Aziz Laouadi - Academia.edu (original) (raw)
Papers by Aziz Laouadi
HVAC&R RESEARCH
Domed cavities are found in many building applications, such as conventional skylights and tubula... more Domed cavities are found in many building applications, such as conventional skylights and tubular daylighting devices. Heat transfer through domed cavities is thus an important parameter for evaluating the energy performance rating of such skylight systems and in calculating the heating and cooling loads of buildings. Although there have been many studies on the convective heat transfer in related geometries, there is a limited information on natural convective heat transfer in domed cavities with planar inner surfaces. In a previous study, numerical modeling was conducted on natural laminar convective heat transfer in horizontal high-profile domed cavities with planar inner surfaces. In this article, the previous study is extended to investigate the natural convective heat transfer in horizontal low-profile spherical cavities with planar inner surfaces. The bounding surfaces are subject to uniform temperature conditions. The numerical model is based on the finite-element method. T...
HVAC&R RESEARCH
Prismatic glazing is found in many building applications, such as complex fenestration systems to... more Prismatic glazing is found in many building applications, such as complex fenestration systems to control solar heat gains and glare and re-direct sunlight to building interior spaces and daylighting (and lighting) systems to enhance their optical and lighting performance. However, modeling and simulation of such prismatic glazing has been a very difficult task due to its versatile and complex geometrics. This article presents the development and validation of a simplified model to compute the optical characteristics and dominant directions of the transmitted and reflected beam rays of sawtooth-like prismatic glazing. The model was based on tracing the average ray and was extensively validated using third-party data derived from ray tracing computer simulations and measurement using integrating spheres and goniophotometers. The model's predictions for the transmittance and reflectance of single and double prismatic panes compared well overall within the accuracy of the third-par...
This paper provides an overview of Daylight1-2-3, a new daylighting/energy analysis software for ... more This paper provides an overview of Daylight1-2-3, a new daylighting/energy analysis software for design professionals and architectural students with an interest in daylighting and sustainable design, but no required previous knowledge of either daylighting concepts or simulations. The initial version of Daylight 1-2-3 focuses on private offices, open-plan offices, and classrooms. The paper describes the process that the tool's development
International Journal of Numerical Methods for Heat & Fluid Flow, 1998
Presents a physical model for determining the effective thermal conductivity of a two-phase compo... more Presents a physical model for determining the effective thermal conductivity of a two-phase composite medium with fixed or moving interfaces. A rigorous numerical method for removing oscillations in the thermal field is proposed. The methodology is based on the volume averaging technique with the assumption that the phases may coexist at a temperature different from that of fusion. The analysis reveals that the effective conductivity of a two-phase medium is dependent on the phase volume fractions, on their thermal conductivities and on a constitutive constant which determines the geometric structure of the medium and the nature of the interface (fixed or moving). The results for the one and two dimensional conduction-dominated phase change problem show that the oscillations produced by previous fixed-grid methods are eliminated.
The daylight coefficient method has been introduced in computer simulation as an efficient approa... more The daylight coefficient method has been introduced in computer simulation as an efficient approach to compute indoor daylight illuminances through building static fenestration systems. A set of coefficients are calculated only once prior to simulation start for a given number of elemental patches making up to sky vault and ground. However, for dynamic complex fenestration systems whose optical behavior (transmission, reflection and scattering) may change during simulation (such as windows with shadings), the efficiency of the daylight coefficient method may be compromised as the whole set of coefficients must be re-calculated during simulation.
Numerical Heat Transfer, Part A: Applications, 1994
The problem of conjugate heat transfer involving mixed convection laminar ascending flow of water... more The problem of conjugate heat transfer involving mixed convection laminar ascending flow of water in inclined circular tubes uniformly heated on their outer surface has been studied numerically using a unified formulation for the solid and fluid domains. The highly coupled governing equations were discretized using the control volume approach, and solved according to the SIMPLER algorithm. Results have clearly
Lighting Research and Technology, 2007
Lighting Research and Technology, 2007
http://irc.nrc-cnrc.gc.ca C o m p l e x f e n e s t r a t i o n s y s t e m s : t o w a r d s p r... more http://irc.nrc-cnrc.gc.ca C o m p l e x f e n e s t r a t i o n s y s t e m s : t o w a r d s p r o d u c t r a t i n g s f o r i n d o o r e n v i r o n m e n t q u a l i t y N R C C -4 5 6 5 4 L a o u a d i , A . ; P a r e k h , A . A version of this document is published in / Une version de ce document se trouve dans:
Lighting Research and Technology, 2009
ABSTRACT This work discusses the use of digital cameras fitted with absorption filters as quasi-s... more ABSTRACT This work discusses the use of digital cameras fitted with absorption filters as quasi-spectral radiometers. By filtering incident light into selected wavelength intervals, accurate estimates of radiances can be made for unknown spectra. This approach is being employed as part of a new video-projection goniophotometer to study the properties of angularly and spectrally selective complex fenestration systems. Complex fenestration systems are increasingly being used to distribute solar radiation purposefully in buildings. They can be utilized to optimize energy performance and enhance daylighting. Radiance estimates from calibrated digital cameras enable the assessment of quasi-spectral, bi-directional scattering distribution functions of total radiance transmitted or reflected by a fenestration system over desired wavelength intervals. A silicon and an indium gallium arsenide digital camera are used to enable measurements across a 380 to 1700 nm wavelength interval. On traite dans ce travail de l'utilisation de caméras numériques munies de filtres à absorption comme radiomètres quasi-spectraux. En filtrant la lumière incidente selon des intervalles de longueurs d'onde présélectionnés, on peut obtenir des estimations précises des valeurs d'irradiance pour des spectres inconnus. Cette méthode est actuellement employée dans le cadre d'une nouvelle goniophotométrie à projection vidéo aux fins de l'étude des propriétés des fenestrages complexes à sélections angulaire et spectrale. Les fenestrages complexes sont de plus en plus souvent utilisés pour distribuer dans un but précis la radiation solaire dans les bâtiments. On peut les utiliser pour optimaliser la performance énergétique et améliorer l'éclairage naturel. Les estimations de l'irradiance à partir de caméras numériques permettent d'évaluer les fonctions de distribution de la diffusion quasi-spectrale et bidirectionnelle de l'irradiance totale qui est transmise ou réfléchie par un fenestrage selon des intervalles de longueurs d'onde voulus. Deux caméras numériques, l'une à avalanche à l'arséniure de gallium et d'indium, et l'autre au silicium, sont utilisées pour permettre des mesures sur un intervalle de longueurs d'onde allant de 380 à 1700 nm. RES
Lighting Research and Technology, 1998
Web page / page Web Transparent domed skylights: optical model for predicting transmittance, abso... more Web page / page Web Transparent domed skylights: optical model for predicting transmittance, absorptance and reflectance Laouadi, A.; Atif, M. R. Access and use of this website and the material on it are subject to the Terms and Conditions set forth at Transparent domed skylights: optical model for predicting transmittance, absorptance and reflectance Laouadi, A.; Atif, M.R.
Lighting Research and Technology, 2000
Journal of the Illuminating Engineering Society, 2002
Web page / page Web Prediction model of optical characteristics for barrel vault skylights Laouad... more Web page / page Web Prediction model of optical characteristics for barrel vault skylights Laouadi, A.; Atif, M. R.
Journal of Solar Energy Engineering, 2007
ABSTRACT A detailed building energy analysis tool is used to model the performance of a forced-ai... more ABSTRACT A detailed building energy analysis tool is used to model the performance of a forced-air system and a radiant floor system. These two systems use a low-temperature tank to store solar energy from a solar collector array. An electrically heated tank at a higher temperature is used to provide any additional heat needed to meet the space heating load. The simulation models developed are then used to compare the performance of the,forced-air and radiant floor systems based on maintaining the same operative temperature inside the space. It is found that the portion of the heating load that comes from solar energy is higher in the case of the radiant system. This portion from solar energy increases even further when the operating temperature of the radiant floor is lowered. The results also show that the energy performance of the radiant floor relative to the forced-air system improves for houses with higher envelope R-values and infiltration rates. Given the many different interacting factors that influence the performance of the solar-assisted systems studied, it is very important to use detailed simulation models to help assess which system is more energy efficient for a particular application.
Journal of Building Performance Simulation, 2008
Journal of Building Performance Simulation, 2011
This paper presents the development of a sufficiently accurate and reliable optical model to pred... more This paper presents the development of a sufficiently accurate and reliable optical model to predict the lighting and thermal performance of the Central Sunlighting System (CSS). The model is based on the ray tracing technique to compute the amount of sunlight flux transmission through the light guide to interior spaces of buildings, and absorption of solar radiation within the components of the CSS, which may become solar heat gains indoors. The model is validated using a detailed ray tracing technique and field measurements carried out on a previous prototype. The validation results show that the model predictions are in good agreement with the ray tracing and measurement results. The model can be integrated in existing fenestration design tools, or in whole-building energy simulation software, with significantly lower calculation time compared to the full integration of suitable lighting simulation software.
Journal of Building Performance Simulation, 2009
Journal of Building Performance Simulation, 2012
This paper presents a simulation study to predict the energy performance of the Central Sunlighti... more This paper presents a simulation study to predict the energy performance of the Central Sunlighting System (CSS) installed in open plan offices. Several simulation tools are combined to conduct the simulations. SkyVision calculates the daylight luminous flux, and lighting and solar heat gains of the CSS. A set of coefficients precalculated using Radiance relates the desktop illuminances to the CSS luminous fluxes. DaySim is used to compute the daylight illuminance from the perimeter windows. ESP-r is used to compute the heating and cooling energy use of the office spaces. The results show that the CSS may save a significant amount of energy in
International Journal of Heat and Mass Transfer, 1999
A theoretical study was conducted to assess the thermal performance of a ventilated panel heating... more A theoretical study was conducted to assess the thermal performance of a ventilated panel heating unit[ The unit employs the latent heat energy storage method to level the electrical energy demand for domestic space heating during peak hours[ A one!dimensional\ semi!empirical model was developed to predict the dynamic thermal behavior of the storage unit under cyclic melting and solidi_cation[ The results show that the storage unit may be charged and discharged more than twice a day with a charge time shorter than the discharge time[ The temperature of the plate in contact with the ambient air may be controlled to reach higher values without compromising the unit heating power[ General correlations of the charge and discharge times are established for a wide range of the governing parameters[ Þ 0887
International Journal of Heat and Mass Transfer, 2001
HVAC&R RESEARCH
Domed cavities are found in many building applications, such as conventional skylights and tubula... more Domed cavities are found in many building applications, such as conventional skylights and tubular daylighting devices. Heat transfer through domed cavities is thus an important parameter for evaluating the energy performance rating of such skylight systems and in calculating the heating and cooling loads of buildings. Although there have been many studies on the convective heat transfer in related geometries, there is a limited information on natural convective heat transfer in domed cavities with planar inner surfaces. In a previous study, numerical modeling was conducted on natural laminar convective heat transfer in horizontal high-profile domed cavities with planar inner surfaces. In this article, the previous study is extended to investigate the natural convective heat transfer in horizontal low-profile spherical cavities with planar inner surfaces. The bounding surfaces are subject to uniform temperature conditions. The numerical model is based on the finite-element method. T...
HVAC&R RESEARCH
Prismatic glazing is found in many building applications, such as complex fenestration systems to... more Prismatic glazing is found in many building applications, such as complex fenestration systems to control solar heat gains and glare and re-direct sunlight to building interior spaces and daylighting (and lighting) systems to enhance their optical and lighting performance. However, modeling and simulation of such prismatic glazing has been a very difficult task due to its versatile and complex geometrics. This article presents the development and validation of a simplified model to compute the optical characteristics and dominant directions of the transmitted and reflected beam rays of sawtooth-like prismatic glazing. The model was based on tracing the average ray and was extensively validated using third-party data derived from ray tracing computer simulations and measurement using integrating spheres and goniophotometers. The model's predictions for the transmittance and reflectance of single and double prismatic panes compared well overall within the accuracy of the third-par...
This paper provides an overview of Daylight1-2-3, a new daylighting/energy analysis software for ... more This paper provides an overview of Daylight1-2-3, a new daylighting/energy analysis software for design professionals and architectural students with an interest in daylighting and sustainable design, but no required previous knowledge of either daylighting concepts or simulations. The initial version of Daylight 1-2-3 focuses on private offices, open-plan offices, and classrooms. The paper describes the process that the tool's development
International Journal of Numerical Methods for Heat & Fluid Flow, 1998
Presents a physical model for determining the effective thermal conductivity of a two-phase compo... more Presents a physical model for determining the effective thermal conductivity of a two-phase composite medium with fixed or moving interfaces. A rigorous numerical method for removing oscillations in the thermal field is proposed. The methodology is based on the volume averaging technique with the assumption that the phases may coexist at a temperature different from that of fusion. The analysis reveals that the effective conductivity of a two-phase medium is dependent on the phase volume fractions, on their thermal conductivities and on a constitutive constant which determines the geometric structure of the medium and the nature of the interface (fixed or moving). The results for the one and two dimensional conduction-dominated phase change problem show that the oscillations produced by previous fixed-grid methods are eliminated.
The daylight coefficient method has been introduced in computer simulation as an efficient approa... more The daylight coefficient method has been introduced in computer simulation as an efficient approach to compute indoor daylight illuminances through building static fenestration systems. A set of coefficients are calculated only once prior to simulation start for a given number of elemental patches making up to sky vault and ground. However, for dynamic complex fenestration systems whose optical behavior (transmission, reflection and scattering) may change during simulation (such as windows with shadings), the efficiency of the daylight coefficient method may be compromised as the whole set of coefficients must be re-calculated during simulation.
Numerical Heat Transfer, Part A: Applications, 1994
The problem of conjugate heat transfer involving mixed convection laminar ascending flow of water... more The problem of conjugate heat transfer involving mixed convection laminar ascending flow of water in inclined circular tubes uniformly heated on their outer surface has been studied numerically using a unified formulation for the solid and fluid domains. The highly coupled governing equations were discretized using the control volume approach, and solved according to the SIMPLER algorithm. Results have clearly
Lighting Research and Technology, 2007
Lighting Research and Technology, 2007
http://irc.nrc-cnrc.gc.ca C o m p l e x f e n e s t r a t i o n s y s t e m s : t o w a r d s p r... more http://irc.nrc-cnrc.gc.ca C o m p l e x f e n e s t r a t i o n s y s t e m s : t o w a r d s p r o d u c t r a t i n g s f o r i n d o o r e n v i r o n m e n t q u a l i t y N R C C -4 5 6 5 4 L a o u a d i , A . ; P a r e k h , A . A version of this document is published in / Une version de ce document se trouve dans:
Lighting Research and Technology, 2009
ABSTRACT This work discusses the use of digital cameras fitted with absorption filters as quasi-s... more ABSTRACT This work discusses the use of digital cameras fitted with absorption filters as quasi-spectral radiometers. By filtering incident light into selected wavelength intervals, accurate estimates of radiances can be made for unknown spectra. This approach is being employed as part of a new video-projection goniophotometer to study the properties of angularly and spectrally selective complex fenestration systems. Complex fenestration systems are increasingly being used to distribute solar radiation purposefully in buildings. They can be utilized to optimize energy performance and enhance daylighting. Radiance estimates from calibrated digital cameras enable the assessment of quasi-spectral, bi-directional scattering distribution functions of total radiance transmitted or reflected by a fenestration system over desired wavelength intervals. A silicon and an indium gallium arsenide digital camera are used to enable measurements across a 380 to 1700 nm wavelength interval. On traite dans ce travail de l'utilisation de caméras numériques munies de filtres à absorption comme radiomètres quasi-spectraux. En filtrant la lumière incidente selon des intervalles de longueurs d'onde présélectionnés, on peut obtenir des estimations précises des valeurs d'irradiance pour des spectres inconnus. Cette méthode est actuellement employée dans le cadre d'une nouvelle goniophotométrie à projection vidéo aux fins de l'étude des propriétés des fenestrages complexes à sélections angulaire et spectrale. Les fenestrages complexes sont de plus en plus souvent utilisés pour distribuer dans un but précis la radiation solaire dans les bâtiments. On peut les utiliser pour optimaliser la performance énergétique et améliorer l'éclairage naturel. Les estimations de l'irradiance à partir de caméras numériques permettent d'évaluer les fonctions de distribution de la diffusion quasi-spectrale et bidirectionnelle de l'irradiance totale qui est transmise ou réfléchie par un fenestrage selon des intervalles de longueurs d'onde voulus. Deux caméras numériques, l'une à avalanche à l'arséniure de gallium et d'indium, et l'autre au silicium, sont utilisées pour permettre des mesures sur un intervalle de longueurs d'onde allant de 380 à 1700 nm. RES
Lighting Research and Technology, 1998
Web page / page Web Transparent domed skylights: optical model for predicting transmittance, abso... more Web page / page Web Transparent domed skylights: optical model for predicting transmittance, absorptance and reflectance Laouadi, A.; Atif, M. R. Access and use of this website and the material on it are subject to the Terms and Conditions set forth at Transparent domed skylights: optical model for predicting transmittance, absorptance and reflectance Laouadi, A.; Atif, M.R.
Lighting Research and Technology, 2000
Journal of the Illuminating Engineering Society, 2002
Web page / page Web Prediction model of optical characteristics for barrel vault skylights Laouad... more Web page / page Web Prediction model of optical characteristics for barrel vault skylights Laouadi, A.; Atif, M. R.
Journal of Solar Energy Engineering, 2007
ABSTRACT A detailed building energy analysis tool is used to model the performance of a forced-ai... more ABSTRACT A detailed building energy analysis tool is used to model the performance of a forced-air system and a radiant floor system. These two systems use a low-temperature tank to store solar energy from a solar collector array. An electrically heated tank at a higher temperature is used to provide any additional heat needed to meet the space heating load. The simulation models developed are then used to compare the performance of the,forced-air and radiant floor systems based on maintaining the same operative temperature inside the space. It is found that the portion of the heating load that comes from solar energy is higher in the case of the radiant system. This portion from solar energy increases even further when the operating temperature of the radiant floor is lowered. The results also show that the energy performance of the radiant floor relative to the forced-air system improves for houses with higher envelope R-values and infiltration rates. Given the many different interacting factors that influence the performance of the solar-assisted systems studied, it is very important to use detailed simulation models to help assess which system is more energy efficient for a particular application.
Journal of Building Performance Simulation, 2008
Journal of Building Performance Simulation, 2011
This paper presents the development of a sufficiently accurate and reliable optical model to pred... more This paper presents the development of a sufficiently accurate and reliable optical model to predict the lighting and thermal performance of the Central Sunlighting System (CSS). The model is based on the ray tracing technique to compute the amount of sunlight flux transmission through the light guide to interior spaces of buildings, and absorption of solar radiation within the components of the CSS, which may become solar heat gains indoors. The model is validated using a detailed ray tracing technique and field measurements carried out on a previous prototype. The validation results show that the model predictions are in good agreement with the ray tracing and measurement results. The model can be integrated in existing fenestration design tools, or in whole-building energy simulation software, with significantly lower calculation time compared to the full integration of suitable lighting simulation software.
Journal of Building Performance Simulation, 2009
Journal of Building Performance Simulation, 2012
This paper presents a simulation study to predict the energy performance of the Central Sunlighti... more This paper presents a simulation study to predict the energy performance of the Central Sunlighting System (CSS) installed in open plan offices. Several simulation tools are combined to conduct the simulations. SkyVision calculates the daylight luminous flux, and lighting and solar heat gains of the CSS. A set of coefficients precalculated using Radiance relates the desktop illuminances to the CSS luminous fluxes. DaySim is used to compute the daylight illuminance from the perimeter windows. ESP-r is used to compute the heating and cooling energy use of the office spaces. The results show that the CSS may save a significant amount of energy in
International Journal of Heat and Mass Transfer, 1999
A theoretical study was conducted to assess the thermal performance of a ventilated panel heating... more A theoretical study was conducted to assess the thermal performance of a ventilated panel heating unit[ The unit employs the latent heat energy storage method to level the electrical energy demand for domestic space heating during peak hours[ A one!dimensional\ semi!empirical model was developed to predict the dynamic thermal behavior of the storage unit under cyclic melting and solidi_cation[ The results show that the storage unit may be charged and discharged more than twice a day with a charge time shorter than the discharge time[ The temperature of the plate in contact with the ambient air may be controlled to reach higher values without compromising the unit heating power[ General correlations of the charge and discharge times are established for a wide range of the governing parameters[ Þ 0887
International Journal of Heat and Mass Transfer, 2001