Fariborz Haghighat | Concordia University (Canada) (original) (raw)
Papers by Fariborz Haghighat
Applications of PCM-to-air heat exchangers (PAHXs) were discussed in literature for free cooling ... more Applications of PCM-to-air heat exchangers (PAHXs) were discussed in literature for free cooling application due to their latent thermal storage abilities. This paper aims to justify the generalization of a numerical model of PAHX and to compare the thermal performance of two different configurations of PAHX system. A generalized numerical model is developed and validated based on general apparent heat capacity method. The validation results show good agreement of the generalized approach in terms of averaged error with the experimental data. Model potential and limitations are discussed, and further recommendations are proposed to improve model accuracy. The paper ensures the significant potential of a PAHX ventilated façade configuration in free cooling applications.
Journal of energy storage, Nov 1, 2023
Solar Energy, Mar 1, 2020
The applications of PCM-to-air heat exchangers (PAHXs) face operational challenges regarding the ... more The applications of PCM-to-air heat exchangers (PAHXs) face operational challenges regarding the local climatic conditions. One of the main issues is the insufficient cooling potential during the phase change material (PCM) solidification process. In order to increase the cooling charging power of the system, in this study, a unique PAHX type is proposed for building envelope applications. The objective is to magnify the thermal radiation losses from the PCM panels to the nocturnal sky during the solidification process. Two real-scale prototypes were designed and constructed to monitor the effect of radiative cooling on the PAHX thermal behavior during solidification. Accordingly, the cooling performance was investigated for different operational scenarios. In addition, specific key performance indicators were defined to analyze the system charging performance. The experimental results proved that exposure to the clear sky during solidification increases the charging power of the system due to the maximized thermal losses by radiation. The results confirmed that the sky condition and the ambient air temperature profile are key factors in determining the cooling potential of the system. It was shown that making use of the radiation thermal loss to the clear sky increased the charging energy by up to 22% of the proposed PAHX application.
Environmental Management, Nov 22, 2022
Volatile organic compounds (VOCs) in urban areas are of great interest due to their significant r... more Volatile organic compounds (VOCs) in urban areas are of great interest due to their significant role in forming ground-level ozone and adverse public health effects. Emission inventories usually compile the outdoor VOCs emission sources (e.g., traffic and industrial emissions). However, considering emissions from volatile chemical products (e.g., solvents, printing ink, personal care products) is challenging because of scattered data and the lack of an effective method to estimate the VOCs emission rate from these chemical products. This paper aims to systematically analyse potential sources of VOCs emission in Canada's built environment, including volatile chemical products. Also, spatial variation of VOCs level in the ambient atmosphere is examined to understand the VOC relationship with ozone and secondary organic aerosol formation. The study shows that VOCs level may vary among everyday microenvironments (e.g., residential areas, offices, and retail stores) depending on the frequency of product consumption, building age, ventilation condition, and background ambient concentration in the atmosphere. However, it is very difficult to establish VOC speciation and apportionment to different volatile chemical products that contribute most significantly to exposure and target subpopulations with elevated levels. Thus, tracer compounds can be used to identify inventory sources at the consumer end. A critical overview highlights the limitations of existing VOC estimation methods and possible approaches to control VOC emissions. The findings provide crucial information to establish an emission inventory framework for volatile chemical products at a national scale and enable policymakers to limit VOCs emission from various volatile chemical products. Keywords Volatile organic compounds • Volatile chemical products • Emission inventory • Built environment • Solvents * Zhi Chen
Building and Environment, Mar 1, 2022
Sustainable Cities and Society, Oct 1, 2023
Solar Energy, Sep 1, 2019
Earlier applications of phase change material (PCM)-to-air heat exchangers (PAHXs) reported the i... more Earlier applications of phase change material (PCM)-to-air heat exchangers (PAHXs) reported the insufficient cooling charging energy needed for complete solidification of the PCM in free cooling systems. Also, the prediction of PAHX performance under low airflow regimes is a system limitation for free cooling applications. Besides, the implementation of the long wave thermal radiation cooling concept has not gained much attention in the free cooling design of PAHX units. This paper reports the development of PAHX system for building envelope applications that promotes the thermal radiation loss to the sky during night-time to maximize the cooling potential. A 2D numerical model has been developed considering the PCM thermal behavior, short and long wave radiation, and convection phenomena. New thermal boundaries of long-wave radiation have been proposed between system elements and the sky temperature. In addition, the model considered various forms of convective heat transfer phenomena. The apparent heat capacity method was used to simulate the thermal storage process. Experimentally obtained data and inter-model comparison were used to validate the proposed model. Two full-scale prototypes of the developed PAHX system were designed and tested under real conditions using two different types of PCMs. A parametric analysis was conducted to investigate the system thermal behavior under various air velocity profiles in the air channel and various inlet air temperature conditions. The results indicate that the building envelope integrated PAHX can use the sky radiation as a cooling source.
Energy, Mar 1, 2021
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
HAL (Le Centre pour la Communication Scientifique Directe), Sep 9, 2008
Energies, Aug 9, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Chemical Engineering and Processing, Mar 1, 2018
Highlights Reviewing four oxidation processes for treatment of petrochemical wastewater Study... more Highlights Reviewing four oxidation processes for treatment of petrochemical wastewater Studying the reaction mechanisms and the system performances of oxidation processes Discussing advantages and challenges associated with applying these methods Recommending an appropriate integration of oxidation and biological treatment
IOP conference series, Oct 23, 2019
Window operation plays a vital role in indoor environmental quality (IEQ) and building energy con... more Window operation plays a vital role in indoor environmental quality (IEQ) and building energy consumption while maintaining occupants' expected IEQ levels. In recent years, the influencing factors of window opening/closing behaviour have been widely investigated and evaluated in residential buildings, aiming at simulating building energy performance in a realistic manner. However, due to the challenges in collecting and analysing occupancy-related data, previous research works emphasized more on indoor/outdoor parameters (e.g. temperature and CO2). Hence, the correlation between occupancy patterns with window behaviour in a household has not been well explored. The aim of this study is to analyse the patterns of window opening and closing behaviour in French households and identify respective driving factors. The analysis was based on the data collected from four apartments in a high-performance residential building located in Lyon, France. The dataset considered in this study includes indoor environment data, weather data and occupancy behaviour with one minute resolution. Both model-dependent and model-independent approaches were adopted to assess the relative importance of driving factors for window operation. The results obtained in this study will provide insights regarding different driving factors for window operation and its related impact on occupant behaviour model performance. The outcomes of this research work can be used as input variables of occupant behaviour models in order to improve the building energy simulation performance.
Energy and Buildings, Sep 1, 2019
Energy feedback systems are recently proposed to help occupants understand and improve their ener... more Energy feedback systems are recently proposed to help occupants understand and improve their energy use behavior. Despite many potential benefits, the question remains, whether useful and straightforward knowledge are transferred to the occupants about their energy use patterns. In this context, the key is to develop methodologies that can effectively analyze occupants' energy use behavior and distinguish their energy-inefficient behavior (if any). Previous studies seldom considered the dynamics of occupancy, which may result in misleading information to the occupants and inefficacy in recognizing the actual wasteful behavior. To fill this gap, this study proposes a data mining framework with a combination of change point analysis (CPA), cluster analysis, and association rule mining (ARM) to explore the relationship between occupancy and building energy consumption, aiming at identifying potential energy waste patterns and to provide useful feedback to the occupants. To demonstrate the capability of the developed framework, it was applied to datasets collected from two different apartments located in Lyon, France. Results indicate that different energy waste patterns can be effectively discovered in both apartments through the proposed framework and a substantial amount of energy savings can be achieved by modifying occupants' energy use behavior. The proposed framework is flexible and can be adaptive to households with different occupancy patterns and habitual energy-use behavior. Nevertheless, the discovered energy saving potentials and benchmark values are limited to the apartments considered in this study and similar analysis based on the proposed framework are needed in wider building stocks to explore its generalizability.
E3S web of conferences, 2023
Photocatalytic oxidation (PCO) is an innovative method of removing volatile organic compounds (VO... more Photocatalytic oxidation (PCO) is an innovative method of removing volatile organic compounds (VOCs) from indoor air. PCO technology employs a semiconductor (such as TiO2) and ultraviolet light to decompose VOCs via successive oxidation processes and creates CO2 and H2O as the ultimate products of complete mineralization. The greatest drawback of this technology is, however, the production of hazardous by-products. The possible health risk posed by hazardous by-products inhibits the commercial adoption of PCO-based air purifiers in the indoor environment. Modeling is a powerful tool to address the chemical interaction and mass transfer phenomenon in the PCO reactor. This study presents the modeling of a ternary mixture of VOCs and generated by-products using a proposed degradation reaction pathway. A onedimensional mathematical model by considering the axially dispersed plug flow and Langmuir-Hinshelwood (L-H) based reaction rate as well as linear source spherical emission model (LSSE) for the irradiation distribution on the media surface were used for modeling of VOCs and by-products. Three VOCs from different chemical groups (aldehyde, ketone, aromatic groups) were chosen as challenge compounds, and a commercial PCO filter (TiO2 coated on silica fiber felts) was considered as a photocatalyst. The model prediction was performed at different levels of concentration (0.1-1 ppm), relative humidity (15-70%), air velocity (0.016-0.1 m/s), and light intensity (7-23W/m2). Among generated by-products, aldehydes were the major by-products of VOCs in the PCO reactor. It was revealed that increasing concentration and irradiation, as well as decreasing relative humidity and velocity, increases by-product generation.
Advances in Building Energy Research
Encyclopedia of Energy Storage, 2021
Sustainable Cities and Society, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Building and Environment, 2021
Applications of PCM-to-air heat exchangers (PAHXs) were discussed in literature for free cooling ... more Applications of PCM-to-air heat exchangers (PAHXs) were discussed in literature for free cooling application due to their latent thermal storage abilities. This paper aims to justify the generalization of a numerical model of PAHX and to compare the thermal performance of two different configurations of PAHX system. A generalized numerical model is developed and validated based on general apparent heat capacity method. The validation results show good agreement of the generalized approach in terms of averaged error with the experimental data. Model potential and limitations are discussed, and further recommendations are proposed to improve model accuracy. The paper ensures the significant potential of a PAHX ventilated façade configuration in free cooling applications.
Journal of energy storage, Nov 1, 2023
Solar Energy, Mar 1, 2020
The applications of PCM-to-air heat exchangers (PAHXs) face operational challenges regarding the ... more The applications of PCM-to-air heat exchangers (PAHXs) face operational challenges regarding the local climatic conditions. One of the main issues is the insufficient cooling potential during the phase change material (PCM) solidification process. In order to increase the cooling charging power of the system, in this study, a unique PAHX type is proposed for building envelope applications. The objective is to magnify the thermal radiation losses from the PCM panels to the nocturnal sky during the solidification process. Two real-scale prototypes were designed and constructed to monitor the effect of radiative cooling on the PAHX thermal behavior during solidification. Accordingly, the cooling performance was investigated for different operational scenarios. In addition, specific key performance indicators were defined to analyze the system charging performance. The experimental results proved that exposure to the clear sky during solidification increases the charging power of the system due to the maximized thermal losses by radiation. The results confirmed that the sky condition and the ambient air temperature profile are key factors in determining the cooling potential of the system. It was shown that making use of the radiation thermal loss to the clear sky increased the charging energy by up to 22% of the proposed PAHX application.
Environmental Management, Nov 22, 2022
Volatile organic compounds (VOCs) in urban areas are of great interest due to their significant r... more Volatile organic compounds (VOCs) in urban areas are of great interest due to their significant role in forming ground-level ozone and adverse public health effects. Emission inventories usually compile the outdoor VOCs emission sources (e.g., traffic and industrial emissions). However, considering emissions from volatile chemical products (e.g., solvents, printing ink, personal care products) is challenging because of scattered data and the lack of an effective method to estimate the VOCs emission rate from these chemical products. This paper aims to systematically analyse potential sources of VOCs emission in Canada's built environment, including volatile chemical products. Also, spatial variation of VOCs level in the ambient atmosphere is examined to understand the VOC relationship with ozone and secondary organic aerosol formation. The study shows that VOCs level may vary among everyday microenvironments (e.g., residential areas, offices, and retail stores) depending on the frequency of product consumption, building age, ventilation condition, and background ambient concentration in the atmosphere. However, it is very difficult to establish VOC speciation and apportionment to different volatile chemical products that contribute most significantly to exposure and target subpopulations with elevated levels. Thus, tracer compounds can be used to identify inventory sources at the consumer end. A critical overview highlights the limitations of existing VOC estimation methods and possible approaches to control VOC emissions. The findings provide crucial information to establish an emission inventory framework for volatile chemical products at a national scale and enable policymakers to limit VOCs emission from various volatile chemical products. Keywords Volatile organic compounds • Volatile chemical products • Emission inventory • Built environment • Solvents * Zhi Chen
Building and Environment, Mar 1, 2022
Sustainable Cities and Society, Oct 1, 2023
Solar Energy, Sep 1, 2019
Earlier applications of phase change material (PCM)-to-air heat exchangers (PAHXs) reported the i... more Earlier applications of phase change material (PCM)-to-air heat exchangers (PAHXs) reported the insufficient cooling charging energy needed for complete solidification of the PCM in free cooling systems. Also, the prediction of PAHX performance under low airflow regimes is a system limitation for free cooling applications. Besides, the implementation of the long wave thermal radiation cooling concept has not gained much attention in the free cooling design of PAHX units. This paper reports the development of PAHX system for building envelope applications that promotes the thermal radiation loss to the sky during night-time to maximize the cooling potential. A 2D numerical model has been developed considering the PCM thermal behavior, short and long wave radiation, and convection phenomena. New thermal boundaries of long-wave radiation have been proposed between system elements and the sky temperature. In addition, the model considered various forms of convective heat transfer phenomena. The apparent heat capacity method was used to simulate the thermal storage process. Experimentally obtained data and inter-model comparison were used to validate the proposed model. Two full-scale prototypes of the developed PAHX system were designed and tested under real conditions using two different types of PCMs. A parametric analysis was conducted to investigate the system thermal behavior under various air velocity profiles in the air channel and various inlet air temperature conditions. The results indicate that the building envelope integrated PAHX can use the sky radiation as a cooling source.
Energy, Mar 1, 2021
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
HAL (Le Centre pour la Communication Scientifique Directe), Sep 9, 2008
Energies, Aug 9, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Chemical Engineering and Processing, Mar 1, 2018
Highlights Reviewing four oxidation processes for treatment of petrochemical wastewater Study... more Highlights Reviewing four oxidation processes for treatment of petrochemical wastewater Studying the reaction mechanisms and the system performances of oxidation processes Discussing advantages and challenges associated with applying these methods Recommending an appropriate integration of oxidation and biological treatment
IOP conference series, Oct 23, 2019
Window operation plays a vital role in indoor environmental quality (IEQ) and building energy con... more Window operation plays a vital role in indoor environmental quality (IEQ) and building energy consumption while maintaining occupants' expected IEQ levels. In recent years, the influencing factors of window opening/closing behaviour have been widely investigated and evaluated in residential buildings, aiming at simulating building energy performance in a realistic manner. However, due to the challenges in collecting and analysing occupancy-related data, previous research works emphasized more on indoor/outdoor parameters (e.g. temperature and CO2). Hence, the correlation between occupancy patterns with window behaviour in a household has not been well explored. The aim of this study is to analyse the patterns of window opening and closing behaviour in French households and identify respective driving factors. The analysis was based on the data collected from four apartments in a high-performance residential building located in Lyon, France. The dataset considered in this study includes indoor environment data, weather data and occupancy behaviour with one minute resolution. Both model-dependent and model-independent approaches were adopted to assess the relative importance of driving factors for window operation. The results obtained in this study will provide insights regarding different driving factors for window operation and its related impact on occupant behaviour model performance. The outcomes of this research work can be used as input variables of occupant behaviour models in order to improve the building energy simulation performance.
Energy and Buildings, Sep 1, 2019
Energy feedback systems are recently proposed to help occupants understand and improve their ener... more Energy feedback systems are recently proposed to help occupants understand and improve their energy use behavior. Despite many potential benefits, the question remains, whether useful and straightforward knowledge are transferred to the occupants about their energy use patterns. In this context, the key is to develop methodologies that can effectively analyze occupants' energy use behavior and distinguish their energy-inefficient behavior (if any). Previous studies seldom considered the dynamics of occupancy, which may result in misleading information to the occupants and inefficacy in recognizing the actual wasteful behavior. To fill this gap, this study proposes a data mining framework with a combination of change point analysis (CPA), cluster analysis, and association rule mining (ARM) to explore the relationship between occupancy and building energy consumption, aiming at identifying potential energy waste patterns and to provide useful feedback to the occupants. To demonstrate the capability of the developed framework, it was applied to datasets collected from two different apartments located in Lyon, France. Results indicate that different energy waste patterns can be effectively discovered in both apartments through the proposed framework and a substantial amount of energy savings can be achieved by modifying occupants' energy use behavior. The proposed framework is flexible and can be adaptive to households with different occupancy patterns and habitual energy-use behavior. Nevertheless, the discovered energy saving potentials and benchmark values are limited to the apartments considered in this study and similar analysis based on the proposed framework are needed in wider building stocks to explore its generalizability.
E3S web of conferences, 2023
Photocatalytic oxidation (PCO) is an innovative method of removing volatile organic compounds (VO... more Photocatalytic oxidation (PCO) is an innovative method of removing volatile organic compounds (VOCs) from indoor air. PCO technology employs a semiconductor (such as TiO2) and ultraviolet light to decompose VOCs via successive oxidation processes and creates CO2 and H2O as the ultimate products of complete mineralization. The greatest drawback of this technology is, however, the production of hazardous by-products. The possible health risk posed by hazardous by-products inhibits the commercial adoption of PCO-based air purifiers in the indoor environment. Modeling is a powerful tool to address the chemical interaction and mass transfer phenomenon in the PCO reactor. This study presents the modeling of a ternary mixture of VOCs and generated by-products using a proposed degradation reaction pathway. A onedimensional mathematical model by considering the axially dispersed plug flow and Langmuir-Hinshelwood (L-H) based reaction rate as well as linear source spherical emission model (LSSE) for the irradiation distribution on the media surface were used for modeling of VOCs and by-products. Three VOCs from different chemical groups (aldehyde, ketone, aromatic groups) were chosen as challenge compounds, and a commercial PCO filter (TiO2 coated on silica fiber felts) was considered as a photocatalyst. The model prediction was performed at different levels of concentration (0.1-1 ppm), relative humidity (15-70%), air velocity (0.016-0.1 m/s), and light intensity (7-23W/m2). Among generated by-products, aldehydes were the major by-products of VOCs in the PCO reactor. It was revealed that increasing concentration and irradiation, as well as decreasing relative humidity and velocity, increases by-product generation.
Advances in Building Energy Research
Encyclopedia of Energy Storage, 2021
Sustainable Cities and Society, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Building and Environment, 2021
This study proposes a whole life asset-supply chain optimization model for integration of biomass... more This study proposes a whole life asset-supply chain optimization model for integration of biomass boilers into non-domestic (non-residential) buildings, under a renewable heat incentive scheme in the UK. The proposed model aims at identifying the optimal energy generation capacities and schedules for biomass and backup boilers, along with the optimal levels of biomass ordering and storage. The sensitivity of these decisions are then analyzed subject to changes in source, types and pricing of biomass materials as well as the choice of technologies and their cost and operational performance criteria. The proposed model is validated by applying it to a case study scenario in the UK. The results indicate that a Renewable Heat Incentive scheme could incentivize the adoption of biomass boilers, with a 3 to 1 ratio for biomass and backup boilers' utilization. As such, the findings from this study will be useful for industry managers, tasked with the decision of which biomass boiler system to utilize, considering the support from RHI. On the other hand, it is shown that RHI does not provide encouragement for efficiency when it comes to the choice of biomass technologies and fuels. This presents itself as a major implication for the success and sustainability of the UK government's renewable heat incentive scheme.