Pub Date : 2023-01-01DOI: 10.1177/17442591221142501
N. Reuge, F. Collet, S. Prétot, S. Moisette, M. Bart, O. Style, A. Shea, C. Lanos
The hygrothermal behavior of a bio-based multilayered wall has been studied by numerical simulations. The key point of these research investigations was to properly describe the hygrothermal transfers occurring inside the studied wall solution. In previous work, the case of the wall subjected to a given real climate (Wroughton HIVE demonstrator, UK, Feb 2018) has been investigated. The present work, focused on the moisture regulation capacity of the wall, considers an improved kinetics model of sorption, different layer configurations, one additional climate (Bordeaux, FR, Apr 2008) and the effect of indoor cyclic loads. Compared to the classical approach, the local kinetics approach results in prediction of stronger and steeper hygric dynamics with larger relative humidity variations at small time scales. The study of the different wall configurations allows to determine the best one in terms of moisture damping: the vapor control membrane is advantageously removed provided the OSB3 12 mm layer is replaced by an OSB4 18 mm layer. Moreover, the simulations show that the Moisture Buffer Value characteristic of each material layer is not a sufficient criterion to evaluate hygric performance of the wall; strong hygric interactions occur with the layer’s permeability independently of its sorption capacity. Finally, water content hysteresis phenomena are studied and it appears that under usual operating conditions, they can be ignored by adjusting the layers’ permeabilities for adequate fits on the Moisture Buffer Value tests.
{"title":"Hygrothermal transfers through a bio-based multilayered wall: Modeling study of different wall configurations subjected to various climates and indoor cyclic loads","authors":"N. Reuge, F. Collet, S. Prétot, S. Moisette, M. Bart, O. Style, A. Shea, C. Lanos","doi":"10.1177/17442591221142501","DOIUrl":"https://doi.org/10.1177/17442591221142501","url":null,"abstract":"The hygrothermal behavior of a bio-based multilayered wall has been studied by numerical simulations. The key point of these research investigations was to properly describe the hygrothermal transfers occurring inside the studied wall solution. In previous work, the case of the wall subjected to a given real climate (Wroughton HIVE demonstrator, UK, Feb 2018) has been investigated. The present work, focused on the moisture regulation capacity of the wall, considers an improved kinetics model of sorption, different layer configurations, one additional climate (Bordeaux, FR, Apr 2008) and the effect of indoor cyclic loads. Compared to the classical approach, the local kinetics approach results in prediction of stronger and steeper hygric dynamics with larger relative humidity variations at small time scales. The study of the different wall configurations allows to determine the best one in terms of moisture damping: the vapor control membrane is advantageously removed provided the OSB3 12 mm layer is replaced by an OSB4 18 mm layer. Moreover, the simulations show that the Moisture Buffer Value characteristic of each material layer is not a sufficient criterion to evaluate hygric performance of the wall; strong hygric interactions occur with the layer’s permeability independently of its sorption capacity. Finally, water content hysteresis phenomena are studied and it appears that under usual operating conditions, they can be ignored by adjusting the layers’ permeabilities for adequate fits on the Moisture Buffer Value tests.","PeriodicalId":50249,"journal":{"name":"Journal of Building Physics","volume":"233 1","pages":"425 - 454"},"PeriodicalIF":2.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76975788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-23DOI: 10.1177/17442591221140470
S. Roels, Astrid Tijskens
Since timber frame constructions can help to reduce CO2-emissions and lower the embodied energy of buildings, the market share of timber-based buildings is growing across Europe. Unfortunately, timber frame constructions are found to be susceptible to moisture damage, such as interstitial condensation, mould growth and wood rot. To avoid moisture damage, a correct design of the wall composition is crucial, with special emphasis on the ratio between vapour resistance of wind and vapour barrier. Given that experimental investigations are time-consuming and expensive, numerical tools are common to assess the hygrothermal behaviour of building components. And although timber frame constructions are inherently two- or even three-dimensional due to the embedded wooden elements, most often, 1D-simulations focussing on the basic configuration with insulation between wind and vapour barrier are conducted. This paper investigates to what extent neglecting the embedded wooden elements influences the risk assessment of the wall. Three different wall configurations have been considered and their hygrothermal response, as predicted by 1D- and 2D-numerical simulations, are compared. Variability of the exterior climate is included by using four distinct different climate regions. Contrary to common assumptions, buffering of moisture in wooden elements does not always lower the risk on moisture damage, but might even increase it. While the predicted risk on mould growth was found to be similar between 1D and 2D-simulations, the opposite was found for the risk on interstitial condensation. Mainly for cold climates and wall configurations with hardly any other hygric buffering capacity, levels of interstitial condensation were found to be significantly higher when taking the wooden elements into account in the numerical simulations. Hence, care should be taken when assessing the reliability of timber frame walls based on 1D-simulations only.
{"title":"The impact of wooden studs on the moisture risk of timber frame constructions","authors":"S. Roels, Astrid Tijskens","doi":"10.1177/17442591221140470","DOIUrl":"https://doi.org/10.1177/17442591221140470","url":null,"abstract":"Since timber frame constructions can help to reduce CO2-emissions and lower the embodied energy of buildings, the market share of timber-based buildings is growing across Europe. Unfortunately, timber frame constructions are found to be susceptible to moisture damage, such as interstitial condensation, mould growth and wood rot. To avoid moisture damage, a correct design of the wall composition is crucial, with special emphasis on the ratio between vapour resistance of wind and vapour barrier. Given that experimental investigations are time-consuming and expensive, numerical tools are common to assess the hygrothermal behaviour of building components. And although timber frame constructions are inherently two- or even three-dimensional due to the embedded wooden elements, most often, 1D-simulations focussing on the basic configuration with insulation between wind and vapour barrier are conducted. This paper investigates to what extent neglecting the embedded wooden elements influences the risk assessment of the wall. Three different wall configurations have been considered and their hygrothermal response, as predicted by 1D- and 2D-numerical simulations, are compared. Variability of the exterior climate is included by using four distinct different climate regions. Contrary to common assumptions, buffering of moisture in wooden elements does not always lower the risk on moisture damage, but might even increase it. While the predicted risk on mould growth was found to be similar between 1D and 2D-simulations, the opposite was found for the risk on interstitial condensation. Mainly for cold climates and wall configurations with hardly any other hygric buffering capacity, levels of interstitial condensation were found to be significantly higher when taking the wooden elements into account in the numerical simulations. Hence, care should be taken when assessing the reliability of timber frame walls based on 1D-simulations only.","PeriodicalId":50249,"journal":{"name":"Journal of Building Physics","volume":"11 1","pages":"455 - 473"},"PeriodicalIF":2.0,"publicationDate":"2022-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86347197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-22DOI: 10.1177/17442591221136274
Jonas Dürr, A. Geissler, C. Hoffmann
An enormous range of building materials that is almost impossible to keep track of is available. The trend toward building densification in cities continues apace. Coupled with climate change, a situation is emerging that poses ecological as well as economic risks in terms of living comfort in public, urban spaces. Building designers need help (tools) to be able to address a wide range of requirements within their planning. The development of the Multi-Criteria Decision-Making (MCDM) model BASK (engl. “Construction Materials for Cities in Climate Change”) is presented. The goal of the model is to assist building designers in determining surface materials for wall, ground and roof construction and help determine the best compromise between environmental, economic, and building practice criteria. Currently available criteria are heat stress, visual reflectance, CO2 equivalents, electricity production, retrofitability, sound absorption, construction costs, and life span. The criteria can be weighted by the designer, resulting in a customized ranking of construction systems that best meets the designer’s prioritized criteria. The design of BASK basically allows for an extension of the criteria. The version of BASK described in this paper includes 10 construction systems covering a wide range of construction types focused on walls. The tool requires technical data for materials considered in construction systems included, which are made available via a data base. The scope of construction systems can also be extended in the future. Based on the restricted set of construction systems the results of a sensitivity analysis and initial validation are given.
{"title":"Development of a Multi-Criteria Decision-Making model to assist building designers in the choice of superficial construction systems in urban areas","authors":"Jonas Dürr, A. Geissler, C. Hoffmann","doi":"10.1177/17442591221136274","DOIUrl":"https://doi.org/10.1177/17442591221136274","url":null,"abstract":"An enormous range of building materials that is almost impossible to keep track of is available. The trend toward building densification in cities continues apace. Coupled with climate change, a situation is emerging that poses ecological as well as economic risks in terms of living comfort in public, urban spaces. Building designers need help (tools) to be able to address a wide range of requirements within their planning. The development of the Multi-Criteria Decision-Making (MCDM) model BASK (engl. “Construction Materials for Cities in Climate Change”) is presented. The goal of the model is to assist building designers in determining surface materials for wall, ground and roof construction and help determine the best compromise between environmental, economic, and building practice criteria. Currently available criteria are heat stress, visual reflectance, CO2 equivalents, electricity production, retrofitability, sound absorption, construction costs, and life span. The criteria can be weighted by the designer, resulting in a customized ranking of construction systems that best meets the designer’s prioritized criteria. The design of BASK basically allows for an extension of the criteria. The version of BASK described in this paper includes 10 construction systems covering a wide range of construction types focused on walls. The tool requires technical data for materials considered in construction systems included, which are made available via a data base. The scope of construction systems can also be extended in the future. Based on the restricted set of construction systems the results of a sensitivity analysis and initial validation are given.","PeriodicalId":50249,"journal":{"name":"Journal of Building Physics","volume":"4 1","pages":"513 - 540"},"PeriodicalIF":2.0,"publicationDate":"2022-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74398028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-17DOI: 10.1177/17442591221140465
Y. Nguyen, V. T. Nguyen
Using solar chimneys in buildings can enhance the thermal insulation of the building envelope and provide sufficient ventilation and cooling. The performance of a solar chimney is strongly affected by its configurational factors. This work examines the effects of the opening heights on the flow field in the cavity of a wall solar chimney with a Computational Fluid Dynamics (CFD) model. Both cases of equal and unequal opening areas were considered. The results show that the induced flow rate increases with the opening height and gradually becomes constant as the opening height is about 2.0–3.0 and 5.0–6.0 times the air gap for heating the left wall (HLW) and the right wall (HRW) of the air cavity, respectively. Particularly, using equal inlet and outlet heights that are equal to the air gap reduces the flow rate of 27% for HLW and 85% for HRW compared to the maximum ones. The optimal design of a wall solar chimney to achieve maximum flow rate is proposed for two cases of heating, that is, (a) for HLW, equal opening heights which are twice the air gap, and (b) for RHW, the inlet height equal to the air gap, and the outlet height equal to five times the air gap.
{"title":"Characterizing the induced flow through the cavity of a wall solar chimney under the effects of the opening heights","authors":"Y. Nguyen, V. T. Nguyen","doi":"10.1177/17442591221140465","DOIUrl":"https://doi.org/10.1177/17442591221140465","url":null,"abstract":"Using solar chimneys in buildings can enhance the thermal insulation of the building envelope and provide sufficient ventilation and cooling. The performance of a solar chimney is strongly affected by its configurational factors. This work examines the effects of the opening heights on the flow field in the cavity of a wall solar chimney with a Computational Fluid Dynamics (CFD) model. Both cases of equal and unequal opening areas were considered. The results show that the induced flow rate increases with the opening height and gradually becomes constant as the opening height is about 2.0–3.0 and 5.0–6.0 times the air gap for heating the left wall (HLW) and the right wall (HRW) of the air cavity, respectively. Particularly, using equal inlet and outlet heights that are equal to the air gap reduces the flow rate of 27% for HLW and 85% for HRW compared to the maximum ones. The optimal design of a wall solar chimney to achieve maximum flow rate is proposed for two cases of heating, that is, (a) for HLW, equal opening heights which are twice the air gap, and (b) for RHW, the inlet height equal to the air gap, and the outlet height equal to five times the air gap.","PeriodicalId":50249,"journal":{"name":"Journal of Building Physics","volume":"297 1","pages":"630 - 653"},"PeriodicalIF":2.0,"publicationDate":"2022-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73168307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-20DOI: 10.1177/17442591221127279
CE Torres-Aguilar, J. Arce, J. Xamán, E. Macias-Melo
Solar chimneys provide natural ventilation for buildings, reducing the energy consumption of mechanical systems. Therefore, analyzing energy losses through solar chimney components and inlet/outlet of air channel is critical to develop a suitable design for this passive ventilation system. In this study, the performance and energy losses analysis of a single-channel solar chimney (SC-SOCH) is described; a parametric study under laboratory conditions was conducted regarding the air gap (0.10, 0.15, and 0.20 m) and heat flux of absorber plate (100, 200, 300, 400, and 500 Wm−2). The energy losses were analyzed with temperature sensors, heat flow transducers, and a net radiation transfer model. The parametric study results showed that between 10% and 15% of the total energy supplied to the absorber plate was dissipated to the laboratory environment through the glass cover. Furthermore, combining the different thermal insulation layers on the backside of the absorber plate and sidewalls of the air channel permitted only energy losses below 8% of the total energy supplied. The highest energy losses occurred due to radiative exchange; the radiative losses through the inlet and outlet of the air channel were between 9.38% and 25.78% of the total energy supplied. However, the radiative energy loss rate decreased as airflow increased; the volumetric flow rate was from 34.11 to 94.92 m3h−1, which was enough to satisfy the requirements of total ventilation rate for spaces of 9, 18, and 36 m2 according to ASHRAE 62.2–2019. Therefore, solar chimney designs must be optimized to minimize energy losses and increase airflow for natural ventilation.
{"title":"Experimental study and numerical analysis of radiative losses of single-channel solar chimney","authors":"CE Torres-Aguilar, J. Arce, J. Xamán, E. Macias-Melo","doi":"10.1177/17442591221127279","DOIUrl":"https://doi.org/10.1177/17442591221127279","url":null,"abstract":"Solar chimneys provide natural ventilation for buildings, reducing the energy consumption of mechanical systems. Therefore, analyzing energy losses through solar chimney components and inlet/outlet of air channel is critical to develop a suitable design for this passive ventilation system. In this study, the performance and energy losses analysis of a single-channel solar chimney (SC-SOCH) is described; a parametric study under laboratory conditions was conducted regarding the air gap (0.10, 0.15, and 0.20 m) and heat flux of absorber plate (100, 200, 300, 400, and 500 Wm−2). The energy losses were analyzed with temperature sensors, heat flow transducers, and a net radiation transfer model. The parametric study results showed that between 10% and 15% of the total energy supplied to the absorber plate was dissipated to the laboratory environment through the glass cover. Furthermore, combining the different thermal insulation layers on the backside of the absorber plate and sidewalls of the air channel permitted only energy losses below 8% of the total energy supplied. The highest energy losses occurred due to radiative exchange; the radiative losses through the inlet and outlet of the air channel were between 9.38% and 25.78% of the total energy supplied. However, the radiative energy loss rate decreased as airflow increased; the volumetric flow rate was from 34.11 to 94.92 m3h−1, which was enough to satisfy the requirements of total ventilation rate for spaces of 9, 18, and 36 m2 according to ASHRAE 62.2–2019. Therefore, solar chimney designs must be optimized to minimize energy losses and increase airflow for natural ventilation.","PeriodicalId":50249,"journal":{"name":"Journal of Building Physics","volume":"2 1","pages":"340 - 371"},"PeriodicalIF":2.0,"publicationDate":"2022-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90088191","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-10-19DOI: 10.1177/17442591221127280
L. P. Thomas, B. M. Marino, N. Muñoz
We introduce a statistical methodology to evaluate the thermal performance of vertical opaque envelopes and provide the most adequate design of energy-efficient buildings located across extended regions. The analytical procedure was applied to the extensive Argentinian territory with a variety of climates and a limited number of networked meteorological stations. Although the study was conducted over a full year, results are presented for January and June, when the building energy demand for heating and cooling is most significant, taking into account the local climate, the thermal properties of the walls and the effects of the daily variation in the solar radiation. By using the Fourier series expansion of the sol-air temperature and multivariate analysis, we first correlated the weather data and the steady-state and time-dependent heat fluxes transmitted by conduction through five types of typical walls facing north and south in 10 climatically differentiated cities where full weather data were recorded. Then, the mean values of the sol-air temperature and the amplitude of its time variations were interpolated throughout the territory, thus yielding the spatial distributions of these parameters for a typical day in the months of interest. Finally, the calculation of the heat fluxes exchanged through building opaque envelopes was extended to the whole country.
{"title":"Multivariate analysis for assessing the thermal performance of vertical opaque envelopes in extended regions","authors":"L. P. Thomas, B. M. Marino, N. Muñoz","doi":"10.1177/17442591221127280","DOIUrl":"https://doi.org/10.1177/17442591221127280","url":null,"abstract":"We introduce a statistical methodology to evaluate the thermal performance of vertical opaque envelopes and provide the most adequate design of energy-efficient buildings located across extended regions. The analytical procedure was applied to the extensive Argentinian territory with a variety of climates and a limited number of networked meteorological stations. Although the study was conducted over a full year, results are presented for January and June, when the building energy demand for heating and cooling is most significant, taking into account the local climate, the thermal properties of the walls and the effects of the daily variation in the solar radiation. By using the Fourier series expansion of the sol-air temperature and multivariate analysis, we first correlated the weather data and the steady-state and time-dependent heat fluxes transmitted by conduction through five types of typical walls facing north and south in 10 climatically differentiated cities where full weather data were recorded. Then, the mean values of the sol-air temperature and the amplitude of its time variations were interpolated throughout the territory, thus yielding the spatial distributions of these parameters for a typical day in the months of interest. Finally, the calculation of the heat fluxes exchanged through building opaque envelopes was extended to the whole country.","PeriodicalId":50249,"journal":{"name":"Journal of Building Physics","volume":"7 1","pages":"259 - 291"},"PeriodicalIF":2.0,"publicationDate":"2022-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78953839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-30DOI: 10.1177/17442591221121918
Jiashuai Wei, Shui Yu, Xiaoting Zhou
The effect of concrete cracks on the evaluation of the thermal performance of walls has not been effectively considered within the assessment of the thermal and hygroscopic performance of buildings. Based on the dual permeability model, a conjugate method is proposed to reconstruct the PDE equation of unsaturated porous materials with cracks. The reliability of the model is verified from three angles: the heat-moisture coupling benchmark of matrix material, the analytical solution of two-dimensional single fracture heat flow coupling problem and the moisture absorption problem of unsaturated cracks. The reliability of the model is verified from three perspectives: the benchmark of thermal and hygroscopic coupling of matrix materials, the analytical solution to the two-dimensional single-break thermal flow coupling problem, and the hygroscopic problem of unsaturated cracks. The effect of heat and moisture transfer in cracked concrete was quantified by detailed modeling of cracks in terms of the probability of over-penetration, crack roughness, crack density, length, and angle of a two-dimensional discrete crack network, showing that cracks contribute to moisture transfer. This is followed by a 10 day experimental simulation of the meteorological environment, comparing the quantities of moisture accumulation, thermal performance, internal surface temperature and humidity within the fractured and non-fractured wall structures, illustrating the potential adverse effects of cracks on thermal performance and moisture transfer in walls under characteristic conditions. Finally, the necessity of applying moisture-proof layer to the damaged wall is demonstrated by comparing the results before and after the application of the moisture-proof layer.
{"title":"Study on influence of geometric characteristics of cracks on HAM coupling transfer and thermal performance of multi-layer cellular concrete wall","authors":"Jiashuai Wei, Shui Yu, Xiaoting Zhou","doi":"10.1177/17442591221121918","DOIUrl":"https://doi.org/10.1177/17442591221121918","url":null,"abstract":"The effect of concrete cracks on the evaluation of the thermal performance of walls has not been effectively considered within the assessment of the thermal and hygroscopic performance of buildings. Based on the dual permeability model, a conjugate method is proposed to reconstruct the PDE equation of unsaturated porous materials with cracks. The reliability of the model is verified from three angles: the heat-moisture coupling benchmark of matrix material, the analytical solution of two-dimensional single fracture heat flow coupling problem and the moisture absorption problem of unsaturated cracks. The reliability of the model is verified from three perspectives: the benchmark of thermal and hygroscopic coupling of matrix materials, the analytical solution to the two-dimensional single-break thermal flow coupling problem, and the hygroscopic problem of unsaturated cracks. The effect of heat and moisture transfer in cracked concrete was quantified by detailed modeling of cracks in terms of the probability of over-penetration, crack roughness, crack density, length, and angle of a two-dimensional discrete crack network, showing that cracks contribute to moisture transfer. This is followed by a 10 day experimental simulation of the meteorological environment, comparing the quantities of moisture accumulation, thermal performance, internal surface temperature and humidity within the fractured and non-fractured wall structures, illustrating the potential adverse effects of cracks on thermal performance and moisture transfer in walls under characteristic conditions. Finally, the necessity of applying moisture-proof layer to the damaged wall is demonstrated by comparing the results before and after the application of the moisture-proof layer.","PeriodicalId":50249,"journal":{"name":"Journal of Building Physics","volume":"40 1","pages":"292 - 339"},"PeriodicalIF":2.0,"publicationDate":"2022-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84628116","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-21DOI: 10.1177/17442591221121924
Mohamed Ouakarrouch, N. Laaroussi, M. Garoum, Said Bousshine, A. Bybi, Abderrahim Benallel, A. Tilioua
The main objective of this paper is to elaborate and characterize new ecological composites based on cardboard waste and abandoned natural fibers, in the Drâa-Tafilalet region (South-East, Morocco), for the manufacture of local thermo-acoustical insulation panels. For this study, 25 samples were prepared by mixing 60% of cardboard waste and 40% of vegetable fibers (Reed tree, esparto fiber, fig tree, and Olive tree). The morphological analysis of the different fibers was carried out by scanning electron microscopy (SEM), while, the physical, thermal, and acoustical properties of samples were measured experimentally using standard methods. The experimental results showed that all new composites have better thermal and acoustical performances comparable to those of synthetic insulation materials. The density, thermal conductivity, thermal diffusivity, and sound absorption coefficient of those composites were in the range of 278.6–343.8 kg/m3; 0.072–0.10 W/m·K; 1254.5–1807.5 J/kg·K; 0.4–0.8, respectively. Consequently, the by-products recovered in this study are good candidates for the development of local insulation materials with useful properties for thermal and acoustical insulation applications in buildings, low environmental impact, low cost, and competition with commercialized synthetic insulation materials.
{"title":"Sustainable thermo-acoustical insulation material from cardboard waste and natural fibers: Elaboration and performance evaluation","authors":"Mohamed Ouakarrouch, N. Laaroussi, M. Garoum, Said Bousshine, A. Bybi, Abderrahim Benallel, A. Tilioua","doi":"10.1177/17442591221121924","DOIUrl":"https://doi.org/10.1177/17442591221121924","url":null,"abstract":"The main objective of this paper is to elaborate and characterize new ecological composites based on cardboard waste and abandoned natural fibers, in the Drâa-Tafilalet region (South-East, Morocco), for the manufacture of local thermo-acoustical insulation panels. For this study, 25 samples were prepared by mixing 60% of cardboard waste and 40% of vegetable fibers (Reed tree, esparto fiber, fig tree, and Olive tree). The morphological analysis of the different fibers was carried out by scanning electron microscopy (SEM), while, the physical, thermal, and acoustical properties of samples were measured experimentally using standard methods. The experimental results showed that all new composites have better thermal and acoustical performances comparable to those of synthetic insulation materials. The density, thermal conductivity, thermal diffusivity, and sound absorption coefficient of those composites were in the range of 278.6–343.8 kg/m3; 0.072–0.10 W/m·K; 1254.5–1807.5 J/kg·K; 0.4–0.8, respectively. Consequently, the by-products recovered in this study are good candidates for the development of local insulation materials with useful properties for thermal and acoustical insulation applications in buildings, low environmental impact, low cost, and competition with commercialized synthetic insulation materials.","PeriodicalId":50249,"journal":{"name":"Journal of Building Physics","volume":"12 1","pages":"372 - 392"},"PeriodicalIF":2.0,"publicationDate":"2022-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78180680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-01DOI: 10.1177/17442591221121932
S. Van Linden, M. Lacasse, N. Van Den Bossche
Drainage reduces the amount of water able to infiltrate toward the interior of wall assemblies. However, a portion of the infiltrated water remains in the assembly after drainage has occurred. The degree to which this retained portion of water affects the durability of the wall assembly can be evaluated by means of hygrothermal simulations. However, the number of studies reporting information on the retention percentage that can be applied as input for hygrothermal simulations and on the drainage performance of wall assemblies is, in general, quite limited. Therefore, an experimental study was developed, to assess governing test methods to evaluate drainage characteristics and to quantify retention of water in wall test specimens having various cavity widths and incorporating different drainage materials. It was concluded that apart from the absolute amount of retained water, the lateral spreading of water in the cavity and the overall wetted area, should also be considered, thereby resulting in reporting the retained amount relative to the wetted area. The latter values provide more detailed information on the behavior of water in the cavity. Additionally, it was concluded that a clear cavity of 1 mm can drain water more efficiently than a cavity of 10 mm. As well, the surface texture of drainage materials affected the spreading and retention of water within the cavity and the use of a drainage mat in the cavity resulted in an increased relative retention but a reduced lateral spreading of the water.
{"title":"Drainage of infiltrated rainwater in wall assemblies: Test method, experimental quantification, and recommendations","authors":"S. Van Linden, M. Lacasse, N. Van Den Bossche","doi":"10.1177/17442591221121932","DOIUrl":"https://doi.org/10.1177/17442591221121932","url":null,"abstract":"Drainage reduces the amount of water able to infiltrate toward the interior of wall assemblies. However, a portion of the infiltrated water remains in the assembly after drainage has occurred. The degree to which this retained portion of water affects the durability of the wall assembly can be evaluated by means of hygrothermal simulations. However, the number of studies reporting information on the retention percentage that can be applied as input for hygrothermal simulations and on the drainage performance of wall assemblies is, in general, quite limited. Therefore, an experimental study was developed, to assess governing test methods to evaluate drainage characteristics and to quantify retention of water in wall test specimens having various cavity widths and incorporating different drainage materials. It was concluded that apart from the absolute amount of retained water, the lateral spreading of water in the cavity and the overall wetted area, should also be considered, thereby resulting in reporting the retained amount relative to the wetted area. The latter values provide more detailed information on the behavior of water in the cavity. Additionally, it was concluded that a clear cavity of 1 mm can drain water more efficiently than a cavity of 10 mm. As well, the surface texture of drainage materials affected the spreading and retention of water within the cavity and the use of a drainage mat in the cavity resulted in an increased relative retention but a reduced lateral spreading of the water.","PeriodicalId":50249,"journal":{"name":"Journal of Building Physics","volume":"43 1","pages":"1022 - 1056"},"PeriodicalIF":2.0,"publicationDate":"2022-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77662761","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-08-10DOI: 10.1177/17442591221109956
Klaus Viljanen, J. Puttonen, Xiaoshu Lü
The study comprises three laboratory tests in which typical Finnish highly insulated (HI) walls were exposed to concentrated leakages of indoor air under steady outdoor temperatures of 1–5°C. Airflows with a relative humidity of 50% and at rates of 1–3 L/min were directed close to the wooden frames inside the walls. The thermal resistance ratios between the exterior sheathing(s) and the whole wall (Γ) were 20%–22% and 1%–10% for the HI and baseline (BL) walls. The HI walls that presented Γ values of at least 20% were observed to be resistant to air exfiltration, and their durability was not affected by the addition of a gypsum sheathing outside the wooden frame or a more permeable vapor retarder. This is related to the negative linear correlation that exists between the moisture accumulation rate in wood-based material and the dew point depression (DPD) value. The developed approach, called the DPD method, shows that a significant degree of moisture accumulation does not occur even for DPD values of as low as −2°C if the exterior sheathing is vapor permeable. The airflow does not penetrate into the rigid mineral wool sheathing, which helps to avoid interstitial condensation. Regardless of thermal transmittance, the HI and BL walls with maximum Γ values of 1% were exposed to a high relative humidity and even interstitial condensation because the DPD values were often below −2°C. For these walls, the mold index analysis and visual observations confirmed the local risk for mold growth on the opposite side of the leakage point. In practice, long-term mold growth may be limited if the seasonal periods during which the outdoor temperature is 1–5°C last for a maximum of about 1 month every year.
{"title":"Hygrothermal performance of highly insulated external walls subjected to indoor air exfiltration","authors":"Klaus Viljanen, J. Puttonen, Xiaoshu Lü","doi":"10.1177/17442591221109956","DOIUrl":"https://doi.org/10.1177/17442591221109956","url":null,"abstract":"The study comprises three laboratory tests in which typical Finnish highly insulated (HI) walls were exposed to concentrated leakages of indoor air under steady outdoor temperatures of 1–5°C. Airflows with a relative humidity of 50% and at rates of 1–3 L/min were directed close to the wooden frames inside the walls. The thermal resistance ratios between the exterior sheathing(s) and the whole wall (Γ) were 20%–22% and 1%–10% for the HI and baseline (BL) walls. The HI walls that presented Γ values of at least 20% were observed to be resistant to air exfiltration, and their durability was not affected by the addition of a gypsum sheathing outside the wooden frame or a more permeable vapor retarder. This is related to the negative linear correlation that exists between the moisture accumulation rate in wood-based material and the dew point depression (DPD) value. The developed approach, called the DPD method, shows that a significant degree of moisture accumulation does not occur even for DPD values of as low as −2°C if the exterior sheathing is vapor permeable. The airflow does not penetrate into the rigid mineral wool sheathing, which helps to avoid interstitial condensation. Regardless of thermal transmittance, the HI and BL walls with maximum Γ values of 1% were exposed to a high relative humidity and even interstitial condensation because the DPD values were often below −2°C. For these walls, the mold index analysis and visual observations confirmed the local risk for mold growth on the opposite side of the leakage point. In practice, long-term mold growth may be limited if the seasonal periods during which the outdoor temperature is 1–5°C last for a maximum of about 1 month every year.","PeriodicalId":50249,"journal":{"name":"Journal of Building Physics","volume":"9 1","pages":"967 - 1021"},"PeriodicalIF":2.0,"publicationDate":"2022-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84221839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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