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Abstract A variety of novel, recyclable and reusable, construction materials has already been studied within literature during the past years, aiming at improving the overall energy efficiency ranking of the building envelope. However, several studies show that a delicate control of indoor climating elements can lead to a significant performance improvement by exploiting the building’s savings potential via smart adaptive HVAC regulation to exogenous uncertain disturbances (e.g. weather, occupancy). Building Optimization and Control (BOC) systems can be categorized into two different groups: centralized (requiring high data transmission rates at a central node from every corner of the overall system) and decentralized 1 (assuming an intercommunication among neighboring constituent systems). Moreover, both approaches can be further divided into two subcategories, respectively: model-assisted (usually introducing modeling oversimplifications) and model-free (typically presenting poor stability and very slow convergence rates). This paper presents the application of a novel, decentralized, agent-based , model-free BOC methodology (abbreviated as L4GPCAO) to a modern non-residential building (E.ON. Energy Research Center’s main building), equipped with controllable HVAC systems and renewable energy sources by utilizing the existing Building Management System (BES). The building testbed is located inside the RWTH Aachen University campus in Aachen, Germany. A combined rule criterion composed of the non-renewable energy consumption (NREC) and the thermal comfort index – aligned to international comfort standards – was adopted in all cases presented herein. Besides the limited availability of the specified building testbed, real-life experiments demonstrated operational effectiveness of the proposed approach in BOC applications with complex, emerging dynamics arising from the building’s occupancy and thermal characteristics. L4GPCAO outperformed the control strategy that was designed by the planers and system provider, in a conventional manner, requiring no more than five test days.

Abstract Integrating low-carbon technologies (e.g. heat pumps, photovoltaic systems) in buildings influences the stability of the low-voltage grid, which therefore often requires to be reinforced. This article proposes a techno-economic methodology to identify the reinforcements needed to maintain grid stability at the lowest life-cycle cost. Novel contributions include the consideration of three-phase connection of low-carbon technologies as a reinforcement option and the fact that we study to what extent grid reinforcements can mitigate voltage unbalance issues. Additionally, to reduce computing time, a dummy island approach is used, whereby one feeder is modelled in detail and the remainder of the distribution island is represented by an aggregated load. Finally, random repetitions are proposed, to consider uncertainties related to building properties, occupants and the location of low-carbon technologies in the feeders. The methodology is applied to investigate the integration of heat pumps and photovoltaic systems in typical Belgian rural and urban grids. For the rural grid, heat pumps may lead to significant reinforcement costs (up to 1230 €/dwelling), mainly due to voltage stability problems. For the urban grid, heat pump and photovoltaic integration causes low reinforcement cost (

100 Positive Energy Districts (PEDs) are to be created in Europe by 2025, with a stated goal of urban decarbonization. These are highly energy efficient residential urban areas, powered entirely through renewables. PED creation is to be guided by principles of quality of life, sustainability, and inclusiveness (specifically focusing on affordability and energy poverty prevention). Although there is research into the decarbonization aspects of PEDs, there has been little focus on the guiding principles, and their potential to reduce energy vulnerability. Using energy vulnerability factors and an energy justice framework, this article examines how the topic of energy vulnerability mitigation is perceived by professional PED stakeholders. Stakeholders from multiple countries were interviewed in order to determine how and to what extent they approached the topic of inclusivity and energy vulnerability. The contribution of this paper to academic research is in helping to frame energy vulnerability in European smart city urban areas, focusing on the perceptions of key stakeholders. This contributes to research on the identification and evaluation of innovations such as PEDs which offer a potential model for an inclusive transition. Furthermore, this article offers a contribution for policymakers, informing PED replication policies with a focus on the synergistic aims of decarbonization and energy vulnerability mitigation.

Abstract In this paper, an open source tool is introduced to represent urban energy infrastructure in the City of Philadelphia, and different renewable energy scenarios are compared with respect to minimization of the standard deviation of the residual load. Renewable energy sources play a critical role in the world’s ongoing energy transition in response to climate change. Urban Energy Systems may be particularly sensitive to this transition due to the high energy demand density associated with urban environments. Open energy analysis and modeling tools can provide important information that can be used by urban energy planners, policy makers, and other stakeholders during this transition. In the present study, we apply FlexiGIS, an open energy modeling tool developed in a European context, to a case study in the City of Philadelphia. Due to the importance of open access to energy data, we pay particular attention to open energy data sources. Notably, OpenStreetMap was incomplete in its spatial coverage, but alternate open data resources were identified. This work conducts an optimization of the renewable energy mix to minimize the amount of balancing energy required for the residual load. We observe that Philadelphia has an optimal mix of renewables that favors a roughly even share of wind and solar, but that, compared to a previous case study in Oldenburg, Germany, requires more balancing energy at comparable levels of renewable penetration.

This paper examines the sources of changes in energy use of the Brazilian economy of industries and households from 1970 to 1996, using structural decomposition analysis based on the logarithmic mean divisia index technique. Energy use can be decomposed into eight factors that explain changes in overall energy use over the entire time period, and within five sub-periods. The growth of energy use between 1970 and 1996 was mainly influenced by changes in affluence, population and intersectoral dependencies, while changes in direct energy intensity and per capita residential energy use had a retarding impact on energy use. The novel contributions of the paper are the alignment of a previously disparate data set, the use of supply-use tables for SDA, and the application of such an SDA to a developing country. Both contributions involve solving a range of methodological issues pertaining to handling of large data sets.

AbstractBioenergy (i.e., bioheat and bioelectricity) could simultaneously address energy insecurity and climate change. However, bioenergy’s impact on climate change remains incomplete when land use changes (LUC), soil organic carbon (SOC) changes, and the auxiliary energy consumption are not accounted for in the life cycle. Using data collected from Belgian farmers, combined heat and power (CHP) operators, and a life cycle approach, we compared 40 bioenergy pathways to a fossil-fuel CHP system. Bioenergy required between 0.024 and 0.204MJ (0.86MJth+0.14 MJel)−1, and the estimated energy ratio (energy output-to-input ratio) ranged from 5 to 42. SOC loss increased the greenhouse gas (GHG) emissions of residue based bioenergy. On average, the iLUC represented ∼67% of the total GHG emissions of bioenergy from perennial energy crops. However, the net LUC (i.e., dLUC+iLUC) effects substantially reduced the GHG emissions incurred during all phases of bioenergy production from perennial crops, turning most pathways based on energy crops to GHG sinks. Relative to fossil-fuel based CHP all bioenergy pathways reduced GHG emissions by 8–114%. Fluidized bed technologies maximize the energy and the GHG benefits of all pathways. The size and the power-to-heat ratio for a given CHP influenced the energy and GHG performance of these bioenergy pathways. Even with the inclusion of LUC, perennial crops had better GHG performance than agricultural and forest residues. Perennial crops have a high potential in the multidimensional approach to increase energy security and to mitigate climate change. The full impacts of bioenergy from these perennial energy crops must, however, be assessed before they can be deployed on a large scale.

Abstract The energetic use of residues from agriculture can foster the transition towards a more renewable energy supply. However, sustainability issues have to be considered along the entire provision chain as they affect the resource and energy potential as well as the achievable contribution to climate mitigation. Straw is one of the most important agricultural residues in Germany. It is not yet used for energy purposes extensively and compared to other agricultural feedstock it shows low competition with food, feed or fiber. This paper analyses on the one hand the sustainable potential of cereal straw for energy application in Germany considering the actual agricultural conditions, and on the other hand the global warming potential from different energy provision chains based on straw. Different humus-balance tools that are able to assess the organic matter (OM) demand to presume soil fertility. The analysis of straw potentials was applied at NUTS 3 level for Germany, based on statistical data. The results of this analysis were used as input data for the modeling of concepts for straw provision and use. Greenhouse gas (GHG) emissions were calculated for each concept in order to compare the global warming potential of various energy applications, to investigate the relative contribution of different production steps and to compare them with fossil energy applications. In total, 29.8 Tg of straw (fresh matter) are produced annually in Germany (1999–2007). Approximately 4.8 Tg of the total straw occurrence are annually required by animal husbandry. Between 7.97 and 13.25 Tg straw can be classified as sustainable straw. Highest straw potential (3.99 Mg ha−1) can be found in parts of Schleswig-Holstein, Mecklenburg–West Pomerania, North Rhine-Westphalia and Lower Saxony. But there are also regions that show a net deficit. The cumulated GHG emissions for the resulting concepts are between 8 and 35 g CO2-eq. MJ−1. In comparison to fossil energy applications, the highest reduction potential occurs for concepts for combined heat and power (CHP) provision, i.e. 223 g CO 2 -eq . MJ el - 1 . This study highlights the possible contribution of straw as renewable energy carrier, but also demonstrates that there are regional restrictions for straw use.

Comprehensive global decarbonization will require that transportation services cease to rely on fossil fuels. Here we develop a generic life-cycle cost model to address two closely related questions central to the emergence of sustainable transportation: (i) the utilization rates (hours of operation) that rank-order alternative drivetrains in terms of their cost, and (ii) the cost-efficient share of clean energy drivetrains in a vehicle fleet of competing drivetrains. Calibrating our model framework in the context of urban transit buses, we examine how the comparison between diesel and battery-electric buses varies with the specifics of the duty cycle (route). We find that even for less favorable duty cycles, battery-electric buses will entail lower life-cycle costs once utilization rates exceed 20% of the annual hours. Yet, the current economics of that particular application still calls for a one-third share of diesel drivetrains in a cost-efficient fleet.