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This paper aims to study the impact of digitalization on energy efficiency in Europe, where institutions are committed to promote both digital transformation and energy transition by implementing the European Twin Transition, ETT [1]. The paper starts by empirically analysing the state of play of the Twin Transition across European Member States (MS) by mapping the Digital Economy and Society Index (DESI), its sub-indices and the energy productivity. We then discuss the impact of the abovementioned digital indicators on energy productivity growth in 26 European MS during the period 2016–2020 by applying a system GMM model. The results show a significant and positive impact of digitalization on energy efficiency and relevant complementarities across diverse digitalization dimensions. This study contributes in an original manner to the literature by applying for the first time DESI and its sub-indices in a European twin transition analysis; moreover, empirical insights have important policy implications because all the variables considered are parts of the European policy targets. • This paper explores the impact of digitalization on energy efficiency. • A statistical investigation of twin transition across European MS is carried out. • DESI and its sub-indices have a positive and significant impact on energy productivity growth. • Potential complementarities exist among DESI sub-indices regarding their impact on energy productivity growth. [ABSTRACT FROM AUTHOR]

This paper delves into the potential impact of a changing climate on the energy performance of European buildings. Research aims to provide a comprehensive evaluation of current energy requirements focusing on the envelope, considering existing regulations in national policies. Energy simulations are conducted at 94 locations across the European Union to cover the climatic variability and Koppen climate classification. The research analyzes future climate scenarios for the years 2030, 2050, and 2070, using three different Representative Concentration Pathways (RCP 2.6, 4.5, 8.5). According to a comprehensive analysis of heating, cooling, and overall energy performance, climate plays a significant role in buildings' energy balance. In moderately cool climate countries, the demand for air conditioning is projected to decrease in the years ahead. Conversely, in countries with a warm climate, there is a projected increase in the overall energy demand. Consequently, a revision of current energy regulations should be a priority. Providing insights into the relation between building design, energy efficiency, and climate change, the research identifies policy adjustments to ensure buildings can effectively respond to changing climatic conditions. A holistic and dynamic approach can support building design accounting for long-term impacts of climate change to create resilient and energy-efficient structures. • National building energy regulations of European Member States do not tackle climate change. • Over next decades, a decrease in heating demand is forecasted across all climate zones. • There is potential for a future considerable increase of cooling demand in Europe. • A reduction in total building energy demand in colder climates and an increase in warmer climates can be expected. • Revise national energy regulations, especially in warmer zones, to curb the expected rise in Europe's total energy demand. [ABSTRACT FROM AUTHOR]

The energy retrofitting of residential stock is not always straightforward where heritage protected housing is concerned. In southern Europe, many examples built under the Modern Movement codes are now obsolete in terms of energy efficiency. The aim of this paper is to assess the potential for improvement of comfort conditions and energy efficiency in Mediterranean heritage residential buildings, through the incorporation of passive strategies in keeping with preserving heritage values. Long-term monitoring and field tests in representative flats of the case-study building were carried out and, focusing on a single example, adaptive comfort equations were used to assess results. The passive strategies considered are the thermal isolation of the air cavities of walls, changing window frames, optimizing window glazing, and setting up regular mechanical ventilation rates for indoor air changes. Although simulation results generally predict a better energy performance after testing retrofit strategies, the potential decrease in energy demand is more noticeable than the potential improvement in comfort conditions. • The improvement of comfort and energy efficiency in a heritage building is assessed. • Long-term monitoring and field tests were carried out in representative flats. • Passive strategies in keeping with preserving heritage values were examined. • Adaptive comfort equations were used to assess results focusing on one flat. • Energy efficiency improvements are more noticeable than those of comfort conditions. [ABSTRACT FROM AUTHOR]

• The new solution for the façade integrated photovoltaic system, En-ActivETICS was proposed and described in detail, including technical recommendations. • The calibrated numerical model was used to determine hygrothermal performance and identify the most crucial issues of En-ActivETICS. • The positive effect of PCM and diffusion channels was revealed based on a numerical study using calibrated thermoelectrical and hygrothermal models. • The En-ActivETICS was investigated considering local climatic and economic conditions among 38 European countries. • The roadmap 2030 for the En-ActivETICS advancement was developed and presented. The main goal of the European building market transformation regards the reduction of CO 2 emissions and energy demand in the built environment towards net zero carbon buildings. This drives research and building practice to search for economically justified solutions that contribute to achieving these objectives. The work presented in this paper is concerned with the technological and economic context. The original solution of photovoltaic integration with the external thermal insulation composite system named the En-ActivETICS was developed, tested and analysed. The energy potential of the En-ActivETICS across Europe, considering south oriented façade is from 88.3 to 195.8 kWh/(m2⋅a), with the efficiency of solar energy conversion of around 13–14%. The problem of system overheating was solved by applying PCM mortar beside the PV panel, which allowed to keep the PV temperature below 70 °C. The risk of moisture load (from driven rain or water vapour condensation) was avoided by diffusion channels pressed in the mortar. Furthermore, the economic analysis of system implementation in Europe is also promising. Considering the availability of solar energy and electricity prices around Europe the payback time of the En-ActivETICS varies between 12 and 44 years for analysed countries. According to the presented roadmap for the En-ActivETICS advancement a payback period of <10 years is possible with a maximum cost of the system <275 EUR/m2 and electricity price >0.25 EUR/kWh. [ABSTRACT FROM AUTHOR]

Abstract Waste heat is an abundant resource that if recovered with a heat pump would increase energy efficiency in industrial processes. This will provide improvements in heat utilization and reduce the environmental impact of greenhouse gas emissions from the combustion of fossil fuel. A hydrocarbon high temperature heat pump has been developed to demonstrate the potential to deliver heat at a temperature of 115 °C. The heat pump provides heat for applications such as drying, pasteurization and other processes. Using hydrocarbons, the heat pump aims for a clean energy system. This paper reports on a 20 kW capacity cascade heat pump with propane in the low temperature cycle and butane in the high temperature cycle. Based on a theoretical model, an experimental setup is built with standard components that are commercially available. A prototype compressor is investigated for its performance at high temperature conditions. The heat pump can recover waste heat at 30 °C and deliver heat up to 115 °C. With an average heating coefficient of performance (COP) of 3.1 for a temperature lift of 58–72 K, the heat pump is a more cost efficient and environmentally friendly system compared to existing solutions of a steam boiler. Highlights • Experimental investigation of a high temperature heat pump up to 115 °C. • Experimental investigation of a modified compressor for high temperature heat pump. • Coefficient of performance (COP) of 2.1 and 3.1 for waste heat at 30 °C and 60 °C. • Heat pump COP at 60 °C waste heat break-evens with gas boilers in less than 3 years. • Carbon emissions reduction of over 95% in Norway and 30% in Europe. [ABSTRACT FROM AUTHOR]

By 2020 Europe has to increase its energy efficiency and share of renewables in 20%. However, even accomplishing these challenging objectives Europe will be effectively wasting energy as we demonstrate in this paper. In our way towards a fully renewable scenario, we need at least to stop wasting energy in order to guarantee the energy supply needed for growth and comfort. We waste energy when we employ more primary energy than the final energy we ultimately use and this excess cannot be reutilized. In this paper we propose the WE (wasted energy) as a novel metric to measure the performance of energy systems and set up appropriate targets. The WE incorporates information about energy efficiency and renewable sources. Unlike European legislation, the WE considers them in an integrated way. This approach will help Member States to exploit their intrinsic capabilities and design their optimum strategy to reach their objectives. Using the information in Eurostat, we calculate the WE of Member States in EU-28 and their evolution. We also analyze illustrative examples to highlight strategies to reduce the WE, study the connection between economic development and WE, and provide a tool to diagnose the potential of improvement of an energy system. [ABSTRACT FROM AUTHOR]

This paper proposes a novel Case Based Reasoning (CBR) application for intelligent management of energy resources in residential buildings. The proposed CBR approach enables analyzing the history of previous cases of energy reduction in buildings, and using them to provide a suggestion on the ideal level of energy reduction that should be applied in the consumption of houses. The innovations of the proposed CBR model are the application of the k -Nearest Neighbors algorithm (k-NN) clustering algorithm to identify similar past cases, the adaptation of Particle Swarm Optimization (PSO) meta-heuristic optimization method to optimize the choice of the variables that characterize each case, and the development of expert systems to adapt and refine the final solution. A case study is presented, which considers a knowledge base containing a set of scenarios obtained from the consumption of a residential building. In order to provide a response for a new case, the proposed CBR application selects the most similar cases and elaborates a response, which is provided to the SCADA House Intelligent Management (SHIM) system as input data. SHIM uses this specification to determine the loads that should be reduced in order to fulfill the reduction suggested by the CBR approach. Results show that the proposed approach is capable of suggesting the most adequate levels of reduction for the considered house, without compromising the comfort of the users. [ABSTRACT FROM AUTHOR]

The role of cities and their commitment to meet the European targets on energy and climate has steadily increased in the latest years as testified by the large number of ambitious initiatives undertaken by European cities to face multiple challenges towards sustainability. Many projects and initiatives have arisen all around Europe to support cities in the achievement of the Europe 2020 targets of smart, sustainable and inclusive growth. RE-SEEties “Towards resource-efficient urban communities in SEE” is one of the projects funded under the South East Europe program aimed to enhance the policy-making and strategic planning competences of municipalities in the field of energy efficiency, renewable energy sources and waste valorization. This paper focuses on the methods developed and the main results achieved in the framework of RE-SEEties. The main focus is on the eight partner cities (The Local Government of Budapest District 18 – Hungary/HU, Municipality of Aigaleo – Greece/EL, Municipality of Potenza – Italy/IT, City of Nitra – Slovakia/SK, City of Skopje – Former Yugoslav Republic of Macedonia/FYROM, City of Miercurea Ciuc – Romania/RO, Municipality of Ptuj – Slovenia/SI, City of Ivanić-Grad – Croatia/HR) and how they were assisted by professional institutions in translating their commitments towards resource efficiency into Local Strategies and Action Plans. A critical comparison of these final results points out differences and similarities in the state-of-the-art of cities across South East Europe as well as a the level of ambition and difficulties faced to turn into resource efficient urban communities. [ABSTRACT FROM AUTHOR]

A very large percentage of the European residential building stock is ageing and does not comply with current energy regulations. The need to complete short-term energy upgrading on these buildings in order to improve performance and meet current regulations poses a considerable challenge. Consistent energy methodologies are needed for mass application of suitable technologies in sensitive points such as the façade, saving time by guiding designers on use of preferred climatic design strategies for each situation and with economic feasibility. The paper presents a methodology with integrative approach between energy and economic aspects, using an inference system to overcome uncertain or unknown information found at the start of the project. Components used in the analysis are studied from a programmatic point of view (input, decision process and output). The methodology is suitable for early stages of the design process and its products enable continuation into more advanced ones. The methodology can form the basis for a software program using either its own databases or integrated energy simulation engines. This work is based on research for a European project concerning energy retrofit of residential building facades, but can be extended to other zones or end-uses having similar approaches. [ABSTRACT FROM AUTHOR]

The massive data centre energy consumption has motivated significant efforts to use energy efficiency strategies and the implementation of renewable energy sources that reduce their operational costs and environmental impact. Considering that the potential of many of these measures is often closely linked to the climate conditions, the location of data centres can have a major impact on their energy demand. Moreover, from a holistic approach, differences among regions become even more important when accounting for the electricity attributes from the grid. To assess these differences this work compares by the use of energy indicators the behaviour of a data centre located at different representative emplacements in Europe. To do so, a dynamic energy model which incorporates free cooling strategy and photovoltaic energy is developed. The paper concludes by suggesting that future data centre developments could consider site selection as a new strategy to limit the environmental impact attributable to this sector. [ABSTRACT FROM AUTHOR]

Europe is encouraging new buildings to minimize their primary energy dependence to be considered, from 2021, Nearly Zero Energy Buildings (NZEB). In this regard, solar thermal energy is being extensively used as a renewable source to produce Domestic Hot Water (DHW). However, solar thermal energy fields may be oversized during the warmest season of the year, rejecting the waste heat to the ambient while increasing the air conditioning demand. The Solar-driven Ejector Refrigeration System (SERS) may be a solution for solar cooling. Nevertheless, the SERS performance is constrained when low to medium temperature solar thermal collectors, commonly installed for DHW production, are used in warm climates. Consequently, this paper reformulates the SERS application as a novel fresh air pre-cooling system for air handling units. Thereby, greater evaporating temperatures that enable the SERS adoption in NZEB are explored. In doing so, the seasonal performance under severe operating conditions is analyzed considering the two-phase flow ejector geometry, as well as refrigerants with low global warming potential. Main results demonstrate a maximum seasonal COP of 0.37 by using R717. Moreover, an average cooling capacity of 28.3 kW could be produced per kW of electricity if an optimized multi-ejector solution with R600 is adopted. • A novel fresh air pre-cooling system for air handling units is presented. • The Solar Ejector Refrigeration System (SERS) is modeled and analyzed. • Low GWP refrigerants and the geometry of two-phase flow multi-ejector modules are considered. • A seasonal based simulation is conducted to obtain the seasonal COP of the system. • A cooling capacity above 28 kW could be produced per kW of electricity consumed by the pump. [ABSTRACT FROM AUTHOR]

Recent public and governmental concerns regarding increasing greenhouse gas (GHG) emissions have drawn the attention to environmental issues in port sector literature. Since eco-efficiency improvements play a crucial role in stimulating clean production in this sector, this paper provides a comparative analysis of the eco-efficiency of twenty-four leading container ports in Europe. The exploration of the most prominent determinants of eco-efficiency and the analysis of the heterogeneity of port behaviours represent additional objectives. Further considerations derive from the assumptions on the selection of indicators that can be involved in the comparative analysis and from the involvement of GHGs in the theoretical model. Data from a sample of 52,697 active firms are considered in this empirical work. The model involves a two-step procedure: the slacks-based measure (SBM) and the response-based procedure for detecting unit segments in partial least squares (REBUS-PLS). The empirical results confirm that significant correlations emerge between the indicators considered and eco-efficiency. The findings validate that unobserved heterogeneity in the port data exists, and that REBUS-PLS allows the predictive capacity of the model to be optimised for European ports. From a policy point of view, the conclusion could offer useful insights to support policy measures targeted at the improvement of clean production. • The paper provides a comparative analysis of the eco-efficiency of twenty-four EU ports. • The paper attempts to explore the most prominent determinants of eco-efficiency. • The research considers a two-step procedure: the SBM and the rREBUS-PLS. • REBUS-PLS is suitable for investigating unobserved heterogeneity in the port data. • An approach based on the NUTS2 levels and NACE codes is considered. [ABSTRACT FROM AUTHOR]

Abstract: Energy efficiency in buildings is essential for economic, social, and environmental reasons. Under current European legislation, buildings have to be certified with an energy efficiency index. To provide a fair comparison of the energy performance in buildings we need a global and unified representation. In this paper we propose the Energy Efficiency Ontology (EEOnt) to provide a foundation upon which this requirement can be built. EEOnt extends the applicability of other ontological models of buildings incorporating energy efficiency data and knowledge that can be calculated with high spatial and temporal resolution in what we call an Energy Efficiency Landscape (EELB). These EELB''s provide significant information which allows a detailed diagnosis of the energy efficiency within the building. Consequently, EEOnt is capable of representing buildings and energy efficiency in a unified way. Furthermore, it supplies a tool for managing the energy efficiency in buildings and constructing national inventories. These two features link the global and particular needs of governments and users, thus becoming key to both improve the energy efficiency in buildings and to implement viable certification schemes. [Copyright &y& Elsevier]

Abstract: The aim of Educa-RUE project is to improve energy performance in building sector at local level and with particular attention to educational buildings, by promoting the ability of local players to guide and orient initiatives, designed to encourage energy saving by means of specific measures and integrated tools. The project is therefore focused to speed up the implementation of European Directive on Energy Performance in Buildings, EPBD (2002/91/EC), in Member States at local government level and to ensure its operability, within the various national legislations of reference. Educa-RUE lasted 30months, from January 2008 to June 2010, and involved the following eight partners: for Italy, Provinces of Potenza (project leader), Perugia, Rieti and Palermo; for other Countries, Climate Energy Ltd. Essex and Energy Solutions North West London (UK), Associación Aragonesa de Entidades Locales ASAEL (Spain), Municipality of Prenzlau (Germany). A number of closely interconnected actions were carried on in eight Work Packages (WPs) to face the energy efficiency aspects identified as primary problems by the partners. The project developed a model process, known as “Educa-RUE method”, to assess possible policies of intervention on educational buildings, owned or managed by each Partner. In particular the Province of Perugia, leader of WP 2 and 5, provided guide lines and tools in order to: identify the state of the art of EPBD implementation and the main non-technological barriers, which are preventing its application at local level; select, within the Province/area patrimony, the most suitable educational building, to be used as a shining example to develop the following testing phases of the project; carry on an energy check, or audit, of selected buildings, by involving the educational community as user and active participant in the whole process; elaborate an executive project, concerning the description of all the building elements (structure, roof, heating/cooling plants, etc.) which need to be replaced/improved and the application of an energy/environmental assessment; plan refurbishing interventions for the rest of the school buildings directly managed by each Partner, according to specific priority selection criteria, which represents a guiding and coordinating act for those Administrations directly or indirectly interested in the Project. This paper presents the results obtained by testing and proving Educa-RUE method in different regional areas. Its findings can be extended to other building typologies in order to create a reference model for local planners and responsible. [Copyright &y& Elsevier]

Abstract: Elevators and escalators have received little attention from an energy efficiency perspective in the past. To close this gap, this paper analyses energy efficiency potentials and suggests policy measures for the European elevator and escalator market. As a precondition, the electrical energy demand of elevators and escalators in the European market is analyzed, based on expert estimations and the results of a monitoring campaign. The estimated current demand is compared to scenarios where the implementation of best available technology for the relevant equipment is assumed and the savings potentials thereof are calculated. The results indicate that considerable technical efficiency potentials exist for elevators (more than 60%) and escalators (around 30%). However, various specific barriers impede the diffusion of these energy-efficient technologies. They include issues like a lack of awareness and relevant information as well as split-incentive problems. The technological analysis is therefore complemented by an investigation of how to overcome these barriers, leading to a set of recommendations on how to improve energy efficiency in the elevator and escalator market. Suitable measures could be implementing standardized methods for electricity measurement, introducing a labeling system and including elevators and escalators in the legislative framework. [Copyright &y& Elsevier]

Abstract: In transmission and distribution systems, the high number of installed transformers, a loss source in networks, suggests a good potential for energy savings. This paper presents how the Spanish Distribution regulation policy, Royal Decree 222/2008, affects the overall energy efficiency in distribution transformers. The objective of a utility is the maximization of the benefit, and in case of failures, to install a chosen transformer in order to maximize the profit. Here, a novel method to optimize energy efficiency, considering the constraints set by the Spanish Distribution regulation policy, is presented; its aim is to achieve the objectives of the utility when installing new transformers. The overall energy efficiency increase is a clear result that can help in meeting the requirements of European environmental plans, such as the ‘20–20–20’ action plan. [ABSTRACT FROM AUTHOR]

Abstract: This paper combines engineering and social science approaches to enhance our understanding of industrial energy efficiency and broaden our perspective on policy making in Europe. Sustainable development demands new strategies, solutions, and policy-making approaches. Numerous studies of energy efficiency potential state that cost-effective energy efficiency technologies in industry are not always implemented for various reasons, such as lack of information, procedural impediments, and routines not favoring energy efficiency. Another reason for the efficiency gap is the existence of particular values, unsupportive of energy efficiency, in the dominant networks of a branch of trade. Analysis indicates that different sectors of rather closed communities have established their own tacit knowledge, perceived truths, and routines concerning energy efficiency measures. Actors in different industrial sectors highlight different barriers to energy efficiency and why cost-effective energy efficiency measures are not being implemented. The identified barriers can be problematized in relation to the social context to understand their existence and how to resolve them. [Copyright &y& Elsevier]

Abstract: This study begins with a review of energy consumption by end-use sector in Hawaii. Then, the energy generated from renewable energy sources is analyzed between 1991 and 2006. The results show that while geothermal is a considerable source of renewable energy on the Island of Hawaii (also known as Big Island), fossil fuel is the main energy source in the State of Hawaii. The energy intensity index for the State of Hawaii is then calculated by dividing energy consumption per capita by the income per capita. The calculated energy intensity index reveals that energy consumption is directly controlled by per capita income. The results also indicate that the energy intensity index increases over time despite positive developments in energy efficient technologies. In the second part of the paper, the effect of the tourism industry on energy usage in the State of Hawaii is analyzed. The results show that tourism volume, measured in terms of tourist arrival numbers, does not change the energy consumption directly. However, a change in tourism volume does affect per capita income within a few months to a year. In the last part of the study, the energy efficiency index of Hawaii is compared with consumption averages for the US, California and the most energy efficient country in Europe, Denmark. The comparison shows that Hawaii lags behind California and Denmark in terms of energy efficiency. The comparison also shows that an increase in energy efficiency corresponds to an increase in per capita income across the board, which is in agreement with a recent report published by the American Physical Society. [Copyright &y& Elsevier]

In the UK, heating systems in the built environment consume a substantial proportion of its total energy and are responsible for about 25% of the total carbon emission. A similar pattern is also exhibited in many other European countries. Despite the enormous effort made over the last decades to improve the energy efficiency of these heating systems, a huge potential for further energy saving still persists. This paper investigates the potential for energy saving in heating systems that can be achieved through improving boiler controls. This investigation was carried out through surveys, simulation and experimental study. Through the surveys, typical boiler control schemes widely used in current practice were identified. The performance of some systems surveyed was monitored through the survey. The data obtained is used to demonstrate the problems associated with the control of boilers in heating systems. These typical control schemes identified through surveys were studied using a simulator that had been rigorously validated. An experiment was carried out to demonstrate how the overall performance of a heating system could be improved by using a better boiler controller. The result shows that improving boiler controls can lead to up to 20% of energy saving and a significant improvement in thermal comfort. [Copyright &y& Elsevier]

Many studies have investigated different aspects in the decarbonisation of the European housing stock. However, a comprehensive quantitative analysis of the literature on the diffusion of energy efficiency technologies is still missing. We conducted a bibliometric analysis to better understand the knowledge base in the field energy efficiency technology diffusion in the European residential building stock. After the scanning and screening process, we identified 954 scientific articles pertinent to this topic. Through a co-citation network analysis, we generated a visual knowledge structure of the field and by the further investigation of the bibliography we were able to synthesize the state-of-the-art and answer to our initial research questions. Results of the co-citation network show a scattered and fragmented field in many domains. The descriptive analysis highlights this fragmentation, especially on a cross-country level among EU country members. Findings from this study contribute to map the scientific knowledge base in relation to technology diffusion in European residential building projects, identify relevant topic areas, visualize the links between the topics, as well as to recognize research gaps and opportunities. The methodology utilized in this paper proved to be viable approach to map and characterize the knowledge base within a field and can, therefore, be replicated in upcoming studies with analogous ambitions. [ABSTRACT FROM AUTHOR]