The present paper introduces an iterative methodology to progressively reduce building simulation... more The present paper introduces an iterative methodology to progressively reduce building simulation model complexity with the aim of identifying potential trade-offs between computational requirements (i.e., model complexity) and energy estimation accuracy. Different levels of model complexity are analysed, from commercial building energy simulation tools to low order calibrated thermal networks models. Experimental data from a residential building in Germany were collected and used to validate two detailed white-box models and a simplified white-box model. The validation process was performed in terms of internal temperature profiles and building thermal energy demand predictions. Synthetic profiles were generated from the validated models and used for calibrating high order models. A reduction (trimming) procedure was applied to reduce the model complexity using an energy performance criterion prior to model trimming. The proposed methodology has the advantage of keeping the physica...
Bei zunehmend dichteren Gebaudehullen energieeffizienter Gebaude werden Luftungskonzepte immer wi... more Bei zunehmend dichteren Gebaudehullen energieeffizienter Gebaude werden Luftungskonzepte immer wichtiger, um eine gute Raumluftqualitat zu garantieren und Feuchteschaden sicher zu vermeiden. Im Wohnungsbau stellt DIN 1946-6 Anforderungen zur Erstellung von Luftungskonzepten erstmalig auch fur den Feuchteschutz, die durch ventilatorgestutzte oder freie Luftung mit Ausendurchlassen erfullt werden. Eine entscheidende Voraussetzung fur die Luftungskonzepte ist dabei, dass diese nutzerunabhangig funktionieren mussen. Fur Nichtwohngebaude werden in DIN EN 13779 Anforderungen an Luftungsanlagen bezuglich des Luftvolumenstroms fur ein gesundheitlich unbedenkliches Innenklima vorgegeben. Daruber hinaus enthalt DIN EN 15251 Kriterien fur das thermische Innenraumklima von naturlich belufteten Gebauden. Die kontrollierte naturliche Luftung durch ansteuerbare Fensterelemente ermoglicht eine konsequente Einhaltung von Raumluftqualitat und Feuchte, bietet daruber hinaus aus Energie- und Komfortgrunden ein hochinteressantes Potential fur die sommerliche Luftung und Gebaudekuhlung ohne Energieeinsatz. Bei der Projektierung und Auslegung der Beluftung von Gebauden werden derzeit die Moglichkeiten der kontrollierten naturlichen Luftung uber automatisch gesteuerte Fenster jedoch kaum genutzt, da die Berechnungen von Luftmengen aufgrund standig wechselnder Randbedingungen komplex und bisher unzureichend in Standards vereinfacht festgelegt sind. In der vorliegenden Untersuchung wurden Rechenverfahren analysiert, welche die Planung luftungstechnischer Masnahmen durch kontrollierte naturliche Luftung unterstutzen und eventuell Eingang in die derzeitige Normung finden konnen. Durch Erstellung eines belastbaren Nachweises hinsichtlich der Funktionalitat der naturlichen Luftung (zur Anhebung der Raumlufthygiene sowie des Feuchteschutzes) wird Planern und Bauherren der Einsatz naturlicher Luftung erleichtert. Method for simplified calculation of controlled natural ventilation. As the building envelopes of energy efficient buildings are becoming increasingly air-tight, ventilation concepts are increasing in importance in order to ensure good quality room air and reliably prevent dampness. DIN 1946-6 contains requirements for producing ventilation concepts in housing – for the first time also in order to prevent dampness – which are satisfied by fan-assisted or free ventilation through external openings. An important prerequisite for these ventilation concepts is that they have to be functionally independent of user interaction. For buildings other than housing, DIN EN 13779 contains requirements for ventilation systems regarding the volume of air flow in order to achieve a healthy indoor climate. Furthermore, DIN EN 15251 contains criteria for the thermal interior climate of naturally ventilated buildings. Controlled natural ventilation through controllable window elements makes it possible to maintain adequate room air quality and humidity; in addition, this type of ventilation is interesting from the point of view of saving energy and increasing comfort levels as part of summer ventilation, and building cooling without energy consumption. However, the possibilities of controlled natural ventilation via automatically controlled windows are currently rarely explored in the design of ventilation systems for buildings, because the calculation of air quantity is complex due to continually changing boundary conditions, and simplified methods have not yet been adequately defined in the standards. This study covers the analysis of calculation methods which support the design of ventilation systems based on controlled natural ventilation and which could be adopted in the current standards. By producing robust proof with respect to the functionality of the chosen natural ventilation (in order to improve room air hygiene and prevent dampness), designers and building owners will find it easier to use natural ventilation.
Cities, undergoing rapid change in all parts of the globe, face a common set of “metabolic” chall... more Cities, undergoing rapid change in all parts of the globe, face a common set of “metabolic” challenges: sustainably provisioning for energy, water, and food supplies under sanitary, healthy, economically productive living conditions. Diverse decision makers, such as government, utilities, project developers and bankers must be able to visualize multiple impacts of plans and proposals. Global urban governance initiatives are currently bringing major cities together to learn from one another in addressing common challenges. Energy-related emissions, produced primarily by cities, are a huge challenge to the global climate, which in impacts growing urban areas. Urban infrastructures will have to be planned to meet the needs of increasing populations under increasingly demanding circumstances. This paper discusses the role of urban energy and climate modeling to analyze and predict trends that are a consequence of today ́s fossil energy economy and to develop strategies for moving toward...
Abstract An integrated urban platform is the essential software infrastructure for smart, sustain... more Abstract An integrated urban platform is the essential software infrastructure for smart, sustainable and resilient city planning, operation and maintenance. Today such platforms are mostly designed to handle and analyze large and heterogeneous urban data sets from very different domains. Modeling and optimization functionalities are usually not part of the software concepts. However, such functionalities are considered crucial by the authors to develop transformation scenarios and to optimize smart city operation. An urban platform needs to handle multiple scales in the time and spatial domain, ranging from long term population and land use change to hourly or sub-hourly matching of renewable energy supply and urban energy demand. The paper discusses software architecture concepts for data and modeling urban platforms, which allow to analyze and optimize the urban infrastructure with their energy, water and further resources such as food or goods consumption. Building, commerce and industry as well as the transport sector are in the focus of the efficiency and renewable supply analysis. The main driver is to derive zero carbon strategies for cities while including all major sectors of CO2 generation. So far, two software architecture concepts have been implemented and tested, both using a 3D CityGML geometry data model: A workflow management system for city scale building energy modeling using a monthly energy balance calculation method and a micro service orchestration for dynamic building simulation modeling. The GIS based data analysis methodology and building energy workflow modeling method are applied to a case study district in New York City to demonstrate the implementation status and derive CO2 mitigation strategies. The results showed how data gathered from different sources for the relevant sectors can be translated into CO2-emissions. For a district in Brooklyn connected to a large electric substation with electricity monitoring data available, every individual building´s heating and cooling demand was simulated and resulted in a total annual heating demand of 1.72 TWh/a and 0.11 TWh/a of cooling. It could be shown that the building sector cooling demand can by reduced by 63% by a change of set point temperature for cooling and reduced infiltration rate, while reducing the heat demand by 12%. In addition, carbon accounting of the food and wastewater sector was done using the same GIS based modeling framework. The analysis showed that the food related electricity consumption for refrigeration corresponds to about 5% of the overall electricity consumption and requires 2.6 GWh/a for transport. Using food waste in co-digestion of wastewater treatment plants could contribute another 7.4 GWh/a of combined heat and power. Such quantification of demand and energy sources could contribute to prioritize actions for CO2 mitigation strategies in urban areas.
In the paper, a method was developed to automatically dimensionalize and calculate central energy... more In the paper, a method was developed to automatically dimensionalize and calculate central energy generation and supply scenarios with a district heating system for cities based on 3D building models in the CityGML format and their simulated heat demand. In addition, the roof geometry of every individual building is used to model photovoltaic energy generation potential. Two types of supply systems, namely a central heat pump (HP) system and a large co-generation (combined heat and power-CHP) system (both with a central storage and district distribution system), are modeled to supply the heat demand of the area under investigation. Both energy generation models are applied to a case study town of 1610 buildings. For the HP scenario, it can be shown that the case study town’s heat demand can be covered by a monovalent, low-temperature system with storage, but that the PV only contributes 15% to the HP electricity requirement. For the CHP scenario, only 61% of the heat demand can be c...
Daylight usage in buildings improves visual comfort and lowers the final energy demand for artifi... more Daylight usage in buildings improves visual comfort and lowers the final energy demand for artificial lighting. The question always occurs: how much conservation can you achieve? New upcoming or rare materials and constructions have a lack of information about their application. Therefore, the current work investigates the daylight performance of a multi-layer textile membrane roof with 2 300 m² on top of a sports hall. A translucent, thermal insulation with a glass fibre fleece between the roof membranes combines daylight usage and heating demand reduction. A sports hall with built year 2017 is selected as the case study building. The optical properties of the roof construction are measured. The (visual) light transmittance amounts to 0.72 % with a clean surface. An accordingly parametrized climate-based annual daylight modeling delivers daylight indicators for different construction scenarios. The results show that in comparison to only one glass facade, the additio...
Wie die nachhaltige Stadt der Zukunft aussehen könnte, zeigt der Stadtteil „Scharnhauser Park“ in... more Wie die nachhaltige Stadt der Zukunft aussehen könnte, zeigt der Stadtteil „Scharnhauser Park“ in Ostfildern bei Stuttgart. In diesem Quartier versuchen Wissenschaftler und Investoren, einen ganzen Stadtteil so optimal wie möglich nach nachhaltigen Gesichtspunkten zu gestalten.
The present paper introduces an iterative methodology to progressively reduce building simulation... more The present paper introduces an iterative methodology to progressively reduce building simulation model complexity with the aim of identifying potential trade-offs between computational requirements (i.e., model complexity) and energy estimation accuracy. Different levels of model complexity are analysed, from commercial building energy simulation tools to low order calibrated thermal networks models. Experimental data from a residential building in Germany were collected and used to validate two detailed white-box models and a simplified white-box model. The validation process was performed in terms of internal temperature profiles and building thermal energy demand predictions. Synthetic profiles were generated from the validated models and used for calibrating high order models. A reduction (trimming) procedure was applied to reduce the model complexity using an energy performance criterion prior to model trimming. The proposed methodology has the advantage of keeping the physica...
Bei zunehmend dichteren Gebaudehullen energieeffizienter Gebaude werden Luftungskonzepte immer wi... more Bei zunehmend dichteren Gebaudehullen energieeffizienter Gebaude werden Luftungskonzepte immer wichtiger, um eine gute Raumluftqualitat zu garantieren und Feuchteschaden sicher zu vermeiden. Im Wohnungsbau stellt DIN 1946-6 Anforderungen zur Erstellung von Luftungskonzepten erstmalig auch fur den Feuchteschutz, die durch ventilatorgestutzte oder freie Luftung mit Ausendurchlassen erfullt werden. Eine entscheidende Voraussetzung fur die Luftungskonzepte ist dabei, dass diese nutzerunabhangig funktionieren mussen. Fur Nichtwohngebaude werden in DIN EN 13779 Anforderungen an Luftungsanlagen bezuglich des Luftvolumenstroms fur ein gesundheitlich unbedenkliches Innenklima vorgegeben. Daruber hinaus enthalt DIN EN 15251 Kriterien fur das thermische Innenraumklima von naturlich belufteten Gebauden. Die kontrollierte naturliche Luftung durch ansteuerbare Fensterelemente ermoglicht eine konsequente Einhaltung von Raumluftqualitat und Feuchte, bietet daruber hinaus aus Energie- und Komfortgrunden ein hochinteressantes Potential fur die sommerliche Luftung und Gebaudekuhlung ohne Energieeinsatz. Bei der Projektierung und Auslegung der Beluftung von Gebauden werden derzeit die Moglichkeiten der kontrollierten naturlichen Luftung uber automatisch gesteuerte Fenster jedoch kaum genutzt, da die Berechnungen von Luftmengen aufgrund standig wechselnder Randbedingungen komplex und bisher unzureichend in Standards vereinfacht festgelegt sind. In der vorliegenden Untersuchung wurden Rechenverfahren analysiert, welche die Planung luftungstechnischer Masnahmen durch kontrollierte naturliche Luftung unterstutzen und eventuell Eingang in die derzeitige Normung finden konnen. Durch Erstellung eines belastbaren Nachweises hinsichtlich der Funktionalitat der naturlichen Luftung (zur Anhebung der Raumlufthygiene sowie des Feuchteschutzes) wird Planern und Bauherren der Einsatz naturlicher Luftung erleichtert. Method for simplified calculation of controlled natural ventilation. As the building envelopes of energy efficient buildings are becoming increasingly air-tight, ventilation concepts are increasing in importance in order to ensure good quality room air and reliably prevent dampness. DIN 1946-6 contains requirements for producing ventilation concepts in housing – for the first time also in order to prevent dampness – which are satisfied by fan-assisted or free ventilation through external openings. An important prerequisite for these ventilation concepts is that they have to be functionally independent of user interaction. For buildings other than housing, DIN EN 13779 contains requirements for ventilation systems regarding the volume of air flow in order to achieve a healthy indoor climate. Furthermore, DIN EN 15251 contains criteria for the thermal interior climate of naturally ventilated buildings. Controlled natural ventilation through controllable window elements makes it possible to maintain adequate room air quality and humidity; in addition, this type of ventilation is interesting from the point of view of saving energy and increasing comfort levels as part of summer ventilation, and building cooling without energy consumption. However, the possibilities of controlled natural ventilation via automatically controlled windows are currently rarely explored in the design of ventilation systems for buildings, because the calculation of air quantity is complex due to continually changing boundary conditions, and simplified methods have not yet been adequately defined in the standards. This study covers the analysis of calculation methods which support the design of ventilation systems based on controlled natural ventilation and which could be adopted in the current standards. By producing robust proof with respect to the functionality of the chosen natural ventilation (in order to improve room air hygiene and prevent dampness), designers and building owners will find it easier to use natural ventilation.
Cities, undergoing rapid change in all parts of the globe, face a common set of “metabolic” chall... more Cities, undergoing rapid change in all parts of the globe, face a common set of “metabolic” challenges: sustainably provisioning for energy, water, and food supplies under sanitary, healthy, economically productive living conditions. Diverse decision makers, such as government, utilities, project developers and bankers must be able to visualize multiple impacts of plans and proposals. Global urban governance initiatives are currently bringing major cities together to learn from one another in addressing common challenges. Energy-related emissions, produced primarily by cities, are a huge challenge to the global climate, which in impacts growing urban areas. Urban infrastructures will have to be planned to meet the needs of increasing populations under increasingly demanding circumstances. This paper discusses the role of urban energy and climate modeling to analyze and predict trends that are a consequence of today ́s fossil energy economy and to develop strategies for moving toward...
Abstract An integrated urban platform is the essential software infrastructure for smart, sustain... more Abstract An integrated urban platform is the essential software infrastructure for smart, sustainable and resilient city planning, operation and maintenance. Today such platforms are mostly designed to handle and analyze large and heterogeneous urban data sets from very different domains. Modeling and optimization functionalities are usually not part of the software concepts. However, such functionalities are considered crucial by the authors to develop transformation scenarios and to optimize smart city operation. An urban platform needs to handle multiple scales in the time and spatial domain, ranging from long term population and land use change to hourly or sub-hourly matching of renewable energy supply and urban energy demand. The paper discusses software architecture concepts for data and modeling urban platforms, which allow to analyze and optimize the urban infrastructure with their energy, water and further resources such as food or goods consumption. Building, commerce and industry as well as the transport sector are in the focus of the efficiency and renewable supply analysis. The main driver is to derive zero carbon strategies for cities while including all major sectors of CO2 generation. So far, two software architecture concepts have been implemented and tested, both using a 3D CityGML geometry data model: A workflow management system for city scale building energy modeling using a monthly energy balance calculation method and a micro service orchestration for dynamic building simulation modeling. The GIS based data analysis methodology and building energy workflow modeling method are applied to a case study district in New York City to demonstrate the implementation status and derive CO2 mitigation strategies. The results showed how data gathered from different sources for the relevant sectors can be translated into CO2-emissions. For a district in Brooklyn connected to a large electric substation with electricity monitoring data available, every individual building´s heating and cooling demand was simulated and resulted in a total annual heating demand of 1.72 TWh/a and 0.11 TWh/a of cooling. It could be shown that the building sector cooling demand can by reduced by 63% by a change of set point temperature for cooling and reduced infiltration rate, while reducing the heat demand by 12%. In addition, carbon accounting of the food and wastewater sector was done using the same GIS based modeling framework. The analysis showed that the food related electricity consumption for refrigeration corresponds to about 5% of the overall electricity consumption and requires 2.6 GWh/a for transport. Using food waste in co-digestion of wastewater treatment plants could contribute another 7.4 GWh/a of combined heat and power. Such quantification of demand and energy sources could contribute to prioritize actions for CO2 mitigation strategies in urban areas.
In the paper, a method was developed to automatically dimensionalize and calculate central energy... more In the paper, a method was developed to automatically dimensionalize and calculate central energy generation and supply scenarios with a district heating system for cities based on 3D building models in the CityGML format and their simulated heat demand. In addition, the roof geometry of every individual building is used to model photovoltaic energy generation potential. Two types of supply systems, namely a central heat pump (HP) system and a large co-generation (combined heat and power-CHP) system (both with a central storage and district distribution system), are modeled to supply the heat demand of the area under investigation. Both energy generation models are applied to a case study town of 1610 buildings. For the HP scenario, it can be shown that the case study town’s heat demand can be covered by a monovalent, low-temperature system with storage, but that the PV only contributes 15% to the HP electricity requirement. For the CHP scenario, only 61% of the heat demand can be c...
Daylight usage in buildings improves visual comfort and lowers the final energy demand for artifi... more Daylight usage in buildings improves visual comfort and lowers the final energy demand for artificial lighting. The question always occurs: how much conservation can you achieve? New upcoming or rare materials and constructions have a lack of information about their application. Therefore, the current work investigates the daylight performance of a multi-layer textile membrane roof with 2 300 m² on top of a sports hall. A translucent, thermal insulation with a glass fibre fleece between the roof membranes combines daylight usage and heating demand reduction. A sports hall with built year 2017 is selected as the case study building. The optical properties of the roof construction are measured. The (visual) light transmittance amounts to 0.72 % with a clean surface. An accordingly parametrized climate-based annual daylight modeling delivers daylight indicators for different construction scenarios. The results show that in comparison to only one glass facade, the additio...
Wie die nachhaltige Stadt der Zukunft aussehen könnte, zeigt der Stadtteil „Scharnhauser Park“ in... more Wie die nachhaltige Stadt der Zukunft aussehen könnte, zeigt der Stadtteil „Scharnhauser Park“ in Ostfildern bei Stuttgart. In diesem Quartier versuchen Wissenschaftler und Investoren, einen ganzen Stadtteil so optimal wie möglich nach nachhaltigen Gesichtspunkten zu gestalten.
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