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。
{"title":"Microscopic moisture localisation in unsaturated materials using nuclear magnetic resonance relaxometry","authors":"Daan Deckers, Hans Janssen","doi":"10.1177/17442591231219931","DOIUrl":"https://doi.org/10.1177/17442591231219931","url":null,"abstract":"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.","PeriodicalId":50249,"journal":{"name":"Journal of Building Physics","volume":"254 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139949541","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 : 2024-01-10DOI: 10.1177/17442591231219025
Tran Van Quang, Dat Tien Doan, Nguyen Lu Phuong, Geun Young Yun
Predicting indoor airflow distribution in multi-storey residential buildings is essential for designing energy-efficient natural ventilation systems. The indoor environment significantly impacts human health and well-being, considering the substantial time spent indoors and the potential health and safety risks faced daily. To ensure occupants’ thermal comfort and indoor air quality, airflow simulations in the built environment must be efficient and precise. This study proposes a novel approach combining Computational Fluid Dynamics (CFD) simulations with machine learning techniques to predict indoor airflow. Specifically, we investigate the viability of employing a Deep Neural Network (DNN) model for accurately forecasting indoor airflow dispersion. The quantitative results reveal the DNN’s ability to faithfully reproduce indoor airflow patterns and temperature distributions. Furthermore, DNN approaches to investigate indoor airflow in the residential building achieved an 80% reduction in the time required to anticipate testing scenarios compared with CFD simulation, underscoring the potential for efficient indoor airflow prediction. This research underscores the feasibility and effectiveness of a data-driven approach, enabling swift and accurate indoor airflow predictions in naturally ventilated residential buildings. Such predictive models hold significant promise for optimizing indoor air quality, thermal comfort, and energy efficiency, thereby contributing to sustainable building design and operation.
{"title":"Data-driven prediction of indoor airflow distribution in naturally ventilated residential buildings using combined CFD simulation and machine learning (ML) approach","authors":"Tran Van Quang, Dat Tien Doan, Nguyen Lu Phuong, Geun Young Yun","doi":"10.1177/17442591231219025","DOIUrl":"https://doi.org/10.1177/17442591231219025","url":null,"abstract":"Predicting indoor airflow distribution in multi-storey residential buildings is essential for designing energy-efficient natural ventilation systems. The indoor environment significantly impacts human health and well-being, considering the substantial time spent indoors and the potential health and safety risks faced daily. To ensure occupants’ thermal comfort and indoor air quality, airflow simulations in the built environment must be efficient and precise. This study proposes a novel approach combining Computational Fluid Dynamics (CFD) simulations with machine learning techniques to predict indoor airflow. Specifically, we investigate the viability of employing a Deep Neural Network (DNN) model for accurately forecasting indoor airflow dispersion. The quantitative results reveal the DNN’s ability to faithfully reproduce indoor airflow patterns and temperature distributions. Furthermore, DNN approaches to investigate indoor airflow in the residential building achieved an 80% reduction in the time required to anticipate testing scenarios compared with CFD simulation, underscoring the potential for efficient indoor airflow prediction. This research underscores the feasibility and effectiveness of a data-driven approach, enabling swift and accurate indoor airflow predictions in naturally ventilated residential buildings. Such predictive models hold significant promise for optimizing indoor air quality, thermal comfort, and energy efficiency, thereby contributing to sustainable building design and operation.","PeriodicalId":50249,"journal":{"name":"Journal of Building Physics","volume":"83 17","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139440807","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 : 2024-01-09DOI: 10.1177/17442591231218831
Huagang Dong, Pengwei Tang, Bo He, Lei Chen, Zhuangzhuang Zhang, Chengqi Jia
The widespread advancement of computer technology resulted in the increasing usage of deep learning models for predicting solar radiation. Numerous studies have been conducted to explore their research potential. Nevertheless, the application of deep learning models in optimizing building energy systems, particularly in a multi-step solar radiation prediction model for model predictive control (MPC), remains a challenging task. This is mainly due to the intricacy of the time series and the possibility of accumulating errors in multistep forecasts. In this study, we propose the development of a transformer-based attention model for predicting multi-step solar irradiation at least 24 h in advance. The model is trained and tested using measured solar irradiation data and temperature forecast data obtained from the Tokyo Meteorological Agency. The findings indicate that the transformer model has the capability to effectively mitigate the issue of error accumulation. Additionally, the generative model exhibits a significant improvement in accuracy, with a 62.35% increase when compared to the conventional regression LSTM model. Additionally, the transformer model has been shown to attain superior prediction stability, mitigate the effects of error accumulation in multi-step forecasting, and circumvent training challenges stemming from gradient propagation issues that can occur with recurrent neural networks.
{"title":"Multi-step solar radiation prediction using transformer: A case study from solar radiation data in Tokyo","authors":"Huagang Dong, Pengwei Tang, Bo He, Lei Chen, Zhuangzhuang Zhang, Chengqi Jia","doi":"10.1177/17442591231218831","DOIUrl":"https://doi.org/10.1177/17442591231218831","url":null,"abstract":"The widespread advancement of computer technology resulted in the increasing usage of deep learning models for predicting solar radiation. Numerous studies have been conducted to explore their research potential. Nevertheless, the application of deep learning models in optimizing building energy systems, particularly in a multi-step solar radiation prediction model for model predictive control (MPC), remains a challenging task. This is mainly due to the intricacy of the time series and the possibility of accumulating errors in multistep forecasts. In this study, we propose the development of a transformer-based attention model for predicting multi-step solar irradiation at least 24 h in advance. The model is trained and tested using measured solar irradiation data and temperature forecast data obtained from the Tokyo Meteorological Agency. The findings indicate that the transformer model has the capability to effectively mitigate the issue of error accumulation. Additionally, the generative model exhibits a significant improvement in accuracy, with a 62.35% increase when compared to the conventional regression LSTM model. Additionally, the transformer model has been shown to attain superior prediction stability, mitigate the effects of error accumulation in multi-step forecasting, and circumvent training challenges stemming from gradient propagation issues that can occur with recurrent neural networks.","PeriodicalId":50249,"journal":{"name":"Journal of Building Physics","volume":"36 3","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139442803","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 : 2024-01-09DOI: 10.1177/17442591231219793
Felicia Wagiri, Shen-Guan Shih, Kevin Harsono, Deser Christian Wijaya
This study explores the optimization of kinetic facades to promote environmental sustainability in building designs, addressing the critical issues of high energy consumption and CO2 emissions prevalent in the construction sector. The focus is on achieving an intricate balance between maximizing natural daylight and minimizing solar radiation using innovative kinetic facade designs. Parametric modeling tools are utilized in the design process to experiment with various facade configurations. The effectiveness of these designs is then validated using both digital and physical prototypes, with their adaptability to diverse climatic conditions evaluated through dynamic simulations. A key component of the study is the application of the Wallacei plugin for Grasshopper, which assists in multi-objective optimization to determine the most effective facade aperture ratios. The results demonstrates a substantial reduction in solar radiation levels, with a 70% decrease on the first floor and a 76% decrease on the seventh floor, achieved by optimizing aperture ratios. The study concludes that optimizing kinetic facades significantly improves building performance compared to traditional glass facades, offering an effective balance between daylight enhancement and solar radiation reduction, influenced by seasonal changes. It also emphasizes the importance of factors such as building height and the surrounding environment in facade design. Overall, the findings highlight kinetic facades as a viable solution for improving building efficiency and occupant comfort, suggesting a promising avenue for advancements in architectural design and construction.
{"title":"Multi-objective optimization of kinetic facade aperture ratios for daylight and solar radiation control","authors":"Felicia Wagiri, Shen-Guan Shih, Kevin Harsono, Deser Christian Wijaya","doi":"10.1177/17442591231219793","DOIUrl":"https://doi.org/10.1177/17442591231219793","url":null,"abstract":"This study explores the optimization of kinetic facades to promote environmental sustainability in building designs, addressing the critical issues of high energy consumption and CO2 emissions prevalent in the construction sector. The focus is on achieving an intricate balance between maximizing natural daylight and minimizing solar radiation using innovative kinetic facade designs. Parametric modeling tools are utilized in the design process to experiment with various facade configurations. The effectiveness of these designs is then validated using both digital and physical prototypes, with their adaptability to diverse climatic conditions evaluated through dynamic simulations. A key component of the study is the application of the Wallacei plugin for Grasshopper, which assists in multi-objective optimization to determine the most effective facade aperture ratios. The results demonstrates a substantial reduction in solar radiation levels, with a 70% decrease on the first floor and a 76% decrease on the seventh floor, achieved by optimizing aperture ratios. The study concludes that optimizing kinetic facades significantly improves building performance compared to traditional glass facades, offering an effective balance between daylight enhancement and solar radiation reduction, influenced by seasonal changes. It also emphasizes the importance of factors such as building height and the surrounding environment in facade design. Overall, the findings highlight kinetic facades as a viable solution for improving building efficiency and occupant comfort, suggesting a promising avenue for advancements in architectural design and construction.","PeriodicalId":50249,"journal":{"name":"Journal of Building Physics","volume":"30 6","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139443528","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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