Search Results (65)

Household appliances constitute the second largest source of residential energy consumption in China, accounting for over 20% of the total and exhibiting a steady growth trend. Despite their substantial impact on energy demand and carbon emissions, a comprehensive analysis of the current status and future trends of household appliances in China is still lacking. This study employs the Long-Range Energy Alternatives Planning (LEAP) system to model energy consumption and carbon emissions for five major household appliances (air conditioners, refrigerators, washing machines, TVs, and water heaters) from 2022 to 2052. Three scenarios were analyzed: a Reference (REF) scenario (current trends), an Existing Policy Option (EPO) scenario (current energy-saving measures), and a Further Strengthening (FUR) scenario (enhanced efficiency measures). Key results show that by 2052, the EPO scenario achieves cumulative savings of 1074.8 billion kWh and reduces emissions by 580.7 million metric tons of CO₂ equivalent compared to REF. The FUR scenario yields substantially greater benefits, demonstrating the significant potential of strengthened policies. This analysis underscores the critical role of improving appliance energy efficiency and provides vital insights for policymakers and stakeholders aiming to reduce residential sector emissions. Full article

With the increasing integration of renewable energy and smart technologies in residential energy systems, proactive household energy management (HEM) have become critical for reducing costs, enhancing grid stability, and achieving sustainability goals. This study proposes a ultra-short-term forecasting-driven proactive energy consumption optimization strategy that integrates advanced forecasting models with multi-objective scheduling algorithms. By leveraging deep learning techniques like Graph Attention Network (GAT) architectures, the system predicts ultra-short-term household load profiles with high accuracy, addressing the volatility of residential energy use. Then, based on the predicted data, a comprehensive consideration of electricity costs, user comfort, carbon emission pricing, and grid load balance indicators is undertaken. This study proposes an enhanced mixed-integer optimization algorithm to collaboratively optimize multiple objective functions, thereby refining appliance scheduling, energy storage utilization, and grid interaction. Case studies demonstrate that integrating photovoltaic (PV) power generation forecasting and load forecasting models into a home energy management system, and adjusting the original power usage schedule based on predicted PV output and water heater demand, can effectively reduce electricity costs and carbon emissions without compromising user engagement in optimization. This approach helps promote energy-saving and low-carbon electricity consumption habits among users. Full article

Heat pump water heaters (HPWHs) are a proven technology for water heating that has been commercialized. The adoption of HPWHs for domestic and commercial water heating is growing rapidly because of their superior performance compared with alternative water heating methods. Whereas most existing systems use R-134a as a working refrigerant, R290 has gained major attention owing to its superior thermodynamic properties. The goal of the current study is to assess the performance of residential HPWH with R290 as a direct refrigerant replacement for R134a. Two units of a 50 gal HPWH were used in this experimental study. A baseline unit contained R134a refrigerant, and a prototype unit contained R290 refrigerant. The prototype unit was developed through the modification of a commercially available HPWH unit to achieve a low charge of R290 refrigerant. Another major modification was the replacement of the baseline compressor with a compressor designed for R290. Tests were conducted in a field environment (a research and demonstration house) using programmed drawn profiles daily. The prototype that reduced the charge by 43–47% provided displayed performance comparable to the baseline unit regarding first-hour rating (FHR) and the uniform energy factor (UEF). Full article

The proposed study incorporates a stochastic demand side management (SDSM) strategy for a self-sufficient residential system powered from a PV source with a hybrid battery–hydrogen storage system to minimize the total degradation costs associated with key components, including Li-io batteries, fuel cells, and PEM electrolyzers. The uncertainty in demand forecasting is addressed through a scenario-based generation to enhance the robustness and accuracy of the proposed method. Then, stochastic optimization was employed to determine the optimal operating schedules for deferable appliances and optimal water heater (WH) settings. The optimization problem was solved using a genetic algorithm (GA), which efficiently explores the solution space to determine the optimal operating schedules and reduce degradation costs. The proposed SDSM technique is validated through MATLAB 2020 simulations, demonstrating its effectiveness in reducing component degradation costs, minimizing load shedding, and reducing excess energy generation while maintaining user comfort. The simulation results indicate that the proposed method achieved total degradation cost reductions of 16.66% and 42.6% for typical summer and winter days, respectively, in addition to a reduction of the levelized cost of energy (LCOE) by about 22.5% compared to the average performance of 10,000 random operation scenarios. Full article

The residential sector is energy-consuming and one of the biggest contributors to climate change. In France, the adoption of photovoltaics (PV) in that sector is accelerating, which contributes to both increasing energy efficiency and reducing greenhouse gas (GHG) emissions, even though the technology faces several issues. One issue that slows down the adoption of the technology is the “duck curve” effect, which is defined as the daily variation of net load derived from a mismatch between power consumption and PV power generation periods. As a possible solution for addressing this issue, electric water heaters (EWHs) can be used in residential building as a means of storing the PV power generation surplus in the form of heat in a context where users’ comfort—the availability of domestic hot water (DHW)—has to be guaranteed. Thus, the present work deals with developing model-based predictive control (MPC) strategies—nonlinear/linear MPC (MPC/LMPC) strategies are proposed—to the management of EWHs in individual dwellings equipped with grid-connected PV systems. The aim behind developing such strategies is to improve both the PV power generation self-consumption rate and the economic gain, in comparison with rule-based (RB) control strategies. Inasmuch as DHW and power demand profiles are needed, data were collected from a panel of users, allowing the development of profiles based on a quantile regression (QR) approach. The simulation results (over 6 days) highlight that the MPC/LMPC strategies outperform the RB strategies, while guaranteeing users’ comfort (i.e., the availability of DHW). The MPC/LMPC strategies allow for a significant increase in both the economic gain (up to 2.70 EUR) and the PV power generation self-consumption rate (up to 14.30%ps), which in turn allows the ${\mathrm{CO}}_2$ emissions to be reduced (up to 3.92 $\mathrm{k}\mathrm{g}{\mathrm{CO}}_{2.\mathrm{eq}})$. In addition, these results clearly demonstrate the benefits of using EWHs to store the PV power generation surplus, in the context of producing DHW in residential buildings. Full article

Residential electric water heaters have the potential to significantly contribute to the balancing of the grid by providing frequency services. However, this entails a large-scale, challenging control problem subject to several uncertainties. In this paper, we perform the first real-life validation of secondary frequency reserve provision with a cluster of residential thermal loads in a near-commercial setting. We adopt an aggregate-and-dispatch control approach, which combines a scalable optimization step enabled by a reduced-order model with a real-time dispatch step. To handle the uncertainty related to service activation, we incorporate chance constraints in the optimization model and reformulate it as a robust problem. We validate the control approach under the assumption of perfect merit order knowledge in different stages, with a cluster of up to 600 electric water heaters, and show that this pool is able to effectively provide reserves, and that the integration of the chance constraints is beneficial for performance. Full article

As new energy-efficient technologies emerge, space and water heating systems are continuously evolving. The latest generation of heating, ventilation, and air conditioning (HVAC) systems in Canada and other countries is shifting away from natural gas heating to cleaner electrical options, such as air-source heat pump water heaters (ASHPWH). While many studies focus on reducing space heating, research on the effectiveness of ASHPWHs in cold climates is limited. This study aims to fill that knowledge gap by analyzing the performance of ASHPWHs in typical home applications across various climates in Canada. An experimental setup was constructed, and TRNSYS modeling was employed to evaluate the techno-economic and environmental performances of these systems in comparison to existing natural gas and conventional electric water heating systems. The findings of this research indicate that ASHPWHs possess the capability to substantially decrease greenhouse gas (GHG) emissions when compared to conventional natural gas-fired water heaters. Despite this significant environmental benefit, ASHPWHs may not be the most cost-effective option due to the prevailing natural gas pricing structure. Nevertheless, there is potential for these systems to become more economically viable in the future, particularly if an appropriate level of carbon pricing mechanisms is implemented. Full article

Residential water heating represents one of the most energy-intensive household applications, particularly in South Africa, where immersed resistive element heating dominates. Solar photovoltaic systems provide a promising solution for augmenting grid-based electrical water heaters, offering energy cost savings and environmental benefits. This study evaluates a novel approach to integrate solar photovoltaic directly into electrical water heater systems without using inverters. Using a combination of field experiments and simulation, four heating strategies were assessed, namely: “grid only”, “solar medium”, “solar heavy”, and “solar timer”. Metrics such as solar augmentation ratio, solar utilization, and cold event frequency were analyzed for different seasons using real-world and simulated water usage profiles. Results demonstrate significant grid energy reductions through solar augmentation, particularly in warmer seasons. However, the effectiveness of the strategies varies, with increased solar utilization often correlated with a higher frequency of cold events. A hybrid seasonal strategy is proposed to optimize energy savings while maintaining user comfort. This work highlights the potential of direct DC solar photovoltaic integration as a cost-effective and sustainable enhancement for residential water heating. Full article

Residential segments are of the greatest interest from the point of view of Demand-Side Resources and Decarbonization. Main end-uses such as water heaters, heating, and cooling have interesting opportunities: first, they can store energy, and this is relevant for the integration of renewables. Second, they are candidates for efficiency and electrification, increasing their demand share and the flexibility of demand. This paper aims to formulate an elemental Physical-Based Heat Pump Water Heater model that will enable the use of these energy-efficient appliances through aggregation in complex products, considering the advantages for demand and supply sides. Simulation results show that the individual performance is quite accurate and that the proposed model is flexible enough to be used to take more profit from energy markets or to easily respond to fast-occurring events. The model can be easily aggregated and used to obtain baselines, an important point for Demand Response evaluation. Results also demonstrate that demand–supply coordination and balance can be improved using these models to reduce or mitigate the risks and volatility of renewables without inducing a noticeable loss of service. Consequently, the contribution of this responsive load can be modelled through this methodology, making the engagement of more customer segments in Demand Response policies more credible and deploying new segments, such as prosumers. Full article

The global population’s growth and increased energy consumption have driven greenhouse gas (GHG) emissions. In Canada, the residential sector accounts for 17% of secondary energy use and 13% of GHG emissions. To mitigate GHG emissions, promoting renewable energy and efficient heating systems is crucial, especially in cold climates like Canada, where there is a heavy dependency on fossil fuels for space heating applications. A viable solution is hybrid fuel heating systems that combine electric-driven air-source heat pumps (ASHPs) with natural gas tankless water heaters (TWHs). This system can alternate its operation between the ASHP and TWH based on efficiency and real-time energy costs, reducing grid peak demand and enhancing resilience during power outages. Although lab experiments have shown its benefits, in situ performance lacks evaluation. This study analyzes the in situ energy performance of a net-zero ready house and its hybrid fuel heating system, assessing energy consumption, hourly space heating output, and system heating performance. HOT2000 is a robust simulation software designed for assessing energy consumption, space heating, cooling, and domestic hot water systems in residential buildings. An artificial neural network model was developed to predict the energy performance of the hybrid fuel system, which was used as a substitute for monitored data for evaluating the HOT2000’s simulation results under the same weather conditions. Therefore, this study proposes a comprehensive framework for the in situ performance analysis of hybrid fuel heating systems. This study then, using HOT2000 energy consumption results, evaluates the life cycle costs of the hybrid fuel system against conventional heating systems. Furthermore, this study proposes an economical control strategy using in situ data or manufacturer specifications. Full article

Taiwan has been actively promoting renewable energy technologies and applications to achieve sustainable development goals, aiming to increase the share of renewable energy in the domestic electricity structure. Among them, solar energy and wind energy have been developed and matured, especially solar water heaters, which have been popularized in people’s homes. This study proposes a triple-effect green energy generator, which is an innovative concept of combining a solar water heater with a wind turbine and thermoelectric devices, which have been gradually emphasized in recent years. Therefore, quality function deployment (QFD) was used to investigate the customer requirements and engineering measures of the product, and the results show that the product has leakage protection, is waterproof and rustproof, and does not affect health; furthermore, the product is resistant to high temperature and heavy rain, has a stable base, is suitable for most residential conditions, has 24 h operation, and has a remarkable power generation effect. Electricity can be used for general household appliances, which are the most important customer needs, and small wind turbines, energy management systems, and exterior materials are the three most important engineering initiatives to be emphasized. Although this study only analyzes preliminary design concepts, the results can provide references for related or similar product development strategies and contribute to the progress of Taiwan’s sustainable development goals. Full article

In dense, energy-demanding urban areas, the effective utilization of solar energy resources, encompassing building-integrated photovoltaic (BIPV) systems and solar water heating (SWH) systems inside buildings, holds paramount importance for addressing concerns related to carbon emission reduction and the balance of energy supply and demand. This study aimed to examine the interplay between urban residential blocks and their solar energy potential, with the objective of promoting environmentally sustainable development within urban residential areas. The primary focus of this study was the hot summer and cold winter zone of China, which serves as a representative case study. Methodologically, we employed Rhinoceros and Grasshopper (GH) software version GH6.0 tools to simulate the solar radiation potential within residential blocks and translated this information into the potential utilization of BIPV and SWH systems. Subsequently, our focus was directed towards identifying optimal locations for mounting BIPV modules and water heaters on roofs and building façades. The study results revealed the following: (1) The floor area ratio (FAR), building density (BD), average building height (ABH), and space layout (SL) exerted substantial influences on the solar potential of a residential block, with correlations of up to 75%, 71%, 78%, and 50%, respectively, concerning the overall solar potential of the entire plot. (2) It is essential to emphasize that, with regard to the BIPV installation potential, façades account for 80% of the overall residential block potential, whereas rooftops contribute only 20%. Both south- and west-facing façades exhibited a BIPV installation ratio of approximately 34%. (3) In the realm of solar water heating, the potential for installations on building façades accounted for 77% of the total living area of the residential blocks, 23% on the rooftops, and 35% on the south-facing façades. This study furnishes practical guidelines for harnessing the potential of BIPV and SWH systems within residential blocks, thereby contributing to the advancement of sustainable urban development practices. Full article

The use of solar water heaters (SWH) in both residential and commercial facilities is one of the possible ways to reduce electricity bills and the release of greenhouse gases (GHG). This study assessed the technical, economic, and environmental performance of a SWH system at six different locations in China (i.e., Lhasa, Lauchang, Wuhan, Kashi, Yumen, and Harbin). A comparison between two different working fluids (i.e., water and glycol) were modeled in the System Advisor Model in all six cities. A sensitivity analysis was conducted on some key technical and economic parameters to assess the impact of such parameters on the performance of SWH systems in the country. According to the results, Lhasa recorded the highest capacity factor of 11% and 10.70% using water and glycol as the working fluid, respectively. Lhasa was identified as the best location among the studied locations due to its high solar irradiation. The optimization study indicates that the optimum azimuth for China is 190°. It was also found that a 25% reduction in the outlet set temperature of the water can reduce the capacity factor from 11% to about 9.2%. Using the SWH as simulated in this study can reduce carbon dioxide emissions from 1252.87–2014.85 kg per year to 138.20–330.23 kg per year; the extent of reduction depends on the location of the SWHS, and the solar energy available at the area. Net electricity bill savings of $156–296 could be obtained if SWH systems were installed and used at the studied locations. Full article

To manage energy-efficient indoor air quality, mechanical ventilation with a heat recovery system provides an effective measure to remove extra moisture and air contaminants, especially in bathrooms. Previous studies reveal that heat recovery technology can reduce energy consumption, and its calculation needs detailed information on the thermal performance of exhaust air. However, there are few studies on the thermal performance of bathroom exhaust air during and after showers. This study proposed a detailed thermal performance prediction model for bathroom exhaust air based on the coupled heat and mass transfer theory. The proposed model was implemented into the AccuRate Home engine to estimate the thermal performance of residential buildings with heat recovery systems. The time variation of the water film temperature and thickness on the bathroom floor can be estimated by the proposed model, which is helpful in determining whether the water has completely evaporated. Simulation results show that changing the airflow rate in the bathroom has little effect on drying the wet floor without additional heating. The additional air heater installed in the bathroom can improve floor water evaporation efficiency by 24.7% under an airflow rate of 507.6 m³/h. It also demonstrates that heat recovery can significantly decrease the building energy demand with the fresh air load increasing and contribute about 0.6 stars improvement for the houses in Hobart (heating-dominated region). It may be reduced by around 3.3 MJ/(m²·year) for the houses in other regions. With this study, guidelines for optimizing the control strategy of the dehumidification process are put forward. Full article

The performance of water heating systems must be evaluated considering energy consumption and efficiency in storing and distributing hot water, together with building and climate characteristics. This work aims to analyse the performance of different water heating systems compared to electric showers, which are widely used in Brazil. Systems with individual gas heaters and solar heaters with electric backup and gas backup were analysed in multi-family buildings. In addition, the influence of thermal insulation of hot water pipes was verified. The analyses were conducted using the EnergyPlus programme, considering three Brazilian cities with different climates: Curitiba, Brasília, and Belém. The results showed that solar heaters are a low primary energy consumption alternative, especially if combined with gas heaters. However, electric showers are the most efficient option for larger buildings and cold-climate cities, where thermal losses in distribution are more significant. Monthly, an electric shower can save up to 1.82 kWh/m² of electricity compared to a solar heating system with an electric backup. The insulation has a limited influence on the performance of short-length pipes (temperature difference less than 0.3 °C in the instantaneous gas system). For longer pipes, the absence of insulation significantly reduces the shower temperature (up to 2.47 °C in solar heating systems), mainly in cold-climate locations. It is concluded that the most suitable water heating system should be determined according to the climate and characteristics of the buildings, such as the size and length of the pipe. Full article