The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Jan Carmeliet - One of the best experts on this subject based on the ideXlab platform.
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impact of radiation exchange between buildings in urban street canyons on Space Cooling demands of buildings
Energy and Buildings, 2016Co-Authors: Jonas Allegrini, Viktor Dorer, Jan CarmelietAbstract:Abstract There is worldwide a trend towards urbanization, and cities try to improve their sustainability by saving natural resources and energy, and to mitigate the impact of climate change. Therefore growing cities need to optimize the energy demand of their new and existing buildings. There are a large number of urban scale phenomena that influence the energy demand of buildings. One of the most important influencing phenomena is the shortwave solar and longwave radiation exchange within an urban environment. It was demonstrated that the influence of neighbouring buildings has to be considered in detail to predict correctly the building energy demand. In this study, Space Cooling demand of stand-alone buildings is compared with buildings in an urban street canyon configuration. Detailed radiation models for the solar and longwave radiation are used to determine the radiation exchange between the buildings. The results show a strong influence of neighbouring buildings on the Space Cooling demands. This influence is strongly dependent on the shading device control strategy incorporated in the building energy management. Counterintuitively the Space Cooling demands are in some cases are higher for low values of solar irradiance, because the shading device control directs the devices to remain open during longer time periods when irradiance values are low, leading to higher total solar gains through the windows.
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influence of the urban microclimate in street canyons on the energy demand for Space Cooling and heating of buildings
Energy and Buildings, 2012Co-Authors: Jonas Allegrini, Viktor Dorer, Jan CarmelietAbstract:Abstract An important part of the world's energy is used for Space Cooling and heating of buildings. Its minimization has great energy saving potential. An important part of the heat exchange between buildings and the ambient surrounding is due to convective and radiative heat flows. In this study detailed building energy simulation (BES) is used to analyse the effect of neighbouring buildings on these heat flows and their influence on the Space Cooling and heating demand of buildings. BESs were conducted for stand-alone buildings and buildings in street canyon. This study demonstrates the importance of accounting for the urban microclimate for the prediction of the energy demand of buildings. With the proposed model most of the thermal effects of the urban microclimate can be captured and quantified on street canyon scale. Due to multiple reflections more solar and thermal radiation is absorbed at the facades of buildings in street canyons than at facades of stand-alone buildings. These effects cause higher surface temperatures in street canyons leading to higher Space Cooling and lower Space heating demands. Other reasons are the lower convective heat transfer coefficients in street canyons, the reduced removal of heat from street canyons and the urban heat island effect.
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analysis of convective heat transfer at building facades in street canyons and its influence on the predictions of Space Cooling demand in buildings
Journal of Wind Engineering and Industrial Aerodynamics, 2012Co-Authors: Jonas Allegrini, Viktor Dorer, Jan CarmelietAbstract:Abstract An important part of the world’s energy is used for Space Cooling of buildings. Minimisation of Space Cooling, especially in hot urban environments, has great energy-saving potential. An important part of the heat exchange between buildings and the ambient surrounding is due to convective and radiative heat flows. The impact of these heat flows on energy consumption for Cooling is much more important in urban areas compared to rural areas. This study aims at quantifying the influence of the urban radiation balance, the urban heat island effect and urban convective heat transfer coefficients (CHTC) on the Space Cooling demands. CHTC correlations were determined using computational fluid dynamics (CFD) for different geometries including stand-alone buildings and street canyons of different lengths. Buoyancy was accounted for by considering differences between building surface and surrounding air temperature. It was found that the building geometry has a large impact on the CHTC correlations and that the effect of buoyancy cannot be neglected when wind speeds are low. These CHTC correlations were used for Building Energy Simulation (BES) predictions of the Space Cooling demand. Space Cooling demands for a building in a street canyon differ up to a factor of 1.8 depending on the CHTC correlations used. Therefore, for accurate predictions of the Space Cooling demand, adequate CHTC correlations have to be used adjusted to the actual building configuration.
Jonas Allegrini - One of the best experts on this subject based on the ideXlab platform.
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impact of radiation exchange between buildings in urban street canyons on Space Cooling demands of buildings
Energy and Buildings, 2016Co-Authors: Jonas Allegrini, Viktor Dorer, Jan CarmelietAbstract:Abstract There is worldwide a trend towards urbanization, and cities try to improve their sustainability by saving natural resources and energy, and to mitigate the impact of climate change. Therefore growing cities need to optimize the energy demand of their new and existing buildings. There are a large number of urban scale phenomena that influence the energy demand of buildings. One of the most important influencing phenomena is the shortwave solar and longwave radiation exchange within an urban environment. It was demonstrated that the influence of neighbouring buildings has to be considered in detail to predict correctly the building energy demand. In this study, Space Cooling demand of stand-alone buildings is compared with buildings in an urban street canyon configuration. Detailed radiation models for the solar and longwave radiation are used to determine the radiation exchange between the buildings. The results show a strong influence of neighbouring buildings on the Space Cooling demands. This influence is strongly dependent on the shading device control strategy incorporated in the building energy management. Counterintuitively the Space Cooling demands are in some cases are higher for low values of solar irradiance, because the shading device control directs the devices to remain open during longer time periods when irradiance values are low, leading to higher total solar gains through the windows.
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influence of the urban microclimate in street canyons on the energy demand for Space Cooling and heating of buildings
Energy and Buildings, 2012Co-Authors: Jonas Allegrini, Viktor Dorer, Jan CarmelietAbstract:Abstract An important part of the world's energy is used for Space Cooling and heating of buildings. Its minimization has great energy saving potential. An important part of the heat exchange between buildings and the ambient surrounding is due to convective and radiative heat flows. In this study detailed building energy simulation (BES) is used to analyse the effect of neighbouring buildings on these heat flows and their influence on the Space Cooling and heating demand of buildings. BESs were conducted for stand-alone buildings and buildings in street canyon. This study demonstrates the importance of accounting for the urban microclimate for the prediction of the energy demand of buildings. With the proposed model most of the thermal effects of the urban microclimate can be captured and quantified on street canyon scale. Due to multiple reflections more solar and thermal radiation is absorbed at the facades of buildings in street canyons than at facades of stand-alone buildings. These effects cause higher surface temperatures in street canyons leading to higher Space Cooling and lower Space heating demands. Other reasons are the lower convective heat transfer coefficients in street canyons, the reduced removal of heat from street canyons and the urban heat island effect.
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analysis of convective heat transfer at building facades in street canyons and its influence on the predictions of Space Cooling demand in buildings
Journal of Wind Engineering and Industrial Aerodynamics, 2012Co-Authors: Jonas Allegrini, Viktor Dorer, Jan CarmelietAbstract:Abstract An important part of the world’s energy is used for Space Cooling of buildings. Minimisation of Space Cooling, especially in hot urban environments, has great energy-saving potential. An important part of the heat exchange between buildings and the ambient surrounding is due to convective and radiative heat flows. The impact of these heat flows on energy consumption for Cooling is much more important in urban areas compared to rural areas. This study aims at quantifying the influence of the urban radiation balance, the urban heat island effect and urban convective heat transfer coefficients (CHTC) on the Space Cooling demands. CHTC correlations were determined using computational fluid dynamics (CFD) for different geometries including stand-alone buildings and street canyons of different lengths. Buoyancy was accounted for by considering differences between building surface and surrounding air temperature. It was found that the building geometry has a large impact on the CHTC correlations and that the effect of buoyancy cannot be neglected when wind speeds are low. These CHTC correlations were used for Building Energy Simulation (BES) predictions of the Space Cooling demand. Space Cooling demands for a building in a street canyon differ up to a factor of 1.8 depending on the CHTC correlations used. Therefore, for accurate predictions of the Space Cooling demand, adequate CHTC correlations have to be used adjusted to the actual building configuration.
Johan Carlsson - One of the best experts on this subject based on the ideXlab platform.
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estimation of european union service sector Space Cooling potential
Energy Policy, 2018Co-Authors: Mindaugas Jakubcionis, Johan CarlssonAbstract:Abstract Data on European service sector Space Cooling demands are scarce and often of poor quality. This article estimates the potential Space Cooling demands in the service sector of the EU using the United States as a proxy. Since the Space Cooling demand in the US is mature and nearly saturated, this provides useful insights of potential future European Space Cooling demand. A georeferenced approach based on comparing Cooling Degree Days and Space Cooling consumption in the USA was used to establish the potential service Space Cooling demand in NUTS-3 regions of EU. The total potential Space Cooling demand of the EU was estimated to be 174 TWh for the service sector in an average year. The estimated potential of Space Cooling demand, identified in this paper for all EU Members States, could be used while preparing the next iteration of EU Member States' Comprehensive Assessments related to the Article 14 of the Energy Efficiency Directive or other energy related studies.
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estimation of european union residential sector Space Cooling potential
Energy Policy, 2017Co-Authors: Mindaugas Jakubcionis, Johan CarlssonAbstract:Abstract Data on European residential Space Cooling demands are scarce and often of poor quality. This can be concluded from a review of the Comprehensive Assessments on the energy efficiency potential in the heating and Cooling sector performed by European Union Member States under Art. 14 of the Energy Efficiency Directive. This article estimates the potential Space Cooling demands in the residential sector of the EU and the resulting impact on electricity generation and supply systems using the United States as a proxy. A georeferenced approach was used to establish the potential residential Space Cooling demand in NUTS-3 regions of EU. The total potential Space Cooling demand of the EU was estimated to be 292 TW h for the residential sector in an average year. The additional electrical capacity needed was estimated to 79 GW. With proper energy system development strategies, e.g. matching capacity of solar PV with Cooling demand, or introduction of district Cooling, the stresses on electricity system from increasing Cooling demand can be mitigated. The estimated potential of Space Cooling demand, identified in this paper for all EU Members States, could be used while preparing the next iteration of EU MS Comprehensive Assessments or other energy related studies.
Viktor Dorer - One of the best experts on this subject based on the ideXlab platform.
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impact of radiation exchange between buildings in urban street canyons on Space Cooling demands of buildings
Energy and Buildings, 2016Co-Authors: Jonas Allegrini, Viktor Dorer, Jan CarmelietAbstract:Abstract There is worldwide a trend towards urbanization, and cities try to improve their sustainability by saving natural resources and energy, and to mitigate the impact of climate change. Therefore growing cities need to optimize the energy demand of their new and existing buildings. There are a large number of urban scale phenomena that influence the energy demand of buildings. One of the most important influencing phenomena is the shortwave solar and longwave radiation exchange within an urban environment. It was demonstrated that the influence of neighbouring buildings has to be considered in detail to predict correctly the building energy demand. In this study, Space Cooling demand of stand-alone buildings is compared with buildings in an urban street canyon configuration. Detailed radiation models for the solar and longwave radiation are used to determine the radiation exchange between the buildings. The results show a strong influence of neighbouring buildings on the Space Cooling demands. This influence is strongly dependent on the shading device control strategy incorporated in the building energy management. Counterintuitively the Space Cooling demands are in some cases are higher for low values of solar irradiance, because the shading device control directs the devices to remain open during longer time periods when irradiance values are low, leading to higher total solar gains through the windows.
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influence of the urban microclimate in street canyons on the energy demand for Space Cooling and heating of buildings
Energy and Buildings, 2012Co-Authors: Jonas Allegrini, Viktor Dorer, Jan CarmelietAbstract:Abstract An important part of the world's energy is used for Space Cooling and heating of buildings. Its minimization has great energy saving potential. An important part of the heat exchange between buildings and the ambient surrounding is due to convective and radiative heat flows. In this study detailed building energy simulation (BES) is used to analyse the effect of neighbouring buildings on these heat flows and their influence on the Space Cooling and heating demand of buildings. BESs were conducted for stand-alone buildings and buildings in street canyon. This study demonstrates the importance of accounting for the urban microclimate for the prediction of the energy demand of buildings. With the proposed model most of the thermal effects of the urban microclimate can be captured and quantified on street canyon scale. Due to multiple reflections more solar and thermal radiation is absorbed at the facades of buildings in street canyons than at facades of stand-alone buildings. These effects cause higher surface temperatures in street canyons leading to higher Space Cooling and lower Space heating demands. Other reasons are the lower convective heat transfer coefficients in street canyons, the reduced removal of heat from street canyons and the urban heat island effect.
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analysis of convective heat transfer at building facades in street canyons and its influence on the predictions of Space Cooling demand in buildings
Journal of Wind Engineering and Industrial Aerodynamics, 2012Co-Authors: Jonas Allegrini, Viktor Dorer, Jan CarmelietAbstract:Abstract An important part of the world’s energy is used for Space Cooling of buildings. Minimisation of Space Cooling, especially in hot urban environments, has great energy-saving potential. An important part of the heat exchange between buildings and the ambient surrounding is due to convective and radiative heat flows. The impact of these heat flows on energy consumption for Cooling is much more important in urban areas compared to rural areas. This study aims at quantifying the influence of the urban radiation balance, the urban heat island effect and urban convective heat transfer coefficients (CHTC) on the Space Cooling demands. CHTC correlations were determined using computational fluid dynamics (CFD) for different geometries including stand-alone buildings and street canyons of different lengths. Buoyancy was accounted for by considering differences between building surface and surrounding air temperature. It was found that the building geometry has a large impact on the CHTC correlations and that the effect of buoyancy cannot be neglected when wind speeds are low. These CHTC correlations were used for Building Energy Simulation (BES) predictions of the Space Cooling demand. Space Cooling demands for a building in a street canyon differ up to a factor of 1.8 depending on the CHTC correlations used. Therefore, for accurate predictions of the Space Cooling demand, adequate CHTC correlations have to be used adjusted to the actual building configuration.
Shiming Deng - One of the best experts on this subject based on the ideXlab platform.
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Operating performances of a Space heating ASHP unit with a foul outdoor coil following a prolonged Cooling operation
International Journal of Refrigeration, 2018Co-Authors: Jingdong Liu, Wei Wang, Yuying Sun, Shiming DengAbstract:Abstract Fouling and frosting of the outdoor coil in an air source heat pump (ASHP) unit are common but undesirable operating problems. At an increased level of air pollution, fouling of an outdoor coil becomes increasingly severe during its Space Cooling operation in summer and may potentially impact its frosting operation in winter. This paper reports on a field study on the operating performances of a Space heating ASHP unit with a foul outdoor coil as a result of a prolonged Cooling operation. Firstly, a detailed description of the field ASHP unit with the foul outdoor coil and test cases is given. Secondly, field study results for the test cases and their analyses are presented. The results demonstrate that fouling of an outdoor coil during its Space Cooling operation in summer can significantly impact its frosting performance during its Space heating operation in winter.
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The characteristics of Space Cooling load and indoor humidity control for residences in the subtropics
Building and Environment, 2006Co-Authors: Zheng Li, Wu Yi-chen, Shiming DengAbstract:For residential buildings located in the subtropics, it is more challenging and difficult to deal with Space latent Cooling load than Space sensible load, using a room air conditioner (RAC), partly due to hot and humid climates. This paper reports a simulation study on the characteristics of Space Cooling load and indoor humidity control for residences in the subtropics, using a building energy simulation program. Both the weather conditions and the typical arrangements of high-rise residential blocks in subtropical Hong Kong were used in the simulation study. The simulation results on both the Space Cooling load characteristics and the hourly application sensible heat ratio (SHR) in the living/dining room and the master bedroom in a selected west-facing apartment under different operating modes of RACs in the summer design day are presented. The problem of indoor humidity control due to the mismatching between an application SHR and an equipment SHR in the two rooms both in the summer design day and during part load operations and the influences of indoor furnishings acting as moisture capacitors on indoor RH level are discussed.
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air cooled heat pump with desuperheater retrofit for year round service hot water supply
Building Services Engineering Research and Technology, 1998Co-Authors: Shiming Deng, Ziyan SongAbstract:In a case study project an air-cooled heat pump unit was retrofitted with a desuperheater to provide service hot water in addition to chilled water for comfort Space Cooling in a 24-room holiday villa located in a subtropical region. The retrofit project is described, and system operating performance and energy efficiency are reported. A standard Cooling tower was used to extract free heat from ambient air in transitional seasons, thus eliminating the need for electric back-up heating for service hot water.
