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Heating networks are highly relevant for the achievement of climate protection goals of urban energy systems. This is due to their high renewable energy potential combined with high plant efficiency and utilization rates. For the optimal integration and sector coupling of heating networks in holistic urban energy systems, open source energy system modeling tools are highly recommended. In this contribution, two open source approaches (the "Spreadsheet Energy System Model Generator"-integrated DHNx-Python module (DHNx/SESMG) and Thermos) are theoretically compared, and practically applied to a real-world energy system. Deviations within the results can be explained by incorrectly pre-defined parameters within Thermos and cannot be adjusted by the modeler. The simultaneity is underestimated in the case study by Thermos by more than 20%. This results in undersized heating plant capacities and a 50% higher number of buildings connected to the network. However, Thermos offers a higher end-user usability and over 100 times faster solving. DHNx/SESMG, in contrast, offers the possibility to adjust more model parameters individually and consider multiple energy sectors. This enables a holistic modeling of urban energy systems and the model-based optimization of multi-sectoral synergies.
Traditionelle, lineare Energiesysteme werden zunehmend zu vernetzten, regenerativen Energiesystemen transformiert. Mit dem auf dem „Open Energy Modelling Framework” (oemof) basierenden „Spreadsheet Energy System Model Generator” (SESMG) wurde ein Tool entwickelt, welches die Komplexität und Wechselwirkungen moderner Energiesysteme auf urbaner Ebene automatisiert abbildet. Zur Erstellung individueller Energiesystemmodelle sind ausschließlich quartiersspezifische Parameter notwendig, technische und wirtschaftliche Parameter sind standardmäßig hinterlegt. Mit Hilfe von Algorithmen werden Energieversorgungsszenarien identifiziert, welche individuell definierte Zielgrößen (z. B. monetäre Kosten oder Treibhausgasemissionen) minimieren. Durch die implementierten Methoden zur Modellvereinfachungen können auch mit begrenzten Rechenressourcen (insb. Rechenzeit und Arbeitsspeicherbedarf) große Systeme modelliert und optimiert werden. Die Zielszenarien werden als Diagramme und für die Weiterverarbeitung mit Geoinformationssystemen aufbereitet, sodass die Ergebnisse analysiert, plausibilisiert und präsentiert werden können.
In Germany, the current sectoral urban planning often leads to inefficient use of resources, partly because municipalities lack integrated planning instruments and argumentation strength toward politics, investors, or citizens. The paper develops the ResourcePlan as (i) legal and (ii) a planning instrument to support the efficient use of resources in urban neighborhoods. The integrative, multi-methodological approach addresses the use of natural resources in the building and infrastructural sectors of (i) water (storm- and wastewater) management, (ii) construction and maintenance of buildings and infrastructure, (iii) urban energy system planning, and (iv) land-use planning. First, the development as legal instrument is carried out, providing (i) premises for integrating resource protection at all legal levels and (ii) options for implementing the ResourcePlan within German municipal structures. Second, the evaluation framework for resource efficiency of the urban neighborhoods is set up for usage as a planning instrument. The framework provides a two-stage process that runs through the phases of setting up and implementing the ResourcePlan. (Eco)system services are evaluated as well as life cycle assessment and economic aspects. As a legal instrument, the ResourcePlan integrates resource protection into municipal planning and decision-making processes. The multi-methodological evaluation framework helps to assess inter-disciplinary resource efficiency, supports the spatial identification of synergies and conflicting goals, and contributes to transparent, resource-optimized planning decisions.
A novel approach for ventilation systems is a periodically varying supply air flow rate, the so-called unsteady mode of operation. So far, useful effects of this unsteady operating mode have been observed, but the effect mechanisms are still unknown. In this manuscript, simulations using the recently proposed k-ω-ζ - f model implemented in a sensitized RANS computational framework for a cuboid room with swirl diffusers are compared and validated with PIV measurements.
The Spreadsheet Energy System Model Generator (SESMG) is a tool for modeling and optimizing energy systems with a focus on urban systems. The SESMG is easily accessible as it comes with a browser-based graphical user interface, spreadsheets to provide data entry, and detailed documentation on how to use it. Programming skills are not required for the installation or application of the tool. The SESMG includes advanced modeling features such as the application of the multi-energy system (MES) approach, multi-objective optimization, model-based methods for reducing computational requirements, and automated conceptualization and result processing of urban energy systems with high spatial resolution. Due to its accessibility and the applied modeling methods, urban energy systems can be modeled and optimized with comparatively low effort.
About 75% of the world's energy consumption takes place in cities. Although their large energy consumption attracts a large number of research projects, only a small fraction of them deal with approaches to model energy systems of city districts. These are particularly complex due to the existence of multiple energy sectors (multi-energy systems, MES), different consumption sectors (mixed-use), and different stakeholders who have many different interests.
This contribution is a review of the characteristics of energy system models and existing modeling tools. It evaluates current studies and identifies typical characteristics of models designed to optimize MES in mixed-use districts. These models operate at a temporal resolution of at least 1 h, follow either bottom-up or hybrid analytical approaches and make use of mixed-integer programming, linear or dynamic.
These characteristics were then used to analyze minimum requirements for existing modeling tools. Thirteen of 145 tools included in the study turned out to be suitable for optimizing MES in mixed-use districts. Other tools where either created for other fields of application (12), do not include any methodology of optimization (39), are not suitable to cover city districts as a geographical domain (44), do not include enough energy or demand sectors (20), or operate at a too coarse temporal resolution (17). If additional requirements are imposed, e.g. the applicability of non-financial assessment criteria and open source availability, only two tools remain.
Overall it can be stated that there are very few modeling tools suitable for the optimization of MES in mixed-use districts.