Showing papers in "Energy Efficiency in 2020"

Data centres in future European energy systems—energy efficiency, integration and policy

Abstract: End-use efficiency, demand response and coupling of different energy vectors are important aspects of future renewable energy systems. Growth in the number of data centres is leading to an increase in electricity demand and the emergence of a new electricity-intensive industry. Studies on data centres and energy use have so far focused mainly on energy efficiency. This paper contributes with an assessment of the potential for energy system integration of data centres via demand response and waste heat utilization, and with a review of EU policies relevant to this. Waste heat utilization is mainly an option for data centres that are close to district heating systems. Flexible electricity demand can be achieved through temporal and spatial scheduling of data centre operations. This could provide more than 10 GW of demand response in the European electricity system in 2030. Most data centres also have auxiliary power systems employing batteries and stand-by diesel generators, which could potentially be used in power system balancing. These potentials have received little attention so far and have not yet been considered in policies concerning energy or data centres. Policies are needed to capture the potential societal benefits of energy system integration of data centres. In the EU, such policies are in their nascent phase and mainly focused on energy efficiency through the voluntary Code of Conduct and criteria under the EU Ecodesign Directive. Some research and development in the field of energy efficiency and integration is also supported through the EU Horizon 2020 programme. Our analysis shows that there is considerable potential for demand response and energy system integration. This motivates greater efforts in developing future policies, policy coordination, and changes in regulation, taxation and electricity market design.

Energy efficiency as energy justice: addressing racial inequities through investments in people and places

Abstract: Structural racism in the form of racial residential segregation and the series of laws, policies and practices that continue to reinforce it, has robbed generations of African Americans of socioeconomic opportunity, wealth accumulation, safe, secure or energy-efficient housing, and full societal inclusion. Research indicates that African Americans are more likely to live in older, energy inefficient homes with structural deficiencies, outdated appliances and faulty energy systems. These conditions lead to a disproportionate burden of energy insecurity, defined as "the inability to adequately meet household energy needs" among African Americans across the economic spectrum. This, in turn, generates increased costs and decreased comfort, conditions closely linked to adverse physical and mental health outcomes. Persistent income inequality, wealth gaps and entrenched racial residential segregation have disenfranchised African Americans and reduced their ability to escape this pernicious cycle. Weatherization, which is the practice of protecting a building's interior from the elements while enhancing its energy efficiency and reducing costs, could be a catalyst for reducing the disproportionate energy burden affecting low-income individuals and ultimately improve health and social outcomes among African Americans. We argue for investing in policies that provide energy efficiency and weatherization assistance -- and not only energy bill assistance -- to provide a long-term and equitable solution to energy insecurity that is also a critical step toward restorative justice.

The effects of behavioral intention on the choice to purchase energy-saving appliances in China: the role of environmental attitude, concern, and perceived psychological benefits in shaping intention

Abstract: Purchasing energy-saving appliances is a sensible and practical way to reduce carbon emissions from the residential sector in China. This study examines the relationship between pro-environment behavioral intention—undergirded by environmental attitude and concern as well as perceived psychological benefits—and the choice to purchase energy-saving appliances among Chinese households. Integrating psychological benefits (i.e., warm glow and self-express benefits) into the theory of planned behavior, a first of its kind for China, we designed and implemented a cross-sectional online survey in 2016. We conducted Probit regression analyses based on the 942 effective responses collected. The results reveal that behavioral intention has significantly positive effects on the choice to purchase energy-saving appliances. Environmental attitude and concern, as well as psychological benefits, have a significantly positive impact on respondents’ behavioral intention to buy energy-saving devices. Also, age and household size significantly and positively correlate with purchasing energy-saving appliance decision. These results point to useful policy implications to boost consumer support for energy-saving appliances in China and provide a foundation for similar research in other developing contexts.

Promoting environmentally sustainable consumption behavior: an empirical evaluation of purchase intention of energy-efficient appliances

Abstract: The energy sector is one of the most prominent sectors in the development of nations. The scarcity of energy in developing nations urged the government and private sector to consider the efficient resources of energy. Energy-efficient appliances help to reduce the consumption of energy and fulfill consumers’ utilitarian needs. The purpose of this study is to empirically evaluate consumers’ purchase intention of energy-efficient appliances. The study employed convenience and quota based on the age sampling technique to select the participants of the study in one of the developing countries (Pakistan). Covariance-based structural equation modeling (CB-SEM) has been applied to test the hypothesized relationships among the constructs. In findings, knowledge of eco-labels, environmental concern, attitude, and perceived consumer effectiveness were found important antecedents of consumers’ purchase intention. Further, the findings provide environmental strategist with meaningful insight into the critical role that knowledge of eco-labels and environmental concern play in achieving energy-efficiency through the use of energy-efficient appliances.

Total factor energy efficiency and economic development in Africa

Abstract: This paper presents an energy efficiency assessment of 46 African countries and analyzes possible bidirectional relationship between energy efficiency and economic development within a three-stage framework. In the first stage, energy efficiency is measured within a total factor framework using the slack-based measure with undesirable output and sub-regional comparisons are done. The second stage assesses the determinants of energy efficiency in Africa by way of a bootstrapped truncated regression. The third stage tests the reverse causal relationship between energy efficiency and economic development using 2-stage least squares. The results showed African countries to be on average, 56% energy efficient within the study period. Other African sub-regions could adopt the energy efficiency policies of North Africa as benchmark to improve energy efficiency. Economic development and technological progress are found to have significant positive effects on energy efficiency of African countries, while higher energy prices lead to higher inefficiency. Also, a bi-causal relationship is found to exist between total factor energy efficiency and economic development, giving support to the concept of sustainable development and confirming the International Energy Agency’s assertion on the positive macroeconomic impacts of energy efficiency. African countries are therefore, encouraged to invest in energy efficiency technologies and policies to drive sustainable economic development.

Energy efficiency in SMEs : overcoming the communication barrier

Abstract: This article discusses ineffective knowledge and information communication as an important barrier to improving energy efficiency in small and medium-sized enterprises (SMEs) and considers how to make functional communication an enabler of future SME energy-efficiency programmes. Energy audits – important tools when addressing energy efficiency in companies – are often performed by professionals with an engineering background, which does not reflect the backgrounds of those receiving the audit, inhibiting the interpretation of those audits. SMEs must actively process the information, and their employees must be able to connect the information to existing knowledge. We analysed two methods used by Swedish municipal energy-efficiency programmes to improve energy efficiency in SMEs. The results indicate that in the programme providing SMEs with third-party information, but without any possibility to process the information, the energy-efficiency results were poor, while in the programme in which SMEs were actively engaged in all stages and could discuss problems and results with peers, the energy-efficiency results were better. In implementing SME energy-efficiency programmes, municipalities should avoid simply offering audits. Instead, they should find methods that facilitate knowledge creation among the participants, allowing the participating SMEs to share experience and knowledge with one another and with experts, and to take home ideas, testing them in their own contexts, and communicating their experiences. This would be a way to make communication an enabler rather than a barrier.

Daily life and demand: an analysis of intra-day variations in residential electricity consumption with time-use data

Abstract: Demand-side flexibility has been suggested as a tool for peak demand reduction and large-scale integration of low-carbon electricity sources. Deeper insight into the activities and energy services performed in households could help to understand the scope and limitations of demand-side flexibility. Measuring and Evaluating Time- and Energy-use Relationships (METER) is a 5-year, UK-based research project and the first study to collect activity data and electricity use in parallel at this scale. We present statistical analyses of these new data, including more than 6250 activities reported by 450 individuals in 173 households, and their relationship to electricity use patterns. We use a regularization technique to select influential variables in regression models of average electricity use over a day and of discretionary use across 4-h time periods to compare intra-day variations. We find that dwelling and appliance variables show the strongest associations to average electricity consumption and can explain 49% of the variance in mean daily usage. For models of 4-h average “de-minned” consumption, we find that activity variables are consistently influential, both in terms of coefficient magnitudes and contributions to increased model explanatory power. Activities relating to food preparation and eating, household chores, and recreation show the strongest associations. We conclude that occupant activity data can advance our understanding of the temporal characteristics of electricity demand and inform approaches to shift or reduce it. We stress the importance of considering consumption as a function of time of day, and we use our findings to argue that a more nuanced understanding of this relationship can yield useful insights for residential demand flexibility.

Design and realisation of the Passive House concept in different climate zones

Abstract: The term Passive House refers to a performance-based energy standard for high-efficiency buildings. It is clearly defined, with validity for all climates of the world. Under cold climate conditions, the design typically focuses on minimising heat losses and optimising solar gains. In milder climates, moderate insulation, including improved window qualities, is sufficient, but on the other hand, the building performance during summer requires more careful consideration. For hotter climates, the insulation requirements increase again, and solar loads through windows, walls and roofs must be limited. In hot and humid climates, humidity loads are also minimised or reduced. In practical implementation, every Passive House has its own, specific boundary conditions which lead to different constructions and technical solutions to fulfil the stringent requirements of the Passive House standard. The paper briefly introduces Passive House design principles and criteria. Then, nine examples for passive houses in climates of Canada, the USA, Germany, China, Greece, Spain, Taiwan, Mexico and the United Arab Emirates illustrate the bandwidth of possible solutions. For many projects, practical experiences are available, which typically reveal high user satisfaction and energy consumptions close to what would be expected from the design calculations. In some cases, a potential for further improvements is described.

An extension of the goal-framing theory to predict consumer’s sustainable behavior for home appliances

Abstract: This study aims to investigate the extended role of goal-framing theory (GFT) on the energy-saving air conditioners called inverter air conditioners (IACs) in the context of the developing market (Pakistan). The GFT has three constructs, gain motivations, hedonic motivations, and normative motivations, which affect consumers’ sustainable behavior. The study is based on a survey of IAC users with the final sample size of 418 and using PLS-SEM. The empirical findings highlight the importance of all the three motivational factors and the negative moderation of perceived behavior control (PBC). There is a substantial direct effect of normative motivations, whereas the direct effect of gain motivations on sustainable intentions is insignificant. Implications for the marketing professionals and policymakers suggested the use of a mix-motivational approach to get sustainable results while promoting sustainable products like IACs. Avenues for further exploration into this area have also been recommended to future researchers.

An ensemble approach for assessment of energy efficiency of agriculture system in Pakistan

Abstract: An efficient assessment of energy consumption, energy flow, and energy use efficiency in crop (maize) production is inevitable to accomplish the intensive demand for energy. Data Envelopment Analysis (DEA) models based on energy input-output analysis are commonly used for the assessment of energy efficiency. However, standard implication of traditional (CCR) and extended (SBM) models has shortcomings in reporting efficiency score; CCR neglects slacks while SBM caused problems when reporting efficiency over time. To overcome this problem, an ensemble approach that compromised the characteristics of two models (CCR-SBM) is proposed in the current study. Based on the weighted average of the relative efficiencies of two contending models, an ensemble efficiency (EE) score was reported for energy efficiency evaluation of considered DMUs. Preliminary analysis ensued average maize yield of 6874 kg ha−1 with an overall energy input of 42,241.45 MJ ha−1, and net energy gain, energy use efficiency (average), specific energy, and energy productivity, were 58,806 MJ ha−1, 2.39, 6.15 MJ kg−1, and 0.16 kg MJ−1, respectively. Using four major shareholders of input energy (i.e., fertilizer, diesel fuel, irrigation water and chemicals) and, maize yield as output, the projected ensemble approach resulted in an unproductive trend of energy use efficiency in Pakistan with an average ensemble efficiency score of 59.67%, and plausible potential of energy saving from 7181.046 to 33,370.74 MJ ha−1. Furthermore, the ensemble approach showed that EE score could help to significantly reduce the shortcomings of slacks and time fluctuation when reporting efficiency score, compared with using individual models. The proposed approach scrutinized and provided a comprehensive state of the actual situation of energy efficiency in maize production of Pakistan that is important in the context of decision-making. Results of the study suggest resource conservation measures through better agricultural management practices, and production methods and extension activities are required to improve the efficiency of energy consumption in maize production of Pakistan.

LMDI decomposition analysis of energy consumption of Turkish manufacturing industry: 2005–2014

Abstract: Decomposition analysis is a proven approach to highlight the trends in energy economics and to clarify the changing factors in energy consumption. In Turkey, industrial sector is one of the major drivers of economy, which accounts for 32% of the final energy consumption. This paper uses the logarithmic mean Divisia index (LMDI) to divide the total energy consumption growth of ten Turkish manufacturing industries into activity effect, structure effect, and intensity effect in the period from 2005 to 2014. Manufacturing subsectors consist of (a) food products, beverages, and tobacco, (b) textile and textile products, (c) wood and wood products, (d) pulp, paper, and paper products; publishing and printing, (e) chemicals, chemical products, and man-made fibers, (f) rubber and plastic products, (g) non-metallic mineral products, (h) primary metals, (i) equipment goods, and (j) other manufacturing. Energy consumption of total manufacturing industry rose from 25,013 ktoe to 27,590 ktoe within the period. The subsector (a), (b), (c), (d), (e), (f), and (i) analyses results reveal that the activity effect has significant contribution to energy consumption, while structure and intensity effects are negligible. On the other hand, for the energy-intensive industries, influence of structure and intensity effects has observed simultaneously. The results also show that intensity and activity effects follow similar trends. Energy intensity of manufacturing industry has followed a slightly decreasing route (0.288 ktoe/$2005 in 2005 and 0.219 ktoe/$2005 in 2014) in the period, which is an indicative of contribution of activity changes, energy efficient technologies, and other energy efficiency efforts.

Retrofitting towards energy-efficient homes in European cold climates: a review

Abstract: Existing buildings represent a significant energy saving potential in Europe, and retrofitting the building stock is essential to reach European targets. Retrofitting measures should reduce the energy consumption as well as improve the indoor climate while still being cost-effective. This can be challenging in European cold climates. This paper discusses energy performance requirements and challenges in the retrofitting process. It also presents an overview of the retrofitting status and relevant energy saving retrofitting measures with their potential for residential buildings. Measures to lower the building’s energy demand and electrical energy consumption and measures to control and monitor the energy use are discussed. Some research directions for the future of building energy usage are suggested. The literature indicates that significant energy savings can be achieved from retrofitting the building envelope. Relatively few research papers have been devoted to the energy saving potential of building control systems for existing residential buildings. However, these savings seem low compared to those that can be achieved through energy conservation. The actual savings from retrofitting the envelope, HVAC-systems and control systems are case specific and should be assessed for reference buildings of each housing typology.

A deep learning approach for anomaly detection and prediction in power consumption data

Abstract: Anomaly detection in power consumption data can be very useful to building managers. It allows them to detect unexpected power consumption values, identify unusual behaviors, and foresee uncommon events. This paper proposes a novel unsupervised approach to detect anomalies in power consumption data. We combine the clustering-based methods with the prediction-based ones to learn typical behavior scenarios and to predict the power consumption of the next hour. These scenarios are explored by applying the K-means algorithm on 24 different K-means groups representing the 24 h of the day. This is based on the assumption that identical daily consumption behavior can appear repeatedly due to users’ living habits. In order to detect the anomaly 1 h before its occurrence, a Long Short-Term Memory (LSTM) has been trained to predict the next power consumption value. This predicted value with some earlier data values are concatenated into a vector then compared with the learned typical scenarios. We used Auto-Encoders to detect anomalous days in general and this novel method to specify at what time the anomaly has occurred. Our approach not only detectss anomalies in off-line mode but also allows real-time detection on live data streams.

Building energy modeling at neighborhood scale

Abstract: The urban climate and outdoor air quality of cities that have a positive thermal balance depending on the thermal consumptions of buildings cause an increase of the urban heat island and global warming effects. The aim of this work has been to develop an energy balance using the energy consumption data of the district heating network. The here presented engineering energy model is at a neighborhood scale, and the energy-use results have been obtained from a heat balance of residential buildings, by means of a quasi-steady state method, on a monthly basis. The modeling approach also considers the characteristics of the urban context that may have a significant effect on its energy performance. The model includes a number of urban variables, such as solar exposition and thermal radiation lost to the sky of the built environment. This methodology was applied to thirty-three 1 km × 1 km meshes in the city of Turin, using the monthly energy consumption data of three consecutive heating seasons. The results showed that the model is accurate for old built areas; the average error is 10% for buildings constructed before 1970, while the error reaches 20% for newer buildings. The importance and originality of this study are related to the fact that the energy balance is applied at neighborhood scale and urban parameters are introduced with the support of a GIS tool. The resulting engineering models can be applied as a decision support tool for citizens, public administrations, and policy makers to evaluate the distribution of energy consumptions and the relative GHG emissions to promote a more sustainable urban environment. Future researches will be carried out with the aim of introducing other urban variables into the model, such as the canyon effect and the presence of vegetation.

Bridging the rural efficiency gap: expanding access to energy efficiency upgrades in remote and high energy cost communities

Abstract: Islands and remote rural communities throughout the USA pay some of the highest costs for electricity and heating fuel in the nation. For areas with such high energy costs, the benefits of energy efficiency can be significant but rural residents face several geographic, financial, and awareness barriers that make it difficult to invest in home energy upgrades. These barriers combine to create a market failure that we call the “rural energy efficiency gap.” The existence of the rural efficiency gap is supported by data collected from Alaska, Maine, New Hampshire, and Vermont which indicate that the “energy burden,” or percentage of household income spent on energy bills, is 33% higher in rural areas and that participation in residential energy efficiency financing and rebate programs can be significantly lower. The combination of higher energy burdens and greater barriers to participation can lead to inequitable distribution of available resources for energy efficiency, meaning that those who could benefit most from efficiency upgrades are often least able to access them. This work is designed to be a resource for energy efficiency program administrators but may also be of interest to energy efficiency program implementers, policymakers, and regulators. It provides data about the rural energy efficiency gap and identifies barriers to energy efficiency in rural communities. It also highlights strategies that are helping to bridge the gap by making it easier for residents in cold climate, petroleum-dependent states—those with high thermal energy burdens—to increase comfort and safety in their homes while also reducing energy bills. The barriers to rural energy efficiency identified in this paper have been grouped into three categories: geographic barriers, financial barriers, and awareness and access barriers. There are many differences between rural areas across the country, e.g., demographics, utility model and rate structures, energy sources, and consumption patterns. This paper is not intended to suggest that the strategies documented here will necessarily be applicable to all rural areas in the USA

Energy taxation policies can counteract the rebound effect: analysis within a general equilibrium framework

Abstract: The rebound effect reflects the difference between the expected energy savings from energy efficiency, and the real ones, considering the former is higher than the latter. In some extreme cases, some scholars consider energy use can even increase after an energy efficiency improvement. This is due to agents’ behavioural responses. After almost four decades of theoretical and empirical studies in the field, there is a strong consensus amongst energy economists that the rebound effect of energy efficiency exists, although its importance is still being discussed. However, there are few empirical studies exploring its potential solutions. In this research, we empirically assess the effects of energy taxation on the rebound effect. Using a dynamic energy-economy computable general equilibrium (CGE) model of the Spanish economy, we test a global energy efficiency increase of 5.00%, and at the same time, different ad valorem tax rates on energy industries. We find that a tax rate of 3.76% would totally counteract the economy-wide rebound effect of 82.82% we estimate for the Spanish economy. This tax rate would still allow some economic benefits provided by the increase of energy productivity.

Durability of building fabric components and ventilation systems in passive houses

Abstract: The passive house concept specifically improves insulation of exterior building components, utilisation of passive solar gains, airtightness and heat recovery from ventilation air. Reducing also heat losses from thermal bridges, the energy balance is improved significantly resulting in net heating demands lower than 15 kWh/(m2a) which is less than one-tenth of the typical heating energy in the average of existing buildings. The design concept can be used for every new building, and many thousand examples have so far been built for different use, in several climates and based on different construction type (e.g. concrete, timber, mixed). The very first prototype is a terraced house with four dwellings built 1990/1991 in Darmstadt. This building uses typical masonry external walls, concrete floors and a timber roof and can be seen as a representative example for highly energy-efficient construction. By monitoring all relevant energy flows through the building’s envelope during a period of more than 25 years, it has been confirmed that the energy consumption is as extraordinarily low as designed and stable over the whole period. This article especially investigates how this has affected the indoor climate, the indoor air quality and the durability of all components. By thorough investigation, an assessment of the maintenance cycles is given, which are representative for this construction type. The main characteristics of the components and the ventilation system after 25 years of performance of the pilot building have been determined; these are typical for passive house quality components; therefore, the results are indicative for the concept. The passive house concept turns out to be not only energy-saving but also most notably very durable and extraordinarily low-maintenance.

Do commercial buildings become less efficient when they provide grid ancillary services

Abstract: Commercial buildings offer a vast thermal energy storage capability. Control of building heating, ventilation, and air conditioning (HVAC) systems can potentially be used to balance variations in renewable generation and load. Specifically, buildings can provide ancillary services to the grid by decreasing and increasing consumption with respect to their baseline, making them appear as energy storage to the power system operator. However, a recent study has shown that buildings providing these services tend to consume more energy, resulting in a low effective round-trip efficiency. To explore this phenomenon further, experiments were conducted on three buildings on the University of Michigan campus. The buildings were chosen to provide a variety in structure, size, and HVAC system layout. They were instrumented in early summer of 2017 and baseline power and building automation system (BAS) data were collected for several months in 2017 and 2018. The building thermostats were then perturbed through predefined patterns emulating ancillary service events, enabling detailed investigation of the resulting electrical energy consumption. This paper presents experimental results, focusing on the additional energy consumed and effective input/output efficiency. The three buildings respond with mean round-trip efficiencies ranging from 34 to 81%, with individual tests yielding efficiencies far outside that range. We also find that the efficiency of building response depends on the magnitude and polarity of the temperature setpoint changes. Our results are consistent with past experimental results, but inconsistent with past modeling results. This indicates that the models need to be improved in order to capture the energy impacts of ancillary service provision by buildings.

High velocity seawater air-conditioning with thermal energy storage and its operation with intermittent renewable energies

Abstract: The rapid increase in cooling demand for air-conditioning worldwide brings the need for more efficient cooling solutions based on renewable energy. Seawater air-conditioning (SWAC) can provide base-load cooling services in coastal areas utilizing deep cold seawater. This technology is suggested for inter-tropical regions where demand for cooling is high throughout the year, and it has been implemented in islands with short distances from the coast and the deep sea. This paper proposes adjustments to the conventional design of SWAC plants to reduce implementation risks and costs. The approach is named high velocity SWAC and consists of increasing the excavation depth of the seawater pump station up to 20 m below the sea level, compared to 2 to 5 m in conventional SWAC projects. This allows a twofold increase in the speed of inlet pipeline seawater and cooling load of the plant. The cooling load can be expanded twofold with only 55% capital cost and 83% project costs, compared with the costs of a new system. In addition, this article shows that high velocity SWAC plants with thermal energy storage will have an important role supporting the dissemination of intermittent renewable sources of energy in regions where SWAC is a viable cooling alternative.

Energy efficiency in postpaid-prepaid metered homes: analyzing effects of socio-economic, housing, and metering factors in Lagos, Nigeria

Abstract: Advances in automated energy metering system over the years have engendered transparency, self-control, efficiency, and equity in energy use especially among residential households globally. Despite this development, only few studies have shown the disaggregated effects of household attributes, dwelling characteristics, and metering systems on residential energy efficiency in the Global South. This paper argues that apart from household contextual factors—socio-economic and housing—the metering systems could indirectly account for energy disparities among urban households. This study therefore compared electricity consumption by urban households under the postpaid meter system and the prepaid meter system using electricity utility data obtained from residents in Ojo Lagos, Nigeria. Findings indicated that electricity consumption levels differed significantly between the postpaid and the prepaid metered households. Further analyses showed that the prepaid meter households used 47% less electricity kWh per annum compared with the postpaid meter households, intra-group variations in domestic electricity use were attributed to the household socio-economic and residential characteristics, and inter-group variations in electricity use rates were attributed to the metering system used by households. This study has both practical and policy implications for urban energy management especially with regard to the metering systems put in place for residential energy use and the need to ensure energy justice in socio-economically polarized cities.

Building analytics and monitoring-based commissioning: industry practice, costs, and savings

Abstract: As building energy and system-level monitoring becomes more common, facility teams are faced with an overwhelming amount of data. This data does not typically lead to insights, corrective actions, and energy savings unless it is stored, organized, analyzed, and prioritized in automated ways. The Smart Energy Analytics Campaign is a public-private sector partnership program focused on supporting commercially available energy management and information systems (EMIS) technology use and monitoring-based commissioning (MBCx) practices. MBCx is an ongoing commissioning process with focus on analyzing large amounts of data on a continuous basis. EMIS tools are used in the MBCx process to organize, present, visualize, and analyze the data. With campaign data from over 400 million square feet (sq. ft.) of installed space, this paper presents the results achieved by owners that are implementing EMIS, along with associated technology costs. The study’s EMIS users that reported savings achieved the median cost savings of $0.19/sq. ft. and 7% annually, with savings shown to increase over time. For 35 portfolio owners, the median base cost to install an EMIS was $0.03/sq. ft., with an annual recurring software cost of $0.02/sq. ft. and an estimated annual labor cost of $0.03/sq. ft. Two types of EMIS systems—energy information systems and fault detection and diagnostic systems—are defined in the body of the paper. Of the two, we find that fault detection and diagnostic systems have both higher savings and higher costs. The paper offers a characterization of EMIS products, MBCx services, and trends in the industry.

Measuring eco-efficiency and its convergence: empirical analysis from China

Abstract: At present, the contradiction between economic development and resource and environmental sustainability has become increasingly acute in China. Improving the quality of the ecological environment has become an important strategic goal for China’s national economic and social development. In this paper, we used the panel data of 30 provinces in China from 1986 to 2016 to measure the eco-efficiency and its decomposition indexes based on a non-radial metafrontier Malmquist-Luenberger data envelopment analysis model. The results showed that the eco-efficiency grows at an annual rate of 0.7% on the whole, with the technical efficiency decreasing at an annual rate of 0.6%, the innovation effect increasing at an annual rate of 2.3%, and the technical leadership effect decreasing at an annual rate of 1%. In the sample study period, the cumulative growth rates of eco-efficiency change index, technical efficiency change index, innovation effect, and technical leadership effect were 20.4%, − 19.4%, 70.5%, and − 30.7%, respectively. It was also found that regional eco-efficiency decreased from east to west. Furthermore, convergence test results showed that there were four convergence clubs and three divergent individuals in terms of eco-efficiency. Areas with high eco-efficiency tended to converge with areas with high eco-efficiency and vice versa.

Energy-efficient off-grid systems—review

Abstract: Globally, around 1.1 billion people do not have access to electricity and 84% of the population who do not have modern energy access are living in rural and remote areas of developing countries. Since the loads are far from the grid and providing the connection by extending from the main grid requires a high investment associated with long and costly transmission and distribution lines, addressing the problem requires innovative solutions. Therefore, off-grid microgrid systems, using solar photovoltaic and storage systems, integrated with very high-efficiency lighting appliances, are a promising solution to supply energy for rural and remote location in areas which lack access to the electric grid. This paper presents an overview on the existing solar photovoltaic technologies for off-grid systems including the most recent plug and play solutions. A characterization of the most common strategies used for control, communication and metering of microgrids is presented, as well as the recent evolution of the associated component technologies. The security and protection systems used to protect the system against theft or robbery of the systems itself or energy theft in remote areas are also addressed. Additionally, a resumed characterization of the sociologic profile and motivation of people to damage off-grid systems is presented. An overview on the main off-grid appliance market evolution and efficiency trends, in terms of energy efficiency, is also addressed in this paper. Finally, a set of recommendations to promote cost-effective systems is made, considering the market evolution path and the large growth potential of off-grid systems. There is an urgent need to reduce the total system costs, namely the soft costs of new microgrid systems in order to further accelerate the market growth, as well as widely accepted open standards to regulate and develop the market.

Thermo-economic and environmental analysis of integrating renewable energy sources in a district heating and cooling network

Abstract: This paper presents the technical, environmental, and economic evaluation of integrating various combinations of renewable energy sources-based systems in the expansion of a district heating and cooling network of a Technology Park near Barcelona in Spain. At present, a combined heat and power plant running on fossil fuels serves the heating, cooling, and electricity demand of the Park. However, this energy demand is expected to increase substantially in the coming years. EnergyPRO software was used to model the energy demand growth till 2030. Validation of the software application was done by making a base model using real plant data from the year 2014. The software was then used to project the energy supply based on three 15-year scenarios, having different combinations of renewable energy technologies, from 2016 until 2030. Primary energy consumption, CO2 emissions, and the net present value obtained in each scenario were used to decide the best combinations of renewable energy sources. The results of the study showed that presently, biomass boilers combined with absorption chillers and supported with solar thermal cooling are the most competitive technologies in comparison to ground source heat pumps for large DHC networks. This is mainly because of the lower primary energy consumption (624,380 MWh/year in 2030 vs. 665,367 MWh/year), higher net present value (NPV) (222 million € vs. 178 million €), and lower CO2 emissions (107,753 tons/year in 2030 vs. 111,166 tons/year) obtained as a result of the simulations.

Are the energy savings of the passive house standard reliable? A review of the as-built thermal and space heating performance of passive house dwellings from 1990 to 2018

Abstract: The Passive House (PH) standard is a voluntary quality assurance standard focused upon maximising the health and wellbeing of occupants, whilst reducing space heating demand to a very low level. To meet the PH standard, well-defined criteria have to be met. However, given literature that suggests a ‘performance gap’ for energy savings, the question remains, how well do PH dwellings perform in situ? This paper presents results from in situ building fabric thermal performance measurements, along with a comparison between the design intent and the measured space heating energy used by over 2000 newly built and retrofitted PH dwellings. The results reveal the in situ thermal performance of the building fabric is close to the design predictions. Within space heating measurements, a standard deviation of up to 50% has to be attributed to the broad spectrum of user behaviour; this is not specific for PH, but a general observation. Despite this, the average values for the PH developments ranged within the uncertainty of the demand calculations. With over 2000 PH dwellings averaging a space heating energy consumption of 14.6 kWh/(m2a), the in situ performance is close to the original design intent and extraordinary low compared to the consumption in ordinary buildings. The results suggest the PH standard is capable of producing dwellings in a verifiable manner. This means, on average, the in situ thermal performance of the building fabric and the energy consumption for space heating match the design intent, i.e. there is no significant ‘performance gap’.

Design and optimization of grid-tied and off-grid solar PV systems for super-efficient electrical appliances

Abstract: Modeling, simulation, and optimization methods are used in the present study to design grid-tied and off-grid solar PV systems for super-efficient electrical appliances for residential buildings. The principal objective of this study is to design a renewable energy system to serve the electric load of super-efficient appliances with high penetration of renewable resources and low greenhouse gas emissions and cost of energy. Hourly calculations using optimization method are used to study the daily and yearly performance and the cost of the renewable energy systems. A comparison between the performance of the grid-tied and off-grid solar PV systems using conventional and super-efficient appliances in Dubai is presented. The comparison includes the total power production from the solar PV system, the power purchased from the grid, the extra power sold to the utility grid, the power used to meet the electrical load of the appliances, the excess power, the renewable fraction, the greenhouse gas emissions, and the levelized cost of energy. The results of the simulation show that the integration of super-efficient appliances powered with the grid-tied solar power system is a good option to control the energy consumption of the residential buildings and to reduce the cost of electricity and greenhouse gas emissions: low building energy consumption (reduction by half of the electrical power consumption: from 62.91 to 30.78 kWh/day using super-efficient appliances); all the electrical power demand for the building is met without shortage; the power systems produce low excess power (0.29–1.82%) compared to the off-grid power system; all the extra power from the solar PV is sold back to the grid to reduce the cost of energy, high renewable fraction (68% of the total energy served to the load is produced from solar PV), low-cost of electricity (12% reduction of the cost of energy compared to the utility grid), and low greenhouse gas emissions (45–51% reductions of the CO2, NOX, and SO2 emissions compared to the conventional electrical appliances).

Rural electrification in Kenya: a useful case for remote areas in sub-Saharan Africa

Abstract: There is a significant proportion of the world’s population living in remote rural areas that are geographically isolated and sparsely populated. This study is based on modeling, computer simulation, and optimization of a hybrid powered mini-grid for a remote area of Korr in the district of Marsabit, Northern Kenya. The solar photovoltaic and wind turbine are considered as the two renewable resources for generating electricity accompanied by a battery (B) for storage and a diesel generator as a backup system. HOMER Pro software is used to perform the design and analysis of a proposed hybrid powered mini-grid model. The simulation results generated by the software indicate that the renewable energy sources may be a competitive technology. It has the potential of being a feasible solution capable of providing sustainable and reliable electric power at remote locations provided adequate amounts of renewable energy resources. The most cost-effective system in this study incorporates photovoltaic arrays, wind turbines, a diesel generator, and a battery bank to provide electricity to the community load demand of 5592 kWh/day at a cost of energy of $0.314.

Potential for energy efficiency improvement and greenhouse gas mitigation in Canada’s iron and steel industry

Abstract: The global demand of steel production is growing, and so are the carbon dioxide emissions from the sector. Research has confirmed that 15 to 20% further energy efficiency improvement is possible, which would reduce the sector’s greenhouse gas emissions and help meet global emission reduction initiatives. In this context, this research aims at developing a bottom-up system-based model to evaluate the long-term potential of energy efficiency alternatives in greenhouse gas mitigation. A case study was conducted for the Canadian iron and steel sector. The developed framework involves review of the state of the art in iron and steel production technologies, demand tree development, energy-environmental modeling, scenario development, and analysis. Twenty-six mitigation scenarios were developed in planning horizons ending in 2030 and 2050. A 13% improvement in Canadian iron and steel energy efficiency could be achieved by increasing the production share of the electric arc furnace route from 41% in the base year to 56% by 2050. The results of the analysis suggest that 19 and 38 million tonnes of greenhouse gas emission reduction are achievable in the 2010–2030 and 2010–2050 planning horizons, respectively. This translates to an approximately 6% reduction in emissions compared to the baseline scenarios at a cost of − $76 and − $51 per tonne of carbon dioxide equivalent in the 2010–2030 and 2010–2050 time periods, respectively. The results also reveal that more than 85% of the potential emission reductions are achievable with negative costs and are economically attractive. The study provides insights to decision makers at different levels of industry and government.

Integration of renewable distributed generation with storage and demand side load management in rural islanded microgrid

Abstract: The integration between distributed generations, storage, and load for islanded microgrids located in rural areas of developing countries offer serious challenges. The rural microgrid, catering the energy needs of rural communities, has no access to modern information and communication amenities like internet, communication architectures, and backup power. The lack of information and communication technologies (ICT) and backup power sources in rural microgrid lead to uncontrolled load consumption and inefficient storage dispatch resulting in system-wide outages. This paper proposes a novel approach to overcome challenges such as affordability and accessibility. A proactive load controlling and prioritized smart load curtailment is proposed in real time using local system parameters and human activities. The objective is to reduce blackouts and ensure maximum load supply without using conventional backup sources, computational forecasting, scheduling tools, and sophisticated communication architectures. The fuzzy logic controller is proposed to proactively decide for a percentage of load to be curtailed. Human Activities Tracking System (HATS) for smart load curtailment is used for balanced and efficient integration between the distributed generation, storage, and load. Four system parameters, storage drain time, state of charge (SoC), running load, and solar irradiations, are used as input to the fuzzy controller. HATS controller is used to smartly prioritize the load curtailment based on human occupancy in different buildings. Human activities are monitored using pyroelectric sensors installed at the entrance of different buildings. The performance of the system has been assessed while comparing the proposed methodology, the SoC controlling method (SCM). While using the proposed methodology, the blackout was drastically reduced to 96 to 100%. State of charge depletion rate was considerably less than conventional methods.

A global level analysis of environmental energy efficiency: an application of data envelopment analysis

Abstract: The objective of this study is to estimate environmental energy efficiency (EEE)—defined as energy efficiency measures incorporating undesirable output in the production process—for high-income, middle-income and low-income economies as well as at the global level for the period 1993–2013. Under the broad framework of Data Envelopment Analysis, the traditional input-oriented measures of efficiency, the joint production approach and the latest by-production approach have been used to assess EEE. The empirical results confirm a gradual improvement in EEE level except in the years 1998–1999 and 2009. The high-income economies spearheaded this improvement in EEE followed by the middle-income and low-income economies. This might be explained by the use of a relatively greater share of renewable energy in high-income economies. Moreover, the middle-income economies appear to converge to global EEE levels while low-income economies have lagged behind. Policy implications of our results are also discussed.