scholarly journals Hygrothermal Behavior of Earth-Based Materials: Experimental and Numerical Analysis

2020 ◽  
Vol 330 ◽  
pp. 01030
Author(s):  
Meriem Saidi ◽  
Amel Soukaina Cherif ◽  
Ezeddine Sediki ◽  
Belkacem Zeghmati
Keyword(s):  
Building Materials ◽  
Moisture Transfer ◽  
Transfer Problem ◽  
Numerical Study ◽  
Water Vapor Permeability ◽  
Average Moisture Content ◽  
Vapor Permeability ◽  
Hygrothermal Behavior ◽  
Coupled Heat And Moisture ◽  
Building Walls

Bio-based building materials such as earth bricks are attracting renewed interest throughout the world due to their thermal and environmental properties. In this work, a numerical study of the hygrothermal behavior of building walls consist of compressed earth bricks (CEB) and stabilized earth bricks (SEB) was performed. A two-dimensional Luikov model for evaluating the temperature and the moisture migration in porous building materials was proposed. The coupled heat and moisture transfer problem was modeled. The governing equations of a mathematical model were solved numerically with the finite difference method. Input parameters in the model and their dependency on stabilizers content were determined by laboratory experiments. In order to specify the effect of chemical stabilization on the heat and mass transfer within studied materials, average moisture content and temperature were presented as a function of time. Results show that the addition of chemical stabilizers enhances the heat transfer through the earthen materials and reduces their water vapor permeability.

Comparison of Numerical HMT Codes to Simulate MBV Test of Hemp-Earth Composites

2022 ◽  
Author(s):  
Sana Khaled ◽  
Marjorie Bart ◽  
Sophie Moissette ◽  
Florence Collet ◽  
Sylvie Prétot ◽  
...  
Keyword(s):  
Indoor Air ◽  
Building Materials ◽  
Numerical Study ◽  
Water Vapor Permeability ◽  
Building Envelope ◽  
Vapor Permeability ◽  
Building Envelopes ◽  
Classical Models ◽  
Points Of View ◽  
Adsorption Curve

Bio-based and earth materials are growingly used for the building envelopes because of their numerous benefits such as slight environmental impact, great hygrothermal performances, effective regulation of the perceived indoor air quality and human comfort. In such materials, the phenomenon of mass transfer is complex and has a great impact on the performance of building envelope. Therefore, it is important to identify and understand the hygrothermal phenomena to be able to simulate accurately the envelope behavior. Nevertheless, the classical models that depict hygric transport within building materials seem not accurate enough for bio-based materials as they are simplified on several points of view. The correlation that exists between water content and relative humidity is mostly simplified and is modeled by a single curve, the hygric storage capacity is often overstated and the hysteresis is neglected. This paper deals with numerical study of hygric transfer within hemp-earth building material by using WUFI® Pro 6.5, a commercial software, and TMC code developed at the LGCGM (Moissette and Bart, 2009) . This code was validated regarding EN 15026 standard (Moissette and Bart, 2009) and has evolved over the years by integrating the hysteresis phenomena (Aït-Oumeziane et al., 2015). Thus, a significant enhancement of the numerical simulations on desorption phase was shown. This study investigates the simulation of MBV test performed on a hemp-earth material for which only the adsorption curve is known as input. Missing parameters (water vapor permeability and desorption curve) are fitted considering the first cycle of MBV test with TMC code. Then, MBV test is simulated with WUFI® Pro 6.5 and TMC code without and with hysteresis. The results highlight the need to include hysteresis to accurately simulate dynamic hygric phenomena, and show that it is possible to find missing parameters by fitting dynamic solicitations.

Development of a numerical approach to assess the effect of coupled heat and moisture transfer on energy consumption of residential buildings in Moroccan context

2021 ◽  
pp. 174425912110560
Author(s):  
Yassine Chbani Idrissi ◽  
Rafik Belarbi ◽  
Mohammed Yacine Ferroukhi ◽  
M’barek Feddaoui ◽  
Driss Agliz
Keyword(s):  
Energy Consumption ◽  
Building Materials ◽  
Moisture Transfer ◽  
Residential Buildings ◽  
Building Design ◽  
Energy Performance ◽  
Climatic Conditions ◽  
Heat And Moisture Transfer ◽  
Coupled Heat And Moisture ◽  
Heat And Moisture

Hygrothermal properties of building materials, climatic conditions and energy performance are interrelated and have to be considered simultaneously as part of an optimised building design. In this paper, a new approach to evaluate the energy consumption of residential buildings in Morocco is presented. This approach is based on the effect of coupled heat and moisture transfer in typical residential buildings and on their responses to the varied climatic conditions encountered in the country. This approach allows us to evaluate with better accuracy the response of building energy performance and the indoor comfort of building occupants. Annual energy consumption, cooling and heating energy requirements were estimated considering the six climatic zones of Morocco. Based on the results, terms related to coupled heat and moisture transfer can effectively correct the existing energy consumption calculations of the six zones of Morocco, which currently do not consider energy consumption due to coupled heat and moisture transfer.

scholarly journals Characteristics of Knitted Structures Produced by Engineered Polyester Yarns and Their Blends in Terms of Thermal Comfort

2015 ◽  
Vol 10 (1) ◽  
pp. 155892501501000 ◽  
Author(s):  
Nida Oğlakcioğlu ◽  
Ahmet Çay ◽  
Arzu Marmarali ◽  
Emel Mert
Keyword(s):  
Water Vapor ◽  
Thermal Comfort ◽  
Moisture Transfer ◽  
Water Vapor Permeability ◽  
Air Permeability ◽  
Vapor Permeability ◽  
Moisture Management ◽  
Thermal Comfort Properties ◽  
Knitted Structure ◽  
Drying Properties

Engineered yarns are used to provide better clothing comfort for summer garments because of their high levels of moisture and water vapor management. The aim of this study was to investigate the characteristics of knitted structures that were produced using different types of polyester yarns in order to achieve better thermal comfort properties for summer clothing. However they are relatively expensive. Therefore, in this study engineered polyester yarns were combined with cotton and lyocell yarns by plying. This way, the pronounced characteristics of these yarns were added to the knitted structure as well. Channeled polyester, hollow polyester, channeled/hollow blended polyester, cotton, and lyocell yarns were plied with each other and themselves. Then, single jersey structures were knitted using these ply yarn combinations and air permeability, thermal resistance, thermal absorptivity, water vapor permeability, moisture management, and drying properties were tested. The results indicate that channeled PES fabrics are advantageous for hot climates and high physical activities with regards to high permeability and moisture transfer and also to fast drying properties. Besides, air permeability and thermal properties improved through the combination of lyocell yarn with engineered polyester yarns. However, the use of lyocell or cotton with engineered yarns resulted in a to a decrease in moisture management properties and an increase in drying times

scholarly journals Numerical modelling of a hemp concrete wall

2019 ◽  
Vol 85 ◽  
pp. 08003 ◽  
Author(s):  
Georges Costantine ◽  
Chadi Maalouf ◽  
Tala Moussa ◽  
Guillaume Polidori ◽  
Elias Kinab
Keyword(s):  
Building Materials ◽  
Moisture Transfer ◽  
Numerical Study ◽  
Object Oriented ◽  
Hysteresis Phenomenon ◽  
Energy Costs ◽  
Concrete Wall ◽  
Heat And Moisture ◽  
Account Heat ◽  
Indoor And Outdoor

In a global warming context associated to the abuse of energy consumption, actual researches focus more and more on reducing energy costs in the building sector. This target could be achieved by using innovative building materials, such as hemp concrete, due to its positive impacts on thermal and environmental levels. The aim of this work is to carry out a numerical study of a hemp concrete wall subjected to several indoor and outdoor conditions of temperature and relative humidity using the program object oriented SPARK. The hygrothermal behaviour of the wall is investigated taking into account heat and moisture transfer within the wall as well as hysteresis phenomenon between the sorption and desorption curves and their temperature dependency.

Hygrothermal Behavior of Thermal Insulating Material Based on Technical Hemp and its Application in Construction

2013 ◽  
Vol 860-863 ◽  
pp. 1223-1226
Author(s):  
Jiri Zach ◽  
Jitka Peterková ◽  
Martin Sedlmajer
Keyword(s):  
Building Materials ◽  
Moisture Absorption ◽  
Moisture Transfer ◽  
Natural Fibers ◽  
High Moisture ◽  
Building Envelopes ◽  
Thermal Insulating ◽  
Energy Demands ◽  
Hygrothermal Behavior ◽  
Heat And Moisture

Natural insulation materials have great potential of development given the contemporary requirements of the society in terms of reducing the energy demands of the production of building materials and the reduction of CO2emissions. Natural fibers are characteristic by their high moisture absorption and combustibility. The paper describes the results of research in the field of heat and moisture transfer within the structure of insulating materials based on natural fibers (hemp). The results of the experiments provided input data for computational simulations of hygrothermal behavior of hemp based fiber insulation applied in building envelopes.

scholarly journals Evaluation of Multiyear Weather Data Effects on Hygrothermal Building Energy Simulations Using WUFI Plus

Energies ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 7157
Author(s):  
Michele Libralato ◽  
Alessandra De Angelis ◽  
Giulia Tornello ◽  
Onorio Saro ◽  
Paola D’Agaro ◽  
...  
Keyword(s):  
Building Materials ◽  
Moisture Transfer ◽  
Weather Conditions ◽  
Building Energy ◽  
Building Envelope ◽  
Weather Data ◽  
Building Simulations ◽  
Coupled Heat And Moisture ◽  
Single Number ◽  
Energy Simulations

Transient building energy simulations are powerful design tools that are used for the estimation of HVAC demands and internal hygrothermal conditions of buildings. These calculations are commonly performed using a (often dated) typical meteorological year, generated from past weather measurements excluding extreme weather conditions. In this paper the results of multiyear building simulations performed considering coupled Heat and Moisture Transfer (HMT) in building materials are presented. A simple building is simulated in the city of Udine (Italy) using a weather record of 25 years. Performing a multiyear simulation allows to obtain a distribution of results instead of a single number for each variable. The small therm climate change is shown to influence thermal demands and internal conditions with multiyear effects. From this results it is possible to conclude that weather records used as weather files have to be periodically updated and that moisture transfer is relevant in energy and comfort calculations. Moreover, the simulations are performed using the software WUFI Plus and it is shown that using a thermal model for the building envelope could be a non negligible simplification for the comfort related calculations.

Coupled heat and moisture transfer in multi-layer building materials

2009 ◽  
Vol 23 (2) ◽  
pp. 967-975 ◽  
Author(s):  
Menghao Qin ◽  
Rafik Belarbi ◽  
Abdelkarim Aït-Mokhtar ◽  
Lars-Olof Nilsson
Keyword(s):  
Building Materials ◽  
Moisture Transfer ◽  
Heat And Moisture Transfer ◽  
Coupled Heat And Moisture ◽  
Heat And Moisture

scholarly journals USING DISCRETE-CONTINUOUS APPROACH FOR THE SOLUTION OF UNSTEADY-STATE MOISTURE TRANSFER EQUATION FOR MULTILAYER BUILDING WALLS

2021 ◽  
Vol 17 (2) ◽  
pp. 50-57
Author(s):  
Kirill Zubarev
Keyword(s):  
Building Materials ◽  
Moisture Transfer ◽  
State Equation ◽  
Climate Impact ◽  
Mineral Wool ◽  
Moisture Regime ◽  
Unsteady State ◽  
Continuous Approach ◽  
Aerated Concrete ◽  
Building Walls

Moisture regime of enclosing structures is one of the most complicated and controversial directions in construction industry. Temporary climate impact on enclosing structures and low moisture inertia of building materials lead to the situation in which it is impossible to calculate the steady-state moisture regime. Numerical methods are usually used to assess the moisture behaviour of the enclosing structures. In the current paper, a differential equation of moisture transfer is formulated. The solution of the unsteady-state equation of moisture transfer was obtained using the discrete-continuous approach. Thus, a formula which allows scientists to calculate unsteady-state moisture transfer in multilayer walls of buildings was obtained. A two-layer building enclosing structure with aerated concrete base and mineral wool insulation was calculated.

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