GEOSPATIAL DATA FOR ENERGY EFFICIENCY AND LOW CARBON CITIES – OVERVIEW, EXPERIENCES AND NEW PERSPECTIVES –
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paper_title: Estimation of Light Pollution Using Satellite Remote Sensing and Geographic Information System Techniques

paper_content:

The primary focus of this research is to estimate light pollution in the urban and suburban regions of Pakistan with the help of satellite remote sensing (SRS) and geographic information system (GIS) techniques. Analog maps and multi-temporal nighttime images of the Defense Meteorological Satellite Program (DMSP) onboard Operational Linescan System (OLS) sensor were used in this study. A series of direct and indirect light pollution maps of the study area were generated and analyzed. The results of the study show that in the urban environment, light pollution is mainly due to artificial nightlight sources.
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paper_title: Improving the energy efficiency of the existing building stock: A critical review of commercial and institutional buildings

paper_content:

The building stock in the world consumes approximately 40% of the energy and emits one third of the total greenhouse gases emissions (GHG). Improving the energy efficiency in buildings is vital to address the climate change and achieve energy independence (i.e. to become net-zero energy). Improving energy performance in existing buildings has been receiving significant attention recently, which entails reducing energy demand for building operations, without affecting the health and comfort of its occupants. This approach requires strategies beyond mere technical advancements. However, there is limited published literature which has comprehensively addressed these issues.
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paper_title: Towards Systematic Prediction of Urban Heat Islands: Grounding Measurements, Assessing Modeling Techniques

paper_content:

While there exists extensive assessment of urban heat, we observe myriad methods for describing thermal distribution, factors that mediate temperatures, and potential impacts on urban populations. In addition, the limited spatial and temporal resolution of satellite-derived heat measurements may limit the capacity of decision makers to take effective actions for reducing mortalities in vulnerable populations whose locations require highly-refined measurements. Needed are high resolution spatial and temporal information for urban heat. In this study, we ask three questions: (1) how do urban heat islands vary throughout the day? (2) what statistical methods best explain the presence of temperatures at sub-meter spatial scales; and (3) what landscape features help to explain variation in urban heat islands? Using vehicle-based temperature measurements at three periods of the day in the Pacific Northwest city of Portland, Oregon (USA), we incorporate LiDAR-derived datasets, and evaluate three statistical techniques for modeling and predicting variation in temperatures during a heat wave. Our results indicate that the random forest technique best predicts temperatures, and that the evening model best explains the variation in temperature. The results suggest that ground-based measurements provide high levels of accuracy for describing the distribution of urban heat, its temporal variation, and specific locations where targeted interventions with communities can reduce mortalities from heat events.
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paper_title: Energy efficiency of lighting installations: Software application and experimental validation

paper_content:

Abstract The rational use of energy and energy-efficient environmental public street lighting is an important topic. In the design of new public lighting installations, national regulations containing energy-efficient guidelines are already used. Nevertheless, either in new installations or in reconstructions of existing lighting, designers do not generally consider all the available means to save energy. In installations of street lighting, energy consumption can be reduced by reducing the losses in the conductors, associated with the efficiency of the equipment, allowing better use of the available energy. The losses in the conductors must be analysed in conjunction with all the loads that contribute to the current in the sections of the installed street lighting. When opting for more efficient lamps and luminaires or lighting control systems, the current decreases in the sections covered with the most significant power loss due to proportionality with the square of the current. This decrease, often forgotten, is considered in this work in the investment analysis of efficiency and sustainable street lighting via simulation and experimental results. This analysis, combined with the features and operating parameters of the electrical installation, accounts for all the gains that can make a difference in the choice of efficient street lighting.
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paper_title: GIS-Based Planning and Modeling for Renewable Energy: Challenges and Future Research Avenues

paper_content:

In the face of the broad political call for an “energy turnaround”, we are currently witnessing three essential trends with regard to energy infrastructure planning, energy generation and storage: from planned production towards fluctuating production on the basis of renewable energy sources, from centralized generation towards decentralized generation and from expensive energy carriers towards cost-free energy carriers. These changes necessitate considerable modifications of the energy infrastructure. Even though most of these modifications are inherently motivated by geospatial questions and challenges, the integration of energy system models and Geographic Information Systems (GIS) is still in its infancy. This paper analyzes the shortcomings of previous approaches in using GIS in renewable energy-related projects, extracts distinct challenges from these previous efforts and, finally, defines a set of core future research avenues for GIS-based energy infrastructure planning with a focus on the use of renewable energy. These future research avenues comprise the availability base data and their “geospatial awareness”, the development of a generic and unified data model, the usage of volunteered geographic information (VGI) and crowdsourced data in analysis processes, the integration of 3D building models and 3D data analysis, the incorporation of network topologies into GIS, the harmonization of the heterogeneous views on aggregation issues in the fields of energy and GIS, fine-grained energy demand estimation from freely-available data sources, decentralized storage facility planning, the investigation of GIS-based public participation mechanisms, the transition from purely structural to operational planning, data privacy aspects and, finally, the development of a new dynamic power market design.
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paper_title: FIRST STEPS TOWARDS AN INTEGRATED CITYGML-BASED 3D MODEL OF VIENNA

paper_content:

Abstract. This paper presents and discusses the results regarding the initial steps (selection, analysis, preparation and eventual integration of a number of datasets) for the creation of an integrated, semantic, three-dimensional, and CityGML-based virtual model of the city of Vienna. CityGML is an international standard conceived specifically as information and data model for semantic city models at urban and territorial scale. It is being adopted by more and more cities all over the world. The work described in this paper is embedded within the European Marie-Curie ITN project “Ci-nergy, Smart cities with sustainable energy systems”, which aims, among the rest, at developing urban decision making and operational optimisation software tools to minimise non-renewable energy use in cities. Given the scope and scale of the project, it is therefore vital to set up a common, unique and spatio-semantically coherent urban model to be used as information hub for all applications being developed. This paper reports about the experiences done so far, it describes the test area and the available data sources, it shows and exemplifies the data integration issues, the strategies developed to solve them in order to obtain the integrated 3D city model. The first results as well as some comments about their quality and limitations are presented, together with the discussion regarding the next steps and some planned improvements.
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paper_title: Beyond energy efficiency in evaluating sustainable development in planning and the built environment

paper_content:

The EU has set the policy target of reducing energy use by 20% by the year 2020. Therefore, a substantial consumption decrease is needed in the built environment sector. Despite the great energy efficiency improvements in households, recent energy consumption data analyses show that these targets will unlikely be reached. The general aim of this study is to point out the need to define new indicators and evaluation approaches in urban planning and the built environment which are based on the concept of ‘energy subsidiarity’, focusing on local renewable resources rather than on current approaches based on energy efficiency. This concept correlates energy consumption with the energy supply from local renewable resources and is here proposed as the new urban planning evaluation approach toward a sustainable built environment.In the paper, the ‘Jevons Paradox’ concept and the ‘energy rebound effect’ phenomenon are used to demonstrate how current approaches based on energy efficiency, alone, cannot lead to a r...
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paper_title: HOW TO PINPOINT ENERGY-INEFFICIENT BUILDINGS? AN APPROACH BASED ON THE 3D CITY MODEL OF VIENNA

paper_content:

This paper describes a methodology to assess the energy performance of residential buildings starting from the semantic 3D city model of Vienna. Space heating, domestic hot water and electricity demand are taken into account. ::: ::: The paper deals with aspects related to urban data modelling, with particular attention to the energy-related topics, and with issues related to interactive data exploration/visualisation and management from a plugin-free web-browser, e.g. based on Cesium, a WebGL virtual globe and map engine. ::: ::: While providing references to existing previous works, only some general and introductory information is given about the data collection, harmonisation and integration process necessary to create the CityGML-based 3D city model, which serves as the central information hub for the different applications developed and described more in detail in this paper. ::: ::: The work aims, among the rest, at developing urban decision making and operational optimisation software tools to minimise non-renewable energy use in cities. ::: ::: The results obtained so far, as well as some comments about their quality and limitations, are presented, together with the discussion regarding the next steps and some planned improvements.
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paper_title: SOLAR RADIATION ESTIMATION ON BUILDING ROOFS AND WEB-BASED SOLAR CADASTRE

paper_content:

The aim of this study is the estimation of solar irradiance on building roofs in complex Alpine landscapes. Very high resolution geometric models of the building roofs are generated by means of advanced automated image matching methods. Models are combined with raster and vector data sources to estimate the incoming solar radiation hitting the roofs. The methodology takes into account for atmospheric effects, site latitude and elevation, slope and aspect of the terrain as well as the effects of shadows cast by surrounding buildings, chimneys, dormers, vegetation and terrain topography. An open source software solution has been developed and applied to a study area located in a mountainous site and containing some 1250 residential, commercial and industrial buildings. The method has been validated by data collected with a pyranometer and results made available through a prototype WebGIS platform.
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paper_title: GIS-Based Energy Consumption Model at the Urban Scale for the Building Stock

paper_content:

Energy efficient buildings' issue integrated into the district and CO2 emission reduction strategies and policies are one of the main concerns in the European Union (EU). In order to achieve an effective impact, instead of just concentrating on the improvement in terms of energy efficiency to one particular building, this approach requires challenges to be solved in an entire municipality or an entire district. Accordingly, it is significant understanding the comprehensive residential building stock models in the urban environment able to promote a sustainable energy planning. In this paper we describe a new methodology based on two different modelling approaches top-down and bottom-up with the aim to evaluate the buildings energy consumption model of a municipality. This methodology is mainly based on information that is already available on building stock from the literature and data collection (i.e., technical department of the municipality, web, energy auditors and others) which is later transferred into the Geographic information system (GIS). Into this, in future studies GIS platform provides the information on energy performance in the whole city as well as creating the urban energy maps for assessing retrofitting scenarios and support decision making for policy implementation to achieve sustainable urban planning. This study is part of an ongoing Smart City research study, national cluster project named Zero Energy Buildings in Smart Urban Districts (EEB) and is tested in a medium sized town in the Piedmont region (Italy), and the results are discussed
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paper_title: Analysis and diagnosis of the energy performance of buildings and districts: Methodology, validation and development of Urban Energy Maps

paper_content:

Abstract A new analytical methodology aimed at characterizing the energy performance of new and existing buildings is proposed for both winter and summer and with reference to entire urban context, and the methodology is transferred into Geographic Information Systems (GISs). The main target is the evaluation of criticalities of the building stock, promoting effective design for new buildings and proper refurbishment of existing buildings. In this regard, the application of standardized procedures is too onerous if the goal is the qualitative distribution of the energy performances with reference to entire urban areas. The energy demands for space heating are evaluated by simplifying the methodology of the European Standard EN ISO 13790, while with reference to summer cooling, a new hybrid method has been specifically developed. The whole method was applied to the entire historical center of the Italian city of Benevento and, thus, to more than 500 buildings. Moreover, comparisons with measured/evaluated energy requests have been performed to identify the reliability of the methodology. Information on energy performances in the whole city center, moreover, allowed for the setting of “Urban Energy Maps,” a tool dedicated to local government, usable for advanced energy planning and territorial control in energy supply.
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paper_title: The city and urban heat islands: A review of strategies to mitigate adverse effects

paper_content:

Cities occupy 2% of the earth's surface but their inhabitants consume 75% of the world's energy resources. Under certain conditions, the heat from solar radiation and different urban activities can make city temperatures rise in certain areas, simply because of the way in which a city is structured. This effect is known as the urban heat island (UHI). This article provides a review of recent research on the urban heat island as well as of the strategies that can be applied to mitigate its adverse effects. Such strategies can be applied in the project design phase of urban planning and thus directly affect city temperatures on a local scale. The elements analyzed in this paper include green spaces, trees, albedo, pavement surfaces, vegetation, as well as building types and materials. The discussion of this research clearly reflects the impact of urban morphology on local temperatures and how urban design can be modified to reduce energy consumption and CO2 emissions into the atmosphere. This study is useful for professionals who are responsible for decision-making during the design phase of urban planning.
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paper_title: 3D Solarweb: A solar cadaster in the Italian Alpine landscape

paper_content:

The paper presents the research carried out in the on-going 3DSolarWeb project to test and implement a complete pipeline for the generation of a solar cadastre of building roofs located in alpine areas. The project aims at providing reliable results in a costeffective way, using (low resolution) available data and new aerial imagery acquisitions as input. The environmental context is digitally represented using already existing low resolution LiDAR data (1–2 m resolution), while the urban area is modelled using high resolution aerial images (10–20 cm GSD) and photogrammetric DSM. Reliable models and algorithms for the estimation of the incoming sun radiance are then adopted and a WebGIS is set up for the interactive calculation of the photovoltaic (PV) potential in a raster-based form. The paper summarizes the entire pipeline and the results (Figure 1) achieved on the test areas to show the potentialities of the method and the web-based service.
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paper_title: High-Resolution Imagery of Earth at Night: New Sources, Opportunities and Challenges

paper_content:

Images of the Earth at night are an exceptional source of human geographical data, because artificial light highlights human activity in a way that daytime scenes do not. The quality of such imagery dramatically improved in 2012 with two new spaceborne detectors. The higher resolution and precision of the data considerably expands the scope of possible applications. In this paper, we introduce the two new data sources and discuss their potential limitations using three case studies. Data from the Visible Infrared Imaging Radiometer Suite Day-Night Band (VIIRS DNB) is shown to have sufficient resolution to identify major sources of waste light, such as airports, and we find considerable variation in the peak radiance of the world's largest airports. Nighttime imagery brings "cultural footprints" to light: DNB data reveals that American cities emit many times more light per capita than German cities and that cities in the former East of Germany emit more light per capita than those in the former West. Photographs from the International Space Station, the second new source of imagery, provide some limited spectral information, as well as street-level resolution. These images may be of greater use for epidemiological studies than the lower resolution DNB data.
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paper_title: LARGE SCALE INTEGRATION OF PHOTOVOLTAICS IN CITIES

paper_content:

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 evaluate the local own consumption of the energy produced.
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paper_title: Mapping Lightscapes: Spatial Patterning of Artificial Lighting in an Urban Landscape

paper_content:

Artificial lighting is strongly associated with urbanisation and is increasing in its extent, brightness and spectral range. Changes in urban lighting have both positive and negative effects on city performance, yet little is known about how its character and magnitude vary across the urban landscape. A major barrier to related research, planning and governance has been the lack of lighting data at the city extent, particularly at a fine spatial resolution. Our aims were therefore to capture such data using aerial night photography and to undertake a case study of urban lighting. We present the finest scale multi-spectral lighting dataset available for an entire city and explore how lighting metrics vary with built density and land-use. We found positive relationships between artificial lighting indicators and built density at coarse spatial scales, whilst at a local level lighting varied with land-use. Manufacturing and housing are the primary land-use zones responsible for the city’s brightly lit areas, yet manufacturing sites are relatively rare within the city. Our data suggests that efforts to address light pollution should broaden their focus from residential street lighting to include security lighting within manufacturing areas.
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paper_title: Automatic façade modelling using point cloud data for energy-efficient retrofitting

paper_content:

Energy-efficient retrofitting of existing buildings is a key aspect for reaching the proposed energy consumption reduction targets fixed by public authorities in different countries. For this task, the availability of as-built building models is of primary importance for both diagnosis of thermal dispersion and designing of retrofitting. In this paper, we present an automated methodology to derive highly detailed 3D vector models of existing building facades starting from terrestrial laser scanning data. The presented methodology first accomplishes the segmentation of the point cloud of a building facade into its planar elements. Then, starting from the identified planar clusters, facade breaklines are automatically extracted to be used later to generate a 3D vector model. During this final step, some priors on urban scenes like the prevalence of straight lines and orthogonal intersections are exploited to set additional constraints. The final product is a semantically enriched 3D model of the building facade that can be integrated in Building Information Model (BIM) for planned maintenance. Eventually, the integration between derived facade models and infrared thermography (IRT) is presented for energy efficiency evaluation of buildings and detection of thermal anomalies.
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paper_title: Solar Urban Planning: A Parametric Approach

paper_content:

Abstract Solar urban planning is a complex process which needs to consider the interplay between multiple factors and variables, depending on urban form and solar energy inputs. This paper presents a methodology based on a parametric approach to quantify solar energy potential from photovoltaic systems in the urban context. Solar power as a source of low carbon energy is an essential component for the sustainability of cities and its implementation and management, through urban planning practices, can play a strategic role in improving the energy efficiency of cities. Within this framework, the amount of energy provided by the integration of photovoltaic systems into existing buildings and their energy consumption, are two key indicators to identify the neighborhoods of the city that behave as urban units with positive, negative or balanced energy performances. On this basis, a workflow that combines geographical information system (ArcGIS®), parametric modeling (Rhinoceros® – GrasshopperTM) and solar dynamic analysis (Geco® – Ecotect®), has been developed. A case study has been conducted in a medium-size city in Portugal: Oeiras. The research also evaluated the implementation of a smart grid model supported in the relationship between urban densities and mixed land-use. This infrastructure provides the connection between the cellular units and the city energy system in order to optimize the demand-supply balance. In this way, the results reveal how widespread integration of PV systems, in the long term, can give rise to cities with better energy performances and thus contribute to mitigate greenhouse gas (GHG) emissions related to fossil fuels consumption.
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paper_title: Assessing solar potential of commercial and residential buildings in Indianapolis using LiDAR and GIS modeling

paper_content:

Renewable energy systems (RES) have become a vital part of energy use due to the fact that fossil energy declines and demand for energy keeps growing. Among all types of renewable energies, solar energy is the most important resource for the urban areas, since it is easy to obtain, renewable, and produces very little waste. In dense urban areas, building roofs have been utilized or are considered as the locations for Photovoltaic system (PV) or solar panel installation. This research aimed at extracting building roofs from LiDAR data using an object-based segmentation method in City of Indianapolis, USA, and calculating annual solar energy yield for each extracted roof. LiDAR Digital Elevation Model (DEM) was subtracted from LiDAR Digital Surface Model (DSM) to produce the Normalized Height Model (NHM), which represented the absolute heights of objects on the ground. The building extraction was implemented by using a fuzzy rule-based classification method to filter out commonly seen features in the urban environment such as trees, lawns, and roads. Annual solar radiation yield for each roof plane was calculated based on a hemispherical viewed algorithm. Shadowing effect caused by surrounding trees and solid objects were also taken into account to obtain more accurate solar energy values. Finally, suitability of PV installation for individual roofs was rated based on their annual solar energy output. All extracted roof planes were saved as polygons containing the information of size, azimuth, slope, and exposure for future use.
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paper_title: Generating web-based 3D City Models from OpenStreetMap: The current situation in Germany

paper_content:

This paper investigates the prospects for the generation of interactive 3D City Models based on free geo-data available from the OpenStreetMap (OSM) project and public domain height information provided by the Shuttle Radar Topography Mission. In particular, the suitability and quality of the OpenStreetMap data for 3D visualizations of traffic infrastructure, buildings and points of interest (POIs) is reviewed. The diversity and quantity of the points of interest provide new opportunities and challenges in creating customized and detailed visualization of cities. Specialized web services were implemented to filter and display the data in an acceptable manner. All applied web services of the 3D spatial data infrastructure are based on standards and draft specifications of the open geospatial consortium (OGC). The service is available online at www.osm-3d.org.
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paper_title: Solar Potential Analysis and Integration of the Time-dependent Simulation Results for Semantic 3D City Models Using Dynamizers

paper_content:

Abstract. Semantic 3D city models play an important role in solving complex real-world problems and are being adopted by many cities around the world. A wide range of application and simulation scenarios directly benefit from the adoption of international standards such as CityGML. However, most of the simulations involve properties, whose values vary with respect to time, and the current generation semantic 3D city models do not support time-dependent properties explicitly. In this paper, the details of solar potential simulations are provided operating on the CityGML standard, assessing and estimating solar energy production for the roofs and facades of the 3D building objects in different ways. Furthermore, the paper demonstrates how the time-dependent simulation results are better-represented inline within 3D city models utilizing the so-called Dynamizer concept. This concept not only allows representing the simulation results in standardized ways, but also delivers a method to enhance static city models by such dynamic property values making the city models truly dynamic. The dynamizer concept has been implemented as an Application Domain Extension of the CityGML standard within the OGC Future City Pilot Phase 1. The results are given in this paper.
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paper_title: Spatial Analytics for Enhancing Street Light Coverage of Public Spaces

paper_content:

ABSTRACTThe spatial distribution of public area lighting in an urban region greatly influences human activities and safety. Such services are not free, often consuming significant budgetary resources to site, maintain, and operate on an annual basis. Further, lighting has been found to negatively impact the environment by limiting visibility in the form of glare, trespass, and sunglow as well disturbing diurnal rhythms, breeding behavior, and migration patterns of fauna, not to mention impacts and costs attributable to energy generation. Enhancing configurations of nighttime lighting sources is therefore important on many fronts to address fiscal limitations and sustainability concerns. There are many implications for system inefficiency that arise due to growth and development, necessitating systematic evaluation approaches. Light provision can be assessed using spatial optimization. Both benefits and impacts can be taken into account, enabling a range of analytical methods to be brought to bear on decis...
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paper_title: Applications of 3D City Models: State of the Art Review

paper_content:

In the last decades, 3D city models appear to have been predominantly used for visualisation; however, today they are being increasingly employed in a number of domains and for a large range of tasks beyond visualisation. In this paper, we seek to understand and document the state of the art regarding the utilisation of 3D city models across multiple domains based on a comprehensive literature study including hundreds of research papers, technical reports and online resources. A challenge in a study such as ours is that the ways in which 3D city models are used cannot be readily listed due to fuzziness, terminological ambiguity, unclear added-value of 3D geoinformation in some instances, and absence of technical information. To address this challenge, we delineate a hierarchical terminology (spatial operations, use cases, applications), and develop a theoretical reasoning to segment and categorise the diverse uses of 3D city models. Following this framework, we provide a list of identified use cases of 3D city models (with a description of each), and their applications. Our study demonstrates that 3D city models are employed in at least 29 use cases that are a part of more than 100 applications. The classified inventory could be useful for scientists as well as stakeholders in the geospatial industry, such as companies and national mapping agencies, as it may serve as a reference document to better position their operations, design product portfolios, and to better understand the market.
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paper_title: 3D Solarweb: A solar cadaster in the Italian Alpine landscape

paper_content:

The paper presents the research carried out in the on-going 3DSolarWeb project to test and implement a complete pipeline for the generation of a solar cadastre of building roofs located in alpine areas. The project aims at providing reliable results in a costeffective way, using (low resolution) available data and new aerial imagery acquisitions as input. The environmental context is digitally represented using already existing low resolution LiDAR data (1–2 m resolution), while the urban area is modelled using high resolution aerial images (10–20 cm GSD) and photogrammetric DSM. Reliable models and algorithms for the estimation of the incoming sun radiance are then adopted and a WebGIS is set up for the interactive calculation of the photovoltaic (PV) potential in a raster-based form. The paper summarizes the entire pipeline and the results (Figure 1) achieved on the test areas to show the potentialities of the method and the web-based service.
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paper_title: Energy planning tools and CityGML-based 3D virtual city models: experiences from Trento (Italy)

paper_content:

This article presents the first results concerning the development and implementation of a tool for the estimation of the energy performance for residential buildings at city scale. Space heating and domestic hot water production are taken into account. Project “EnerCity” focuses on two main topics: (a) the creation of a CityGML-compliant 3D city model from sub-optimal datasets and (b) its adoption as information hub to develop energy-related assessment tools. A part of the city of Trento, in northern Italy, was chosen as the case study area for testing purposes; however, the methodology was developed to be extended to the whole city. Only publicly available data were used. The energy demand calculation method is based on the Italian Technical Specifications UNI/TS 11300:2008. For each building, the primary energy demand for space heating and domestic hot water production, as well as the resulting energy performance index, are estimated. In order to characterise the buildings, heterogeneous datasets (cadastral data, statistical data, etc.) were harmonised and integrated. All residential buildings were successively classified into distinct building types according to the criteria defined for Italy in the European project “Tabula”. The developed tool allows for data visualisation, editing as well as interactive refurbishment of the buildings. The article describes all relevant steps of the project and discusses possible enhancements and the future improvements.
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paper_title: Applications of 3D City Models: State of the Art Review

paper_content:

In the last decades, 3D city models appear to have been predominantly used for visualisation; however, today they are being increasingly employed in a number of domains and for a large range of tasks beyond visualisation. In this paper, we seek to understand and document the state of the art regarding the utilisation of 3D city models across multiple domains based on a comprehensive literature study including hundreds of research papers, technical reports and online resources. A challenge in a study such as ours is that the ways in which 3D city models are used cannot be readily listed due to fuzziness, terminological ambiguity, unclear added-value of 3D geoinformation in some instances, and absence of technical information. To address this challenge, we delineate a hierarchical terminology (spatial operations, use cases, applications), and develop a theoretical reasoning to segment and categorise the diverse uses of 3D city models. Following this framework, we provide a list of identified use cases of 3D city models (with a description of each), and their applications. Our study demonstrates that 3D city models are employed in at least 29 use cases that are a part of more than 100 applications. The classified inventory could be useful for scientists as well as stakeholders in the geospatial industry, such as companies and national mapping agencies, as it may serve as a reference document to better position their operations, design product portfolios, and to better understand the market.
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paper_title: Topologically consistent 3D city models obtained by extrusion

paper_content:

One of the simplest methods to construct a 3D city model is to extrude building footprints to obtain 'block-shaped' polyhedra representing buildings. Although the method is well known and easy to implement, if the 2D topological relationships between the footprints are not taken into account, the resulting 3D city models will not necessarily be topologically consistent (i.e. primitives shared by 3D buildings will be duplicated and/or intersect each others). As a result, the model will be of little use for most applications, besides visualization that is. In this article, we present a new extrusion procedure to construct topologically consistent 3D city models. It is based on the use of a constrained triangulation, is conceptually simple and offers great flexibility to create city models in different formats (e.g. CityGML or a surface-based representation). We have implemented the procedure, tested it with real-world data sets and validated it.
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paper_title: Towards generating highly detailed 3D CityGML models from OpenStreetMap

paper_content:

About one decade has passed since US vice president Al Gore articulated his vision of Digital Earth DE. Within this decade, a global multi-resolution and three-dimensional 3D representation of the Earth, which sums up the DE vision, increasingly gained interest in both public and science. Due to the desired high resolution of the available data, highly detailed 3D city models comprise a huge part of DE and they are becoming an essential and useful tool for a range of different applications. In the past as well as at present, 3D models normally come from a range of different sources generated by professionals, such as laser scans or photogrammetry combined with 2D cadaster data. Some models are generated with semi-automated or fully automated approaches, but in most cases manual fine tuning or even manual construction from architectural plans is required. Further beyond outdoor city models, DE additionally envisages the provision of indoor information. That is, the interior structure of public or publically accessible buildings, such as airports or shopping malls, is represented and made available in 3D; however, at the moment, such models are mostly created by hand and essentially based on professional data sources. In contrast to such professional data, which is mainly captured by surveyors or companies, the last few years revealed the phenomenon of crowdsourced geodata, which receives an increasing attractiveness as an alternative data source for many Geographic Information Systems GIS. Former research already demonstrated the power and richness of such geodata – especially OpenStreetMap OSM – and it has also been proved that this non-standardized, crowdsourced geodata can be combined with international standards of the Open Geospatial Consortium OGC. For example, CityGML Level-of-Detail 1 LoD1 and LoD2 models have already been created automatically from OSM. The research presented in this article will further continue on the automated generation of CityGML models from OpenStreetMap. Essentially, a method for the creation of highly detailed CityGML LoD4 models with interior structures will be explained. By applying the invented approach on existing OSM data, limitations and restrictions of the IndoorOSM mapping proposal, the available data and the developed approach are revealed and discussed.
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Title: GEOSPATIAL DATA FOR ENERGY EFFICIENCY AND LOW CARBON CITIES – OVERVIEW, EXPERIENCES AND NEW PERSPECTIVES –

Section 1: INTRODUCTION
Description 1: Summarize the importance of urban areas in energy consumption, the need for energy efficiency, and the potential of geospatial tools.

Section 2: Aims and structure of the paper
Description 2: Outline the goals of the paper and provide an overview of its structure.

Section 3: RELATED WORKS
Description 3: Review existing interdisciplinary projects and studies utilizing ICT and geospatial solutions for energy management and efficiency.

Section 4: PROJECTS AND BEST PRACTICES IN 3D URBAN ENERGY SYSTEMS
Description 4: Describe various projects and best practices using 3D urban energy systems to enhance energy efficiency and renewable energy usage.

Section 5: The Energy and Climate Atlas - Helsinki, Finland
Description 5: Detail the development and features of the Helsinki Climate and Energy Atlas, including its applications and benefits.

Section 6: The Energy Atlas - Berlin, Germany
Description 6: Explain the creation and components of the Berlin Energy Atlas and its role in strategic energy planning.

Section 7: DYNAMIC PUBLIC LIGHTING
Description 7: Discuss the Dynamic Light project focused on improving energy efficiency and reducing light pollution in urban street lighting.

Section 8: Pilot areas
Description 8: Provide information on the pilot areas for the Dynamic Light project and their specific implementations.

Section 9: Methodology
Description 9: Describe the methodology for creating geospatial databases and integrating them with 3D models for efficient streetlight management.

Section 10: ENERGY MANAGEMENT IN PUBLIC BUILDINGS
Description 10: Present the BOOSTEE-CE project aimed at improving the energy performance of public buildings through smart energy management tools.

Section 11: Estimation of the amount of heating losses
Description 11: Detail the approach for estimating heating losses in public buildings as part of the BOOSTEE-CE project.

Section 12: CONCLUSIONS
Description 12: Summarize the findings and emphasize the importance of geospatial data and ICT tools in fostering energy efficiency in urban areas.