Performance of Photovoltaic-double skin façade (Photovoltaic-DSF) system in summer has been critical. Owing to high solar ingress, cooling requirement of a building significantly increases. Photovoltaic-DSF system provides a shield and controls the heat gain through fenestration in the interior spaces. In the present article, mathematical correlations are developed to analyse energy behaviour of forced-ventilated Photovoltaic-DSF system in India’s hot summer zone, that is, Jaipur. The Photovoltaic-DSF system has been installed and monitored for Jaipur’s summer months (May to July). L25 Orthogonal array of design parameters (air cavity thickness, air velocity and PV panel’s transparency) and their respective levels have been developed using Taguchi design to perform experiments. Based on experimental results, multiple linear regression has been used to forecast solar heat gain coefficient, PVs electrical power and daylighting illuminance indoors as function of design factors. The statistical significance of mathematical relationships is supported by variance analysis, which is found to be in good accord with field measurements ( R2 > 0.90). The proposed correlations are pragmatic in designing Photovoltaic-DSF systems for hot summer conditions. The Photovoltaic-DSF system with 30% transmittance and air velocity of 5 m/s in 200 mm air cavity thickness achieved maximum energy performance in hot summers.
{"title":"Development of mathematical correlations to predict performance of forced ventilated Photovoltaic-DSF system in hot composite climate","authors":"Sajan Preet, Sanjay Mathur, Jyotirmay Mathur, Manoj Kumar Sharma, Amartya Chowdhury","doi":"10.1177/17442591241247327","DOIUrl":"https://doi.org/10.1177/17442591241247327","url":null,"abstract":"Performance of Photovoltaic-double skin façade (Photovoltaic-DSF) system in summer has been critical. Owing to high solar ingress, cooling requirement of a building significantly increases. Photovoltaic-DSF system provides a shield and controls the heat gain through fenestration in the interior spaces. In the present article, mathematical correlations are developed to analyse energy behaviour of forced-ventilated Photovoltaic-DSF system in India’s hot summer zone, that is, Jaipur. The Photovoltaic-DSF system has been installed and monitored for Jaipur’s summer months (May to July). L25 Orthogonal array of design parameters (air cavity thickness, air velocity and PV panel’s transparency) and their respective levels have been developed using Taguchi design to perform experiments. Based on experimental results, multiple linear regression has been used to forecast solar heat gain coefficient, PVs electrical power and daylighting illuminance indoors as function of design factors. The statistical significance of mathematical relationships is supported by variance analysis, which is found to be in good accord with field measurements ( R<jats:sup>2</jats:sup> > 0.90). The proposed correlations are pragmatic in designing Photovoltaic-DSF systems for hot summer conditions. The Photovoltaic-DSF system with 30% transmittance and air velocity of 5 m/s in 200 mm air cavity thickness achieved maximum energy performance in hot summers.","PeriodicalId":50249,"journal":{"name":"Journal of Building Physics","volume":"32 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141502655","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}
Examining the thermodynamics of phase change materials (PCMs) when merged into construction materials is a significant subject within the realm of building science and environmental responsibility. When infused to construction materials like bricks, PCMs have the capacity to elevate a building’s temperature regulation by minimizing the energy required for thermal contentment. This research is dedicated to learn about the thermal conduct and the consequences of the fusion of calcium chloride hexahydrate mineral (CCHPCM) within the pores of a masonry unit. To achieve this, we implemented a practical testing specifically designed to scrutinize how CCHPCMs alter the thermal performance of studied compounds. Multiple configurations were designed by adjusting the arrangement of CCHPCM within the bricks, resulting in three distinct setups. The first set involved filling one row of the bricks, the second set entailed filling two rows, and the final configuration entailed filling all the pores with PCM. Additionally, a computational modeling was executed to survey the thermic behavior of bricks infused with CCHPCM, operating with COMSOL Multiphysics application program. The elaborated work concluded to having an enhancement of the brick’s thermal storage capacity, for Set-3, in which all rows of bricks are filled with PCM, a delay of 2 h is observed compared to Set-0 the brick without CCHPCM. This simulation also encompassed comparative findings regarding the thermal performance of CCHPCM when incorporated into the masonry unit. Overall, this study supplied the valorization of CCHPCMs infused in masonry units and their usage in distinct layouts on upgrading its candidature to achieving environmental responsibility.
{"title":"Computational and experimental analysis of PCM-infused brick for sustainable heat regulation","authors":"Amira Dellagi, Rabeb Ayed, Salwa Bouadila, AmenAllah Guizani","doi":"10.1177/17442591241255966","DOIUrl":"https://doi.org/10.1177/17442591241255966","url":null,"abstract":"Examining the thermodynamics of phase change materials (PCMs) when merged into construction materials is a significant subject within the realm of building science and environmental responsibility. When infused to construction materials like bricks, PCMs have the capacity to elevate a building’s temperature regulation by minimizing the energy required for thermal contentment. This research is dedicated to learn about the thermal conduct and the consequences of the fusion of calcium chloride hexahydrate mineral (CCHPCM) within the pores of a masonry unit. To achieve this, we implemented a practical testing specifically designed to scrutinize how CCHPCMs alter the thermal performance of studied compounds. Multiple configurations were designed by adjusting the arrangement of CCHPCM within the bricks, resulting in three distinct setups. The first set involved filling one row of the bricks, the second set entailed filling two rows, and the final configuration entailed filling all the pores with PCM. Additionally, a computational modeling was executed to survey the thermic behavior of bricks infused with CCHPCM, operating with COMSOL Multiphysics application program. The elaborated work concluded to having an enhancement of the brick’s thermal storage capacity, for Set-3, in which all rows of bricks are filled with PCM, a delay of 2 h is observed compared to Set-0 the brick without CCHPCM. This simulation also encompassed comparative findings regarding the thermal performance of CCHPCM when incorporated into the masonry unit. Overall, this study supplied the valorization of CCHPCMs infused in masonry units and their usage in distinct layouts on upgrading its candidature to achieving environmental responsibility.","PeriodicalId":50249,"journal":{"name":"Journal of Building Physics","volume":"41 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141502656","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 : 2024-05-04DOI: 10.1177/17442591241246053
Hela Guesmi, Meriem Soussi, Fakhreddine Abbassi, Ali Adili, Leila Dehmani
Improving the thermal insulation and energy efficiency of building envelopes is a major objective worldwide and has significantly developed in the recent years. This study aims to evaluate the impact of ecological additive and passive strategies on building energy efficiency. An experimental study was carried out to examine the effect of the incorporation of treated Alfa and Posidonia-Oceanica fibers on the thermal properties of cement and gypsum composite samples. The experimental results were then introduced in a numerical study using TRNSYS software to perform a comparison of the energy efficiency and thermal performance of three individual buildings; two ones constructed with our ecological materials and the third one with typical materials is considered as a reference case under the Tunisian climate. The obtained results indicate that the buildings built with Alfa fibers (BAF) and Posidonia-Oceanica fibers (BPOF) are economically effective since they allow a decrease of about 48.20% and 43.48% in heating, 45.71% and 42.77% in cooling, leading to a reduction in CO2 emission of 47.90% and 43.40%, respectively, in comparison with the reference case. The investigation also focuses on the improvement of the ecological building envelope by a storage wall integrated on the south front and shaded by solar movable overhangs during the summer season. The indoor climate results reveal that incorporating passive strategies into the building improves indoor air temperature and preserves a comfortable indoor relative humidity. Heating requirements decrease by 82.82% for BAF and by 79.76% for BPOF. The cooling requirements of the reference building are also reduced by 63.46% for BAF and 60.45% for BPOF by the use of natural night ventilation (4 ACH) and the appropriate shading for Trombe walls and windows. Consequently, the implementation of passive strategies on the ecological buildings led to a net reduction in CO2 emissions by up to 80.55% for BAF, compared to the reference case.
{"title":"Energy efficiency of ecological buildings in Tunisia: Natural fiber composites and passive strategies impact","authors":"Hela Guesmi, Meriem Soussi, Fakhreddine Abbassi, Ali Adili, Leila Dehmani","doi":"10.1177/17442591241246053","DOIUrl":"https://doi.org/10.1177/17442591241246053","url":null,"abstract":"Improving the thermal insulation and energy efficiency of building envelopes is a major objective worldwide and has significantly developed in the recent years. This study aims to evaluate the impact of ecological additive and passive strategies on building energy efficiency. An experimental study was carried out to examine the effect of the incorporation of treated Alfa and Posidonia-Oceanica fibers on the thermal properties of cement and gypsum composite samples. The experimental results were then introduced in a numerical study using TRNSYS software to perform a comparison of the energy efficiency and thermal performance of three individual buildings; two ones constructed with our ecological materials and the third one with typical materials is considered as a reference case under the Tunisian climate. The obtained results indicate that the buildings built with Alfa fibers (BAF) and Posidonia-Oceanica fibers (BPOF) are economically effective since they allow a decrease of about 48.20% and 43.48% in heating, 45.71% and 42.77% in cooling, leading to a reduction in CO<jats:sub>2</jats:sub> emission of 47.90% and 43.40%, respectively, in comparison with the reference case. The investigation also focuses on the improvement of the ecological building envelope by a storage wall integrated on the south front and shaded by solar movable overhangs during the summer season. The indoor climate results reveal that incorporating passive strategies into the building improves indoor air temperature and preserves a comfortable indoor relative humidity. Heating requirements decrease by 82.82% for BAF and by 79.76% for BPOF. The cooling requirements of the reference building are also reduced by 63.46% for BAF and 60.45% for BPOF by the use of natural night ventilation (4 ACH) and the appropriate shading for Trombe walls and windows. Consequently, the implementation of passive strategies on the ecological buildings led to a net reduction in CO<jats:sub>2</jats:sub> emissions by up to 80.55% for BAF, compared to the reference case.","PeriodicalId":50249,"journal":{"name":"Journal of Building Physics","volume":"1 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140829133","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 : 2024-04-10DOI: 10.1177/17442591241238436
Irati Uriarte, Aitor Erkoreka, Maria Jose Jimenez, Koldo Martin-Escudero, Hans Bloem
There still exists a considerable difference when comparing the real and the design energy consumption of buildings. The difference between the design and the real building envelope energy performance is one of its main reasons. The building envelope can be characterised through the individual characterisation of its different building envelope components such as opaque walls or windows. Therefore, the estimation of parameters such as their transmission heat transfer coefficient (UA) and their solar aperture (gA) is usually implemented. Although building components have been analysed over the years, the thermal characteristics of buildings have mainly been estimated through steady-state laboratory tests and simplified calculation/simulation procedures based on theoretical data. The use of inverse modelling based on registered dynamic data has also been used; however, unfortunately, the models used tend to significantly simplify or neglect the solar radiation effect on the inner surface heat flux of opaque building envelope elements. Therefore, this work presents an experimental, dynamic and inverse modelling method that accurately models non-linear phenomena through the use of a user-friendly simulation programme (LORD). The method is able to analyse in detail the effect of the solar radiation on the inner surface heat flux of opaque building envelope elements, without the necessity of knowing their constructive details or thermal properties. The experiment is performed in a fully monitored test box, where different models are tested with different opaque walls to find the best fit. Finally, the solar irradiance signal is removed from the best models so as to accurately quantify the weight of the solar radiation on the inner surface heat flux of each wall for two extreme periods, one for sunny summer days and other for cloudy winter days.
{"title":"Experimental method for estimating the effect of solar radiation on the inner surface heat flux of opaque building envelope elements","authors":"Irati Uriarte, Aitor Erkoreka, Maria Jose Jimenez, Koldo Martin-Escudero, Hans Bloem","doi":"10.1177/17442591241238436","DOIUrl":"https://doi.org/10.1177/17442591241238436","url":null,"abstract":"There still exists a considerable difference when comparing the real and the design energy consumption of buildings. The difference between the design and the real building envelope energy performance is one of its main reasons. The building envelope can be characterised through the individual characterisation of its different building envelope components such as opaque walls or windows. Therefore, the estimation of parameters such as their transmission heat transfer coefficient (UA) and their solar aperture (gA) is usually implemented. Although building components have been analysed over the years, the thermal characteristics of buildings have mainly been estimated through steady-state laboratory tests and simplified calculation/simulation procedures based on theoretical data. The use of inverse modelling based on registered dynamic data has also been used; however, unfortunately, the models used tend to significantly simplify or neglect the solar radiation effect on the inner surface heat flux of opaque building envelope elements. Therefore, this work presents an experimental, dynamic and inverse modelling method that accurately models non-linear phenomena through the use of a user-friendly simulation programme (LORD). The method is able to analyse in detail the effect of the solar radiation on the inner surface heat flux of opaque building envelope elements, without the necessity of knowing their constructive details or thermal properties. The experiment is performed in a fully monitored test box, where different models are tested with different opaque walls to find the best fit. Finally, the solar irradiance signal is removed from the best models so as to accurately quantify the weight of the solar radiation on the inner surface heat flux of each wall for two extreme periods, one for sunny summer days and other for cloudy winter days.","PeriodicalId":50249,"journal":{"name":"Journal of Building Physics","volume":"59 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140567901","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}
Current exterior wall assembly designs for new low-rise residential buildings targeting low-energy demand in heating dominated countries include split-insulation wall and thick-wall assembly designs. Both have been shown to result in thermal efficiency gains compared to building-code minimum assemblies, however long-term hygrothermal performance can vary depending on boundary conditions and the presence of construction deficiencies. Future climate scenarios estimate many heating-dominated climates will experience a reduction in heating-degree day hours and an increase in annual rainfall. Using validated assembly performance data from a Passive House certified facility, a sensitivity analysis is performed to determine the impact of rainwater wetting, air exfiltration and insulation material properties on the hygrothermal response of a thick-wall assembly. Results show that rainwater leakage values of 0.50% and greater of the adhering rainfall on the exterior surface of the assembly results in the greatest risk for failure. The hygrothermal response of the assembly is then examined under a global temperature rise scenario of 3.5°C for five geographic locations across Canada. Results show that an increase in average annual total rainfall does not directly result in an increase in the failure rate of the assembly when a rainwater leak is present. Additional climatic factors, including outdoor air temperature, driving rain and solar radiation received will influence the hygrothermal response of the assembly and need to be considered when modelling the performance under future climate change scenarios.
{"title":"Hygrothermal response of a wood-frame thick-wall assembly to rainwater wetting under future climate scenarios in Canada","authors":"Alison Conroy, Phalguni Mukhopadhyaya, Guido Wimmers","doi":"10.1177/17442591241238621","DOIUrl":"https://doi.org/10.1177/17442591241238621","url":null,"abstract":"Current exterior wall assembly designs for new low-rise residential buildings targeting low-energy demand in heating dominated countries include split-insulation wall and thick-wall assembly designs. Both have been shown to result in thermal efficiency gains compared to building-code minimum assemblies, however long-term hygrothermal performance can vary depending on boundary conditions and the presence of construction deficiencies. Future climate scenarios estimate many heating-dominated climates will experience a reduction in heating-degree day hours and an increase in annual rainfall. Using validated assembly performance data from a Passive House certified facility, a sensitivity analysis is performed to determine the impact of rainwater wetting, air exfiltration and insulation material properties on the hygrothermal response of a thick-wall assembly. Results show that rainwater leakage values of 0.50% and greater of the adhering rainfall on the exterior surface of the assembly results in the greatest risk for failure. The hygrothermal response of the assembly is then examined under a global temperature rise scenario of 3.5°C for five geographic locations across Canada. Results show that an increase in average annual total rainfall does not directly result in an increase in the failure rate of the assembly when a rainwater leak is present. Additional climatic factors, including outdoor air temperature, driving rain and solar radiation received will influence the hygrothermal response of the assembly and need to be considered when modelling the performance under future climate change scenarios.","PeriodicalId":50249,"journal":{"name":"Journal of Building Physics","volume":"49 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140567805","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 : 2024-03-23DOI: 10.1177/17442591241238437
Kazuma Fukui, Satoru Takada
When the water content of a porous material is high, air entrapped in the pore space is expected to affect water transfer through the pores. To understand the effects of air entrapment on water transfer in porous building materials in the high-water-saturation region, we examined the water transfer characteristics corresponding to significantly small air entrapment effects. First, we conducted two sets of water uptake experiments. In the first experiment, using three building materials, the time evolution of the amount of water absorption was measured at a low air pressure near vacuum (several kPa). In the second experiment, the water content profile during water uptake was measured using the gamma-ray attenuation method. The experimental results showed that low air pressure accelerated the water uptake by the brick and aerated concrete specimens, whereas water uptake by the calcium silicate board specimens was not significantly affected. These differences among materials were analyzed from a pore structure viewpoint. Moreover, gamma-ray attenuation measurements confirmed that the obtained water content profile was qualitatively similar at atmospheric and low air pressures, although the low air pressure increased both the water content of the material after capillary absorption and the wetting front propagation rate. Finally, simultaneous water and air transfer calculations based on the air and liquid water balance in a material reproduced the measured water absorption rates well, confirming that air entrapment and pressure development in the pores can significantly reduce the rate of water uptake and water content after capillary absorption. The calculation results also indicated that the air pressure in a material did not significantly increase at early water uptake stages where local water content was not high, which supported the general assumption that treating the liquid-water transfer in porous building materials as a one-component flow is valid in most cases.
{"title":"Impact of air entrapment on capillary absorption in porous building materials","authors":"Kazuma Fukui, Satoru Takada","doi":"10.1177/17442591241238437","DOIUrl":"https://doi.org/10.1177/17442591241238437","url":null,"abstract":"When the water content of a porous material is high, air entrapped in the pore space is expected to affect water transfer through the pores. To understand the effects of air entrapment on water transfer in porous building materials in the high-water-saturation region, we examined the water transfer characteristics corresponding to significantly small air entrapment effects. First, we conducted two sets of water uptake experiments. In the first experiment, using three building materials, the time evolution of the amount of water absorption was measured at a low air pressure near vacuum (several kPa). In the second experiment, the water content profile during water uptake was measured using the gamma-ray attenuation method. The experimental results showed that low air pressure accelerated the water uptake by the brick and aerated concrete specimens, whereas water uptake by the calcium silicate board specimens was not significantly affected. These differences among materials were analyzed from a pore structure viewpoint. Moreover, gamma-ray attenuation measurements confirmed that the obtained water content profile was qualitatively similar at atmospheric and low air pressures, although the low air pressure increased both the water content of the material after capillary absorption and the wetting front propagation rate. Finally, simultaneous water and air transfer calculations based on the air and liquid water balance in a material reproduced the measured water absorption rates well, confirming that air entrapment and pressure development in the pores can significantly reduce the rate of water uptake and water content after capillary absorption. The calculation results also indicated that the air pressure in a material did not significantly increase at early water uptake stages where local water content was not high, which supported the general assumption that treating the liquid-water transfer in porous building materials as a one-component flow is valid in most cases.","PeriodicalId":50249,"journal":{"name":"Journal of Building Physics","volume":"366 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140203885","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 : 2024-03-16DOI: 10.1177/17442591241238438
Mohammed Nouali, Elhem Ghorbel
This paper aims to valorize the excavated earth (ExE) generated from the tunnel digging works, to elaborate excavated earth-based plasters for masonry walls. Excavated earth is an admixture of water, gravel, sand, and fine particles. A small amount of gravel (<4% by weight) was removed, and the tunnel-excavated earth is used to elaborate plasters. Cement and slag are used as stabilizers in ExE-based plasters and reinforced with natural hemp fibers. The physical, mechanical, thermal, and hydric properties of ExE-based plasters are investigated. The increase in cement content affects the workability of ExE-based plasters in a fresh state, while the addition of natural hemp fibers has no significant effect on the workability. It has been demonstrated that the mechanical performances (compressive strength, flexural strength, and dynamic modulus) of ExE-based plasters increase with the increase of cement content and decrease with the increase in slag content. The hemp fiber addition (0.8% by weight) shows no considerable effect on the ExE-based plaster’s mechanical performance. As for the thermal properties, the increase of cement and slag contents negatively affects the thermal conductivity. The increase in cement content decreases the water absorption of earth-plasters. Except for some tests (shrinkage, main cohesion, and cracking tests), which have not been done in this study, the results of cement-stabilized ExE-based plasters (7% and 9%) are in accordance with the recommendation of the DIN 18947 standard, indicating that the tunnel excavated earth can be used as earth-plasters.
{"title":"Hygro-thermo-mechanical properties of tunnel excavated earth-based plasters","authors":"Mohammed Nouali, Elhem Ghorbel","doi":"10.1177/17442591241238438","DOIUrl":"https://doi.org/10.1177/17442591241238438","url":null,"abstract":"This paper aims to valorize the excavated earth (ExE) generated from the tunnel digging works, to elaborate excavated earth-based plasters for masonry walls. Excavated earth is an admixture of water, gravel, sand, and fine particles. A small amount of gravel (<4% by weight) was removed, and the tunnel-excavated earth is used to elaborate plasters. Cement and slag are used as stabilizers in ExE-based plasters and reinforced with natural hemp fibers. The physical, mechanical, thermal, and hydric properties of ExE-based plasters are investigated. The increase in cement content affects the workability of ExE-based plasters in a fresh state, while the addition of natural hemp fibers has no significant effect on the workability. It has been demonstrated that the mechanical performances (compressive strength, flexural strength, and dynamic modulus) of ExE-based plasters increase with the increase of cement content and decrease with the increase in slag content. The hemp fiber addition (0.8% by weight) shows no considerable effect on the ExE-based plaster’s mechanical performance. As for the thermal properties, the increase of cement and slag contents negatively affects the thermal conductivity. The increase in cement content decreases the water absorption of earth-plasters. Except for some tests (shrinkage, main cohesion, and cracking tests), which have not been done in this study, the results of cement-stabilized ExE-based plasters (7% and 9%) are in accordance with the recommendation of the DIN 18947 standard, indicating that the tunnel excavated earth can be used as earth-plasters.","PeriodicalId":50249,"journal":{"name":"Journal of Building Physics","volume":"40 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140153909","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}
{"title":"Editorial: Building physics process integrated renewables energy – Contributions from COBEE 2022","authors":"Dahai Qi, Dengjia Wang, Yupeng Wu, Liangzhu (Leon) Wang, Dominque Derome","doi":"10.1177/17442591241234454","DOIUrl":"https://doi.org/10.1177/17442591241234454","url":null,"abstract":"","PeriodicalId":50249,"journal":{"name":"Journal of Building Physics","volume":"14 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139949544","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 : 2024-02-20DOI: 10.1177/17442591241230677
Botao Zhou, Juan Zhao, Yongcai Li, Junmei Gao, Bojing Huang, Ritu Wu, Wenjie Zhang, Biao Tan
Reasonable thermal insulation in cold regions is the key to improve the indoor thermal environment. In this paper, the detached house is taken as the research object, and the sensitivity analysis method is used to quantify the influence of each parameter on the building heat load in three different climate zones. The attenuation characteristics of the heat storage body to the outdoor temperature wave are studied by using the A·M Shklovel calculation method, and the thermal insulation strategy of the envelope structure is optimized by genetic algorithm (GA). The results show that the heat transfer coefficient of roof and exterior wall has the most significant influence on the building heat load. The mean effect response of each factor shows that the Delta (Delta is the value used in Taguchi design methodology to express the relative effect of each factor on the response) of roofs in the three regions is the highest, 3.061, 4.061, and 5.88, respectively. The influence of the type and thickness of the insulation material on the heat storage performance is different. The indoor and outdoor temperature wave penetration attenuation multiple increases with the increase of the thickness of the insulation layer, increases with the decrease of the thermal conductivity of the insulation material, and increases with the increase of the specific heat capacity. The choice of insulation materials is not only related to the above two parameters, but also directly affected by the price. Considering the influence of various factors, the economy of choosing expanded polystyrene board for thermal insulation in the three regions is the best. The optimal thermal insulation thickness of the north wall and roof is 8 and 16 cm (3A climate zone), 10 and 17 cm (2B climate zone), 13 and 20 cm (2A climate zone), respectively.
{"title":"Optimization strategies of the envelope insulation for a detached house based on load sensitivity and thermal storage performance","authors":"Botao Zhou, Juan Zhao, Yongcai Li, Junmei Gao, Bojing Huang, Ritu Wu, Wenjie Zhang, Biao Tan","doi":"10.1177/17442591241230677","DOIUrl":"https://doi.org/10.1177/17442591241230677","url":null,"abstract":"Reasonable thermal insulation in cold regions is the key to improve the indoor thermal environment. In this paper, the detached house is taken as the research object, and the sensitivity analysis method is used to quantify the influence of each parameter on the building heat load in three different climate zones. The attenuation characteristics of the heat storage body to the outdoor temperature wave are studied by using the A·M Shklovel calculation method, and the thermal insulation strategy of the envelope structure is optimized by genetic algorithm (GA). The results show that the heat transfer coefficient of roof and exterior wall has the most significant influence on the building heat load. The mean effect response of each factor shows that the Delta (Delta is the value used in Taguchi design methodology to express the relative effect of each factor on the response) of roofs in the three regions is the highest, 3.061, 4.061, and 5.88, respectively. The influence of the type and thickness of the insulation material on the heat storage performance is different. The indoor and outdoor temperature wave penetration attenuation multiple increases with the increase of the thickness of the insulation layer, increases with the decrease of the thermal conductivity of the insulation material, and increases with the increase of the specific heat capacity. The choice of insulation materials is not only related to the above two parameters, but also directly affected by the price. Considering the influence of various factors, the economy of choosing expanded polystyrene board for thermal insulation in the three regions is the best. The optimal thermal insulation thickness of the north wall and roof is 8 and 16 cm (3A climate zone), 10 and 17 cm (2B climate zone), 13 and 20 cm (2A climate zone), respectively.","PeriodicalId":50249,"journal":{"name":"Journal of Building Physics","volume":"12 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139949464","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 : 2024-01-27DOI: 10.1177/17442591231219931
Daan Deckers, Hans Janssen
Due to the detrimental effects of moisture in the built environment, there is a continuous interest in non-destructive experimental techniques that quantify and/or localise moisture in materials. Most existing experimental techniques, however, typically focus on macroscopic moisture contents in samples rather than the microscopic distribution of water in the individual pores of building materials. For the latter, a popular method such as X-ray computed tomography is not readily applicable, due to the gap between its spatial resolution limit and the typical pore sizes of building materials. Nuclear magnetic resonance (NMR) relaxometry is capable of measuring water in pores of both the nanometer and micrometer scale and is therefore an interesting possibility. While most NMR research focusses on water-saturated materials or overall moisture contents, this study determines the size distributions of the water islands in unsaturated materials with NMR, and compares results to X-ray computed tomography (XCT) images and pore network model (PNM) simulations. Results on unsaturated materials show that NMR focusses on the biggest water islands (i.e. in capillary filled pores) and disregards the hydrogen nuclei in smaller water islands (i.e. stored in pore corners). NMR relaxometry is therefore only adept at providing very rough estimates of the size of water-filled pores, especially since post-processing of the NMR experiments to obtain these water island size distributions involves a lot of uncertainty.
由于湿气在建筑环境中的有害影响，人们对量化和/或定位材料中湿气的非破坏性实验技术一直很感兴趣。然而，大多数现有的实验技术通常侧重于样品中的宏观含水量，而不是建筑材料单个孔隙中水的微观分布。对于后者，X 射线计算机断层扫描等常用方法并不适用，因为其空间分辨率限制与建筑材料的典型孔隙尺寸之间存在差距。核磁共振（NMR）弛豫测量法能够测量纳米级和微米级孔隙中的水，因此是一种有趣的可能性。大多数核磁共振研究侧重于水饱和材料或总体含水量，而本研究则利用核磁共振确定非饱和材料中水岛的尺寸分布，并将结果与 X 射线计算机断层扫描（XCT）图像和孔隙网络模型（PNM）模拟进行比较。对不饱和材料的研究结果表明，核磁共振聚焦于最大的水岛（即毛细管填充孔隙中的水），而忽略了较小水岛（即储存在孔隙角落中的水）中的氢核。因此，核磁共振弛豫测量法只能对充满水的孔隙的大小提供非常粗略的估计，特别是因为对核磁共振实验进行后处理以获得这些水岛的大小分布涉及很多不确定性。
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