. To circumvent these difficulties, the numerical model is based on the Du Fort-Frankel explicit and unconditionally stable scheme for the exclusively diffusion equation. It is combined with a two-step Runge-Kutta scheme in time with the Scharfetter-Gummel numerical scheme in space for the coupled advection-diffusion equations. At the end, the numerical model enables to relax the stability condition, and, therefore, to save important computational efforts. A validation case is considered to evaluate the efficiency of the model for a nonlinear problem. Results highlight a very accurate solution computed about 16 times faster than standard approaches. After this numerical validation, the reliability of the mathematical model is evaluated by comparing the numerical predictions to experimental observations. The latter is measured within a multi-layered wall submitted to a sudden increase of vapor pressure on the inner side and driven climate boundary conditions on the outer side. A very satisfactory agreement is noted between the numerical predictions and experimental observations indicating an overall good reliability of the proposed model.
... Then, a boundary value problem is defined to compute the spatial coefficients of the reduced model. The idea originates from recent works on the method of horizontal lines proposed in [34]. Then, a step further is proposed compared to approaches from the literature in building physics. ...
... Another method is explored following the works on horizontal lines applied to complete models in [34,51]. The proposed approximation of the solution is the following: ...
Article
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Within the environmental context, numerical modeling is a promising approach to assess the energy efficiency of building. Resilient buildings need to be designed, capable of adapting to future extreme heat. Simulations are required assuming a one-dimensional heat transfer problem through walls and a simulation horizon of several years (nearly 30). The computational cost associated with such modeling is quite significant and model reduction methods are worth investigating. The objective is to propose a reliable reduced-order model for such long-term simulations. For this, an alternative model reduction approach is investigated, assuming a known Proper Orthogonal Decomposition reduced basis for time, and not for space as usually. The model enables computing parametric solutions using basis interpolation on the tangent space of the Grassmann manifold. Three study cases are considered to verify the efficiency of the reduced-order model. Results highlight that the model has a satisfying accuracy of 10-3 compared to reference solutions. The last case study focuses on the wall energy efficiency design under climate change according to a four-dimensional parameter space. The latter is composed of the load material emissivity, heat capacity, thermal conductivity and thickness insulation layer. Simulations are carried over 30 years considering climate change. The solution minimizing the wall work rate is determined with a computational ratio of 0.1% compared to standard approaches.
... Its estimation would be based on the solution of coupled heat and mass transfer equations [46,47,48]. The initial condition is the one reached by the material after the preconditioning phase. ...
Article
Similarities are mathematical laws, which are based on the dimensionless formulation of the governing equation of a physical phenomenon. Consequently, a set of characteristic dimensionless numbers is obtained. Similarities aim, via these numbers, to find equivalences between particular configurations. This approach is widely adopted, especially in fluid and aerodynamic problems. In the building context, the phenomena of heat and mass transfer in porous media occur with slow kinetics. Thus, similarities can be employed to reduce the duration of experimental campaigns to characterize material properties. These laws were investigated here in the case of a heat transfer problem through an experimental campaign. Two equivalent configurations were submitted to a heat stress. Temperatures inside materials were measured and compared to assess the validity of thermal similarity. A complete evaluation of uncertainty propagation was then carried out. Uncertainties related to the sensor position, its response time, the omission of mass transfer, the sensor systematic accuracy, the random measurement aspect, the one-dimensional transfer hypothesis and the boundary condition modeling were evaluated. The comparison of both configurations was carried out based on the confidence interval of both measurements. The results showed a good agreement between the reference and reduced experiment. On the basis of these findings, similarities were experimentally verified within a margin of discrepancy that was justified. Thus, they can be adopted in heat transfer experiments in order to identify equivalent configurations that are easier to conduct.
... They used WUFI software to solve the non-linear transport equations. Over the past twenty years, many mathematical models and numerical methods applying to different fields have been described [5][6][7][8][9][10][11]. ...
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Plant-based concrete is a construction material which, in addition to having a very low environmental impact, exhibits excellent hygrothermal comfort properties. It is a material which is, as yet, relatively unknown to engineers in the field. Therefore, an important step is to implement reliable mass-transfer simulation methods. This will make the material easy to model, and facilitate project design to deliver suitable climatic conditions. In recent decades, numerous studies have been carried out to develop models of the coupled transfers of heat, air and moisture in porous building envelopes. Most previous models are based on Luikov’s theory, considering mass accumulation, air and total pressure gradient. This theory considers the porous medium to be homogeneous, and therefore allows for hygrothermal transfer equations on the basis of the fundamental principles of thermodynamics. This study presents a methodology for solving the classical 1D (one-dimensional) HAM (heat, air, and moisture) hygrothermal transfer model with an implementation in MATLAB. The resolution uses a discretization of the problem according to the finite-element method. The detailed solution has been tested on a plant-based concrete. The energy and mass balances are expressed using measurable transfer quantities (temperature, water content, vapor pressure, etc.) and coefficients expressly related to the macroscopic properties of the plant-based concrete (thermal conductivity, specific heat, water vapor permeability, etc.), determined experimentally. To ensure this approach is effective, the methodology is validated on a test case. The results show that the methodology is robust in handling a rationalization of the model whose parameters are not ranked and not studied by their degree of importance.
... In this context, the initial boundary value problem Eq. (5) is semi-discretized along the time line [9]. The time discretization parameter is denoted by ∆t , corresponding to the time step of coupling between the numerical models of the co-simulation. ...
Preprint
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Estimating the temperature field of a building envelope could be a time-consuming task. The use of a reduced-order method is then proposed: the Proper Generalized Decomposition method. The solution of the transient heat equation is then re-written as a function of its parameters: the boundary conditions, the initial condition, etc. To avoid a tremendous number of parameters, the initial condition is parameterized. This is usually done by using the Proper Orthogonal Decomposition method to provide an optimal basis. Building this basis requires data and a learning strategy. As an alternative, the use of orthogonal polynomials (Chebyshev, Legendre) is here proposed.
... For the sake of clarity, the so-called global heat storage coefficient c T W · s/(m 3 · K) is introduced as in [36]: ...
... The moisture transfer is driven by vapor and liquid diffusions. According to [12,23], the mathematical model to represent the energy and mass conservation in a building porous material can be formulated as follows: ...
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The reliability of mathematical models for heat and mass transfer in building porous material is of capital importance. A reliable model permits to carry predictions of the physical phenomenon with sufficient confidence in the results. Among the physical phenomena, the hysteresis effects on moisture sorption and moisture capacity need to be integrated in the mathematical model of transfer. This article proposes to explore the use of an smooth Bang-Bang model to simulate the hysteresis effects coupled with heat and mass transfer in porous material. This model adds two supplementary differential equations to the two classical ones for heat and mass transfer. The solution of these equations ensures smooth transitions between the main sorption and desorption curves. Two parameters are required to control the speed of transition through the intermediary curves. After the mathematical description of the model, an efficient numerical model is proposed to compute the fields with accuracy and reduced computational efforts. It is based on the DuFort-Frankel scheme for the heat and mass balance equations. For the hysteresis numerical model, an innovative implici-explicit approach is proposed. Then, the predictions of the numerical model are compared with experimental observations from literature for two case studies. The first one corresponds to a slow cycle of adsorption and desorption while the second is based on a fast cycling case with alternative increase and decrease of moisture content. The comparisons highlight a very satisfactory agreement between the numerical predictions and the observations. In the last Section, the reliability and efficiency of the proposed model is investigated for long term simulation cases. The importance of considering hysteresis effects in the reliability of the predictions are enhanced by comparison with classical approaches from literature.
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In order to better predict the hygrothermal behavior of porous building envelopes, it is essential to develop reliable mathematical models which accurately capture the coupled heat, air, and mass (HAM) transport and its influence on the indoor atmosphere. Recently, numerous models have been developed to predict the performance of bio-based building envelopes. However, the large number of input parameters and lack of knowledge of the intrinsic characteristics of the materials mean these models are quite difficult to implement. To determine the most influential hygrothermal parameters for a hemp concrete wall, a sensitivity study was conducted on the input parameters, based on the probability density distribution of Gaussian centered law; the results are presented herein. A reduced model was developed by eliminating the parameters with little or no influence on HAM transfer. Then, a dimensionless study of the reduced model was carried out. This generated an indicative parameter ς, which can be used to classify building materials and identify the most suitable. In MATLAB software, the simulated results for a hemp concrete wall showed satisfactory concordance with the experimental results found in the literature. The temperature profiles are accurately estimated. Note that the model must always take account of the evolution of water content to ensure accurate RH predictions.
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Estimating the temperature field of a building envelope could be a time-consuming task. The use of a reduced-order method is then proposed: the Proper Generalized Decomposition method. The solution of the transient heat equation is then re-written as a function of its parameters: the boundary conditions, the initial condition, etc. To avoid a tremendous number of parameters, the initial condition is parameterized. This is usually done by using the Proper Orthogonal Decomposition method to provide an optimal basis. Building this basis requires data and a learning strategy. As an alternative, the use of orthogonal polynomials (Chebyshev, Legendre) is here proposed. Highlights • Chebyshev and Legendre polynomials are used to approximate the initial condition • Performance of Chebyshev and Legendre polynomials are compared to the POD basis • Each basis combined with the PGD model is compared to laboratory measurements • The influence of four different parameters on the accuracy of the basis is studied • For each approximation basis, CPU calculation times are evaluated and compared
Thesis
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For a general class of methods, which includes linear multistep and Runge-Kutta methods as special cases, A concept of order relative to a given starting procedure is defined and an order of convergence theorem is proved. The definition is given an algebraic interpretation and illustrated by the derivation of a particular fourth-order method.
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Excessive levels of moisture in buildings lead to building pathologies. Moisture also has an impact on the indoor air quality and the hygrothermal comfort of the building's occupants. A comprehensive list of the possible types of damage caused by moisture in buildings is discussed in the present paper. Damage is classified into four types: damage due to the direct action of moisture, damage activated by moisture, damage that occurred in a moist environment and deterioration of the indoor environment. Since moisture pathologies strongly depend on the hygrothermal fields in buildings, integrating these factors into a global model combining heat air and mass transfers and building energy simulation is important. Therefore, the list of moisture damage types is completed with a proposal of factors governing the risk of occurrence of each type of damage. The methodology is experimented on a simple test case combining hygrothermal simulations with the assessment of possible moisture disorders.
Article
Heat and mass transfer between capillary-porous bodies and surrounding incompressible liquid accompanied by a change of phase is not only of theoretical interest but also of great practical importance for some technological processes. Heat and mass transfer inside a porous body (internal heat and mass transfer) also has its unique character. Even now the mechanism of heat and mass transfer in evaporation processes is scantily investigated, and analytical investigations do not, therefore, lead to reliable results. This chapter presents an experimental study of heat and mass transfer in evaporation processes. To elucidate peculiarities of heat transfer with simultaneous mass transfer, a dry body (pure heat transfer) and a moist body (heat transfer in the presence of mass transfer) are investigated. Such a comparison makes it possible to establish relations for interconnected heat and mass transfer processes. In order to describe quantitative relations it is necessary to have a method of analysis which makes it possible to consider the interaction of the heat and mass transfer processes. One such method is the thermodynamics of irreversible processes. The experimental data presented well confirm the mathematical theory of thermodynamics of irreversible transfer processes.
Article
Moisture plays a central role in the provision of healthy buildings, both in relation to indoor humidity levels, which impacts on air quality and thermal comfort, and in relation to interstitial/surface condensation leading to fabric deterioration and mould growth, which impacts on performance and occupant well-being. Integrated building performance simulation (IBPS) provides a means to ensure that due consideration is given to these aspects at the design stage as designers attempt to deploy new approaches to energy demand reduction and sustainable supply. This paper describes how building space and construction moisture flow is modelled within the ESP-r system in a manner that is appropriately coupled to other domain models representing the heat, power, air and light flows within building/plant systems of arbitrary complexity (but with the focus here only on those domains that impact directly on moisture flow). The purpose of the paper is to describe the role of moisture flow modelling within IBPS, the barriers that are likely to be encountered in practice and future development needs. The application of the integrated approach is summarized for the case of mould growth alleviation and the deployment of passive methods for moisture control.
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Article
Water infiltration is known to play an important part in the degradation process of construction materials. Over time, microscopic and macroscopic cracks progressively develop under the effects of mechanical loading and sorption/desorption cycles: their influence is to be accounted for in long-term hygrothermal performance assessments of the building envelope. The present work aims at showing the potential consequences of cracking on the heat and moisture transfer across building facades, in order to justify the need for the identification of damage to prevent durability and thermal issues. Specific simulation cases of insulated and non-insulated building facades were defined, and submitted to atmospheric boundary conditions for simulation times of one month. Some of the simulation geometries included previous measurements of crack patterns in concrete. The comparison of fractured and non-fractured building facades showed the effects of cracks on the moisture accumulation and thermal performance of these wall configurations, thus giving an estimate of what these effects might be in real conditions. A methodology is thus proposed for the identification of renovation needs, which may be applied for the purpose of durability assessments as well.
Article
Deep basements, crawl spaces and slab on grade are typical foundations in residential buildings in North America. The foundation of a house is a somewhat invisible and at sometimes ignored component of the building. Appropriate foundation design and construction practice must not only include thermal performance, but also design for a durable and safe hygrothermal performance. A hygrothermal simulation tool can be used to evaluate and predict the hygrothermal behavior of an insulated foundation constructions, in cooperation with the surrounding soil. Though, further development of the tool might first be needed and validated to fulfill the prerequisites. Transient hygrothermal simulation tools have existed in Building Science for more than 20 years, but are mainly used for building envelope simulation above ground. A lot of knowledge already exists in Soil Science concerning the variation of the soil material properties in relation to soil texture, moisture content etc. However, Soil Science uses these properties for other purpose and with different modeling approaches, hence a conversion is needed. This paper studies the existing knowledge of soil properties, converted to apply for simulation in Building Science. Further, the soil properties are implemented in a transient hygrothermal simulation tool, studying the applicability for modeling soil temperature and moisture flow. Finally the results are compared with measurement and followed by a discussion of further investigations and development needed.
Article
The main objective of this work is to present the impact of atmospheric pressure gradient on the hygrothermal transfers in porous material. In this way, a mathematical model described by driving forces of temperature, moisture content and total pressure gradient has been addressed. The non-linear partial differential equations are defined through the balance equations of mass and energy development. After that, a numerical implementation focused on the wood drying behavior is treated for one dimensional Fourier boundary conditions. In order to evaluate the pressure sensitivity, temperature and moisture content profiles are presented and compared to the ones obtained by the classical models 15 and 16. Results show that the atmospheric pressure gradient may cause significant influence on the hygrothermal behavior of the porous materials especially for wood process. A significant effect, up to 15%, on moisture content profile distribution is observed.
Article
The Korteweg-de Vries equation (KdVE) is a classical nonlinear partial differential equation (PDE) originally formulated to model shallow water flow. In addition to the applications in hydrodynamics, the KdVE has been studied to elucidate interesting mathematical properties. In particular, the KdVE balances front sharpening and dispersion to produce solitons, i.e., traveling waves that do not change shape or speed. In this paper, we compute a solution of the KdVE by the method of lines (MOL) and compare this numerical solution with the analytical solution of the kdVE. In a second numerical solution, we demonstrate how solitons of the KdVE traveling at different velocities can merge and emerge. The numerical procedure described in the paper demonstrates the ease with which the MOL can be applied to the solution of PDEs using established numerical approximations implemented in library routines.
Article
In the building science area, mathematical models are developed to provide better indoor thermal comfort with lower energy consumption. Although the fact moisture and air transfer can strongly affect the temperature distribution within constructions, whole-building simulation codes do not take into account the convective air transport in porous materials. In this way, this article presents a heat, air, and moisture (HAM) transfer model based on driving potentials of temperature, air pressure, and water vapor pressure gradients for consolidated porous material in both pendular and funicular states. The solution of the set of governing equations has been simultaneously obtained using the MTDMA (MultiTriDiagonal-Matrix Algorithm) for the three potentials. To conclude, results are presented showing the impact of convective terms on the HAM transfer through a two-layer porous building envelope.
Article
Runge-Kutta methods are applied to the numerical solution of hyperbolic partial differential equations. Conditions that they are locally stable are derived.
Article
A standard for binary floating-point arithmetic is being proposed and there is a very real possibility that it will be adopted by many manufacturers and implemented on a wide range of computers. This development matters to all of us concerned with numerical software. One of the principal motivations for the standard is to distribute more evenly the burden of portability between hardware and software. At present, any program intended to be portable must be designed for a mythical computer that enjoys no capability not supported by every computer on which the program will be run. That mythical computer is so much grubbier than almost any real computer that a portable program will frequently be denigrated as "suboptimal" and then supplanted by another program supposedly "optimal" for the real computer in question but often inferior in critical respects like reliability. A standard --- almost any reasonable standard --- will surely improve the situation. A standard environment for numerical programs will promote fair comparisons and sharing of numerical codes, thereby lowering costs and prices. Furthermore, we have chosen repeatedly to enrich that environment in order that applications programs be simpler and more reliable. Thus will the onus of portability be shared among hardware manufacturers and software producers.
Article
Factors influencing the choice of ODE solver for the numerical solution of PDEs by the method of lines are investigated. The advection—diffusion equation is used to gain insight that is generalized to some classes of nonlinear PDEs. Numerical results for several nonlinear PDEs illustrate the theoretical developments. © 1994 John Wiley & Sons, Inc.
Article
The finite element method is used to analyse heat and mass transfer problems in porous media, in which the thermophysical properties are allowed to vary as functions of temperature and moisture. An example is given of the application of the method to the problem of timber drying.
Article
Drying is a process which involves heat and mass transfer both inside the porous material, where a phase change in moisture occurs from the liquid to the gaseous state, and in the external boundary layer of the convected hot dry air, which heats the porous medium. The equations which govern this process consist of three tightly coupled, highly non-linear partial differential equations for the unknown system variables of moisture content, temperature and pressure. Due to the inherently complex boundary conditions and intricate physical geometries in any practical drying problem, an analytical solution is not possible. In order to obtain a transient drying solution it is necessary to resort to a numerical technique. The numerical solution techniques which were employed in this research were the finite element method and the control volume method. The transient numerical results were compared and contrasted for two timber drying problems, first, at a dry bulb temperature of 50°C, and secondly, at 80°C, both cases being below the boiling point of water.
Article
It is well known that a necessary condition for the Lax-stability of the method of lines is that the eigenvalues of the spatial discretization operator, scaled by the time stepk, lie within a distanceO(k) of the stability region of the time integration formula ask→0. In this paper we show that a necessary and sufficient condition for stability, except for an algebraic factor, is that the ε-pseudo-eigenvalues of the same operator lie within a distanceO(ε)+O(k) of the stability region ask, ε→0. Our results generalize those of an earlier paper by considering: (a) Runge-Kutta and other one-step formulas, (b) implicit as well as explicit linear multistep formulas, (c) weighted norms, (d) algebraic stability, (e) finite and infinite time intervals, and (f) stability regions with cusps. In summary, the theory presented in this paper amounts to a transplantation of the Kreiss matrix theorem from the unit disk (for simple power iterations) to an arbitrary stability region (for method of lines calculations).
Article
Most building materials are porous, composed of solid matrix and pores. The time varying indoor and outdoor climatic conditions result heat, air and moisture (HAM) transfer across building enclosures. In this paper, a transient model that solves the coupled heat, air and moisture transfer through multilayered porous media is developed and benchmarked using internationally published analytical, numerical and experimental test cases. The good agreements obtained with the respective test cases suggest that the model can be used to assess the hygrothermal performance of building envelope components as well as to simulate the dynamic moisture absorption and release of moisture buffering materials.
Article
In order to precisely predict ground heat transfer, room air temperature and humidity, a combined model has been developed and conceived to calculate both the coupled heat and moisture transfer in soil and floor and the psychrometrics condition of indoor air. The present methodology for the soil is based on the theory of Philip and De Vries, using variable thermophysical properties for different materials. The governing equations were discretized using the finite-volume method and a three-dimensional model for describing the physical phenomena of heat and mass transfer in unsaturated moist porous soils and floor. Additionally, a lumped transient approach for a building room and a finite-volume multi-layer model for the building envelope have been developed to integrate with the soil model. Results are presented in terms of temperature, humidity and heat flux at the interface between room air and the floor, showing the importance of the approach presented and the model robustness for long-term simulations with a high time step.
Article
A mathematical formulation applied to a numerically robust solver is presented, showing that moisture content gradients can be used as driving forces for heat and moisture transport calculation through the interface between porous materials with different pore size distribution functions. For comparison purposes, several boundary conditions are tested—in order to gradually increase the discontinuity effects—and a detailed analysis is undertaken for the temperature and moisture content distributions and sensible and latent heat fluxes, when the discontinuity on the moisture content profile is taken or not into account.
Article
Wind-driven rain (WDR) or driving rain is rain that is given a horizontal velocity component by the wind. WDR research is of importance in a number of research areas including earth sciences, meteorology and building science. Research methods and results are exchangeable between these domains but no exchanges could yet be noted. This paper presents the state-of-the-art of WDR research in building science. WDR is the most important moisture source affecting the performance of building facades. Hygrothermal and durability analysis of facades requires the quantification of the WDR loads. Research efforts can be classified according to the quantification methods used. Three categories are distinguished: (1) experimental methods, (2) semi-empirical methods and (3) numerical methods. The principles of each method are described and the state-of-the-art is outlined. It has been the intent of the present paper to bring together the reports, papers and books—published and unpublished—dealing with WDR research in building science to provide a database of information for researchers interested in and/or working in WDR research, independent of their field of expertise.
Article
This paper gives an onset to whole building hygrothermal modelling in which the interaction between interior and exterior climates via building enclosures is simulated under a moderately cold and humid climate. The focus is particularly on the impact of wind-driven rain (WDR) on the hygrothermal response, mould growth at interior wall surfaces, indoor climate and energy consumption. First the WDR load on the facades of a 4 m × 4 m × 10 m tower is determined. Then the hygrothermal behaviour of the brick walls is analysed on a horizontal slice through the tower. The simulations demonstrate that the impact of WDR loads on the moisture contents in the walls is much larger near the edges of the walls than at the centre. The obtained relative humidity and temperature at the interior wall surfaces are combined with isopleths of generalised spore germination time of fungus mould. The results show that WDR loads can have a significant impact on mould growth especially at the edges of the walls. Finally, for the case analysed, the WDR load causes a significant increase of indoor relative humidity and energy consumption for heating.
Article
The study of moisture migration in materials and building elements is of great importance for the characterization of their behaviour, and affects their durability, waterproofing, degradation and thermal performance. The different mechanisms of moisture transport in building walls and the analysis of interface phenomena have been investigated. Based on the theory proposed by Luikov and Philip—De Vries, a computer program has been developed. The comparison of calculated and measured values obtained by using gamma-ray equipment to measure water content profiles, is considered satisfactory.
Contribution à la modélisation hygrothermique des bâtiments: Application des méthodes de réduction de modèle
  • J Berger
J. Berger. Contribution à la modélisation hygrothermique des bâtiments: Application des méthodes de réduction de modèle. Phd thesis, Université de Grenoble, 2014. 2
  • G I M Lucas
  • O Müller
  • E F Toro
G.I.M. Lucas, O. Müller, E.F. Toro, Some issues in modelling venous haemodynamics, Numer Meth Hyperbolic Equ (2013) 347-354.
Vers une méthode de conception HYGRO-thermique des BATiments performants
  • Anr Project
ANR Project HYGRO-BAT. Vers une méthode de conception HYGRO-thermique des BATiments performants, 2014. 26