District Energy Research Articles

DESIGN OF PUMPING INSTALLATIONS: DEVELOPMENT OF AN EXCEL WORKBOOK FOR HYDRAULIC MACHINES LECTURES

Nowadays, pumps are used worldwide in a very wide range of facilities and for countless purposes, including HVAC, domestic and commercial buildings, district energy, industrial processes and water treatment, municipal wastewater and water supply, agriculture and irrigation, among others. Accordingly, the number of applications is also very diverse. The purpose of present contribution is to introduce an Excel Workbook that represents a friendly easy to use tool that enables the design of pumping systems. It was first thought for Hydraulic Machines Master lectures, but its use might be looked at in a wider perspective. The Workbook includes 17 worksheets (Figure 1), all linked to each other, addressing different aspects of the design. Special attention is paid to the major and minor head losses calculation, the cavitation phenomenon, the use of dimensionless coefficients to determine the rotation speed to obtain a specific operating point and to the calculation of the system curve. Energy efficiency represents today an important goal in every pumping facility; therefore, one of the objectives of this tool is to enable the user to quantify both the shaft power and the efficiency of different operating points thus allowing a sustained definition of the best solution.

Energy Management System for a Residential Positive Energy District Based on Fuzzy Logic Approach (RESTORATIVE)

There is a clear European Strategy to transition by 2050 from a fossil fuel-based economy to a completely new system based on renewable energy resources, with electricity as the main energy carrier. Positive Energy Districts (PEDs) are urban areas that produce at least as much energy as their yearly consumption. To meet this objective, they must incorporate distributed generation based on renewable systems within their boundaries. This article considers the fluctuations in electricity prices and local renewable availability and develops a PED model with a centralised energy storage system focused on electricity self-sufficiency and self-consumption. We present a fuzzy logic-based energy management system which optimises the state of charge of the energy storage solution considering local electricity production and loads along with the contracted electric tariff. The methodology is tested in a PED comprising 360 households in Bilbao (a city in the north of Spain), setting various scenarios, including changes in the size of the electric storage, long-term climate change effects, and extreme changes in the price of energy carriers. The study revealed that the assessed PED could reach up to 75.6% self-sufficiency and 76.8% self-consumption, with climate change expected to improve these values. On economic aspects, the return on investment of the proposal ranges from 6 up to 12 years depending on the configuration choice. Also, the case that boosts the economic viability is tight to non-business as usual (BaU), whichever event spiked up the prices or climate change conditions shortens the economic variables. The average bill is around 12.89 EUR/month per house for scenario BaU; meanwhile, a catastrophic event increases the bill by as much as 76.7%. On the other hand, climate crisis events impact energy generation, strengthening this and, as a consequence, slightly reducing the bill by up to 11.47 EUR/month.

Decarbonizing cities through electrification: A strategic study for densely built residential districts in Southern Italy

This paper presents a strategic analysis of the potential for energy savings and decarbonization in a densely built residential district through the synergistic implementation of electrification and building retrofitting measures. The study specifically focuses on the energy performance achievable when completely electrifying the Heating, Cooling, and Domestic Hot Water (DHW) services of a densely built urban district in Catania (Italy), including more than 200 residential buildings. The research thus models the district's energy systems to assess the impact of various scenarios, which include individual measures tailored for thermal systems as well as a comprehensive approach that combines full electrification, on-site renewable energy integration and building envelope retrofitting. The findings underline the effectiveness of the combined scenario, which results in cancelling natural gas consumption while also reducing by around 57 % the amount of electrical energy purchased from the grid, with a final 70 % decrease in carbon emissions. Of particular relevance is the efficacy of upgrading thermal systems alongside PV system installation, under the hypothesis of creating a stand-alone electric grid for the entire district that can exchange electricity with the existing network when needed. Under these premises, the energy procurement from the electric network can be reduced by 40 %.

Optimizing government strategy for deep decarbonization in towns: A game theory approach incorporating energy storage services

Renewable district energy systems present a promising solution for decarbonizing the energy sector. However, optimal strategies to mitigate the financial challenges of deep decarbonization are still underexplored. This study aims to optimize government subsidy strategies and users' system designs to facilitate cost-effective deep decarbonization using game theory. Two indicators, the renewable generation rate (RGR) and the self-sufficiency rate (SSR), are formulated to understand the principles of achieving deep decarbonization. Additionally, the study introduces a new strategy called subsidy plus energy storage service (SUB + ESS), contrasting it with the traditional subsidy-only strategy. Key findings indicate that merely increasing the RGR requirements does not achieve deep decarbonization due to energy mismatches. Restricting the SSR requirements proves effective in achieving deep decarbonization but imposes a significant economic burden on the government. When the SSR requirement is set at 100%, carbon emissions are reduced by 93%, but the government's subsidy expenditure increases nearly fivefold. In contrast to the subsidy-only strategy, the novel SUB + ESS strategy, with a 100% SSR requirement, reduces government expenditure by approximately 52% and lowers total expenditure by 19.7%. A two-stage decarbonization strategy is proposed: initially, offering subsidies is sufficient, but as deeper decarbonization is pursued, establishing energy storage service becomes essential.

Thermoeconomic analysis of a novel topology of a 5th generation district energy network for a commercial user

This research compares an existing 4th generation heating and cooling network with a novel 5th generation heating and cooling network, driven by renewables. The networks are designed to cover the energy demand of a large shopping center. The existing network uses the thermal energy recovered from a trigenerative reciprocating engine coupled with an absorption chiller, to supply the heating and cooling networks. The proposed renewable 5th generation network consists of two neutral rings: the first one is the cold sink for the water-to-water heat pumps, installed in the substations; the second one is the hot sink for the heat pumps installed in the substations. One of the main novelties of the proposed layout consists in the use of a heat exchanger between these two rings. This heat exchanger recovers the heat rejected by the condensers of the heat pumps operating in cooling mode, supplying the evaporators of the heat pumps operating in heating mode. A photovoltaic field equipped with a lithium-ion battery partially matches the electricity demand of the network. The models of the shopping center and the existing and proposed networks are developed in TRNSYS environment. The proposed system achieves promising results: renewable electricity matches roughly 89% of the shopping mall electricity load can be covered by renewable power.

Towards a positive energy balance: A comparative analysis of the planning and design of four positive energy districts and neighbourhoods in Norway and Sweden

Positive energy districts and sustainable plus energy neighbourhoods are developed in the European context to reduce energy use and greenhouse gas emissions from the building sector. The planning and development of positive energy districts and sustainable plus energy neighbourhoods is complex and requires collaboration between stakeholders and new measures to achieve high energy efficiency, local renewable energy generation, energy storage and flexibility, and energy sufficiency. This paper examines the implementation of energy measures in the planning and design of four positive energy district and neighbourhood development projects in Norway and Sweden. The paper compares the two different institutional and energy system contexts and how these affect the development of positive energy districts, focusing on the perspectives of the municipality and developers. Existing academic literature and positive energy district guidelines are used to develop an analytical framework for the planning and design of positive energy districts and sustainable plus energy neighbourhoods. Results highlight an early focus on energy ambitions, wide stakeholder involvement, and the importance of aligning interests between stakeholders and working interdisciplinary in the planning and design phases to find optimal energy measures. Both the building and the neighbourhood/district level are important to increase energy efficiency, energy sufficiency, and energy flexibility, and consequently lower the environmental impact of the whole development project.

A novel methodology and a tool for supporting the transition of districts and communities in Positive Energy Districts

Positive Energy Districts are expected to play a major role in the energy transition of cities. Hence, this paper aims at introducing a novel methodology useful for district energy and environmental analysis and intended to support the accomplishment of the targets of Positive Energy Districts at the district or community level. The proposed approach relies on the basic concepts underpinning the “Baseline Emission Inventory” but encompasses the ambitious and challenging objectives characterizing Positive Energy Districts. For making the proposed evaluation framework accessible to as many user categories as possible (researchers, local institutions, urban planners, etc.), the calculation steps have been transposed in a user-friendly, ready-to-use tool called “En-to-EnD. Energy and Environmental analysis of Districts”. The applicability and replicability of the outputs of this work have been proven through the energy and environmental assessment of a reference case study. In particular, the district being analysed is in the South of Italy and is equipped with photovoltaic plants and a wind turbine. The results obtained show that the proposed approach may serve not only to prove the achievement of the Positive Energy District status, but also to guide the design of more sustainable district-based energy systems, thus supporting the decarbonization of cities.

Sustainable Energy Planning and Management with PV, Waste heat, positive energy districts and CO2 accounting

This 41st volume of the International Journal of Sustainable Energy Planning and Management includes three categories of papers: Ordinary submissions, submissions from the 2023 Smart Energy Systems Conference held in Copenhagen, Denmark and a submission from the 2023 Sustainable Development of Energy, Water and Environmental Systems (SDEWES) conference series. The work presented address photo voltaics (PV) in the arctic and in Sweden and electricity system scenarios of Indonesia based on, e.g. PV. Staying with PV a study investigated the interplay between PV and electric vehicles in Denmark. Moving to district heating, two papers address waste heat utilisation and positive energy districts respectively, and finally a study proves into unavoidable carbon dioxide emissions in Austria accounts for carbon capture and storage (CCS) and carbon capture and utilisation (CCUS) needs and possibilities.

Transition towards Positive Energy District: a case study from Latvia

The transition from a fossil fuel-based energy system to renewable energy sources has become a crucial consideration in both national-scale planning processes and local-scale energy system planning. Research has been conducted to seek technical solutions for a specific district of a university campus located on the peninsula of Riga to implement a smart energy system with multiple energy sources, storage systems, and energy efficiency measures. The solutions for the transformation of Energy Island to an Energy Community include power generation by building integrated solar panels with different power storage alternatives, such as thermal storage, batteries, hydrogen, and fuel cells. The simulation also evaluates the potential for heat recovery and waste heat integration from the data center and cooling systems to cover the heat demand. The interlinkage with energy efficiency improvements through improved building management systems provides an opportunity to increase RES utilization rates and improve overall energy efficiency. To provide a holistic overview of the future development of the urban area, the research also compares the connection to the district heating network. Results show that the analyzed energy community can achieve up to 80% of the RES self-consumption level as cost-optimal solutions by combining off-site wind turbine, solar PV panels, water source heat pumps, waste heat recovery and adjusted power storage.

Recommendations for a positive energy district framework – Application and evaluation of different energetic assessment methodologies

Positive Energy Districts are seen as a stepstone towards climate-neutrality for European cities. The concept aims to make districts an active contributor to urban energy systems. However, the definition of PEDs is relatively loose and there is currently a lack of a common European assessment methodology, which makes it difficult to evaluate PED in practice. This research evaluates the energetic assessment methodologies developed in three PED-relevant projects in Europe – namely MAKING CITY, Zukunftsquartier Wien, and Zero Emission Neighbourhood – in order to derive recommendations for a common PED assessment framework. For this purpose, the three methodologies have been applied to case study districts in Germany. Subsequently, the application of the methodologies has been analysed based on their general practicality as well as their fulfilment of the PED objectives. The findings suggest that a positive energy balance might not be considered as a prerequisite of PEDs as this strict requirement sets a high entry barrier for districts that lack the intrinsic factors for surplus renewable energy production. For PED as an inclusive framework, the focus should be on delivering positive impacts for the districts and the wider energy systems; whilst the positive energy balance can be seen as a complementary rather than a mandatory condition.

Exploring Multiple Benefits of Urban and Energy Regeneration Projects: A Stakeholder-Centred Methodological Approach

An effective way to promote energy transition while tackling climate change involves redefining cities from being part of the problem to integral parts of the solution. Positive energy districts and climate positive circular communities are excellent examples of how this is feasible. But how do we understand which are the multiple benefits that these projects can bring to the local territory and relative community? This article aims to answer this question by developing a specific engagement and evaluation methodology. Our approach involves consulting with project partners to explore the multiple benefits of each case study. Subsequently, it plans to engage the stakeholders through the submission of a questionnaire to gather information regarding the relative importance of different benefits as perceived by each stakeholder. The questionnaire is based on the best–worst scaling method, which is a survey technique for determining people’s priorities. The preliminary findings of the study conducted on project partners of two European projects, ARV and ProLight, indicate a strong alignment with current European policy priorities. The involvement of other stakeholders in the study will serve to assess whether bottom-up priorities coincide with broader perspectives or whether adaptations to project strategies and dissemination approaches are needed.

Predicting hourly heating load in district heating system based on the hybrid Bi-directional long short-term memory and temporal convolutional network model

Accurate heating load prediction is essential to supply-demand collaboration in district heating systems and energy sustainability. With the development of the Internet of Things technology, massive monitoring data is collected that provides abundant data sources for the prediction models. However, the missing data from equipment anomalies, network transmissions and the complexity of heat load changing cause difficulty in realizing accurate heat load prediction. Therefore, the hybrid model based on bidirectional long short-term memory network and temporal convolutional network proposed in this paper to improve the accuracy of the heat load prediction from the aspects of reconstruction of missing values and extraction of complex features. The bidirectional long short-term memory algorithm imputes missing values based on bi-directional features of existing data and provides solid data foundation for subsequent training of predictive models. The temporal convolutional network achieves high-level feature extraction and parallel computation, which contributes to the effective modeling of complex changes in heat load and the realization of accurate heat load prediction. Comparative study was conducted with four heat exchange stations of actual environment to evaluate the performance of the prediction model. The results showed the mean absolute percentage error of the hybrid model decreased to 2.47% which is lower than the State-of-the-Art models, such as long short-term memory, temporal convolutional network, and support vector regression etc. The superior results further validated the feasibility of this hybrid model in heat load prediction.

A probabilistic model for residential community heating load calculation based on occupancy patterns

Ensuring precise prediction of community heating loads is crucial for optimizing the performance of district heating systems. However, the currently prevalent methods, like the simultaneous usage coefficient method and the area index method (AIM), which heavily rely on practical engineering experience, may not be suitable for ultra-low energy residential buildings (UERBs). Applying these methods to UERBs may result in overcapacity of the heating system, which increases energy consumption and costs. This study aims to enhance the accuracy of heating load calculations for UERB communities. A probabilistic model for heating load calculation was proposed, considering the “part time, part space” spatiotemporal distribution characteristics of residents. Typical occupancy patterns in cold zones of China were identified through questionnaire surveys and K-means cluster analysis, and typical models of UERBs were established, with both the building models and survey data validated. The residential building energy model (RBEM) was applied to a case community in Dalian, analyzing the impact of occupancy patterns on heating loads. The results indicate that the RBEM method increased the system's heating load factor by 6.9 % and reduced its design capacity by 32.9 % compared to the AIM. The proposed method might guide the development of management strategies in the energy planning stage of district energy systems.

Design and Operational Indicators to Foster the Transition of Existing Renewable Energy Communities towards Positive Energy Districts

Design and Operational Indicators to Foster the Transition of Existing Renewable Energy Communities towards Positive Energy Districts

Towards Positive Energy Districts: Multi-criteria framework and Quality Assurance

Towards Positive Energy Districts: Multi-criteria framework and Quality Assurance

Centralised monitoring and control of buildings using open standards

Abstract. Due to the necessary heat turnaround, buildings are increasingly seen as part of districts, e. g. Positive Energy Districts. Optimizing the energy efficiency of buildings is an essential part of implementing the heat turnaround. As a result, sensor/actuator systems are becoming increasingly important, both at building level and district level. Various proprietary and open standards for monitoring and control are used at building level. This heterogeneity makes it difficult to jointly optimize energy efficiency in buildings. OGC Sensorthings API (STA) is an open standard that defines a common language for sensor data and even tasking processes. In addition, KNX and LoRaWAN are available as standards for building monitoring and control. This article therefore proposes a solution that combines these standards. As proof of concept, two different buildings are equipped with KNX and LoRaWAN. Sensor data is collected in both buildings and merged centrally in a so-called building data lake based on OGC STA Sensing Part, e.g. temperature or indoor air quality. In addition, OGC STA Tasking Part is used to trigger actuator commands centrally and independently of the communication standard used in the controlled building, e. g. temperature setting of thermostats. As part of the proof of concept, it is shown how standardized sensor data can be visualized based on available visualization software, e. g. Grafana, and how the standardized actuator control level can be used for optimizations such as the night setback of heating systems.

Urban Digital Twins Empowering Energy Transition: Citizen-Driven Sustainable Urban Transformation towards Positive Energy Districts

Urban Digital Twins Empowering Energy Transition: Citizen-Driven Sustainable Urban Transformation towards Positive Energy Districts

Enhancing the Evaluation of District Heating System Resilience: A Literature Review

Ensuring an uninterrupted supply of energy, electricity, and heat is becoming an increasingly pressing necessity. Energy provides both social and economic growth therefore, the energy systems should be resilient to different external conditions. Resilience is the ability of a system to recover from adversity [1] and in connection with the critical infrastructure - the ability to prepare for and adapt to changing conditions and withstand and recover rapidly from disruptions. Resilience includes the ability to withstand and recover from deliberate attacks, accidents, or naturally occurring threats or incidents. Several factors influence the resilience of the energy supply system: energy security, reliability, robustness, flexibility, and resilience. If energy resilience has not been well considered or even ignored in the planning, design, and operation stages in district energy communities can lead to system fragility and vulnerability. Therefore, the research assesses the different methods for resilience assessment in energy systems by focusing on district heating. During climate change mitigation and adaptation energy supply system resilience is unclear. Based on current studies, the energy resilience factor for most is considered in the context of the electricity transmission system, and the heat transmission resilience study is limited. During the research of the literature, it has been concluded that there is no consistent quantitative and quality approach to resilience because there is no consistent treatment of the concept of resilience. The available literature sources about energy resilience are limited in their scope and usability and hence are not amenable for use outside the scope where they have been developed. The metric and formula used for calculating resilience, if any, and the input data required for such calculations are also dependent on the research scope. There is a need for a fundamental generic quantitative and quality approach for resilience that would be usable and useful across various scopes or sectors in a consistent manner, which can be used for the development of resilient systems and effective resilience strategies for district heating systems.

ENERGY Pro: Spatially explicit agent-based model on achieving positive energy districts

This article describes the ENERGY Pro agent-based model using the Overview, Design Concept, and Details + Human Decision-making (ODD+D protocol). The model is empirically explicit and aims to investigate the adoption decisions of homeowners in Amsterdam on different energy-efficient retrofitting (EER) measures. Following the ODD+D protocol, this study uncovers the conceptual framework used for model construction, the spatial microsimulation process of expanding the data, and the model implementation details. The article also describes sensitivity analysis, validation results, and how to use and adapt the model. With this article, the authors aim to make the model replicable and accessible to other researchers and inspire them using the combination of social simulation and spatial microsimulation in studying the energy transition.•The agent-based model is described using the ODD+D protocol.•The combination of simulation methods is used for constructing an empirical model.•The model on energy transition can be adapted for other cities.

Methodologies for the design of positive energy districts: A scoping literature review and a proposal for a new approach (PlanPED)

Cities can substantially contribute to European Green Deal targets by accelerating their transition towards smarter, more efficient, and renewable-based energy models. In that context, European cities need to increase their self-sufficiency and the resilience of their energy system especially through the promotion of district and neighbourhood scale energy projects such as positive energy districts (PEDs). Despite the increasing interest for PEDs experienced in the last years, their deployment is currently hindered by the absence of an energy planning culture and the lack of adequately skilled personnel in cities. Indeed, there is a strong need for practical tools and guidelines that support practitioners in the design and implementation of PEDs. In that context, the present paper introduces PlanPED, a framework for the conception of methodologies for PED planning, design, and implementation, to support municipalities in their energy transition. PlanPED aims at providing a multiple perspective approach based on the most important elements from existing methodologies. In that sense, the paper begins with an overview of the state of the art, leading to the identification of trends, gaps, and good practices of current research. Then, based on this analysis, the novel framework PlanPED is introduced. It consists of three interconnected workflows that, if followed, enable to know which steps and resources need to be put into practice to initiate the transition towards PED, while recognizing the variability of contexts and necessities. By doing so, PlanPED seeks to facilitate the elaboration of tailored and practical roadmaps for the deployment of PEDs in cities.