energies Review Simulation Tools to Build Urban-Scale Energy Models: A Review Alaia Sola *, Cristina Corchero, Jaume Salom and Manel Sanmarti IREC Catalonia Institute for Energy Research, 08930 Sant Adrià de Besòs, Spain; [email protected] (C.C.); [email protected] (J.S.); [email protected] (M.S.) * Correspondence: [email protected]; Tel.: +34-933-562-615 Received: 31 October 2018; Accepted: 16 November 2018; Published: 23 November 2018 Abstract: The development of Urban-Scale Energy Modelling (USEM) at the district or city level is currently the goal of many research groups due to the increased interest in evaluating the impact of energy efficiency measures in city environments. Because USEM comprises a great variety of analysis areas, the simulation programs that are able to model urban-scale energy systems actually consist of an assemblage of different particular sub-models. In order to simulate each of the sub-models in USEM, one can choose to use either existing specific simulation engines or tailor-made models. Engines or tools for simulation of urban-scale energy systems have already been overviewed in previous existing literature, however the distinction and classification of tools according to their functionalities within each analysis area in USEM has not been clearly presented. Therefore, the present work aims at reviewing the existing tools while classifying them according to their capabilities. The ultimate goal of this classification is to expose the available resources for implementing new co-simulation approaches in USEM, which may reduce the modelling effort and increase reliability as a result of using established and validated simulation engines. Keywords: urban modelling; co-simulation; simulation engines; building stock energy demand 1. Introduction Cities have proved to be one of the largest energy consumer groups and emitters of greenhouse gases in the world [1]. Consequently, urban areas offer a large potential for energy efficiency improvement and greenhouse gases mitigation. One of the key aspects to evolve towards a more sustainable city energy system is to develop integrated or multi-energy systems, where electricity, heating, cooling, and transport interact with each other at various levels. This new urban energy paradigm presents challenges and uncertainty of systems interaction. In order to assess the behavior of urban energy systems, the research field of multi-domain Urban-Scale Energy Modelling (USEM) has experienced a considerable progress in the recent years. USEM platforms are being developed and used as means of anticipating the resulting performance of different scenarios and/or finding the optimal scenario according to given criteria. In fact, USEM comprises a great variety of analysis areas, thus USEM platforms (i.e., simulation programs able to model urban-scale energy systems) actually represent an assemblage of different particular sub-models, as depicted in Figure1. A sub-model in this context is defined as a model developed specifically to reproduce the behavior of a sub-system within the urban context, aiming at estimating the performance of a simpler system compared to the more complex overall urban-scale energy system. Based on the previous statements, modelling tools are defined as either specific simulation engines or tailor-made models capable of simulating one part of the urban energy system (one or multiple sub-models). In contrast, heterogeneous USEM platforms are capable of simulating a broad urban energy system including different sub-models. It has been noticed by the authors that the distinction Energies 2018, 11, 3269; doi:10.3390/en11123269 www.mdpi.com/journal/energies Energies 2018, 11, 3269 2 of 24 Energies 2018, 11, x FOR PEER REVIEW 2 of 23 between the existing modelling tools and the existing heterogeneous USEM platforms has been partly been partly omitted in existing reviews. However, it is believed that these two concepts must be omitted in existing reviews. However, it is believed that these two concepts must be differentiated. differentiated. Towards this end, the present review article aims at strictly focusing on the state-of- Towards this end, the present review article aims at strictly focusing on the state-of-the-art of the the-art of the relevant available simulation engines for each sub-model in USEM. relevant available simulation engines for each sub-model in USEM. Figure 1. Sub-models in Urban-Scale Energy Modelling platforms. Figure 1. Sub-models in Urban-Scale Energy Modelling platforms. 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Finally, Tools thefor selectionenergy optimization of tools and simulation modelling engines are discussed in this study in Section is also classified 7. Conclusions in different are Tablespresented which in Section indicate 8. the Finally, main the capabilities selection of of each tools tool and concerning simulation topics engines such in asthis the study analyses is also of theclassified environment, in different energy Tables demand, which indicate energy generation,the main capabilities energy distribution, of each tool and concerning optimization topics insuch an urban-scaleas the analyses energy of the system. environment, energy demand, energy generation, energy distribution, and optimization in an urban-scale energy system. 2. Review Methodology The subject area of Urban-Scale Energy Modelling encompasses numerous techniques and application domains. We therefore conducted a dedicated survey of the literature in order to identify Energies 2018, 11, 3269 3 of 24 2. Review Methodology The subject area of Urban-Scale Energy Modelling encompasses numerous techniques and application domains.