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An evaluation of a variety of efficient water heating strategies for an all-electric single family home located in a mixed-humid climate is conducted using numerical modeling. The strategies considered include various combinations of solar thermal, heat pump, and electric resistance water heaters. The numerical model used in the study is first vali...
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![Table 1 . Assumptions for the buildings [1]](publication/318204308/figure/tbl1/AS:667765010599936@1536218993147/Assumptions-for-the-buildings-1_Q320.jpg)
The domestic energy demand of buildings is responsible for one third of the world's final energy consumption. To increase the sustainability of new housing areas, the identification of innovative heat supply concepts based on renewable energy sources (RES) is required. For the new housing area “Zum Feldlager”(Kassel, Germany), various supply concep...
Distributed electric heating system assistssolar heating systemby using air-source heat pump. Air-source heat pump as auxiliary heat sourcecan make up the defects of the conventional solar thermal system can provide a 24 - hour high - efficiency work. It has certain practical value and practical significance to reduce emissions and promote building...
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... Microglia dysregulation has been associated with neuroinflammation induced by the binding of CX3CL1, IL-6, TGF-β and other cytokines [40][41][42]. Activated glial cells then initiate intracellular signaling cascades to trigger the release of both proand anti-inflammatory signals [43]. In this study, we identified several miRNAs in the circulation of IS patients that contribute to these mechanisms. ...
Ischemic stroke (IS) is the majority of strokes which remain the second leading cause of deaths in the last two decades. Circulating microRNAs (miRNAs) have been suggested as potential diagnostic and therapeutic tools for IS by previous studies analyzing their differential expression. However, inconclusive and controversial conclusions of these results have to be addressed. In this study, comprehensive analysis and real-world validation were performed to assess the associations between circulating miRNAs and IS. 29 studies with 112 miRNAs were extracted after manual selection and filtering, 12 differentially expressed miRNAs were obtained from our results of meta-analysis. These miRNAs were evaluated in 20 IS patients, compared to 20 healthy subjects. 4 miRNAs (hsa-let-7e-5p, hsa-miR-124-3p, hsa-miR-17-5p, hsa-miR-185-5p) exhibited the significant expression level in IS patient plasma samples. Pathway and biological process enrichment analysis for the target genes of the 4 validated miRNAs identified cellular senescence and neuroinflammation as key post-IS response pathways. The results of our analyses closely correlated with the pathogenesis and implicated pathways observed in IS subjects suggested by the literature, which may provide aid in the development of circulating diagnostic or therapeutic targets for IS patients.
... One major area of global interest is the use of hybrid technology in residential hot water [4][5][6][7][8][9][10]. Water heating is the third-largest consumer of household energy besides space heating [11][12][13]. According to several studies, building accounts for 42% of global energy demand [14]. ...
The global energy deficit is currently a critical issue in the energy sector. As a result, the rising energy demand increases the consumption of conventional fossil fuels, contributing to the climate crisis and greenhouse gas emissions. Therefore, the over-reliance on fossil-fuel-based energy necessitates the development of a sustainable energy system to meet the lingering heat demand. Hence, renewable energy and efficient hybrid water heating technologies are viable options for achieving net-zero energy. The economic benefits of these hybrid technologies offer a promising prospect for widespread adoption in increasing hot water production in developing countries. These hybrid technologies are becoming increasingly popular for domestic thermal applications in remote areas to compensate for energy shortages. The paper aims to provide an overview of hybrid renewable water heating technologies, focusing on hybrid configurations, optimization techniques, mono-particle, and hybrid nanofluids and modelling. This paper also highlights the prospects of increasing such systems' economic attractiveness and public adoption.
... Despite the renewable and environmentally friendly benefits of solar water heaters, their adoption in residential housing has been low due to the instability of solar collection and the limitation of installation space [21]. Currently, the electric water heater is still the primary source of domestic hot water, and its market share ranks first all year round [22,23]. However, the efficiency improvement of electric water heaters is mainly focused on the heater structure, and usage mode since the heating technology of electric water heaters is mature. ...
In this study, a waste heat recovery method based on the thermoelectric effect was proposed to improve the thermal performance of electric water heaters. The method collected the surplus thermal energy in the high- temperature zone and released heat for reuse in the low-temperature zone through the thermoelectric element. A heat-recovery device using a thermoelectric element was designed and conducted experimentally to verify the method’s feasibility and energy conservation effect. The device performance of heat absorption and
heat release were investigated under various working thermal states. The experimental results showed that the
heating COP of the system could be improved to 1.2–2.3 under different temperature conditions, which means
the device can save energy than using electric power directly. The heat flux through the device can be actively
controlled for an optimal effect of heat recovery. The source-sink matching effect of the device was investigated,
and the results indicated that the device’s energy efficiency could be higher than 75%. The thermal performance
of an improved electric water heater using the heat recovery device was investigated numerically under a specific
working condition. The results verified that the heat recovery device reduced heat dissipation and simulta-
neously increased the temperature of the water outlet.
... The water was first heated by a solar subsystem, and then by a HPWH, if needed, before being distributed to the plumbing fixtures. For the same NZEB, Balke et al. [132] used simulations to compare three water-heating methods including an electric-resistance water heater, a HPWH, and a HPWH with solar-thermal preheating, with respective annual COPs of 0.95, 1.90, and 2.87. Biaou and Bernier [133] simulated different DHW systems for NZEBs in Canada equipped with PV modules for on-site electricity generation. ...
Advancements in residential net-zero energy buildings (NZEBs) could significantly reduce energy consumption and greenhouse gas emissions. NZEB design considerations broadly categorize into energy infrastructure connections, renewable energy sources, and energy-efficiency measures. There is a lack of systematic literature review focused on recent progress in residential NZEBs. Therefore, this work provides an overview of each category including recent developments (last ≈ 10 years), aiming to provide references and support of wider and more successful implementation of residential NZEBs throughout the globe. The discussed energy infrastructure connections include electrical grids, district heating/cooling networks, and energy storage options including vehicle-to-home and hydrogen storage. Renewable energy sources considered here are solar photovoltaic and solar thermal, wind, and biomass including micro combined heat and power (CHP) systems. The final category detailed is energy-efficiency measures, which include improved building envelope designs, efficient HVAC systems, efficient domestic hot water systems, and phase change material integration. Within these categories there are many technology options, which makes selecting the ‘best’ configuration more difficult but allows design flexibility to adapt to local climates and other considerations (i.e. building codes, energy resources, costs). This paper provides references and highlights technology options to achieve residential NZEBs throughout the world.
... Many research papers used the data set to address various aspects of this building. Studies that have focused on the water heating system in this building include the evaluation of efficient water heating strategies for an all-electric building (Balke et al., 2016), year-long performance analysis of the heat pump water heater , and evaluation of heat losses of the hot water distribution system (Ullah and Healy, 2015). Different from the previous papers, the current study focuses on developing an energy use prediction model using real data from this case study building. ...
With improved insulation of building envelopes and the use of low-temperature space heating systems, the share of energy use for domestic hot water (DHW) production in buildings has increased significantly, and nearly become the most energy-expensive service in modern buildings. Early prediction of the energy use for DHW is required for many advanced applications such as smart control, demand-side management, and optimal operation of electric or heat storage. However, predicting energy use of the solar-assisted water heating system is more challenging than typical DHW systems, as it is strongly affected by two stochastic phenomena, demand pattern and solar radiation.
Given the increasing use of solar-assisted water heating systems, this paper aims to evaluate the potential to predict energy use in such systems using a novel machine learning approach. In this novel model, a Long-Short Term Memory (LSTM) neural network is enhanced by (1) implementing the attention mechanism, a recent development in deep learning inspired by human vision to pay selective attention to the input data, and (2) decomposition of input data into sub-layers. The performance of simple LSTM neural network, Attention-based LSTM neural network (ALSTM) and Attention-based LSTM using decomposed data (ALSTM-D) are compared to a Feed-Forward neural network as a baseline model. Results show that LSTM, ALSTM and ALSTM-D models have a Mean Absolute Error (MAE) of 25%, 28% and 41% lower than Feed-Forward model, respectively. These results indicate the superior performance of the proposed ALSTM-D model over conventional models for solar-assisted DHW systems.
... As a consequence, it is opted for four distinct DHW consumption classes, and the boundaries are presented in Table 7.2. Therefore, the corresponding tapping event interpretation is assumed based on existing research results [245] and the current guidelines (DIN EN 16147 [244] The second model conguration consists of the ensemble of four separately trained binary SVMs and an overview of the model's design is presented in Figure 7.4. The optimal hyperparamter combination for each classier is searched. ...
... A typical hourly profile for domestic hot water consumption was also assumed, which considers the larger peak in the morning, a small hot water usage at lunch and a second peak of hot water usage in the late afternoon and dinner time [28] . Houses with electric DHW feature an equal distribution between electric hot water tanks (efficiency of 93% [29] ) and heat pumps with a coefficient of performance (COP) of 3 [30] , since these are well-established technologies their efficiency were considered constant over time. ...
The future residential energy demand is expected to be significantly affected by increasing electrification rates and climate change. This study uses a Monte Carlo-based approach and an ensemble of climate models to address potential changes in electricity demand in this sector. The whole Portuguese residential building stock in 2050 is used as a case study. It is performed a sensitivity analysis for the retrofitting and new construction, floor area of new buildings, electrification of domestic hot water and cooking and, finally, adoption of heat pumps for space heating and cooling. Results show a potential increase of 5 to 60% of the total electricity consumption in the sector. Space heating is expected to decrease by 33% while space cooling shows a possible 20-fold increase. The electrification of domestic hot water and the development of housing stock characteristics are the factors with the largest impact on the overall electricity consumption changes.
... Their calculations showed that natural gas-driven heat pumps achieve about the same efficiency and CO2 emissions as electrically driven heat pumps powered with electricity from the most modern natural gasfired combined cycle power plants. Balke et al [9] evaluated the efficiency of water heating for electrical family homes. The results showed the system studies had a COPsys of 2.87. ...
The objective of this research is to compare the efficiency of a direct current (DC) heating system with an electrical furnace coil. This was done using a house lab as a test bed located on the Durham College Whitby Campus in Canada. The house is approximately 1000 square feet, originally built circa 1950's/1960's, with an existing gas furnace of 60,000 BTUs and an energy efficiency EnerGuide rating of 95.5. Three options were tested during winter 2016 along with the electrical heating element. Weather normalization was taken into consideration using data provided by the weather network. The analysis showed that the direct current heating system option 3 had a higher BTUH/Watt= 3.73 compared to the furnace heating element=2.25 BTUH/Watt which represent a difference of 39.6%. An energy simulation was run using the HOT2000 software to evaluate the direct current technology vs gas, oil, propane and electricity. In each case the direct current technology showed an energy savings better than the comparative technology. From the data collected and analysis, it can be concluded that the direct current system is a valid technology for heating buildings. It is more efficient than the industry standard electrical heating coil with an efficiency of up to 40% better.
... EnergyPlus was also used by Vieira et al. [17], who compared the performance of solar water heating systems, electric heaters and heat pumps in dwellings in Australia. Comparisons among different water heating systems in homes located in different cities in the United State were performed by Maguire et al. [15], Cassard et al. [18], Karki et al. [19] and Balke et al. [20]; in South Africa by Hohne et al. [21]; in Australia by Kumar and Mathew [22]; in Canada by Leidl and Lubitz [23]. Simulations of water heating systems in single-family dwellings were also conducted by (i) Biaou and Bernier [24], considering the climate of Montreal (Canada) and Los Angeles (United States), (ii) Hobbi and Siddiqui [25], for the climate of Montreal, and (iii) Kalogirou [26], in Nicosia, Cyprus. ...
The objective of this paper was to compare primary energy consumption and energy efficiency during the operation phase of different types and combinations of water heating systems in single-family dwellings. Systems with an electric shower, liquefied petroleum gas heater, and solar heater with electric backup were analysed. The analysis was performed by means of computer simulation using EnergyPlus. Three Brazilian cities with different climates were assessed, i.e., Curitiba, Brasília and Belém. The systems were compared in terms of final energy and primary energy consumption. Results showed that systems with an electric shower, which have a lower water flow rate, led to lower primary energy consumption. The solar heating system combined with an electric shower was the option with the lowest energy consumption, and the solar heating system with a heating element in the storage tank was the option that consumed more energy. The systems were sized according to the requirements of the Brazilian energy efficiency labelling for residential buildings, and the efficiency level was compared to the results of primary energy consumption. The electric shower was found to be the third lowest energy consumer, but it was ranked the least energy efficient by Brazilian labelling, while systems with high energy consumption, such as gas heaters and solar heaters with a heating element in the storage tank, were ranked the most energy efficient. Therefore, a review of the requirements and methodology of the Brazilian energy efficiency labelling for residential buildings is recommended in order to encourage the use of truly efficient systems. Public policies that encourage solar heating systems should establish requirements regarding the configuration and sizing both the solar heating system and the backup system.
... Traditional heating systems have an efficiency of 0.5 to 0.99 with respect to primary energy of fuel [3,4]. Heat pumps are strongly recommended for house heating due to their effectiveness, and are treated as renewable energy source [4,5]. The heat pumps might be on-line controlled and the data are registered, many parameters might be optimized by the user [6,7]. ...
... The COP coefficient during work of the heat pump in the experiment was quite high: from 2.23 to 4.50. Similar achievements were presented by the other authors [1][2][3]5]. The results show that highest efficiency of the heating pump, determined as the COP coefficient, depends on the external air temperature. ...
The subject of the research was an air-water heat pump, model PCUW 2.5kW from HEWALEX, installed in a single-family house. The pump is only used for heating water. The research was carried out from 25-08-2017 to 18-09-2017 in the village of Zborowice, in Malopolska region, Poland. The data were recorded from the heat pump system: temperature of the lower heat source (external air), temperature of the upper heat source (water temperature in the tank), time of heat pump was calculated during the analysed cycle of work and electrical energy consumption. The Coefficient Of Performance (COP) of the analysed air-water heat pump was determined. The analysis of the results was carried out using the MATLAB and EXCEL statistical tools. The correlation between COP coefficient and external air temperature is strong: 0.67.
