Due to the need of good thermal performance, external wall insulation (EWI) is usually made of materials that are not fire resistant and sometimes flammable. That restricts its application to a particular circumstance such as limited building height. Hence, a material with good thermal insulation and fire resistance performance would allow EWI to be more widely applied. This paper introduces a novel material: a silica-based aerogel porous board, which differs itself from mainstream products available in the market because of its outstanding properties, such as low density, high surface area, low thermal conductivity and superhydrophobicity. Herein, its thermal insulation and fire-resistant performance were tested and compared with commercial products. The cone calorimeter analysis results indicated that the aerogel porous board could improve the fire resistance performance. Moreover, the evaluation of thermal insulation performance suggested that the application of an aerogel porous bo... [more]

The adoption of electric vehicles promises numerous benefits for modern society. At the same time, there remain significant hurdles to their wide distribution, primarily related to battery-based energy sources. This review concerns the systematization of knowledge in one of the areas of the electric vehicle control, namely, the energy management issues when using braking controllers. The braking process optimization is summarized from two aspects. First, the advantageous solutions are presented that were identified in the field of gradual and urgent braking. Second, several findings discovered in adjacent fields of automation are debated as prospects for their possible application in braking control. Following the specific classification of braking methods, a generalized braking system composition is offered, and all publications are evaluated primarily in terms of their energy recovery abilities as a global target. Then, conventional and intelligent classes of braking controllers are... [more]

Evidence collected by researchers over several decades suggests that the successful implementation of the Energy Efficiency Obligation Scheme (EEOS) may deliver significant, cost-effective energy savings over many years. However, before starting EEOS in Latvia, predictions by energy efficiency policy researchers envisaged that it is at high risk of savings shortfalls. This study aims to carry out an ex-post policy evaluation of EEOS in Latvia and assess its ability to deliver significant savings in the first phase of the new EEOS. This paper questions whether the new EEOS can reach savings goals without prior experience with voluntary agreement schemes and emulation of successful EEOS from other countries. The second goal of the research is to create a web-based optimization tool as an Interactive Learning Environment to help policymakers and EEOS-obliged parties to create goal-oriented strategies. The study has found that, contrary to expectations, Latvia has reached and even overfulf... [more]

The purpose of this study is to identify the most relevant renewable energy technologies for buildings and to assess the effectiveness of their implementation in the long term for Kuwait. Methods of analogies and comparisons were used to determine the features of energy efficiency based on the technologies under study. The study proposes the methodological approach to assessing the effectiveness of the introduction of renewable energy technologies, determining the direction of increasing the energy efficiency of buildings and the investment efficiency of introducing these technologies. Renewable energy efficiency analysis for buildings in Kuwait confirms that solar energy systems have been the most widely available for widespread use of solar energy over the past three years. An increasing level of energy efficiency with a decrease in the notional cost of increasing energy savings is characteristic of solar collectors with booster reflectors. The proposed model for assessing the level... [more]

This paper contains the basic definition and application of the physical optimum as a method for process evaluation and optimization. By means of the exemplary balance of a wood pellet-fired boiler, the conventional efficiency is compared to the PhO. Furthermore, this study demonstrates the possibility of applying the thermodynamic state variable exergy as a physical reference property of a system within the PhO method. To explain the approach, the heat generation in the wood pellet-fired boiler is compared to the supply from a heat pump, which itself is connected to a power plant. Furthermore, the process-independent PhO is explained in order to illustrate the limitations of feasible optimization. Additionally, possible research topics such as the integration of dynamic behavior in the method are approached. As a conclusion, the differences between the methods outline the advantage of the PhO in the optimization process.

The digitalization of the forest sector, the increased demand of energy-wood, as well as faster market changes have increased the number of challenges for wood procurement of the forest industry. The aim of the study is to optimize wood procurement (upstream of supply chain) of energy and material production in integrated situations, and to consider the effects of production changes on the management of procurement regions. Three scenarios described integrated production situations in a carbon-neutral forest industry: (1) declining export, (2) energy reform, and (3) extensive energy reform. Time-varying capital-, cost-, and energy efficiency of the dynamic wood-flow model affected the competitiveness of the procurement regions. As a novel contribution, energy efficiency was modeled using the price of emission allowance as a cost parameter. The results show the positive effects of the energy reforms, which partly compensate for the declining exports. In addition, it is possible to chang... [more]

In the Industrial Internet of Things (IIoT), non-orthogonal multiple access (NOMA) has emerged as a viable multiple access method due to its superior efficiency. In this paper, a new power allocation technique for NOMA-enabled IIoT devices is presented with trade-offs between increasing energy efficiency and decreasing power consumption. We present a joint optimization of transmission rate and energy harvesting in simultaneous wireless information and power transfer (SWIPT) NOMA-enabled IIoT devices. With the power splitting (PS) approach, we examine how to improve overall transmission rate and harvested energy, simultaneously, while fulfilling the minimum rate and harvested energy needs of each IIoT device in a SWIPT-enabled NOMA system. An objective function is established by adding transmission rates obtained from information decoding and the transformed throughput from energy harvesting. The combination of management approaches with Industry 4.0 technology provides a viable strateg... [more]

Small-scale combined heat and power (micro-CHP or mCHP) plants generate heat in the process of localised electricity production that can usefully be captured and employed for domestic space and water heating. Studies of the relative merits of three alternative network-connected mCHP plants are reviewed based respectively on an Internal Combustion engine (ICE), a Stirling engine (SE), and a Fuel Cell (FC). Each plant will, in most cases, result in lower carbon dioxide (CO2) emissions, relative to those from the most efficient condensing boilers. In addition, they lead to operational cost savings for the consumer, depending on house type. However, their capital costs are presently more expensive than a conventional boiler, with the FC being prohibitively so. The ICE and SE variants display the greatest economic and environmental benefit. Nevertheless, the performance and costs associated with these innovative technologies have rapidly improved over the last decade or so. Comparisons are... [more]

In the last few years, deep reinforcement learning has been proposed as a method to perform online learning in energy-efficiency scenarios such as HVAC control, electric car energy management, or building energy management, just to mention a few. On the other hand, quantum machine learning was born during the last decade to extend classic machine learning to a quantum level. In this work, we propose to study the benefits and limitations of quantum reinforcement learning to solve energy-efficiency scenarios. As a testbed, we use existing energy-efficiency-based reinforcement learning simulators and compare classic algorithms with the quantum proposal. Results in HVAC control, electric vehicle fuel consumption, and profit optimization of electrical charging stations applications suggest that quantum neural networks are able to solve problems in reinforcement learning scenarios with better accuracy than their classical counterpart, obtaining a better cumulative reward with fewer parameter... [more]

The increase in energy demand requires urgent investments in sustainable energy. It is vital to the success of the 2030 Agenda, adopted by the United Nations General Assembly. The article aimed to assess the situation of the European Union countries with regard to energy use. Indicators related to the implementation of SDG7 and environmental and resource productivity of the economy were adopted for the study. The research presented in this article fits into contemporary debates on the effectiveness of implementing one of the SDG7: ensuring access to affordable, reliable, sustainable, and modern energy for all. The analysis included 26 countries that have been in the European Union since 2010. The study’s originality lies in the use of primary data obtained from the Eurostat database for three research periods: 2010, 2015, and 2020, which will allow for assessing the situation of the surveyed EU countries in the area of energy use. In order to achieve the research objective, selected me... [more]

Applications of the Internet of Things (IoT) are rapidly utilized in smart buildings and smart cities to reduce energy consumption. This advancement has caused a knowledge gap in applying IoT effectively by experts in the built environment to achieve energy efficiency. The study aims to provide an extensive review of IoT applications for energy savings in buildings and cities. This study contributes to the field of IoT by guiding and supporting built environment experts to utilize IoT technologies. This paper performed a thorough study using a systematic review that covered an overview of IoT concepts, models, applications, trends and challenges that can be encountered in the built environment. The findings indicated limitations in developing IoT strategies in buildings and cities by professionals in this field due to insufficient comprehension of technologies and their applied methods. Additionally, the study found an indefinite implementation and constraints on using IoT when integra... [more]

Most of the charcoal in the world comes from small and medium-sized producers, using rudimentary carbonization kilns that require significant time or energy during the heating and cooling stages of the process. Despite advances in improving the performance, the influence of materials used in the sidewalls of these kilns has been scarcely studied. Therefore, based on numerical simulations, the present study analyses the thermal performance of cylindrical sidewalls composed of combinations of metallic materials, ceramic materials, and insulating blankets grouped in three configurations: configuration I (sidewall with just one material), configuration II (sidewall with two materials assembled in series), and configuration III (pivoting sidewall). Results were encouraging, especially when comparing kiln configuration I with the novel configuration III. Simulations suggested that the proposed configuration III could reduce the heating time by 62%, the cooling time by 91%, the heat supplied... [more]

Jevons Paradox has fundamental implications on sustainable development and the UN Sustainable Development Goals (SDGs). The paradox states that technological improvements aiming to increase the energy efficiency risk causing a rebound effect, and an increase in demand, production, and resource exploitation. Third world countries undergoing early-stage technological development may be particularly vulnerable, but it is also relevant in complex economic systems, where policymaking on climate and energy building on insufficient knowledge and attention to rebound effects can impair the desired outcome in terms of climate change mitigation, resource use and sustainable development.

This paper presents the experimental research conducted for the Biomimetic Unmanned Underwater Vehicle (BUUV). The study’s major goal is to create a single, flexible side fin with adequate proportions and stiffness for an energy-efficient propulsion system. The experiments were carried out in a laboratory water tunnel equipped with a sensor for direct thrust measurement for various fin dimensions. Further, the particle image velocimetry (PIV) approach was used for a more in-depth examination of fluid−structure interaction (FSI) phenomena. The given experiments indicate the region of superior propulsion system performance and explain the main aspects that have influenced thrust generation using image processing and the PIV approach.

Designing eco-friendly products involves energy efficiency improvements. Eco-friendly products must consider not only raw materials and manufacturing processes to improve energy efficiency but also energy needed when designing them. This research shows how eco-routing (ER), eco-charging (EC), eco-driving (EDR), vehicle-to-grid (V2G) and electric vehicles (EVs) can contribute to the reduction of energy consumption during product design. To do this, a group of 44 engineers assigned to the project was chosen to assess the total energy available for V2G when driving EVs from their homes to the design center by using ER, ED and EC by running an application coded by the authors. The energy stored in EVs was used to quantify the reduction in energy consumption of the buildings present in the design center. The results show that the energy saving ranges from 2.89% to 6.9% per day—in other words, 93 kWh per day during the design process. In addition, the fact of making the design process greene... [more]

Energy consumption is a critical issue for the communications network operators, impacting deeply the cost of the services, as well as the ecological footprint. Network slicing architecture for 5G mobile communications enables multiple independent virtual networks to be created on top of a common shared physical infrastructure. Each network slice needs different types of resources, including energy, to fulfill the demands requested by each application, operator, or vertical market. The existing literature on network slicing is mainly targeted at the partition of network resources; however, the corresponding management of energy consumption is an unconsidered critical concern. This paper analyzes the requirements for an energy-aware 5G network slicing provisioning according to the 3GPP specifications, proposes an architecture, and studies the strategies to provide efficient energy consumption in terms of renewable and non-renewable sources. NFV and SDN technologies are the essential ena... [more]

We analyze energy use efficiency of manufacturing industries in US manufacturing over five decades from 1960 to 2011. We apply a 4-component stochastic frontier model, which allows disentangling efficiency into a short- and long-term efficiency as well as accounting for industry heterogeneity. The data come from NBER-CES Manufacturing Industry Database. We find that relative to decade-specific frontiers, the overall efficiency of manufacturing industries, which is a product of transient and persistent efficiencies has deteriorated greatly in the 1970s and rebounded only in the 2000s. The industries are very efficient in the short-term and this has not changed over five decades. The high level of overall inefficiency is almost completely due to the structural inefficiency which can be explained by what is referred to as the “energy paradox”. Finally, higher energy-intensive industries perform worse in terms of energy use efficiency than their low energy-intensity counterparts.

With the development of the convergence of IT and automotive technology, platoon-based driving systems are getting more attention and how to disseminate messages in the platoon is an important issue. In this paper, to enhance the energy efficiency and traffic throughput (e.g., average velocity) while meeting transmission deadlines, we propose an energy efficient message dissemination scheme (EMDS) in platoon-based driving systems, which also provides proper power control and relay selection. To find out the optimal policy to balance the probability of successful message dissemination and transmission power cost in EMDS, we formulate a Markov decision process (MDP) problem that considers the velocity of the vehicles in the platoon. To evaluate the performance of EMDS, we analyze the outage probability, the average velocity, and the expected power consumption using the discrete-time Markov chain (DTMC) model. Evaluation results demonstrate EMDS with the optimal policy improves the averag... [more]

Power quality and energy efficiency are of great importance in motor control. The motor of any medical device needs to have a smooth torque and minimal vibration in order to maximise its energy efficiency and patient comfort. Furthermore, in rotary blood pumps, excessive energy wasted due to vibration is converted into uncontrolled movement of the mechanical parts and thus could reduce the life of the motor-pump. Besides mechanical or hydraulic origin, one of the causes of vibration in any pump is torque ripple resulting from motor phase commutation. In this paper, using relevant equipment, two extreme scenarios were examined for vibration and electrical efficiency comparison due to power quality in a blood pump: one trapezoidal control with a trapezoidal phase current output; the other a field oriented control (FOC) with a non-distorted sinusoidal phase current. The test motor-pump was the Arteriovenous Fistula Eligibility (AFE) System that is used prior to haemodialysis. The trapezoi... [more]

The energy storage field is nowadays a highly ranking topic. This research deals with the installation and analysis of the ice storage system which combines heat pump, solar absorber, and ice storage tank (phase change material—PCM). This system uses a special kind of solar absorber − header pipes (HDP), which have no thermal isolation compared to the common solar absorber. Thanks to that the HDP, pipes can absorb thermal energy not only from the sun but also from the environment. The rain or snow also affects heat exchange. All that is provided by one technical device. The system can store thermal energy gained from the solar absorber into the ice storage tank for future usage. Research works with data from the real operation, for a period of the year covering all working phases/modes of the system. The analysis of the data led to the identification of several specific modes of the system, especially from the processes taking place in the PCM storage tank during its charging and disch... [more]

In this paper, we examine the energy efficiency performance of the Belt and Road Initiative (BRI) countries using a newly developed panel data stochastic frontier model that allows for estimation of both persistent and transient efficiency while controlling for random country effects and noise. By this, we contribute to the energy economic literature by providing a complete picture of the level of persistent, transient, and total energy efficiency estimates from a cross country perspective for a panel of 48 BRI countries during the period 1990−2015. Adding that there is little evidence to support energy efficiency convergence in the energy economic literature, we went further to check whether energy efficiency converges in the BRI countries. The results show that (1) persistent efficiencies are much lower than transient efficiencies, suggesting that the energy problem in the BRI countries is more of a structural issue; (2) while energy efficiency varies widely across the countries, hig... [more]

The use of renewable energies, energy saving, and efficiency are needs of global society. According to the latest estimates, global energy demand could triple by 2050 and, by then, 70% of the world’s population will live in cities. Cities are currently responsible for 80% of greenhouse gas emissions, so they have a key role to play in shifting towards a sustainable energy future. Cities are threatened not only by overcrowding, but also by rising energy demand, obsolete infrastructure, volatile energy markets, and the effects of climate change. This Special Issue aims to advance the contribution of energy saving and the use of renewable energies in order to achieve more sustainable cities.

Since pneumatic systems are widely used in various branches of industry, the need to find ways to reduce energy consumption in these systems has become very pressing. The reduction in energy consumption in these systems is reflected in the reduction of compressed air consumption. The paper presents a cylinder control system with a piston rod on one side, in which the reduction in energy consumption is ensured by using different levels of supply pressure in the working and the return stroke, and by holding the cylinder piston rod in its final positions with a clamping cartridge. Clamping and holding the piston rod in its final position further affects the reduction in energy consumption. Experimental data show that the application of the proposed control leads to a decrease in compressed air consumption of 25.54% to 32.97%, depending on the compressed air pressure used in the return stroke. The cost-effectiveness of the proposed cylinder control with different levels of compressed air p... [more]

In this work, we investigate the potential of using last generation photovoltaic systems in traditional building components of historical buildings. The multifunctional photovoltaic components also open new application and implementation horizons in the field of energy retrofitting in historical buildings. Some of the Building-Integrated Photovoltaics (BIPV) solutions lend themselves optimally to solving the problems of energy efficiency in historical buildings. For the next few years, Italian legislation foresees increasing percentages of energy production from renewable sources, including historical buildings. The opportunities and constraints analysed are presented through a specific approach, typical of building processes for innovative technological BIPV solutions on historical buildings.

The importance and urgency of energy efficiency in sustainable development are increasing. Accurate assessment of energy efficiency is of considerable significance and necessity. The data envelopment analysis (DEA) method has been widely used to study energy efficiency as a total factor efficiency assessment method. In order to summarize the latest research on DEA in the field of energy efficiency, this article first analyzes the overall situation of related literature published in 2011−2019. Subsequently, the definition, measurement and evaluation variables of energy efficiency are introduced. After that, this article reviews the current DEA model and its extension models and applications based on different scenarios. Finally, considering the shortcomings of the existing DEA model, possible future research topics are proposed.