Publications
This is an overview of the SimStadt-related papers that have been published either in scientific journals or have been presented at conferences.
2022
Bao, Keyu and Kalisch, Louis and Santhanavanich, Thunyathep and Thraen, Daniela and Schroeter, Bastian. A bottom-up GIS-based method for simulation of ground-mounted PV potentials at regional scale in Energy Reports (8, 2022, 5053-5066).
Abstract: Solar photovoltaic (PV) is a key technology for any renewable energy system. As subsidy-free PV becomes more and more economically feasible, region-specific planning tools that define areas suitable for ground-mounted PV are needed. While many top-down studies have assessed suitable areas at a national scale, an accurate scalable bottom-up assessment of regional ground-mounted PV potentials in high spatial and temporal resolution that goes further than a mere identification of appropriate land areas is missing. This work introduces such a method based on digital landscape models that consider terrain slope, orientation, location-specific irradiation, and land use type, and combines this geoinformatical information with a PV yield model that allows to assess hourly PV generation potential on suitable areas. The method is validated with three existing ground-mounted PV plants in Germany, where a comparison of real and simulated annual electricity yields shows average deviations of 5%. Subsequently, ground-mounted PV potentials in three German counties with varying settlement structures as well as topographic and weather patterns are assessed and a comparison of yearly and hourly simulated generation potentials with regional electricity demand is performed. While the yearly analysis demonstrates the substantial overall potentials of local ground mounted-PV in all regions, with demand coverages ranging from 80% to hypothetically more than 40 times of current electricity demand according to current regulations, the hourly autarky ratio, defined as the share of hours of a year where ground-mounted PV can satisfy demand, ranges from 25% to 40%, without consideration of storage or demand side management. A subsequent investigation of the ability to export excess electricity generation from ground-mounted PV shows that the two regions with highest ground-mounted PV potentials have less-developed grid infrastructures, thus restricting excess electricity generation export potentials. Keywords: Photovoltaic; Ground-mounted PV; Bottom-up simulation; Geographic Information System (GIS); Food–water–energy nexus; Potential simulation
Verena Weiler, Daniel Lust, Marcus Brennenstuhl, Kai-Holger Brassel, Eric Duminil, Ursula Eicker. Automatic dimensioning of energy system components for building cluster simulation, in Applied Energy (Volume 313, 2022, 118651, ISSN 0306-2619)
Abstract: In this paper, we present an approach on automatic energy system modeling and simulation. We develop two different methods to dimension the components of energy systems: one approach is an easy-to-use and to-adapt rule-based method, where the size of components is based e.g. on the heat demand of the buildings. The second approach is to dimension components with a genetic algorithm with a target function to reduce total annual cost. We apply and compare the methods for two different system designs to a building cluster case study in Germany. One system is a decentral heat pump system with back-up gas boiler, thermal and electrical storage and PV, the other system is a hydrogen-based central fuel cell system with electrolyzer, thermal and electrical storage and PV. We compare both systems based on current (2020) and future (2050) framework conditions. Through the application of the genetic algorithm a reduction of equivalent annual cost of up to 27% (2020 scenario) and 21% (2050 scenario) is achieved for the heat pump system. The hydrogen system with optimized dimensioning becomes economically viable under 2050 conditions due to reduced fuel prices and a higher electricity feed-in tariff compared to 2020. Depending on the use case, both approaches have their merit: rule-based dimensioning can quickly simulate a variety of different scenarios, the genetic algorithm can achieve economically ideal system designs, but with longer computation time, especially with unfamiliar framework conditions.
Keywords: Urban simulation; System dimensioning; Genetic algorithm; Total annual cost; Modular approach; Power-to-hydrogen
2021
Weiler, Verena; Duminil, Eric; Schröter, Bastian; Coors, Volker; Brüggeman, Thilo; Balbach, Bodo; Goll, Laura, Klöber, Andreas. Automatisierte Modellierung von Quartierswärmebedarfen auf Basis von 3D-Gebäudemodellen. EuroHeat&Power 4-5.2021.
Abstract: Eine nachhaltige Wärmeversorgung von Bestands- und Neubauquartieren kann maßgeblich dazu beitragen, die klimapolitischen Zielsetzungen Deutschlands und der EU zu erreichen. Der 3D-Gebäudeenergie-Workflow-Manager SimStadt hilft dabei, die energetische Quartiersplanung zu vereinfachen.
Weiler, Verena; Duminil, Eric; Balbach, Bodo; Schröter, Bastian; Tool Development for Automatic Simulation of central and decentral Heat Supply Scenarios and Application to a district in the City of Mainz, Germany (SimStadt 2.0 project). Building Simulation 2021 Conference, Bruges
Abstract: Often enough, when new constructions or changes in existing built-up areas are planned, energetic assessments such as the choice among heat supply options, are done at a late stage in the process, with key decisions on the area already made. Our tool, called SimStadt, enables local decision makers to perform an early-stage analysis of possible planning scenarios, with limited data requirements on the technical backgrounds and exact design of potential future scenarios. SimStadt is a scientific workflow management platform, which can be coupled to a number of external tools and libraries. The existing functionalities have been described in various publications ([1]–[4]) and shall not be the focus here. The new developments in the (ongoing) SimStadt 2.0 project are the connection of heat demand calculations to heat supply models. They are modelled in INSEL (www.insel.eu), with the district heating network dimensioned in more detail in STANET (www.stafu.de/en). Additionally, an energy components library contains relevant parameters for various heat supply models. The new development was tested with a district of 65 buildings in Mainz, Germany, where options for a central network system were compared against a decentral air-water heat pump system along technical and economic indicators.
2020
Dochev, Ivan; Gorzalka, Philip; Weiler, Verena; Estevam Schmiedt, Jacob; Linkiewicz, Magdalena; Eicker, Ursula; Hoffschmidt, Bernhard; Peters, Irene; Schröter, Bastian. Calculating urban heat demands: An analysis of two modelling approaches and remote sensing for input data and validation. Energy & Buildings 226.
Abstract: Building stocks account for a large share of energy consumption and harbour great potential for reducing greenhouse gas emissions. The field of urban building energy modelling (UBEM) offers a range of approaches to inform climate protection policies, producing output of different granularity and quality. We compare two typology-based (archetype) approaches to urban heat demand calculation in a mixed-use area in Berlin, Germany. The goal is to show challenges and pitfalls and how remote sensing can improve the modelling. The first approach uses 2D cadastral data and specific heat demand values from a typology. For the second approach, we derive a 3D building model from aerial imagery, use parameters from the same typology, and calculate the heat balance for each building. We compare the differences in several geometric parameters, U-values and the heat demand. Additionally, we analyse if window detection on aerial image textures and surface temperatures from aerial infrared thermography can improve the estimated window-wall ratios and U-values. The two heat demand approaches lead to different results for individual buildings. Averaging effects reduce the differences at an aggregated level. Remote sensing can be used to improve some geometric parameters needed for modelling, but still requires additional research regarding U-value estimation.
Eicker, Ursula, Weiler, Verena, Schumacher, Jürgen, Braun, Reiner. On the design of an urban data and modeling platform and its application to urban district analyses. Energy and Buildings 217.
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.
Coors, Volker; Matthias Betz; Duminil, Eric. A Concept of Quality Management of 3D City Models Supporting Application-Specific Requirements. PFG–Journal of Photogrammetry, Remote Sensing and Geoinformation Science (2020): 1-12.
Abstract: In this paper, a novel approach to specify application-specific requirements for 3D City Models is proposed. A modular set of geometric and semantic requirements that are based on the OGC CityGML Quality Interoperability Experiment (Coors and Wagner in Fernerkundung und Geoinformation eV 24:288–295, 2015) has been specified. Depending on the purpose of the model, not all requirements are mandatory. For example, if the model is used for visualization only, solid geometry is not required. However, if the same model should be used for analytic purpose such as heating demand simulation, solid geometry is mandatory. A formal definition of a validation plan is proposed in this paper to specify the application-specific set of requirements. This gives the city model manufacturers the possibility to provide proof that their model is usable in certain applications and can certify a certain level of quality. The concept is evaluated with the definition of a validation plan for heating demand simulation. It has been successfully implemented using the Software CityDoctor and SimStadt.
Bao, Keyu; Rushikesh Padsala; Volker Coors; Daniela Thrän; Bastian Schröter. GIS-Based Assessment of Regional Biomass Potentials at the Example of Two Counties in Germany. 28th European Biomass Conference and Exhibition Proceedings, pp. 77-85. 2020.
Abstract: The assessment of theoretical and technical biomass potential from different types of natural land cover is an integral part of simulation tools that aim to assess local multi-energy systems. This work introduces a new workflow which evaluates the local biomass potential from various sources, its transformation to different forms of biofuel and their thermal and electrical energy potentials, based on GIS-based land use data, satellite map on local crop types, and crop-specific energy yields from literature. One of the workflow’s two test cases is the county of Ludwigsburg in the south of Germany, where the annual technical local biomass potential was calculated to be close to 700 GWh, or 8% of total electricity and heating demand (based on 2018 demand data) – compared to an actual contribution of biomass to the local energy mix of about 2% (2012). The second test case is the northern German county of Dithmarschen, where local technical biomass is about 2248 GWh, or 19% of electricity and heating demand according to our simulation. Under current utilization situation bioenergy potential s are not completely in use and can contribute to local energy concept. This new workflow will further complement an existing local energy system simulation platform that has so far focused on urban energy demands and potentials.
Bao, Keyu; Rushikesh Padsala; Volker Coors; Daniela Thrän; Bastian Schröter. A Method for Assessing Regional Bioenergy Potentials Based on GIS Data and a Dynamic Yield Simulation Model. Energies 13, no. 24 (2020): 6488.
Abstract: The assessment of regional bioenergy potentials from different types of natural land cover is an integral part of simulation tools that aim to assess local renewable energy systems. This work introduces a new workflow, which evaluates regional bioenergy potentials and its impact on water demand based on geographical information system (GIS)-based land use data, satellite maps on local crop types and soil types, and conversion factors from biomass to bioenergy. The actual annual biomass yield of crops is assessed through an automated process considering the factors of local climate, crop type, soil, and irrigation. The crop biomass yields are validated with historic statistical data, with deviation less than 7% in most cases. Additionally, the resulting bioenergy potentials yield between 10.7 and 12.0 GWh/ha compared with 13.3 GWh/ha from other studies. The potential contribution from bioenergy on the energy demand were investigated in the two case studies, representing the agricultural-dominant rural area in North Germany and suburban region in South Germany: Simulation of the future bioenergy potential for 2050 shows only smaller effects from climate change (less than 4%) and irrigation (below 3%), but the potential to cover up to 21% of the transport fuels demand in scenario supporting biodiesel and bioethanol for transportation.
Bao, Keyu; Rushikesh Padsala; Daniela Thrän; Bastian Schröter. Urban Water Demand Simulation in Residential and Non-Residential Buildings Based on a CityGML Data Model. ISPRS International Journal of Geo-Information 9, no. 11 (2020): 642.
Abstract: Humans’ activities in urban areas put a strain on local water resources. This paper introduces a method to accurately simulate the stress urban water demand in Germany puts on local resources on a single-building level, and scalable to regional levels without loss of detail. The method integrates building geometry, building physics, census, socio-economy and meteorological information to provide a general approach to assessing water demands that also overcome obstacles on data aggregation and processing imposed by data privacy guidelines. Three German counties were used as validation cases to prove the feasibility of the presented approach: on average, per capita water demand and aggregated water demand deviates by less than 7% from real demand data. Scenarios applied to a case region Ludwigsburg in Germany, which takes the increment of water price, aging of the population and the climate change into account, show that the residential water demand has the change of −2%, +7% and −0.4% respectively. The industrial water demand increases by 46% due to the development of economy indicated by GDP per capita. The rise of precipitation and temperature raise the water demand in non-residential buildings (excluding industry) of 1%.
2019
Eicker, Ursula; Schumacher, Jürgen; Weiler, Verena; Braun, Reiner On the design of an urban modelling platform and its application for a New York analysis at IBPSA Building Simulation Rome
Abstract: Urban platforms are essential for smart and sustainable city planning and operation. Today they are mostly designed to handle and connect large urban data sets from very different domains. Modelling and optimisation functionalities are usually not part of the cities software infrastructure. However, they are considered crucial for transformation scenario development and optimized smart city operation. The work discusses software architecture concepts for such urban platforms and presents case study results on the building sector modelling, including urban data analysis and visualisation. Results from a case study in New York are presented to demonstrate the implementation status.
Köhler, Sally; Betz, Matthias; Eicker, Ursula Stochastic generation of household electricity load profiles in 15 minute resolution on building level for whole city quarters at 16th IAEE Conference Ljubljana
Abstract: This paper presents a new method for generating synthetic household electricity load profiles by using a small data set of measured time series data as an input. In general, electricity demand can be determined by either bottom-up or top-down methods. The bottom-up method is very detailed, taking single devices and user occupancy into account [1]. Top-down modelling uses regionally aggregated data [2] to draw conclusions about consumption based on building characteristics and attributes. The method presented is neither one of the mentioned above but a black-box modelling approach. Goal of this study is to simulate building electricity demand with as little input data as possible, while taking stochastics and randomness of occurrences into account. Additionally, this method should be able to produce synthetic time series with a customizable resolution on single building level for whole city quarters (up to several 100 buildings). Simultaneously the time complexity of the algorithm should be reasonable. Most of the freely available existing synthetic load profile generators work with a bottom-up approach, like [3] or [4] and are applicable only for a certain amount of households/buildings before the computational effort gets impractical. This study uses 3D CityGML files as a source of information for building properties and then applies the new method to the building stock using SimStadt as simulation platform.
Mittelstädt, Alexandra; Köhler, Sally; Kesnar, Chris; Sihombing, Rosanny; Duminil, Eric; Coors, Volker; Eicker, Ursula; Schröter, Bastian A multi-scale, web-based interface for strategic planning of low-carbon city quarters at ICUI Hongkong
Abstract: SimStadt is a simulation environment for strategic modelling of sustainable city quarters and other urban or regional areas. It interlinks GIS-based 3D city models with stationary or dynamic building models and power generation technologies, integrating them into a user-friendly, web-based platform. It allows evaluating potentials and relevant cost parameters for increased building energy efficiency as well as renewable power generation in a given geography. Today, SimStadt can assess the changes in the heat demand of buildings through energetic refurbishment scenarios. Furthermore, it can evaluate the potential for photovoltaics (PV) and solar thermal energy and the associated investment, operating and levelized costs over the lifetime of hundreds of individual buildings in parallel. This will be supplemented in the near future by other renewable energy technologies such as wind, biomass and geothermal energy, thus making it possible to assess the feasibility, benefits and economic viability of energy-related urban renewal measures and to compare them with each other in even greater detail and on a more holistic basis. SimStadt enables its users to develop granular sustainable city (quarter) strategies and energy concepts through an intuitive, web-based interface and supports them in promoting the energy system transformation on an urban and local level.
Weiler, Verena; Stave, Jonas; Eicker, Ursula Renewable energy generation scenarios using 3D urban modeling tools—methodology for heat pump and co-generation systems with case study application in Energies
Abstract: 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 covered by the CHP, as it was designed for a minimum of 4000 operating hours. Both the PV and the CHP excess electricity are fully injected into the grid. As a result, the primary energy comparison of both systems strongly depends on the chosen primary energy factors (PEF): with given German regulations the CHP system performs better than the HP system, as the grid-injected electricity has a PEF of 2.8. In the future, with increasingly lower PEFs for electricity, the situation reverses, and HPs perform better, especially if the CHP continues to use natural gas. Even when renewable gas from a power to gas (P2G) process is used for the CHP, the primary energy balance of the HP system is better, because of high conversion losses in the P2G process.
Weiler, Verena; Würstle, Patrick; Schmitt, Andreas; Stave, Jonas; Braun, Reiner; Zirak, Maryam; Coors, Volker; Eicker, Ursula Methoden zur Integration von Sachdaten in CityGML Dateien zur Verbesserung der energetischen Analyse von Stadtquartieren und deren Visualisierung at BauSIM 2018 Karlsruhe
Abstract: Auf Basis von 3D-Gebäudemodellen im CityGML-Standard kann mit der Simulationsplattform SimStadt unter anderem der Heiz- und Kühlenergiebedarf von Gebäuden sowie das PV Potential in Stadtquartieren berechnet werden. In der Praxis zeigt sich jedoch, dass Informationen wie Gebäudebaujahr, Sanierungsfortschritt oder genaue Angaben zur Nutzung der Gebäude teilweise fehlen oder fehlerhaft sind und somit nicht ausreichend, um gesamte Quartiere im gewünschten Detailierungsgrad zu analysieren. In diesem Artikel werden verschiedene Ansätze methodisch vorgestellt, wie eine Anreicherung der Eingangsdaten aus verschiedenen Quellen, wie OpenStreetMap oder durch Crowdsourcing durchgeführt werden und dadurch eine Verbesserung des Simulationsmodells erreicht werden kann.
Weiler, Verena; Eicker, Ursula Individual Domestic Hot Water Profiles for Building Simulation at Urban Scale at IBPSA Building Simulation Rome
Abstract: Many urban simulation tools focus mainly on the calculation of space heating (SH) demand and not on the domestic hot water (DHW) demand. Instead, DHW is often assumed as an always constant value that does not change during the day or year. In this paper, the importance of differentiated, hourly domestic hot water profiles for residential buildings in urban energy demand simulations is shown. The comparison between the use of DHW profiles and the use of a constant value for the DHW demand shows a high underestimation of the DHW demand during the morning peaks on weekdays and in the afternoon on weekends, as well as a high overestimation of the demand during the night. There is also a notable difference between summer and winter days, which is not represented when using a constant value.
Zirak, Maryam; Weiler, Verena; Hein, Martin; Eicker, Ursula Urban models enrichment for energy applications: Challenges in energy simulation using different data sources for building age information in Energy
Abstract: 3D city models are increasingly used for heating demand analyses at urban scale. Many studies have been done for standardization of required attribute data for energy analysis of buildings. The U-values which can be derived from the building age are one of the main influencing attributes for heat demand modelling. The question remains how building age can be provided. Often, the information on the year of construction of each building is not accessible. On the other hand, statistics about building ages are often available on an aggregated level. This paper compares data provided by municipalities to two statistical data sources: Census 2011 data on municipality level and country-wide statistics for Germany. The result shows building age distribution presented by the census leads to an acceptable total heat demand prediction compared with the results based on the data from the municipality. Therefore, the decision making at urban level can rely on census data if more detailed information is unavailable or inaccessible. Moreover, the role of refurbishment data is discussed in the paper. Finally, it is recommended to standardise census data for different applications. For energy application, distribution of building age over living area is more demanded than over the number of buildings.
2018
Braun, Reiner; Weiler, Verena; Zirak, Maryam; Dobisch, Lara; Coors, Volker; Eicker, Ursula Using 3D CityGML Models for Building Simulation Applications at District Level at IEEE International Conference on Engineering, Technology and Innovation Stuttgart
Abstract: The paper analyses the potential of 3D CityGML geometry models for building heating demand simulation. Various aspects of processing 3D data to make it suitable for building simulation are discussed. To validate and calibrate the simulation models, block level aggregated heating consumption data for the city district of Stuttgart Stöckach was used in conjunction with other data such as weather data. The work tries to identify sources of problems in the workflow of using 3D city models and other data bases such as building physics or usage libraries which can lead to a deviation between simulated and measured demand. Depending on the type of CityGML data, adjustments might be necessary to account for missing terrain intersection curves, for wrong wall or roof attributes etc. Only if the 3D model is of sufficient quality, heating demand simulations can yield realistic values. For the case study district the corrections improved the initial mean error of 61% to 29%. A higher accuracy could be achieved for building blocks which have a high share of residential buildings.
Weiler, Verena; Stave, Jonas; Eicker, Ursula Assessment of different renewable energy generation scenarios using 3D urban modelling tools at 13th SDEWES Conference Palermo
Abstract: In the paper, a method was developed to automatically generate energy supply scenarios for cities based on 3D building modelling of the heat demand. In addition, the roof geometry of every individual building was used to model photovoltaic energy generation. From the heat demand analysis hourly load profiles were derived and used to dimension two types of supply systems, namely a heat pump (HP) and a cogeneration (combined heat and power - CHP) system with storage and distribution system. For the HP scenario, it could be shown that the case study city´s heat demand could be covered by a monovalent, low temperature system with storage, but that the PV only contributed 15% to the HP electricity requirement. For the CHP scenario, only 61% of the heat demand could be covered by the CHP, as it was designed for a minimum of 4,000 operating hours. Both the PV and the CHP electricity are fully injected into the grid. As a result, the primary energy comparison of both systems strongly depends on the chosen primary energy factors (PEF): with given German regulations the CHP system performs better than the HP system, as the grid injected electricity has a PEF of 2.8. In the future with increasingly lower PEFs of electricity, the situation reverses and HPs perform better, especially if the CHP continues to use natural gas. Only if biogas or power to gas (P2G) from renewables is used for the CHP, the primary energy balance of the CHP system can compete with the HP system.
2017
Eicker, Ursula; Harter, Hannes; Weiler, Verena Life cycle assessment of buildings and city quarters analysing the influence of different climatic conditions at 15th IBPSA Building Simulation Conference San Francisco
Abstract: In this study, a method for evaluating the energy demand and greenhouse gas emissions during the three life cycle stages production, use and end-of-life of a building or city quarter is presented and applied to different case studies. The main result is that from the life cycle energetic point of view, refurbishment to a high building standard is better than demolition and reconstruction to a similar standard under the condition that the structural condition of the building allows it. The analysis includes different climatic conditions and their high influence on the life cycle energy demand and greenhouse gas emissions.
Harter, Hannes; Weiler, Verena; Eicker, Ursula Developing a roadmap for the modernisation of city quarters – Comparing the primary energy demand and greenhouse gas emissions in Building and Environment
Abstract: In this study, a new method based on 3D urban geometry in CityGML format is presented and used to evaluate the energy demand and greenhouse gas emissions during the different life cycle stages of a city quarter. The method is applied to a case study in Stuttgart/Germany, while considering the specific building characteristics of the city quarter. Four different development scenarios to reach a similar building standard for all residential buildings are assessed, which include either the refurbishment or the demolition and reconstruction or a combination of both. The total reduction of the primary energy demand for building operation is the same in each scenario. However, different production and construction energy inputs are needed for the four scenarios, which are highest for new constructions. The end-of-life energy demand is negligible by comparison. This leads to the conclusion that from the life cycle energy point of view, refurbishment to a high building standard is better than reconstruction under the condition that the structural condition of the building allows it. If the plan is to refurbish or partially reconstruct all buildings in a city quarter, a specific order needs to be chosen. This order has a high influence on the temporal development of the energy demand reduction of the city quarter.
Monien, Dirk; Stzalka, Aneta; Koukofikis, Athanasios; Coors, Volker; Eicker, Ursula Comparison of building modelling assumptions and methods for urban scale heat demand forecasting in Future Cities and Environment
Abstract: Building energy evaluation tools available today are only able to effectively analyse individual buildings and usually either they require a high amount of input data or they are too imprecise in energy predictions at a city (district) scale because of too many assumptions made. In this paper, two tools based on 3D models are compared to see whether there is an approach that would probably be able to fit both – the amount of data available and the number of assumptions made. A case study in the German town of Essen was chosen in the framework of the research project WeBest, where six building types representing the most important building periods were analysed. The urban simulation tool SimStadt, an in-house development of HFT Stuttgart, based on 3D urban geometry, is used to calculate the heat demand for both single building scale and city district scale. The individual building typology results are compared with the commercial dynamic building simulation software TRNSYS. The influence of the availability and quality of data input regarding the geometrical building parameters on the accuracy of simulation models are analysed. Different Levels of Details (LoDs) of the 3D building models are tested to prove the scalability of SimStadt from single buildings to city districts without loss of quality and accuracy in larger areas with a short computational time. Keywords:
Nouvel, Romain; Zirak, Maryam; Coors, Volker; Eicker, Ursula The influence of data quality on urban heating demand modeling using 3D city models in Computers, Environment and Urban Systems
Abstract: 3D city models are rich data sets for urban energy analyses, providing geometrical and semantic data required to estimate the energy demand of entire districts, cities and even regions. However, given the diverse availability, uncertainty and Level of Details of these data and the resources required to collect them, managing data quality is a common challenge of urban energy modeling. Knowing the influences of the different input data for different configurations and applications enables to control the result accuracy and recommend intelligent and adequate data collecting strategies, by assigning resources on the most important parameters. This paper investigates the influences of geometrical, meteorological, semantic and occupancy related data quality on the heating demand estimated by the urban energy simulation platform SimStadt, applied to the City of Ludwigsburg in Germany. A focus on a district with consumption data available at building block level allows for a critical comparison be- tween estimated and measured energy demands. Although the quantified information presented in this paper is specific to a case study, the main trends and developed methods are transferable to other urban energy analysis studies based on 3D city models.
Romero Rodriguez, Laura; Nouvel, Romain; Duminil, Eric; Eicker, Ursula Setting intelligent city tiling strategies for urban shading simulations in Solar Energy 157
Abstract: Assessing accurately the solar potential of all building surfaces in cities, including shading and multiple reflections between buildings, is essential for urban energy modelling. However, since the number of surface interactions and radiation exchanges increase exponentially with the scale of the district, innovative computational strategies are needed, some of which will be introduced in the present work. They should hold the best compromise between result accuracy and computational efficiency, i.e. computational time and memory requirements.
In this study, different approaches that may be used for the computation of urban solar irradiance in large areas are presented. Two concrete urban case studies of different densities have been used to compare and evaluate three different methods: the Perez Sky model, the Simplified Radiosity Algorithm and a new scene tiling method implemented in our urban simulation platform SimStadt, used for feasible estimations on a large scale. To quantify the influence of shading, the new concept of Urban Shading Ratio has been introduced and used for this evaluation process. In high density urban areas, this index may reach 60% for facades and 25% for roofs. Tiles of 500 m width and 200 m overlap are a minimum requirement in this case to compute solar irradiance with an acceptable accuracy. In medium density areas, tiles of 300 m width and 100 m overlap meet perfectly the accuracy requirements. In addition, the solar potential for various solar energy thresholds as well as the monthly variation of the Urban Shading Ratio have been quantified for both case studies, distinguishing between roofs and facades of different orientations.
Romero Rodriguez, Laura; Duminil, Eric; Sanchez Ramos, Jose; Eicker, Ursula Assessment of the photovoltaic potential at urban level based on 3D city models: A case study and new methodological approach in Solar Energy 146
Abstract: The use of 3D city models combined with simulation functionalities allows to quantify energy demand and renewable generation for a very large set of buildings. The scope of this paper is to determine the solar photovoltaic potential at an urban and regional scale using CityGML geometry descriptions of every building. An innovative urban simulation platform is used to calculate the PV potential of the Ludwigsburg County in south-west Germany, in which every building was simulated by using 3D city models.
Both technical and economic potential (considering roof area and insolation thresholds) are investigated, as well as two different PV efficiency scenarios. In this way, it was possible to determine the fraction of the electricity demand that can be covered in each municipality and the whole region, deciding the best strategy, the profitability of the investments and determining optimal locations. Additionally, another important contribution is a literature review regarding the different methods of PV potential estimation and the available roof area reduction coefficients. An economic analysis and emission assessment has also been developed.
The results of the study show that it is possible to achieve high annual rates of covered electricity demand in several municipalities for some of the considered scenarios, reaching even more than 100% in some cases. The use of all available roof space (technical potential) could cover 77% of the region’s electricity consumption and 56% as an economic potential with only high irradiance roofs considered. The proposed methodological approach should contribute valuably in helping policy-making processes and communicating the advantages of distributed generation and PV systems in buildings to regulators, researchers and the general public.
Weiler, Verena; Harter, Hannes; Eicker, Ursula Life cycle assessment of buildings and city quarters comparing demolition and reconstruction with refurbishment in Energy and Buildings
Abstract: In the building sector, the energy and the greenhouse gases embodied in the building materials are becoming increasingly important. Combined with the operational primary energy demand and the end-of-life, the whole life cycle of buildings can be assessed. In this paper, a comprehensive method for calculating the life cycle of individual buildings is presented. First, their material composition has been determined and generic values for the embodied energy, embodied greenhouse gases, energy needed and greenhouse gases emitted during disposal of the different building materials have been calculated. Subsequently these values have been integrated into an urban energy simulation software to simulate energy and emission values for buildings. A given building geometry with four different building standards was considered. The results can help to decide between building refurbishment or demolition and new construction. For example it could be shown that the share of the life cycle stage production compared to the total value rises with a better building insulation standard, as the share of the use stage decreases. The highest building refurbishment standard resulted in the best life cycle performance when compared with less ambitious refurbishment or construction of a new building of today's standards.
2016
Parag Wate, Preston Rodrigues, Eric Duminil, and Volker Coors. Urban energy simulation based on 3D city models: a service-oriented approach. In ISPRS Annals of Photogrammetry, Remote Sensing and Spatial Information Sciences, vol. 4, pp. 75-80. Copernicus GmbH, 2016
Abstract: Recent advancements in technology has led to the development of sophisticated software tools revitalizing growth in different domains. Taking advantage of this trend, urban energy domain have developed several compute intensive physical and data driven models. These models are used in various distinct simulation softwares to simulate the whole life-cycle of energy flow in cities from supply, distribution, conversion, storage and consumption. Since some simulation software target a specific energy system, it is necessary to integrate them to predict present and future urban energy needs. However, a key drawback is that, these tools are not compatible with each other as they use custom or propriety formats. Furthermore, they are designed as desktop applications and cannot be easily integrated with third-party tools (open source or commercial). Thereby, missing out on potential model functionalities which are required for sustainable urban energy management. In this paper, we propose a solution based on Service Oriented Architecture (SOA). Our approach relies on open interfaces to offer flexible integration of modelling and computational functionality as loosely coupled distributed services.
2015
Monsalvete, Pilar; Robinson, Darren; Eicker, Ursula Dynamic simulation methodologies for urban energy demand at 6th International Building Physics Conference, IBPC 2015
Abstract: This paper presents a new dynamic physical energy model of building for simulating the energy demand of cities. Firstly, a justification it is given regarding the necessity of a new building model and the advantages of using modular building simulation when dealing with large numbers of buildings in an urban context. The main motivation was a flexible and very modular interaction of 3D urban geometry description with the CityGML data format and energy related attributes for building parts. The paper then presents the modular dynamic building model and its validation with a real case of study for single buildings. The model integration into an urban modeling platform named SimStadt is explained with the necessary input data for a city heat demand calculation
Nouvel, Romain; Brassel, Kai-Holger; Bruse, Marcel; Duminil, Eric; Coors, Volker; Eicker, Ursula; Robinson, Darren SimStadt, a new workflow-driven urban energy simulation platform for CityGML models at CISBAT 2015
Abstract: In this paper, we introduce new urban energy simulation platform SimStadt, which has been developed to support public authorities and engineering companies in the planning of the energy transition at urban scale. SimStadt design is marked by two particular features: 1- it is based on the open 3D city model CityGML and, 2- its workflow-driven structure is highly modular and extensible. These particularities allow him for a potentially unlimited variety of urban analysis, benefiting from the big geo data possibilities. This first version contains the workflows Solar and PV potential analysis, Energy demand and CO2 emission calculation, and refurbishment scenarios generation and simulation. Other workflows and plug-ins are under way, in particular district network design and simulation. This paper details these features and workflows, and presents an application on the administrative district of Ludwigsburg, a case study of half a million inhabitants spread over 34 municipalities
Stzalka, Aneta; Monien, Dirk; Koukofikis, Athanasios; Eicker, Ursula Sensitivity analysis for minimization of input data for urban scale heat demand forecasting at 14th International Conference on Sustainable Energy Technologies - SET 2015
Abstract: In the paper a methodology based on 3D building and city models is presented to calculate urban heat demand for different refurbishment scenarios. This methodology is validated on six case study buildings of the City of Essen in Germany. The influences of the availability and quality of data input regarding the geometrical and physical parameters on the accuracy of simulation models are analysed. Different CityGML Levels of Details (LoDs) of the building models as well as different sources of the physical parameters are tested in order to investigate the uncertainty of the methods used. In the first step, a semi-automated method with data pre-processing (FME software) as well as simulation of the heat demand (INSEL8 software) are used. The results are compared with a fully-automated method implemented in the urban simulation platform SimStadt, whose development is ongoing in the project with the same name (www.simstadt.eu). This platform has a special module integrated, which allows an automatic data pre- processing. Both methods calculate heat demand based on monthly energy balance (standardised in Germany with the DIN V 18599, or in Europe with the ISO 13790). The calculation of the heat demand with different accuracy of the data input enables to make a statement about which parameters have the most influence on the results. Considering the difficulties in obtaining data available at a city scale this information is very useful for future reductions of the effort of data capturing. For example, the analysis showed that the geometrical Level of Detail can give up to 12% of error depending which of the LoDs are available for the analysed building. In the next stage, the methods tested first on the six case study buildings can be extrapolated for the whole City of Essen. This methodology could be even extended to other cities on condition that they have 3D city models available.
Wate, Parag and Coors, Volker: 3D Data Models for Urban Energy Simulation at 6th International Building Physics Conference, IBPC 2015
Abstract: Sustainable use and management of energy resources is a challenging task for growing urban population. Especially, an urban environment in temperate continental climate consumes high energy resources for their space heating and domestic hot water demands. Assessment of thermal energy requirements for future energy demands is fundamental to sustainable urban environment. Thermal energy demand can be simulated using physical and empirical laws from building physics domain. Physical laws compute thermal energy consumption based on heterogeneous datasets from various data sources. These datasets may include information from cadastre, building registers, inhabitant census, 3D building models, ground surveys and meteorological databases. Furthermore, depending upon availability, accessibility and level of detail, specific simulation methods are usually employed for evaluation of energy consumption at different spatial scales. This paper attempts to identify input data parameters which could facilitate validation and calibration of thermal energy demand based on input data sensitivity using simulation methods.
2014
Nouvel, Romain; Zirak, Maryam; Dastageeri, Habiburrahman; Coors, Volker; Eicker, Ursula Urban energy analysis based on 3D city model for national scale applications at IBPSA Germany Conference Aachen
Abstract: In this paper, we present a methodology based on 3D city model to manage a realistic energy analysis of the building stock, building per building, at a very large scale (national application for instance). This methodology is tested on the City of Ludwigsburg and its more than 14.000 buildings. The influences of the data availability and quality on the model accuracy is analysed, for both geometrical and semantical information data. This paper is ended up by exposing some technological trends and policy needs to improve the realism and potentials of this methodology
2013
Eicker, Ursula; Nouvel, Romain; Duminil, Eric; Coors, Volker Assessing passive and active solar energy resources in cities using 3D city models at 2013 ISES Solar World Congress
Abstract: Many cities today are committed to increasing the energy efficiency of buildings and the fraction of renewables. However, quantitative data on urban energy performance are rarely available during the design stage of new towns or for rehabilitation scenarios of existing cities. Three dimensional city models based on the spatio-semantic data format CityGML offer powerful new methods for the quantitative evaluation of urban energy demand and costs, and simultaneously allow the simulation of renewable energy systems. Such a ‘semantically enriched’ models was used in this work for energy demand diagnostics, refurbishment forecast and renewable supply scenarios. A case study was done using this method in an existing urban quarter in Ludwigsburg/Germany. Based on its three dimensional representation, the photovoltaic potential has been calculated and compared with the electricity demand to establish the photovoltaic fraction. On the thermal side, the passive solar gains were simulated for each building in the city quarter to analyse the solar contribution for heating demand reduction. The simulations were validated with measured gas consumptions. Some rehabilitation scenarios have also been simulated. In such a moderately dense post-war district, the calculated energy savings potential reach in total 65%, equally distributed between heat savings following building envelope refurbishment, and electricity savings due to the installation of PV on the roofs.
2012
Strzalka, Aneta; Alam, Nazmul; Duminil, Eric; Coors, Volker; Eicker, Ursula Large scale integration of photovoltaics in cities in Applied Energy
Abstract: For a large scale implementation of photovoltaics (PV) in the urban environment, building integration is a major issue. This includes installations on roof or facade surfaces with orientations that are not ideal for maximum energy production. To evaluate the performance of PV systems in urban settings and compare it with the building user’s electricity consumption, three-dimensional geometry modelling was combined with photovoltaic system simulations. As an example, the modern residential district of Scharnhauser Park (SHP) near Stuttgart/Germany was used to calculate the potential of photovoltaic energy and to eval- uate the local own consumption of the energy produced. For most buildings of the district only annual electrical consumption data was available and only selected buildings have electronic metering equipment. The available roof area for one of these multi- family case study buildings was used for a detailed hourly simulation of the PV power production, which was then compared to the hourly measured electricity consumption. The results were extrapolated to all buildings of the analyzed area by normalizing them to the annual consumption data. The PV systems can produce 35% of the quarter’s total electricity consumption and half of this generated electricity is directly used within the buildings.