Indoor Energy Consumption Research Articles

Achieving Broadband Microwave Shielding, Thermal Management, and Smart Window in Energy‐Efficient Buildings

AbstractEnergy‐efficient building materials are eye‐catching for reducing indoor energy consumption via eliminating electromagnetic interference and pollution, controlling the thermal transfer, and promoting sunlight harvesting and providing a comfortable living environment. To realize broadband microwave shielding, the elaborate control of microstructures has showed great potential and research direction. By composition regulation and structure design with various dimension, the synergistic effects including conductive networks, interfacial polarization, magnetic coupling, dipole polarization, and dielectric‐magnetic synergy, can significantly improve electromagnetic (EM) shielding capacity. Thermal management including thermal conversion, thermal storage, thermal radiation, and thermal conduction has enormous potential in enhancing the sustainability and energy efficiency for future buildings. Smart windows are able to switch optical transmittance and colors, which is contributed to saving building energy. Herein, in this review, the recent progress of broadband shielding, thermal management, and smart window in the field of energy‐efficient buildings is summarized, from the aspects of materials, mechanisms, and scenarios. Further, the main bottlenecks and problems are discussed, and potential research opportunities are further highlighted.

Research on Application of Composite Facades for Civilian Reconstruction of Industrial Heritage in Cold Regions Based on Thermal Buffering Effect

Previous studies on the civil transformation of industrial heritage have been conducted mainly from the perspective of architectural history, culture and aesthetics, but rarely focus on energy-saving and the comfort of the new users. Most industrial heritage facades are of high conservation value, but efforts to preserve the authenticity of the facade can lead to the application of limited energy-saving technologies, ultimately resulting in poor indoor thermal environments. Therefore, it is valuable to research how to solve the contradiction between protecting the authenticity of the preserved facades of industrial heritage and improving the indoor environmental performance. This paper proposes two composite facade application strategies based on thermal buffer effects, takes two composite facades renovation methods of Shenyang Dongmao No. 2 Warehouse as an example, utilizes the natural environmental resources to enhance the spatial quality of industrial heritage. With the help of DesignBuilder software modelling simulation analysis, in-depth comparative analysis of the two types of composite facades on the indoor thermal environment of the industrial heritage of the impact and scope. Key findings show that the application of two different composite facade retrofitting techniques not only protects the skin texture of the wall, but also effectively increases the indoor temperature and reduces the indoor energy consumption of the industrial heritage. The composite facade of the external solid wall and the internal glass is more stable in raising the indoor temperature, more effective in reducing the building energy consumption, and more suitable for the civilian transformation of industrial heritage in cold areas. The research findings provide reference for studies on the civil transformation of industrial heritage, and serve as technical references for architects.

Do blue-green roofs yield optimal thermal performance? Synergy analysis of the combination of green roofs and water retention layer

Blue-green roofs can potentially enhance the outdoor thermal environment in urban areas and reduce indoor energy consumption. By integrating a water retention layer with green roofs, blue-green roofs maximize environmental benefits through rainwater storage and increased evapotranspiration. This study evaluates the thermal performance of blue-green roofs during summer and examines their potential for microclimate improvement and energy savings. The study investigates the individual and interactive effects of the blue-green roof components by measuring the upper and lower surface temperatures with incremental application of soil, blue, and green layers and analyzing their synergistic benefits. The results indicate that blue-green roofs exhibited a cooling effect of up to 7.5 °C on the upper surface temperature and up to 17.4 °C on the lower surface temperature, showing the greatest potential for improving indoor and outdoor thermal comfort. The synergistic effect of the blue-green roof was −0.80 °C on the upper surface and +1.59 °C on the lower surface. This research provides an in-depth investigation into the thermal performance of blue-green roofs in both indoor and outdoor spaces, highlighting their synergistic effects through incremental application. This contributes to climate-responsive architectural design and practices aimed at enhancing energy efficiency in building retrofitting for hot climates.

Trade-Off Judgement for Daylighting and Energy Consumption in the High and Large Space of the University Gymnasium in Beijing

Taking the high and large space of the University of Science and Technology Beijing Gymnasium as this research object, this paper analyzes the influence of different window positions, window-to-wall ratio (WWR), solar heat gain coefficient (SHGC), heat transfer coefficient (K), and visible light transmittance (VT) on the total indoor energy consumption in winter and summer and obtains the relationship between the daylight factor and VT formed when the window is opened per unit area. Through energy consumption simulation, the variation law and calculation formula for indoor total energy consumption are obtained. The results show that the SHGC and K of the exterior window have a significant influence on the total energy consumption. By using the energy consumption simulation of different types of exterior windows, it is concluded that the SHGC of the south-facing window is negatively correlated with the variation of air conditioning energy consumption per unit area Δe1,w, while the others are positively correlated. Moreover, the SHGC and K of the skylight have the most significant influence on the Δe1,w. The total energy consumption decreases and then increases with the increase in the window area, and there is a lowest point, so the right side of the lowest point is less than or equal to 105% of the lowest total energy consumption as a reasonable window area zone. Finally, a progressive optimization method for weighing daylighting and energy consumption in university gymnasiums in Beijing is proposed.

Investigation of Greening Façade and Retrofitting strategies on Outdoor Thermal Comfort and Indoor Energy Consumption in New Assiut City, Egypt

Investigation of Greening Façade and Retrofitting strategies on Outdoor Thermal Comfort and Indoor Energy Consumption in New Assiut City, Egypt

The potential of a tree to increase comfort hours in campus public space design

The rising global temperatures have led people to avoid outdoor activities, especially during the day in tropical countries, because of the high average temperatures when the comfort hours are relatively low. This problem has led to higher indoor energy consumption, health problems, and problems in social interaction. One way to encourage people to use outdoor public spaces is to design them to increase their comfort hours. This study focused on increasing the number of comfort hours through the influence of trees as one of the green infrastructure and using simulation methods in the ENVI-met version 4 program. For the simulation, we gathered field data for the correction of weather data from a weather station representing 52 weeks at the outdoor space in the Faculty of Engineering campus, Chiang Mai University, which is a target area for development from the campus policy. The alternative design was created by adding a Millingtonia hortensis, a local plant for the location. The results showed that a single large tree strongly influenced annual comfort hours in campus outdoor public spaces. The simulation results throughout 52 weeks showed that a tree increases by 7.37% in comfort hours while an 8.65% decrease in overheating hours. This study can provide an alternative approach for designing public spaces on campuses and encourage the use of more effective design in the future.

Holistic analysis for the efficiency of the thermal mass performance of precast concrete panels in hot climate zones

PurposeThis paper investigates thermal mass performance (TMP) in hot climates. The impact of using precast concrete (PC) as a core envelope with different insulation materials has been studied. The aim is to find the effect of building mass with different weights on indoor energy consumption, specifically cooling load in hot climates.Design/methodology/approachThis research adopted a case study and simulation methods to find out the efficiency of different mass performances in hot and humid climate conditions. Different scenarios of light, moderate and heavyweight mass using PC have been developed and simulated. The impact of these scenarios on indoor cooling load has been investigated using the integrated environment solution-virtual environment (IES-VE) software.FindingsThe results showed that adopting a moderate weight mass of two PC sheets and a cavity layer in between can reduce indoor air temperature by 1.17 °C; however, this type of mass may increase the cooling demand. On the other hand, it has been proven that adopting a heavyweight mass for building envelopes and increasing the insulation material has a significant impact on reducing the cooling load. Using a PC Sandwich panel and increasing the insulation material layers for external walls and thickness by 50 mm will reduce the cooling load by 15.8%. Therefore, the heavyweight mass is more efficient compared to lightweight and moderate mass in hot, humid climate areas such as the UAE, in spite of the positive indoor TMP that can be provided by the lightweight mass in reducing the indoor air temperature in the summer season.Originality/valueThis research contributes to the thermal mass concept as one of these strategies that have recently been adopted to optimize the thermal performance of buildings and developments. Efficient TMP can have a massive impact on reducing energy consumption. However, less work has investigated TMP in hot and humid climate conditions. Furthermore, the impact of the PC on indoor thermal performance within hot climate areas has not been studied yet. The findings of this study on TMP in the summer season can be generated in all hot climate zones, and investigating the TMP in other seasons can be extended in future studies.

Green, Sustainable Architectural Bamboo with High Light Transmission and Excellent Electromagnetic Shielding as a Candidate for Energy-Saving Buildings.

Currently, light-transmitting, energy-saving, and electromagnetic shielding materials are essential for reducing indoor energy consumption and improving the electromagnetic environment. Here, we developed a cellulose composite with excellent optical transmittance that retained the natural shape and fiber structure of bamboo. The modified whole bamboo possessed an impressive optical transmittance of approximately 60% at 6.23mm, illuminance of 1000 luminance (lux), water absorption stability (mass change rate less than 4%), longitudinal tensile strength (46.40MPa), and surface properties (80.2 HD). These were attributed to not only the retention of the natural circular hollow structure of the bamboo rod on the macro, but also the complete bamboo fiber skeleton template impregnated with UV resin on the micro. Moreover, a multilayered device consisting of translucent whole bamboo, transparent bamboo sheets, and electromagnetic shielding film exhibited remarkable heat insulation and heat preservation performance as well as an electromagnetic shielding performance of 46.3dB. The impressive optical transmittance, mechanical properties, thermal performance, and electromagnetic shielding abilities combined with the renewable and sustainable nature, as well as the fast and efficient manufacturing process, make this bamboo composite material suitable for effective application in transparent, energy-saving, and electromagnetic shielding buildings.

Effects of crystal structure and morphology on the electrochromic properties of CsxWO3

Smart windows have been used to reduce indoor energy consumption by utilizing materials with excellent near-infrared absorption properties, among which cesium tungsten bronze CsxWO3 is one of the widely used materials. However, the stability of CsxWO3 during applications is a very challenging problem. The electrochromic technology can be used to solve it. Here, nano CsxWO3 with space group P63/mcm has been synthesized to study the effects of the crystal structure and morphology on the electrochromic properties by tailoring the reaction condition during the solvothermal process. The sizes of hexagonal and trigonal channels in WO6 framework change with the reaction condition of samples and reach to their maximum values at the highest Cs content. The cluster-shaped grains uniformly distribute in the sample with the highest Cs content. Both of the transmittance modulation range and coloration efficiency of this sample are about several times than those of other samples. The large-size channels in WO6 framework and rod-like cluster morphology facilitate the enhancement of electrochromic properties.

Strong Cellulose-Based Light-Management Film with Ultraviolet Blocking and Near-Infrared Shielding Performance.

Light-management materials play a great significant role in efficient-energy buildings because they reduce indoor energy consumption by adjusting to natural sunlight, enhancing heat insulation, and creating comfortable indoor lighting. Here, we fabricated an ecofriendly and sustainable lignocellulose-based light-management film via a facile homogenization and mechanical hot-pressing method without complicated treatment or toxic reagents. The resulting film exhibited a favorable ultraviolet (UV) blocking performance of 82.25% for UVA, high visible light transmittance, and high haze, with a desirable tensile strength of 197 MPa, which was significantly higher than those of most petroleum-based plastics. Accordingly, the film was further endowed with near-infrared absorption performance by spray-coating with lanthanum hexaboride (LaB6) nanoparticles─there were almost no adverse effects on its light transmittance or mechanical strength. Meanwhile, the high haze of the film implied that it met the requirement for privacy protection in smart buildings. The MFC/lignin/LaB6 composite film has potential applications in energy-saving buildings and optoelectronic devices.

An Evaluation of the PV Integrated Dynamic Overhangs Based on Parametric Performance Design Method: A Case Study of a Student Apartment in China

A photovoltaic shading device (PVSD) is a promising technology that can both generate electricity and provide shading to reduce indoor energy consumption. This paper aims to evaluate the performance of three PVSD design strategies in five Chinese cities by using a proposed all-in-one simulation program, according to the parametric performance design method. The program can be used to predict the energy consumption, power generation, and economic feasibility of different PVSD strategies. It was, firstly, calibrated through an actual experiment which was carried out in Qingdao and, secondly, used to simulate the energy consumption and generation of the three PVSD strategies in relation to the optimal angles and heights. Finally, the program was used to calculate the energy efficiency and economic feasibility of the three strategies. The findings indicated that the move-shade strategy of PVSD can provide the best energy-saving performance, followed by rotate-shade and fixed-shade strategies. Compared to the no-shade strategy, the reduction of the net energy use intensity by using the move-shade strategy was 31.80% in Shenzhen, 107.36% in Kunming, 48.37% in Wuhan, 61.79% in Qingdao, and 43.83% in Changchun. The payback periods of the three strategies ranged from 5 to 16 years when using the PVSD in China.

Cost Effective Indoor HVAC Energy Efficiency Monitoring based on Intelligent Decision Support System under Fermatean Fuzzy Framework

The heating, ventilation, and air conditioning (HVAC) control system is responsible for the efficient building energy system. Indoor energy consumption patterns can be monitored and reduced intelligently. Occupancy information plays a vital role to save a reasonable amount of energy. Traditional energy monitoring and control systems can be improved with the installation of the occupancy monitoring system which will consist of a network of sensors and cameras. In this research work, we propose a new and revolutionary convolutional neural network (CNN) based on real-time camera occupancy detection and recognition techniques across different sorts of sensors that provide realistic low-cost energy-saving solutions with robust graphical processing units (GPUs). This occupancy information will decide the energy behaviour inside buildings. Decision-making tools can be used to select the appropriate occupancy detection and recognition alternative for indoor environment and energy monitoring and management. In this research work, we introduce and develop the "Fermatean fuzzy prioritized weighted average and geometric operator". These aggregation operators (AOs) are a modern approach to modelling complexities in decision-making. In the end, we give an algorithm for an intelligent decision support system (IDSS) using proposed AOs to compare our CNN based method with other existing sensors techniques.

Turing Pattern‐Inspired Highly Transparent Wood for Multifunctional Smart Glass with Superior Thermal Management and UV‐Blocking Ability

AbstractTransparent wood for smart glass can decrease indoor energy consumption, while simultaneously offering a comfortable indoor temperature and facilitating effective light harvesting. However, high transparency and ultraviolet (UV)‐blocking ability are mutually exclusive in wood‐based materials due to the presence of lignin. Herein, a Turing pattern‐inspired highly transparent wood (TP‐TW) is fabricated via infiltrating the thermal management materials doped‐epoxy (TMM‐epoxy) into the delignified wood with a Turing pattern. Afterward, the Turing pattern possesses outstanding optical properties (high visible transmittance of ≈76% and low UV transmittance of ≈15%). Moreover, TP‐TW can reduce adverse effects caused by indoor temperature fluctuation and outdoor sunlight, demonstrating high latent heat (25.30 J g−1) and low near‐infrared transmittance. Compared with glass, TP‐TW exhibits a low thermal conductivity of 0.21 W m−1 K−1 and excellent shock‐resistant characteristics. Taken together, these results indicate that TP‐TW is an attractive material for smart glass applications.

Research on heat transfer mechanism and performance of a novel adaptive enclosure structure based on micro-channel heat pipe

In this paper, a novel adaptive enclosure structure (AES) combining the building wall and heat pipe is proposed for building wall energy saving. The theoretical heat transfer process of the structure is analyzed, and its heat transfer performance is obtained. The theoretical thermal resistance of the structure is about 0.165 K/W. The one-dimensional steady-state heat transfer experiment has been carried out. Under the temperature difference of 35 °C, the surface temperature of the AES is much higher than that of the traditional wall on the heating demand side (about 9.5 °C). The heat transfer experiment under the influence of multiple factors has been carried out. Under heating demand, the indoor side surface temperature of the AES is higher than that of the traditional wall (about 1.5 °C). Under cooling demand, the indoor side surface temperature of the structure is lower than that of the traditional wall (about 0.8 °C). In addition, it is realizable to switch the performance of the AES between efficient heat transfer or good thermal insulation according to requirements. The proposed structure has great potential for reducing the indoor energy consumption and improving thermal comfort, and could provide a new solution for passive energy-saving technology based on building envelope.

Urban block configuration and the impact on energy consumption: A case study of sinuous morphology

Building morphology and urban block configuration are influential urban design elements that control and optimize the outdoor and indoor thermal performance. In hot climate areas, cooling load is the major contribution to the total energy consumption, so it is essential to adopt design tools to enhance the building performance and reduce energy consumption and emissions. Previous studies proved the impact of urban block morphology on indoor energy consumption. However, the performance of buildings in Sinuous Configuration (SC) within the urban block has not been investigated in previous literature. This study aims to find the impact of SC of urban block configuration on outdoor microclimate parameters and indoor energy consumption. The UAE climate hot conditions were adopted to explore the SC of the urban block on outdoor thermal performance and indoor energy consumption using two simulation programs ENVI-MET and IES-VE. The outdoor thermal performance in this study is expressed by; 1) air temperature, 2) wind velocity, and 3) relative humidity at the height of the pedestrian level, 1.4 m from the ground. The results show that the SC where the buildings are arranged alternatively within the urban block, reduced the air temperature by 1.9 °C compared to the base case of grid arrangement. This result was reflected positively on energy consumption by reducing the conduction and solar gains, consequently, the cooling load decreased by 4.9% compared to the base case. Furthermore, the SC has a clear impact on wind speed and behavior, as wind speed reduced up to 68%, but the airflow and distribution enhanced within the urban block canyons and alleys around the buildings. This study contributes to urban planning policies and regulations by providing an optimized urban block configuration for hot climate areas. However, the impact of SC on outdoor thermal comfort in hot and humid areas can be recommended for further studies.

Numerical simulation for energy consumption and thermal comfort in a naturally ventilated indoor environment under different orientations of inlet diffuser

This study numerically analyses a well-validated comprehensive work on IEQ in a naturally ventilated, occupied 3-dimensional office building with installed furniture and internal heat-generating surfaces. This study analyzes the effect of the inlet diffuser orientation (IDO) on the indoor thermal comfort (ITC) of occupants and the energy demand of the building for heating indoor air. The Optimization of ITC has also been calculated for the acceptable indoor occupant comfort and energy consumption. The study is valuable to analyze the relationship between IDO of 0°, 15°, 30°, 45°, 60°and 75°, on ITC and the energy consumption of the indoor environment. Different methods have been chosen to study the ITC of the occupants such as air temperature, air movement in the occupied zone, vertical temperature gradient, and PMV and PPD index according to ISO7730. The results show that under a uniform indoor air distribution, the variation in IDO considerably affects the ITC and energy consumption. Optimized ITC can reduce indoor energy consumption by 35.14%. The IDO slightly affects the PMV and PPD index. Occupant's legs are more sensitive to the naturally ventilated indoor environment due to the adverse effect of buoyancy force which may create the problem of the cold draft. For optimization of the ITC, the air temperature in the occupied zone plays a key role.

Tough, Highly Oriented, Super Thermal Insulating Regenerated All-Cellulose Sponge-Aerogel Fibers Integrating a Graded Aligned Nanostructure.

Thermal insulating fibers can effectively regulate the human body temperature and decrease indoor energy consumption. However, designing super thermal insulating fibers integrating a sponge and aerogel structure based on biomass resources is still a challenge. Herein, a flow-assisted dynamic dual-cross-linking strategy is developed to realize the steady fabrication of regenerated all-cellulose graded sponge-aerogel fibers (CGFs) in a microfluidic chip. The chemically cross-linked cellulose solution is used as the core flow, which is passed through two sheath flow channels, containing either a diffusion solvent or a physical cross-linking solvent, resulting in CGFs with a porous sponge outer layer and a dense aerogel inner layer. By regulating and simulating the flow process in the microfluidic chip, CGFs with adjustable sponge thicknesses, excellent toughness (26.20 MJ m-3), and ultralow thermal conductivity (0.023 W m-1 K-1) are fabricated. This work provides a new method for fabricating graded biomass fibers and inspires attractive applications for thermal insulation in textiles.

Applications of Nondominated Sorting Genetic Algorithm II Combined with WKNN Online Matching Algorithm in Building Indoor Optimization Design.

The present work aims to improve the comfort of architectural interior design and reduce indoor energy consumption. The Weight K-Nearest Neighborhood (WKNN) algorithm and Nondominated Sorting Genetic algorithm are proposed to locate and analyze the spatial location of indoor personnel and optimize the indoor energy consumption in combination with residential behavior. Firstly, the indoor human behavior data and energy-saving problems are analyzed based on residential behavior theory and architectural physics. The indoor positioning algorithm is proposed to identify the personnel activities to realize the optimization of indoor energy distribution. Secondly, mean filtering and cluster analysis are adopted to optimize sampling points' data and fingerprint database to eliminate data noise. Besides, the WKNN algorithm is used for Wireless Fidelity (Wi-Fi) indoor location fingerprint location. Then, aiming at the multiobjective optimization problem of building indoor energy consumption, the Nondominated Sorting Genetic algorithm obtains the optimal solution of the model. Combined with the indoor location information of personnel, the indoor heating and cooling system is monitored and distributed to reduce the energy consumption in the building while ensuring the living comfort of personnel. The test and simulation results demonstrate that the mean filtering algorithm can solve the room's fluctuation problem of Wi-Fi signals. The cluster analysis algorithm can eliminate the data noise of the fingerprint database and improve the positioning accuracy of the positioning algorithm. Moreover, the location result is independent of the number of nodes; the number of sampling points does not affect the location result. The positioning accuracy of the WKNN algorithm is 2 m, and the positioning error rate within 2 m is about 60%. Compared with other algorithms, the WKNN algorithm has better positioning accuracy and positioning stability. Therefore, the location algorithm designed here can be applied to indoor location optimization. This study provides a reference for optimizing buildings' indoor positioning and energy consumption.

On Venetian Campi Resilience to Climate Change

Venice is known for its history and beauty and its fragility and potential demise. The city is experiencing an increase in yearly average temperatures affecting outdoor - indoor comfort and average energy expenditure. Owing to existing literature demonstrating how local microclimate depends on urban density, shape, and orientation of buildings and materials, the work studies the influence of changing Venice temperatures by targeting such issues, focusing on an urban fabric typical form, known as Campi. Based on IPCC’s future weather predictions for 2050 scenario A1B, the work highlights how the urban fabric configuration affects the local microclimate and outdoor conditions to define how buildings will mitigate and adapt to environmental transitions. The method couples microclimate and outdoor comfort users’ perception of Physiological Equivalent Temperature (PET), via ENVI-met. Preliminary results show that the compactness of the urban fabric in Venetian Campi significantly reduces outdoor temperatures due to the increased density of shadow areas in the courtyard or in narrow Venice streets. The role of water is also simulated via ENVI-met, as buildings’ materials and indoor energy consumption are assumed as invariant to evaluate the historic urban fabric climate resilience. The results constitute a first step towards understanding to what extent a particular urban fabric type is thermally resilient.

Experimental and Numerical Investigation of Composite Phase Change Materials for Building Energy Saving

Composites composed of paraffin wax and copper foam with porosity of 95 % and pore density of 15 ppi, 30 ppi, and 50 ppi were prepared by the melt impregnation method. Two building models of the same size were made using gypsum board. The roof of the experimental model was covered with 50ppi copper foam /paraffin composite phase change board, and the roof of the reference model was covered with foam insulation board. The heat transfer experiment was conducted with a constant heat flux. EnergyPlus software was also employed to simulate the energy saving effects of the building models. The size and material of the model established during the simulation are consistent with the experimental model. Experimental results showed that the phase change composite board delayed the highest indoor temperature for 1.5 h, and it also reduced the indoor maximum temperature by 1.2° and the indoor energy consumption by 21 %. The simulation results showed that the phase change composites board delayed the appearance of the highest indoor temperature by 1.3 h and reduced the highest indoor temperature by 1.1°C, and the maximum indoor energy consumption decreased by 19 %. The copper foam/paraffin composite material can effectively improve the thermal comfort and reduce the energy consumption of the building model.