The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Robin Wilson - One of the best experts on this subject based on the ideXlab platform.
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analysis of the daylight performance of a Glazing System with parallel slat transparent insulation material ps tim
Energy and Buildings, 2017Co-Authors: Yanyi Sun, Robin WilsonAbstract:Daylight plays an important role in the energy efficiency and indoor environmental quality of an office building. An innovative facade System where parallel transparent/translucent plastic slats are sandwiched between glass panes to form a Parallel Slat Transparent Insulation Material (PS-TIM) is proposed as a strategy to effectively increase the thermal resistance of window Systems, while providing better daylight performance. In this paper, the optical performance (as defined by Bidirectional Scattering Distribution Function) of a double glazed window containing PS-TIM Systems with different slat pitches (the distance between neighbouring slats), slat tilt angles, as well as the slat materials (transparent and translucent) was obtained using a ray-tracing technique. Then, the annual daylight performance of a typical office building with various PS-TIM applied under different climatic conditions and at different orientations was investigated using RADIANCE. The simulation results show that PS-TIM with translucent slats offers better daylight performance than conventional double Glazing: it can increase the percentage of annual working hours under daylight, where the illuminance lies in the useful range by up to 79%. It also achieves a homogenous distribution of daylight within the internal working space and effectively reduces the possibility of glare. When applying PS- TIM at higher site latitude, smaller slat pitches are required to maximise useful daylight. Optimised PS-TIM geometry is also affected by local prevailing sky conditions.
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Experimental measurement and numerical simulation of the thermal performance of a double Glazing System with an interstitial Venetian blind
Building and Environment, 2016Co-Authors: Yanyi Sun, Robin WilsonAbstract:Venetian blinds, which were originally designed to provide sun shading and privacy, also have the potential to reduce heat transfer caused by internal and external temperature difference when integrated within the cavity between the two panes of a double Glazing unit. In this paper, the thermal performance of a Glazing System with and without a Venetian blind with various slat orientation angles under different temperature conditions is investigated through both experiment (undertaken in a large climate chamber) and numerical simulation (obtained via Computational Fluid Dynamic modelling). The thermal resistance of a Venetian blind Glazing System varies with the change of slat inclination angle, and it also highly depends on the mean temperature of the Glazing and the temperature difference between the indoor and outdoor environment. Inclusion of a Venetian blind modifies both the absolute and relative strengths of convection and radiation. Vertically oriented slats showed the most significant contribution to increasing radiative thermal resistance, which led to the best overall thermal performance. The System achieved up to 28% improvement of U-value when compared with a Glazing unit without a Venetian blind. Empirical correlations generated based on simulations could be used for future building energy simulation.
Yanyi Sun - One of the best experts on this subject based on the ideXlab platform.
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analysis of the daylight performance of a Glazing System with parallel slat transparent insulation material ps tim
Energy and Buildings, 2017Co-Authors: Yanyi Sun, Robin WilsonAbstract:Daylight plays an important role in the energy efficiency and indoor environmental quality of an office building. An innovative facade System where parallel transparent/translucent plastic slats are sandwiched between glass panes to form a Parallel Slat Transparent Insulation Material (PS-TIM) is proposed as a strategy to effectively increase the thermal resistance of window Systems, while providing better daylight performance. In this paper, the optical performance (as defined by Bidirectional Scattering Distribution Function) of a double glazed window containing PS-TIM Systems with different slat pitches (the distance between neighbouring slats), slat tilt angles, as well as the slat materials (transparent and translucent) was obtained using a ray-tracing technique. Then, the annual daylight performance of a typical office building with various PS-TIM applied under different climatic conditions and at different orientations was investigated using RADIANCE. The simulation results show that PS-TIM with translucent slats offers better daylight performance than conventional double Glazing: it can increase the percentage of annual working hours under daylight, where the illuminance lies in the useful range by up to 79%. It also achieves a homogenous distribution of daylight within the internal working space and effectively reduces the possibility of glare. When applying PS- TIM at higher site latitude, smaller slat pitches are required to maximise useful daylight. Optimised PS-TIM geometry is also affected by local prevailing sky conditions.
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Glazing System with transparent insulation material for building energy saving and daylight comfort
2017Co-Authors: Yanyi SunAbstract:Concerns over sustainability in the built environment have resulted in continuous efforts to improve the performance of window System or glazed facade and hence indoor comfort and building energy conservation. An innovative facade System where parallel transparent/translucent plastic slats are sandwiched between glass panes to form a Parallel Slat Transparent Insulation Material (PS-TIM) is proposed as a strategy to effectively reduce heat transfer between the panes of a double glazed window, while maintaining access to daylight. A holistic investigation of the window System with PS- TIMs is conducted in terms of thermal and optical properties, as well as detailed daylight and energy performance predictions of applying PS-TIMs in buildings. Firstly, an experimental investigation is undertaken in a large climate chamber, and the measurement results were used to validate a two-dimensional Computational Fluid Dynamics (CFD) model. Secondly, the validated 2D CFD model is used to solve the dynamic thermal properties of different configurations of PS-TIMs under various environmental conditions. The optical properties (i.e. Bidirectional Scattering Distribution Function (BSDF)) of PS-TIMs are obtained via a ray-tracing technique based on the structures’ geometries and the material optical characteristics of the interstitial structure. The detailed annual daylight performance in different climates and building orientations are predicted using RADIANCE. Finally, the optical and thermal properties obtained from the previous fundamental models are applied in EnergyPlus to predict the energy performance (i.e. heating, cooling and lighting energy consumption) of applying PS-TIMs in buildings in different climates. The investigation results provide a better understanding of the benefits of PS-TIM in terms of energy saving and daylight comfort improvement, as well as offer some tentative suggestions as to how architects and engineers might apply PS-TIM to window System or glazed facade.
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Experimental measurement and numerical simulation of the thermal performance of a double Glazing System with an interstitial Venetian blind
Building and Environment, 2016Co-Authors: Yanyi Sun, Robin WilsonAbstract:Venetian blinds, which were originally designed to provide sun shading and privacy, also have the potential to reduce heat transfer caused by internal and external temperature difference when integrated within the cavity between the two panes of a double Glazing unit. In this paper, the thermal performance of a Glazing System with and without a Venetian blind with various slat orientation angles under different temperature conditions is investigated through both experiment (undertaken in a large climate chamber) and numerical simulation (obtained via Computational Fluid Dynamic modelling). The thermal resistance of a Venetian blind Glazing System varies with the change of slat inclination angle, and it also highly depends on the mean temperature of the Glazing and the temperature difference between the indoor and outdoor environment. Inclusion of a Venetian blind modifies both the absolute and relative strengths of convection and radiation. Vertically oriented slats showed the most significant contribution to increasing radiative thermal resistance, which led to the best overall thermal performance. The System achieved up to 28% improvement of U-value when compared with a Glazing unit without a Venetian blind. Empirical correlations generated based on simulations could be used for future building energy simulation.
Siqian Zheng - One of the best experts on this subject based on the ideXlab platform.
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climate adaptive optimal design of an aerogel Glazing System with the integration of a heuristic teaching learning based algorithm in machine learning based optimization
Renewable Energy, 2020Co-Authors: Yuekuan Zhou, Siqian ZhengAbstract:Abstract Integrating advanced materials in building Glazing Systems is critical for promoting net-zero energy buildings. In this research, both experimental and numerical studies were conducted on an aerogel Glazing System. In order to provide climate adaptive designs on the aerogel Glazing System with optimal geometric and operating parameters, a generic optimization methodology was developed by flexibly integrating supervised machine learning and advanced teaching-learning-based optimization algorithm. The proposed optimization methodology was thereafter used for optimal System designs in different climate regions. Results indicate that the proposed surrogate model can intelligently and accurately learn and update the optimization function with straightforward mathematical associations between multivariables and objectives. In addition, within optimal cases, total heat gain and heat flux are dominated by the extinction coefficient in southern cities, whereas the total heat gain is dominated by the thermal conductivity in the northern city, LanZhou. By adopting the proposed technique in this study, compared to optimal results following the Taguchi standard orthogonal array, the total heat gain can be reduced by 62.5% to 36.27 kWh/m2 in LanZhou, and by 5.9% to 267.18 kWh/m2 in GuangZhou, respectively. This study formulates a general methodology for climate adaptive optimal designs on aerogel Glazing Systems in different climatic regions.
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Machine learning-based multi-objective optimisation of an aerogel Glazing System using NSGA-II—study of modelling and application in the subtropical climate Hong Kong
Journal of Cleaner Production, 2020Co-Authors: Yuekuan Zhou, Siqian ZhengAbstract:Abstract Application of super-insulating materials in building Glazing System shows promising prospects for low-energy buildings. In this research, the heat transfer, solar radiation transmission and indoor illuminance of an aerogel Glazing System were characterized through an experimentally validated numerical model. Contribution ratios of multi-variables to multi-objectives were thereafter quantified, following the Taguchi standard orthogonal array. In respect to the application of aerogel Glazing System in subtropical climates, an energy-related contradiction between indoor illuminance from solar and indoor heat gain, has been presented, discussed, together with effective solutions. In order to minimise the total heat gain and maximise the indoor illuminance transmitted through the aerogel Glazing System, a generic multi-objective optimisation methodology, with high computational efficiency and accuracy, has been developed, to identify the optimal design. The results indicate that through the Pareto front from the multi-objective optimisation results, a significant reduction of total heat gain and an obvious increase of the indoor illuminance can be noticed. Compared to the optimal case in the standard orthogonal array, with the application of the proposed multi-objective optimisation methodology, the annual total heat gain could be reduced from 489305.5 to 333396.4 Wh by 31.9% and the annual indoor illuminance could be increased from 56786.6 to 172973.5 lux by 67.2%. The year-round performance indicates that, compared to the bi-objective optimisation (annual transmitted heat gain and annual indoor illuminance) with the annual total heat gain at 333.4 kWh/m2 and annual indoor illuminance at 162.3 klux, the bi-objective optimisation (annual total heat gain and annual indoor illuminance) shows a lower annual total heat gain at 322.4 kWh/m2 by 3.4%) and a higher annual indoor illuminance at 173 klux by 6.6%. This study proposes an overall framework and technical guidance of a new multi-objective optimisation methodology, which can automatically learn mechanisms of heat transfer and solar radiation transmittance through nanoporous aerogel granules, and identify the optimal multi-variables setting for the robust System design and operation.
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Uncertainty study on thermal and energy performances of a deterministic parameters based optimal aerogel Glazing System using machine-learning method
Energy, 2020Co-Authors: Yuekuan Zhou, Siqian ZhengAbstract:Abstract Uncertainty and sensitivity analyses of deterministic parameters based optimal aerogel Glazing System are necessary due to multi-dimensional uncertainties in the real working condition, whereas thermal and energy performances of aerogel Glazing System, in the academia, are normally characterized by deterministic parameters. In this study, a generic uncertainty quantification methodology was proposed using the two-dimensional Markov Chain Monte Carlo to quantify both aleatory and epistemic uncertainties of scenario parameters in the aerogel Glazing System. A surrogate model, trained by mathematical heat and optical models using the machine-learning based data-driven method, was developed to predict the thermal and energy performances under multi-level scenario uncertainties. Results showed that, the developed surrogate model is efficient to deal with computational complexity of sophisticated light and heat transfer processes. When considering scenario uncertainties, the annual value of heat flux is reduced from 237.2 to 185.3 kWh/(m2.a) by 21.9%, and the annual value of total heat gain is reduced from 267.2 to 209.5 kWh/m2.a by 21.6%. This study proposes a generic methodology for multi-dimensional uncertainties’ quantification and a surrogate model for thousands of cases-based uncertainty analysis. Approaches for the stochastic uncertainty analysis on aerogel Glazing System were presented, which can promote the optimal design in buildings.
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a model and method to determine solar extinction coefficient of aerogel granules layer through experiment under real climatic condition
Energy and Buildings, 2019Co-Authors: Youming Chen, Siqian Zheng, Yupeng Li, Bin Lu, Menglei Lu, Dingri ZhangAbstract:Abstract Solar extinction coefficient is an important parameter in simulating the thermal and energy performances of Glazing, but it is difficult to obtain the solar extinction coefficient of aerogel granules layer (SECAL) due to its nano-porous network structure. In this study, an in-field test room is built to measure the irradiance at both sides of granular nano-porous silica aerogel Glazing System under different climatic conditions. The SECAL is estimated through an optical model and mathematical methodology from the measurement data. The optical model is proposed on the base of interface energy balance principle, in which the incident angle and scattering phenomena happening in the nano-porous silica aerogel are taken into account. Through the optical model, the irradiation transmittance is calculated by an assumed SECAL value and indoor irradiance is predicted. The SECAL value is estimated by finding the minimal error between the predicted and measured indoor irradiance. The SECAL values for clear and overcast sky are respectively obtained, and the values are 0.0392/mm and 0.0296/mm respectively. Sky clearness factor is used as the index of weather condition to select the SECAL values. The optical model and methodology is valid to determine SECAL and the optical model is accurate to calculate solar irradiance through aerogel Glazing System.
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Dynamic heat transfer model and applicability evaluation of aerogel Glazing System in various climates of China
Energy, 2018Co-Authors: Youming Chen, Yaling Xiao, Siqian Zheng, Yang LiuAbstract:Abstract Aerogel is a super insulation material and it has absorptivity to solar radiation. Indoor heat gain through aerogel Glazing System and its temperature distribution depend strongly on the climatic conditions and geographical position of a building. In this paper, a dynamic heat transfer model and an optical model for granular aerogel Glazing System are developed and validated through an experiment. By employing the validated model, the applicability of aerogel Glazing System in various climates has been evaluated. By comparing the total heat loss in heating season, it is found that aerogel Glazing System has great energy saving potential in Severe Cold Region and Temperate Region. The comparative analysis of total heat gain in cooling season indicates that aerogel Glazing System in Hot-Summer Warm-Winter Region performs slightly better than the commonest double Glazing System, but inferior to low-e double Glazing System. In Cold Region and Hot-Summer Cold-Winter Region, there both have heating and cooling seasons all year round. The sum of total heat loss and total heat gain is used to evaluate the annual applicability. The results show that aerogel Glazing System is suitable to apply in Cold Region and in the south and north orientations of Hot-Summer Cold-Winter Region.
Francesco Goia - One of the best experts on this subject based on the ideXlab platform.
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improving thermal comfort conditions by means of pcm Glazing Systems
Energy and Buildings, 2013Co-Authors: Francesco Goia, Marco Perino, Valentina SerraAbstract:Abstract The adoption of phase change materials (PCMs) in Glazing can represent a way of improving the low thermal inertia of transparent envelope components. PCM allows the internal surface temperatures of the Glazing to be controlled, and this could improve the energy efficiency and thermal comfort performance of a facade. In the present work, a prototype of a simple PCM Glazing System is proposed and its behaviour is compared with that of a conventional reference double glazed unit. The surface temperatures and the transmitted irradiances of the PCM Glazing prototype and of a reference fenestration, measured over a six-month experimental campaign, have been used to numerically evaluate the indoor thermal conditions inside a typical office room. Different boundary conditions, ranging from summer to winter season, including the mid-season, have been analysed. The results concerning thermal comfort are illustrated and discussed in this work and the Glazing prototype, the experimental set-up and the measurement methods are presented. The obtained results demonstrate the promising performance of the PCM glaizing System, which is able to contribute to the attainment of a better indoor thermal environment.
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a numerical model to evaluate the thermal behaviour of pcm Glazing System configurations
Energy and Buildings, 2012Co-Authors: Francesco Goia, Marco Perino, Matthias HaaseAbstract:Abstract The adoption of Phase Change Materials (PCMs) in building components is an up-to-date topic and a relevant number of research activities on this issue is currently on the way. A particular application of PCMs in the building envelope focuses on the integration of such a kind of material into transparent envelope components. A numerical model that describes the thermo-physical behaviour of a PCM layer in combination with other transparent materials (i.e. glass panes) is developed to perform numerical analyses on various PCM Glazing Systems configurations. The paper illustrates the structure of the model, the main equations implemented and the hypotheses adopted for the model development. The comparison between numerical simulations and experimental data of a simple PCM Glazing configuration is also presented to show the potentials and the limitations of the numerical model. While a good agreement between simulations and experimental data can be shown for the surface temperature of the Glazing, the comparison between simulated and measured transmitted irradiances and heat fluxes does not always reach the desired accuracy. However, the numerical tool seems to predict well the thermo-physical behaviour of the System and may therefore represent a good starting point for simulations on different configurations of PCM Glazing Systems.
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characterization of the optical properties of a pcm Glazing System
Energy Procedia, 2012Co-Authors: Francesco Goia, Michele Zinzi, Emiliano Carnielo, Valentina SerraAbstract:Abstract The optical char acteristics of an advan ced glazin g sy stem are p resented in this p ap er. The investigated glazin g sy stem is based on the incorp oration of a p araffin-based Phase Change M aterial (PCM) into a transp arent comp onent, made of two extra-clear glass p anes and a cavity where the PCM lay er is p laced. Due to the highly scattering p rop erty of the sy stem (when the PCM is in solid state), the use of a lar ge integr ating sp here equip ment (75 cm diameter) is necessary to obtain reliable results. The sp ectral transmission, reflection and absorp tion coefficients of the PCM glazin g sy stem are measured b etween 400 and 2000 nanometers, and the integr ated valu es are calcu lated accordin g to the relevant standards. The optical p rop erties are determined with a maximu m relative error of 4% (on the sum of the transmission, reflection and absorption coefficients), when the PCM lay er is either in comp lete solid state or liqu id state. The average error for all the op tical p rop erties is 2%. Different thicknesses of the PCM lay er are used in order to assess the dep endency of the optical p rop erties on the PCM lay er thickness. The angular dep endency is also investigated for beam angle up to 45 deg.
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Thermo-physical behaviour and energy performance assessment of PCM Glazing System configurations: A numerical analysis
Frontiers of Architectural Research, 2012Co-Authors: Francesco GoiaAbstract:The adoption of Phase Change Materials (PCMs) in Glazing Systems was proposed to increase the heat capacity of the fenestration, being some PCMs partially transparent to visible radiation. The aim of the PCM Glazing concept was to let (part) of the visible spectrum of the solar radiation enter the indoor environment, providing daylighting, while absorbing (the largest part of) the infrared radiation. In this paper, the influence of the PCM Glazing configuration is investigated by means of numerical simulations carried out with a validated numerical model. Various triple Glazing configurations, where one of the two cavities is filled with a PCM, are simulated, and PCM melting temperatures are investigated. The investigation is carried out in a humid subtropical
Jianlei Niu - One of the best experts on this subject based on the ideXlab platform.
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Application of super-insulating translucent silica aerogel Glazing System on commercial building envelope of humid subtropical climates - Impact on space cooling load
Energy, 2015Co-Authors: Yu Huang, Jianlei NiuAbstract:Abstract Solar radiation through Glazing area is one major source of the space cooling load in subtropical cooling-dominant climates. Application of energy-efficient Glazing System can significantly reduce the energy consumption of air-conditioning Systems in summer, thus has become a hot research topic. In this paper, a super-insulating Glazing System was studied, which was formed by two layers of conventional single clear glass panes and a layer of silica aerogel filled in between. Several Glazing samples were prepared. The thermal and optical parameters were measured. An annual HVAC (heating, ventilation and air conditioning) System energy analysis was also conducted based on the space cooling load simulation. The result indicated that in humid subtropical climates like Hong Kong, the application of silica aerogel Glazing System can reduce the annual space cooling load by around 4% in a typical commercial building. With respect to the envelope heat gain, the reduction could be around 60%. It was also found that the silica aerogel Glazing System performed better if the internal heat source in a building took a small proportion in the total space cooling load.
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Energy and visual performance of the silica aerogel Glazing System in commercial buildings of Hong Kong
Construction and Building Materials, 2015Co-Authors: Yu Huang, Jianlei NiuAbstract:Abstract To achieve a more comfortable indoor environment while still retaining low energy consumption level is an exciting challenge for designers and owners of buildings. In this paper, a silica-aerogel filled super-insulating Glazing System was proposed. A numerical study was conducted to analyze the energy performance and visual performance of the proposed Glazing System. Two popular building simulation programs namely EnergyPlus and Radiance were applied in the numerical study. In the study of the energy performance, three control strategies (space temperature control, operative temperature control and PMV control) were applied to simulate the occupant’s control behavior toward the air-conditioning System in reality. The result indicated that compared with conventional single clear Glazing, the silica aerogel Glazing could retain a 4% longer thermally comfort period, while the energy consumption of HVAC System was reduced by 4–7%. The performance of the silica aerogel Glazing was almost equal to that of the state-of-art low-e Glazing. It is also concluded that as the occupant’s request on thermal comfort got stricter, the performance of the silica aerogel Glazing would became better. In the visual comfort point of view, it can be concluded that the glare effect and near-window bright zone could be reduced significantly while indoor illumination level still met the requirement.