Search Results (89)

The effect of induction heating on alumina ceramics and alumina ceramic composites based on α-Al₂O₃ nanopowders (additives: SiC, Si₃N₄, SiO₂, ZrO₂) has been examined. Various factors such as the structure, grain size, distribution of elements, hardness, fracture toughness, and wear rate of hot-pressed ceramic materials were assessed. Despite achieving improved densification of alumina ceramics at a higher temperature of 1720 °C, there is a consistent trend toward a decline in hardness and fracture toughness. Heating at lower temperatures of 1300–1500 °C results in the development of a strengthened surface layer with a fine-grained structure enriched with carbon. Therefore, the wear rate behavior of such ceramics differs from the behavior of samples made at higher temperatures of 1600–1720 °C. This fact indicates the presence of a non-thermal microwave effect of induction heating. The incorporation of additives to alumina leads to the formation of novel structures with altered crack propagation patterns. The optimal ceramic composite, containing 5 wt. % SiC, displayed superior hardness and the lowest wear rate when compared to pure alumina ceramics. Across all investigated composites, a short dwell time at 1700 °C results in an enhancement of the mechanical properties. Full article

Directed energy deposition (DED) additive manufacturing (AM) enables the production of components at a high deposition rate. For certain alloys, interpass temperature requirements are imposed to control heat accumulation and microstructure transformation, as well as to minimize distortion under varying thermal conditions. A typical strategy to comply with interpass temperature constraints is to increase the interpass dwell time, which can lead to an increase in the total deposition time. This study aims to develop an optimized tool path that ensures interpass temperature compliance and reduces overall deposition time relative to the conventional sequential deposition path during the DED process. To evaluate this, a compact analytic thermal model is used to predict the thermal history during laser-based directed energy deposition (DED-LB/M) hot wire (lateral feeding) of ER100S-G, a welding wire equivalent to high yield steel. A greedy algorithm, integrated with the thermal model, identifies a tool path order that ensures compliance with the interpass requirement of the material while minimizing interpass dwell time and, thus, the total deposition time. The proposed path planning algorithm is validated experimentally with in situ temperature measurements comparing parts fabricated with the baseline (sequential) deposition path to the modified path (resulting from the greedy algorithm). The experimental results of this study demonstrate that the proposed path planning algorithm can reduce the deposition time by 9.2% for parts of dimensions 66 mm × 73 mm × 16.5 mm, comprising 15 layers and a total of 300 beads. Predictions based on the proposed path planning algorithm indicate that additional reductions in deposition time can be achieved for larger parts. Specifically, increasing the (experimentally validated) part dimension perpendicular to the deposition direction by five-times is expected to result in a 40% reduction in deposition time. Full article

This study explores the challenges faced by traditional dwellings amid modernization and urbanization, with a particular focus on Huizhou dwellings, which struggle with issues such as inefficient space use and suboptimal spatial quality. This study employs UWB (ultra-wideband) indoor positioning technology to examine differences in residents’ production/living behaviors and their spatial usage preferences between two Huizhou traditional dwellings with distinct preservation statuses during both the summer and winter seasons. The study reveals the following findings: (1) The hall, courtyard, and kitchen spaces are the most frequently used living areas, followed by wing rooms and patio spaces. Differences in spatial organization patterns significantly influence residents’ preferences for alternating between various functional spaces. Residents tend to favor functional spaces centered around or adjacent to key circulation areas; (2) In summer, the patio space provides shade and ventilation, creating a cool and comfortable environment that supports a variety of living activities, resulting in high utilization rates. In winter, however, the patio space hinders heat retention for the inner facade, leading to lower temperatures and reduced usage; (3) The utilization rate of wing room spaces has significantly improved after simple renovations, whereas unrenovated wing rooms and side rooms exhibit relatively low utilization rates; (4) During fine weather in winter, the courtyard space maintains a relatively comfortable temperature, making it highly utilized. In contrast, the courtyard becomes excessively hot in summer, leading to significantly lower utilization rates compared with winter. By analyzing residents’ behavioral trajectories, the study explores the differences in living behaviors and their correlation with residential spaces across the different seasons and preservation states of traditional dwellings. These results offer important perspectives for the sustainable development of residential conservation and renewal efforts. 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

Passive buildings are increasing in popularity in Canada. This paper examines two passive buildings initially constructed in the past decade: the Peterborough passive multi-unit residential building (MURB) and the Wolfe Island single-family dwelling. A post-occupancy evaluation was performed on the buildings. The buildings were modelled in HOT2000 and the Passive House Planning Package (PHPP) to ensure the validity of the results. The energy bills were collected from the building owners to acquire the real-time consumption of the buildings. The models have shown a good agreement with the collected data. Furthermore, data loggers were installed in both buildings for indoor temperature monitoring to ensure that they adhere to the passive house explicit criteria. Internal gains, shading, and orientation were analyzed to assess their effect on heating and cooling loads. Peterborough MURB has shown more energy-saving potential compared to the Wolfe Island passive house. Heating load reduction has been compared, more than five times, to the cooling load reduction potential. The reduction in GHG emissions can be up to 39% when passive house parameters are applied to the Wolfe Island house. This paper has shown the potential of the passive house in relation to sustainable buildings in Northern climates. Full article

Energy consumption in buildings plays a significant role in the global energy demand. The European Union has promoted different regulatory directives in the framework of energy efficiency to develop the construction of buildings with nearly zero energy consumption. The main objective of this paper is to simulate how the design characteristics of different factors of the window elements of buildings (frame, glass, and shading systems) located in a hot climate region affect their cooling primary energy consumption. For this purpose, a comparative analysis is carried out with multiple simulations of different types of single-family residential dwellings using the EnergyPlus energy model. From the results obtained, it can be deduced that, compared to the standard design configuration, the primary energy consumption for cooling of the buildings studied can be reduced by up to 12.7% and 29.5% by modifying the design characteristics of the frame–glass assembly or the shading system of the window openings, respectively. The conclusions drawn from this study can serve as a reference in normative and regulatory documents affecting the building sector for the establishment of minimum requirements for certain characteristics of the constructive design of buildings. Full article

In recent years, block-style commercial complexes have become a prominent form of commercial architecture in many Chinese cities. The thermal comfort of their outdoor spaces significantly influences people’s activities and the overall quality of these areas. This study explores the relationship between the morphological elements of outdoor spaces in such complexes and thermal comfort, using quantifiable methods to identify key control indicators. Enhancing thermal comfort is crucial for improving spatial quality, increasing dwell time, and boosting commercial vibrancy. Focusing on the hot summer and cold winter climate of Shanghai, this research analyzed two representative block-style commercial complexes. It employed computer simulations and sensory comfort surveys to demonstrate that block morphology significantly impacts outdoor thermal comfort. Three control variables—street density, number of street intersections, and street orientation—were selected to study their effects. Spatial prototypes were categorized, and their thermal comfort performance was evaluated using numerical simulations. Based on these findings, spatial morphology was iteratively optimized. This study concluded by proposing evaluation indicators for spatial morphology control elements to enhance outdoor thermal comfort. It also provided external spatial layout strategies for block-style commercial complexes in similar climates, offering architects and urban designers decision-making criteria to improve thermal comfort in outdoor spaces. This research contributes to creating more comfortable and vibrant urban environments. Full article

The traditional timber architecture of Qiandongnan represents a rich cultural heritage. However, urbanization has led to the replacement of these structures with concrete and brick buildings, resulting in the loss of both functionality and cultural identity. To bridge the gap between traditional architecture and modern building needs, this study conducted field surveys to extract key design parameters from local structures, enabling the development of a modular framework for Structural Insulated Panels (SIPs) based on the dimensions of traditional dwellings. Four types of SIPs were developed using Chinese fir, OSB, EPS, and XPS, and their thermal performance and heat stability were evaluated through theoretical analysis and hot box testing. The results show that all specimens met the required heat transfer coefficient. The combination of OSB and XPS showed a slightly lower heat transfer coefficient of 0.60 compared to Chinese fir, which had a coefficient of 0.62. However, the Chinese fir–XPS combination provided the longest time lag of 6.34 h, indicating superior thermal stability. Due to the widespread use of Chinese fir in local construction and its compatibility with the landscape, this combination is ideal for both energy efficiency and cultural preservation. Full article

This paper proposes an innovative system that integrates two thermoelectric heat pumps (one air–water and the other water–water) with two thermal storage tanks at different temperatures to provide heating and domestic hot water to a 73.3 m² passive-house-certified dwelling in Pamplona (Spain). The air–water thermoelectric heat pump extracts heat from the ambient air and provides heat to a tank at intermediate temperature, which supplies water to a radiant floor. The water–water heat pump takes heat from this tank and provides heat to the other tank, at higher temperature, which supplies domestic hot water. The system performance and comfort conditions are computationally analyzed during the month of January under the climate of Pamplona and under different European climates. The COP of the system lays between 1.3 and 1.7, depending on the climate, because of the low COP of the air–water thermoelectric heat pump. However, it is able to provide water for the radiant floor and to maintain the temperature of the dwelling above 20 °C 99.8% of the time. Moreover, it provides domestic hot water at a temperature above 43 °C 99.9% of the time. Noteworthy is the fact that the water–water heat pump presents a COP close to 4, which opens up the possibilities of working in combination with more efficient heat pumps for the first stage. Full article

Weed infestations pose significant challenges to global crop production, demanding effective and sustainable weed control methods. Traditional approaches, such as chemical herbicides, mechanical tillage, and plastic mulches, are not only associated with environmental concerns but also face challenges like herbicide resistance, soil health, erosion, moisture content, and organic matter depletion. Thermal methods like flaming, streaming, and hot foam distribution are emerging weed control technologies along with directed energy systems of electrical and laser weeding. This paper conducts a comprehensive review of laser weeding technology, comparing it with conventional methods and highlighting its potential environmental benefits. Laser weeding, known for its precision and targeted energy delivery, emerges as a promising alternative to conventional control methods. This review explores various laser weeding platforms, discussing their features, applications, and limitations, with a focus on critical areas for improvement, including dwell time reduction, automated navigation, energy efficiency, affordability, and safety standards. Comparative analyses underscore the advantages of laser weeding, such as reduced environmental impact, minimized soil disturbance, and the potential for sustainable agriculture. This paper concludes by outlining key areas for future research and development to enhance the effectiveness, accessibility, and affordability of laser weeding technology. In summary, laser weeding presents a transformative solution for weed control, aligning with the principles of sustainable and environmentally conscious agriculture, and addressing the limitations of traditional methods. Full article

Domestic hot water (DHW) consumption represents a significant portion of household energy usage, prompting the exploration of smart heat pump technology to efficiently meet DHW demands while minimizing energy waste. This paper proposes an innovative investigation of models using deep learning and continual learning algorithms to personalize DHW predictions of household occupants’ behavior. Such models, alongside a control system that decides when to heat, enable the development of a heat-pumped-based smart DHW production system, which can heat water only when needed and avoid energy loss due to the storage of hot water. Deep learning models, and attention-based models particularly, can be used to predict time series efficiently. However, they suffer from catastrophic forgetting, meaning that when they dynamically learn new patterns, older ones tend to be quickly forgotten. In this work, the continuous learning of DHW consumption prediction has been addressed by benchmarking proven continual learning methods on both real dwelling and synthetic DHW consumption data. Task-per-task analysis reveals, among the data from real dwellings that do not present explicit distribution changes, a gain compared to the non-evolutive model. Our experiment with synthetic data confirms that continual learning methods improve prediction performance. Full article

The environmental impact of building energy renovation is commonly evaluated through life cycle assessment (LCA). However, existing LCA studies often overlook the energy performance gap—a substantial disparity between calculated and actual energy use—when estimating operational energy use before and after renovation. This paper examines the influence of the energy performance gap on the comparative LCA between unrenovated and renovated buildings. First, a statistical correction model, based on a recent large-scale Flemish study, is developed to correct regulatory calculated energy use for space heating and domestic hot water in a pragmatic way. Subsequently, the model is applied to four single-family dwellings with different energy characteristics that underwent renovation in accordance with Flemish energy regulations. The results show that the anticipated environmental savings over a 60-year study period decrease significantly when the correction model is applied, reducing the estimated savings of 49–80% to 21–49%. Moreover, environmental payback times increase from 2.9–9.1 years to 10.4–22.5 years. Notably, neglecting the energy performance gap in LCAs leads to systematic underestimations of the material use significance. This research underscores the importance of integrating the energy performance gap into LCAs to obtain more accurate estimations of the environmental benefits of energy renovations. Full article

A study reviewing overheating in historic buildings in the context of extant climate change. Due to global warming, more research is required when considering summertime thermal comfort in the UK, which is a more significant topic of conversation due to the heatwave in 2022. With a large demographic of the UK population residing in dwellings with historic value, this paper aimed to contribute findings that review their specific traits with respect to overheating. This was achieved by monitoring and analysing internal (and external environmental data) in three case studies in the south-east. Upon examination of the literature, many buildings in the UK are consistently subject to temperatures that exceed overheating. It was found that many properties of historic buildings lend themselves to summertime cooling such as higher thermal mass, better ventilation (without the use of mechanical or active systems), and less insulation. This, however, could come at the cost of winter thermal comfort. In all three case studies, the surveyed buildings passed the CIBRE criteria, but users still commented on being ‘too hot’. The high recorded RH levels in all properties, coupled with the inadequate overheating criteria, were deemed the cause. There are new regulations in place to minimise overheating in new buildings but no support for those that are already existing. Full article

With the background of rural revitalization, the urgent demand for energy conservation and improved living quality arises alongside the issues of high energy consumption and low comfort in residential buildings. Located in a region with a hot summer and cold winter climate, Hanzhong faces significant energy consumption for heating and cooling throughout the year, considering both winter insulation and summer heat insulation. Based on the energy consumption simulation and analysis of folk dwellings in Hanzhong, this paper employs a single-objective optimization method to explore the optimization of building envelope structures, including the window-to-wall ratio, bay width, number of floors, orientation, and floor height. Additionally, it investigates building layout, spatial organization, regional design methods, and energy acquisition. Through energy consumption simulation and validation of thermal comfort evaluation index PMV-PPD, design strategies such as building scale, layout organization, indoor and outdoor buffer space design, and building material selection are proposed to effectively improve indoor thermal comfort during the winter and summer seasons. This research provides insights and references for the low-carbon design and optimization of residential buildings. Full article

The building sector, which is responsible for a significant amount of total global energy consumption, provides substantial opportunities for energy efficiency studies. In the context of historic and traditional buildings, this matter becomes more crucial, as energy efficiency is more complex and challenging. The complexity partly derives from the multiple and diverse values with which the buildings are associated. These values are dynamic. In this paper, we chose historic houses in Gaziantep as our focal point. They provide an indicative example of houses with architectural features that help residents deal with the adverse effects of the hot climate. These specific features are significant for the users not only in terms of thermal comfort but also in terms of heritage values. The value that users attribute to the neighbourhood and their attitude towards buildings change over time. It is seen that thermal comfort plays a key role in energy efficiency and heritage conservation. Hence, understanding the role of thermal comfort perceptions and the ways in which they dictate certain energy efficiency and heritage conservation actions is critical. In this context, this paper addresses these dynamic, complex, and changing interrelationships over time. Drawing upon the dynamic analysis of in-depth, semi-structured interviews with three dwellings in Gaziantep’s Bey neighbourhood, we will discuss how residents of historic houses perceive thermal comfort and how they negotiate and prioritise energy efficiency and heritage conservation. Full article