Karl-Heinz Häfele - Academia.edu (original) (raw)

Papers by Karl-Heinz Häfele

Due to the transition from fossil energy carriers to more renewable energy resources, the availab... more Due to the transition from fossil energy carriers to more renewable energy resources, the availability of energy in future will be fluctuating. Under these conditions, an accurate energy demand simulation for buildings is strongly needed as planning instrument on district or city level. This paper introduces a new data model for the energy relevant properties of buildings. It extends the existing standard CityGML for 3D city models by energy relevant properties like, e.g., physical materials, thermal zones and thermal boundaries, and building occupant's behaviour. The energy extension of CityGML is designed as system-independent interface to energy simulation systems and shall support detailed simulation on the level of single buildings as well as energy demand assessments on district and city level.

2022 IEEE PES Innovative Smart Grid Technologies Conference Europe (ISGT-Europe), Oct 10, 2022

Building Simulation Conference proceedings, Jun 23, 2020

A fundamental problem to perform reliable energy simulation on urban level is that available data... more A fundamental problem to perform reliable energy simulation on urban level is that available data from statistics or cadastral agencies is not sufficient. To perform an energetic simulation based on such data, each simulation tool has its own strategies to enrich the data with missing, energy relevant information. In most cases, these enrichment mechanisms are not transparent for the user and the obtained results are strongly dependent on the used tool. The present paper describes a new approach to achieve more transparency in analysing the energetic performance of buildings on urban scale. Thereby a transparent enrichment process based on the standardized 3D city model CityGML and its energy-related extension (EnergyADE) is used. Basic concepts of this process and its implementation with two building energy simulation systems are described.

Building and Environment, 2022

Climate change, increasing emissions and rising global temperatures have gradually affected the w... more Climate change, increasing emissions and rising global temperatures have gradually affected the way we think about the future of our planet. Urban areas possess significant potential for reducing the energy consumption of the overall energy system. In recent years, there is an increasing number of research initiatives related to Urban Building Energy Modelling (UBEM) that focus on simulation processes and validation techniques. Although input data are crucial for the modelling process as well as for the validity of the results, the availability of input data and associated data formats were not analysed in detail. This paper closes the identified knowledge gap by presenting a taxonomic analysis of key UBEM components including: input data formats, simulation tools, simulation results and validation techniques. This paper concludes that over ∼ 95% of the studies analysed were not reproducible due to the absence of information relating to key aspects of the respective methodologies such as data sources and simulation workflows. This paper also qualifies how weak levels of interoperability, with respect to input and output data, is present in all phases of UBEM.

An important aspect of reverse engineering is the production of digital representations of physic... more An important aspect of reverse engineering is the production of digital representations of physical objects for CAD systems. The first stage involves taking 3D coordinate measurements for points on the surface of the object and producing in general an unstructured set of points, called a point cloud. A triangulated surface can be generated from such a point cloud, allowing copies of the original object to be manufactured. However, these triangulated surfaces generally consist of a very large number of triangles with small errors in the positions of their vertices. In many cases the original object is made up of parts of a number of simple geometric objects. Our aim is to segment the triangulated surface into a small number of components, each of which approximates to part of a simple geometric shape. We have developed algorithms for curvature estimation in order to support a 'region growing' method of segmentation.

The present paper describes a semi-automatic process, in which a typical CityGML 3D building mode... more The present paper describes a semi-automatic process, in which a typical CityGML 3D building model is enriched with explicit thermal energy related information and stored in a CityGML Application Domain Extension (ADE). Special emphasis is given to the discussion of suitability of existing CityGML models for city-wide energy simulations. Possible conflicts between the requirements of urban energy simulation systems, the capabilities of the CityGML Energy ADE and the available data are presented, which can be partly resolved by specific geometric / semantic corrections of the model data. For testing and evaluating the approach, interfaces for two building energy simulation systems have been developed.

In designing new buildings, a number of constraints need to be considered. Among these are requir... more In designing new buildings, a number of constraints need to be considered. Among these are requirements concerning the overall building size as well as the number, function, and size of the needed spaces. Additional boundary conditions are implied by the neighborhood of the planned building (e.g. existing buildings and infrastructure, natural environment). In state-of-the-art design processes, these constraints mostly are taken into account only formally. This paper proposes to formalize the space requirements and use a geospatial data model of the surrounding area in order to easily generate different design alternatives in the early design phase. Such approach has a number of advantages. Based on a machine-readable description of the space requirements, different alternatives for a simplified building envelope and a basic space layout can be generated semi-automatically. At least on large sites like hospital districts or industrial sites, different alternatives for the location of a new building may exist. By using geospatial data, it can be checked whether a specific design variant can be realized at a certain location. This will support the decision-making process in finding the most promising early design model, which is promoted in the following design steps. This paper describes a software prototype using a proof-of-concept algorithm to generate several first drafts of building floor plans. These are enriched with additional data like placement or information about volume and used space. Finally, the floor plans are extruded to volumetric objects and exported into the IFC format.

The increasing use of neutral semantic data models in the areas of spatial data and architectural... more The increasing use of neutral semantic data models in the areas of spatial data and architectural design suggest a need to perform building licensing automatically or semi-automatically. Building licensing requires that different types of spatial data be integrated into a single model without losing semantic information. During the checking process it may not be possible to compare and check all data parameters directly. Therefore, models must be evaluated and semantically and geometrically transformed when necessary. This paper introduces a potential workflow concept for building licensing. An approach on how to use data from different models and how to transform data for parameter checking is presented, and a brief outlook is given.

POMOS — POint based Modelling System — developed in the Research Centre Karlsruhe is designed to ... more POMOS — POint based Modelling System — developed in the Research Centre Karlsruhe is designed to close the gap between measuring devices and following CAX-applications. The capabilities of POMOS are focused on point operations, surface generation, surface analysis and interfaces from and to neutral file formats.

2023 Joint Urban Remote Sensing Event (JURSE)

Proceedings of BauSim 2022: 9th Conference of IBPSA-Germany and Austria

The Karlsruhe Institute of Technology maintains a virtual 3D Campus Model for its Campus North, w... more The Karlsruhe Institute of Technology maintains a virtual 3D Campus Model for its Campus North, which represents the building stock, vegetation and infrastructures. For a long period of time, energyrelevant data for each building has been recorded and stored. In addition, sensors and systems are being installed on the campus that provide corresponding measurements on various time scales. This contribution describes the methods used to acquire and monitor the sensor data, and the infrastructure to store the data. Furthermore, visual representations of the sensor data are introduced and the workflow for integration into the virtual campus model is explained. Finally, an implementation is presented that monitors the measured values and generates notifications in case of certain conditions.

Building Simulation Conference proceedings

In diesem Beitrag wird die Anwendung Early Design Configurator (EDC) vorgestellt, die in der Konz... more In diesem Beitrag wird die Anwendung Early Design Configurator (EDC) vorgestellt, die in der Konzeptionsphase Layouts erzeugt und präsentiert. Als Eingabeparameter für die Erzeugung von Layouts werden Umrisse des Gebäudes, das Raumbuch und Entwurfsregeln benötigt. Die Generierung der Raum-Grundrisse des geplanten Gebäudes erfolgt automatisch mit einem evolutionären Algorithmus, in dessen Zielfunktion die Anforderungen und Restriktionen von Raumbuch und Entwurfsregeln eingehen. Durch mehrfache Ausführung des evolutionären Algorithmus lassen sich bei veränderter Gewichtung der Regeln verschiedene Layouts erzeugen. Der beschriebene Prozess zielt nicht darauf ab, fertig geplante Gebäudemodelle automatisiert zu generieren, sondern die Informationen aus der Konzeptionsphase als Building Information Model in den Lebenszyklus des Gebäudes einzubringen.

Second International Conference on 3-D Digital Imaging and Modeling (Cat. No.PR00062)

2000 IEEE Conference on Information Visualization. An International Conference on Computer Visualization and Graphics, 2000

The reverse engineering of a physical object often requires the production of a digital represent... more The reverse engineering of a physical object often requires the production of a digital representation of the object. The object surface is scanned and a large number of points are obtained. These points are often organised in some way which provides adjacency information. However, in other cases, the result is an unstructured set of points, or point cloud. From such a point cloud a triangulated surface can be generated, so in all cases adjacency information can be obtained. Copies of the original object can be manufactured using the triangulated surface to define the shape. Often the original object is made up of parts of a number of simple geometric primitives and could be represented much more simply. Our aim is to segment a discretely represented surface into a small number of such simple geometric components using a 'region growing' approach. This paper describes an improved algorithm (with 'super triangles') for planar extraction, which requires only the data p...