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This study assesses alternative energy technologies (i.e., PV and battery systems, electric heat pumps, hybrid gas heating with solar thermal energy) in terms of profitability and CO 2 emissions, for the case of two simulated typical households living in detached houses in Germany. Under the status-quo regulatory framework, the energy transition in the heating sector is fostered through grants for replacing old heating systems, whereas PV generation is fostered by feed-in tariffs and indirect subsidies for self-consumption. This study considers an alternative regulatory scenario with a more market-oriented approach, finding that a CO 2 -oriented reform of energy surcharges and taxes, as well as a reform of network charges, can support a more cost-efficient energy transition in the residential sector. The paper concludes with a discussion of the consistency, cost efficiency and effectiveness of past and current policies underpinning the energy transition in the residential sector. • Assessment of home energy systems across 2 households and 2 regulatory scenarios. • Consideration of PV, batteries, heat pumps and hybrid gas-solar heating systems. • Comparison of subsidies and flat energy tariffs vs. cost-reflective, dynamic tariffs. • Market-oriented approach incentivizes far more cost-efficient CO 2 emission reduction. • The German residential energy sector needs a consistent regulatory framework. [ABSTRACT FROM AUTHOR]

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 The terms “decentralized”, “distributed” and “agent-based” are considered to have similar meanings herein. 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 FROM AUTHOR]

The adequate planning of district energy systems is a key process to provide communities with proper heating and cooling networks. To find cost-effective planning solutions, this decision-making process is usually formulated as mathematical model, which is optimized to determine where and how many assets should be installed in the network. However, this optimization problem is becoming more complex as district energy systems evolve and become more elaborate. For the 5th generation district heating and cooling (5GDHC) networks, this planning framework comprises multiple building energy systems, a thermal and electrical network as well as central heating and cooling units. As a result, the optimization problem associated with these circumstances can easily become intractable as the number of elements of the network increases. To alleviate this tractability problem, in this paper, a Dantzig–Wolfe approach is devised to decompose a mixed-integer linear program into multiple subproblems (for every building) and a master problem (thermal and electrical network and central units). A realistic case study based on a 5GDHC system in Germany is considered. For this case study, it is demonstrated that the proposed decomposition approach yields the same results attained by the original not decomposed problem while achieving significant gains in terms of scalability and computational times. More specifically, the decomposition approach reduces the computational time for districts with more than 10 buildings by in average 94%. This corroborates the potential of the proposed approach to improve the computational efficiency of models that will deliver cost-effective investment plans for 5GDHC networks. • Design optimization model for 5th generation district heating and cooling networks. • Dantzig–Wolfe decomposition for a 5GDHC optimization model. • Validation of decomposition approach with full model formulation. • Performance test of decomposed models for large districts. • Analysis of shadow prices (heat and electricity) for a 5GDHC system. [ABSTRACT FROM AUTHOR]

[Display omitted] • Simulation of residential building energy supply with heat pump or hydrogen systems. • 2050: Hydrogen economically-viable if H 2 -/Elec.-price is less than 34–61 % per kWh. • For conservative price predictions: Electric heat pumps are most economical solution. • Energy carrier switch for single-family houses: H 2 -/Elec.-price below 44 % per kWh. • Energy carrier switch for multi-family houses: H 2 -/Elec.-price below 58 % per kWh. • Fuel cells are emerging as an economically-viable option for multi-family houses. Fossil-fueled heating in the building sector is responsible for 16 % of Germany's total CO 2 emissions. Options for the climate-neutral heating of buildings include renewable electricity or renewable hydrogen. In this paper, we conduct a bottom-up study to investigate the role of hydrogen in the climate-neutral energy supply of ten selected residential buildings in comparison to electricity-based systems. Based on a demand simulation and linear optimization of the supply system, sensitivity analyses identify the threshold values of the hydrogen price for the use of hydrogen technologies (hydrogen boilers or fuel cells) in building energy systems and make the quantities of hydrogen consumed visible. The results specify the first installations of hydrogen-operated fuel cells in multi-family houses if the hydrogen price reaches 0.17 €/kWh H2 in 2050 at an electricity price of 0.31 €/kWh el. Generally, for different building types and electricity supply prices, it indicates that the use of hydrogen becomes economically-viable if the price of hydrogen supply is in the range of 34–61 % of the price of the electricity supply per kWh and below. For the case of green hydrogen obtained using renewable electricity, it is highly questionable whether hydrogen supply will be that much cheaper than direct electricity supply, making its economical use in buildings uncertain. [ABSTRACT FROM AUTHOR]

• Long-distance heat transport reduce the cost of heat supply by 15% • Cost of geothermal heat supply is competitive with other heat technologies. • Economic performance of geothermal systems increases with high full-load hours. • Geothermal energy can transition from a local to a regional use. • Geothermal district heating systems contribute to the low-carbon heat supply. Geothermal energy can play an important role in decarbonizing the heating sector, however, a limiting factor is that heat demand in urban areas does not usually coincide spatially with geological settings favorable to the extraction of geothermal energy. Long-distance heat transport could enable the direct use of geothermal resources even in areas with low or no geothermal potential. This paper proposes the cost-optimal coordinated deployment of geothermal heating plants together with heat transport and distribution networks to simultaneously supply geothermal heat to multiple urban areas. To this end, a holistic approach comprising the mapping of geothermal potential for direct-use, the estimation of district heating potential, and a two-step optimization model to calculate cost-optimal large-scale geothermal district heating systems, is presented and applied to the Free State of Bavaria in Germany. As a result, heat supply costs can be reduced by 15% if fewer geothermal wells are drilled in more geologically favorable areas at greater distances from heat sinks. Calculated levelized costs of heat without local distribution networks of 33–39 €/MWh show that geothermal energy could transition from a local to a regional use if utilized in in scenarios with high full-load hours. The proposed methodology can be adapted to develop expansion strategies for deep geothermal energy in other similar regions worldwide. [ABSTRACT FROM AUTHOR]

Passive Houses are buildings which provide comfortable indoor conditions at an extremely low heating and cooling load. The peak daily average heating and cooling loads are typically below 10 W/m 2 and annual useful energy demands are below 15 kW h/(m 2 a). The Passive House standard was originally developed in Germany. In this paper we show by hygro-thermal dynamic simulation that it is possible to realize residential Passive Houses in all of the world's relevant climate zones, represented here by Yekaterinburg, Tokyo, Shanghai, Las Vegas, Abu Dhabi, and Singapore. The window quality, insulation levels, and mechanical services all depend on the climate as well as on the building's shape and orientation. The resulting annual energy demand for space conditioning of the Passive Houses is 75 to 95% lower than that of a traditionally insulated building of the same geometry. In humid climates like Shanghai or Singapore, special attention must be paid to humidity aspects. In climates which are hot and humid all year long, the total useful energy demand for sensible and latent cooling may exceed 70 kW h/(m 2 a) even in a Passive House. Finally, it is shown that the architectural quality is not compromised by the Passive House requirements. [ABSTRACT FROM AUTHOR]

District heating is expected to play an essential role in the cost-effective decarbonisation strategy of many countries. Resource-optimised management of district heating networks depends on a wide range of factors, including demand forecasting, operational flexibility, and increasingly volatile market conditions. However, traditional operations often still rely on static models and rather simple heuristics, while holistic optimisation requires dynamic cross-domain interoperability to allow the consideration of all these factors. This paper demonstrates a proof-of-concept for a knowledge graph based optimisation problem to minimise total heat generation cost for a district heating provider. The optimisation follows a hierarchical approach based on a merit-order principle and is embedded in a model predictive control framework to allow the system to incorporate most recent information and react to disturbances promptly. A detailed sensitivity study is conducted to identify key model parameters and assess the impact of anticipated changes in regulation and market conditions. Simulation-based optimisation is used to determine the short-term heat generation mix based on data-driven gas consumption models and day-ahead forecasts for the network's energy demand and grid temperatures. Seasonal autoregressive integrated moving average models with exogenous predictor variables are found to be sufficiently accurate and precise. The effectiveness of the approach is demonstrated for a case study of an existing heating network of a midsize town in Germany, where a reduction of approximately 20% and 40% compared to baseline operational data is obtained for operating cost and CO 2 emissions, respectively. [Display omitted] • Developed heat generation optimisation framework for district heating providers. • Identified key cost drivers and market dynamics using a detailed sensitivity analysis. • Developed high accuracy time series forecasting models for key input variables. • Assessed optimisation effectivity using a German municipal utility case study. • Improvement potential for operational cost and CO 2 emissions both exceed 20%. [ABSTRACT FROM AUTHOR]

Abstract: This paper assesses the practicability of meeting the German federal government''s energy-political targets for the residential sector by analysing the potential future development of this sector in an aggregated bottom-up model. The domestic building stock is considered in terms of the likely developments in the housing market, as well as the energetic characteristics of current and future buildings. The employed method is based on deterministic projections of demand floor space and demolition/refurbishment rates. The key novelty lies in the focus on developments in this sector in Germany; existing studies have not had this focus and have therefore employed a more rudimentary methodology, for example with static refurbishment rates, shorter time horizons or no spatial differentiation. The total resulting final heating demand of domestic buildings of about 500 TWh lies above that of other studies in 2050, which is mainly due to the conservative assumptions regarding renovation activity and new build made in the present case. Hence in the reference scenario the target for 2020 is not met, suggesting that further political intervention is required. In another scenario, it is shown that a drastic increase of the renovation rate is required in order to meet the 2020 target, especially amongst existing single family buildings. The supply side is only indirectly considered due to the aggregated nature of the model, which could be improved for further work, but the presented method nevertheless represents a good compromise between using solely freely available data and obtaining superior degree of precision to previous studies. [Copyright &y& Elsevier]

Abstract: This paper presents a detailed meta-analysis of end and primary energy use for heating, cooling and ventilation of 11 low-energy non-residential buildings and one residential building in Germany that belong to the EnOB research program launched by the German Federal Ministry for Economy. In particular, the analysis emphasizes the substantial impact of auxiliary energy use on the efficiency of heating and cooling performance. The investigated buildings employ environmental energy sources and sinks – such as the ground, ground water, rainwater and the ambient air – in combination with thermo-active building systems. These concepts are promising approaches for slashing the primary energy use of buildings without violating occupant thermal comfort. A limited primary energy use of about 100kWhprim/(m2 neta) as a target for the complete building service technology (HVAC and lighting) was postulated for all buildings presented. With respect to this premise, a comprehensive long-term monitoring in high time resolution was carried out over the course of two to five years, with an accompanying commissioning of the building performance. Measurements include the energy use for heating, cooling, and ventilation, as well as the auxiliary equipment, the performance of the environmental heat source and sink, and local climatic site conditions. [Copyright &y& Elsevier]

This paper presents the preliminary results of the District Heating Atlas, an online tool to collect and visualize key metrics of district heating systems in Germany. Since the scarce available public information on district heating systems is widely spread and not accessible via central data, the District Heating Atlas shall be the platform to enter and call up information centrally. With its online platform it provides a user interface where relevant information can be entered and system components of the currently recorded 82 district heating systems can be compared. So far, nearly 50 % of the thermal energy fed into district heating is covered by the District Heating Atlas. The analysis shows that the data availability is more than 60 % for five of the ten key metrics recorded. On the one hand, missing correlations between the key metrics show the diversity of the district heating systems and make it difficult to formulate general valid statements that could help to calculate missing data. On the other hand, this means that district heating systems are very diverse in their structure and thus offer versatile potential for sector coupling. In addition, district heating systems must be individually optimised in order to best utilize their potential for flexibility for the entire energy system. Finally, the first comparisons with information from the biggest district heating association in Germany show a high match with the currently collected data set. • The first online-tool that is giving detailed key metrics on district heating systems. • Nearly 50 % of the thermal energy fed into district heating is covered by the District Heating Atlas. • The data availability is more than 60 % for five of the ten key metrics recorded. [ABSTRACT FROM AUTHOR]