Solar Gain Research Articles

Influence of the shading nets on indoor thermal environment and air-conditioning energy consumption in lightweight buildings

Lightweight envelopes are increasingly utilized in temporary relief and shelter buildings, due to their cost-effectiveness and efficient construction process. However, these envelopes often result in inadequate indoor thermal conditions during the summer months, which can negatively impact the physical and psychological well-being of occupants, particularly victims and patients in disaster or epidemic situations. Addressing this challenge necessitates the use of simple yet effective materials and technologies to improve indoor thermal environments even with limited resources. This study explores the potential of shading nets to enhance indoor thermal conditions in lightweight buildings by mitigating solar radiation gain during the summer period. A comparative experiment was conducted on two lightweight buildings, one of which was equipped with standard six-needle black shading nets, to assess the impact of shading nets on the indoor thermal environment and air-conditioning energy consumption. The findings reveal that shading nets can reduce solar radiation intensity by approximately 57.86%, resulting in a significant decrease in peak indoor air temperatures by 2.3°C to 3.4°C under natural ventilation and a reduction in air-conditioning energy consumption by up to 23% under air-conditioned conditions. These findings demonstrate that shading nets are effective in improving indoor comfort and reducing energy usage, providing a practical solution for enhancing living conditions in lightweight structures during hot weather.

Specification of a greenhouse in cold climate condition, mathematical model and optimization

In order to optimize the energy requirements (heating/cooling) of a multi-zone greenhouse, and investigate its heat recovery potential, a mathematical, dynamic energy model, coded in the MATLAB/Simulink platform, is developed. For validation, a case study in cold climate conditions is evaluated. This dynamic model, based on both energy and water vapor mass balances, was able to calculate the year-round monthly energy demand for the case study. The model calculations were compared with actual energy consumption data and were shown to have an accuracy between 6% and 15.5% for different months. The results highlighted the potential of applying a heat recovery strategy, whether with a Phase Change Material (PCM) or a Heat Recovery Ventilator (HRV). It is shown that using a HRV can reduce the energy demand of the greenhouse by 5% for January and 4% for December. Regarding the greenhouse radiation performance, the south roof contributes the most to solar heat gain in winter and summer, while the north wall makes the minimum contribution. Consequently, it is proposed to increase the area of the south roof and insulate the north wall. Thus, an asymmetrical roof configuration can receive 6% more solar radiation. Calculations show that an east-west greenhouse orientation lowers energy demand by 3%.

Fuzzy clustering-based climatic zoning method for building climate responsiveness in Qinba region, China

Accurate climate zoning is crucial for enhancing energy efficiency. This study aims to further subdivide microclimate zones to enhance the precision of climate zoning and subsequently propose climate response strategies for the refined areas. The Qinba region, a climatic transition zone between northern and southern China, serves as the focal point of this study. The research employs a fuzzy clustering method, utilizing integrated weights on seven meteorological indicators spanning 40-year period, to delineate climate zones in the Qinba region. The results indicate that parts of Qinba region can be categorized into three clusters significantly correlated with altitude, which are closely consistent with the distribution of climate data and previous researches. Lower altitude areas experience hot summers and warm winters, while higher altitude regions have warm summers and cold winters with a larger increase in average annual temperature. Furthermore, this research confirms the alignment of climate zones with climate response strategies through investigation of over 30 traditional villages with climatic experience and simulation of three typical cities using climate software. Both sources emphasize the significance of sun shading, ventilation, and solar gain as key strategies applicable across all three zones. The proposed method accurately synthesizes various dimensions of meteorological data and is suitable for small-scale climate zoning. It can provide valuable insights for advancing climate-complex small-area zoning and climate-responsive strategies.

Spectrally selective design and energy-saving demonstration of a novel liquid-filled window in hot and humid region

Spectrally selective window provides a positive solution for the sustainable development of buildings in hot regions. In this study, a novel filuis-based spectrally selective design was proposed to achieve the light/heat decoupling of windows. In detail, the cooper ions and chlorophyll were blended in the aqueous solution to efficiently block the near-infrared (NIR) and ultraviolet (UV) energy, whilst maintaining a high visible transmittance. The blended solution was demonstrated to be highly advanced in solar light/heat decoupling, with a high light-to-solar heat gain (LSG) above 2.5. Meanwhile, the weathering assessment of the prepared solution indicates that it can maintain a fairly constant optical transmittance over a period of 8 months. With the light/heat decoupling solution, a triple-layered liquid-filled window (LFW) was conceptualized, and a model was then developed to calculate the window's annual energy-saving performance in a hot and humid city, i.e., Hong Kong. Results demonstrate that the LFW can ensure a feasible luminous that is higher than 40 % and low monthly average solar heat gain coefficient (SHGC) values ranging from 0.24 to 0.26 in all seasons. These features hold great promise for buildings located in hot regions, as they enable low-carbon operation.

Using Building Orientation to Promote Sustainability

Maximizing energy efficiency and overall performance is paramount in sustainable architectural design. Building orientation is proving to be a cornerstone of strategy in achieving these goals. This paper explores the critical role of building orientation in promoting sustainability in the built environment. It delves into the complex relationship between the layout and placement of structures and their impact on energy consumption, natural lighting and occupant comfort. The orientation of the building is carefully designed to interact harmoniously with the elements of the environment, especially the path of the sun and the prevailing winds. By strategically arranging structures, architects and designers can use natural resources to minimize energy demands and optimize building performance. For example, the right orientation can harness solar energy for passive heating and cooling, reducing reliance on mechanical systems and reducing carbon emissions. In addition, the orientation of the building deeply affects the distribution of natural light in the space. By strategically orienting openings such as windows and skylights, designers can maximize daylight penetration, reduce the need for artificial lighting and increase visual comfort for occupants, thoughtful building placement can mitigate glare and solar heat gain, promoting a more comfortable indoor environment while minimizing reliance on energy-intensive cooling systems.

Analysis of the performance of V-type solar stills coupled with flat plate collectors and the potential use of artificial intelligence

The exponential rise in global population and pollution from industrialization exacerbates water scarcity. Solar desalination offers a carbon-neutral solution to freshwater production. The V-type double-sloped solar desalination system, renowned for its simplicity and compact size, outperforms single-sloped systems. This study compares the performance of a double inward slope desalination still with and without a flat plate collector. Results show a 74% increase in water production with the modified still, achieving 3020 mL/day and 633 mL/hr on clear, sunny days. Energy efficiency also improves by 18% to 0.13 mL/kJ with the addition of the flat plate collector. Conducted in Thalassery, India, the experiment demonstrates potential for home applications. Shadowing on the collector plate can diminish solar energy gain, addressed through mathematical modeling using Artificial Neural Networks (ANN) in this study.

Efficient Cooling for Agricultural Greenhouses in Hot Climates: A Novel Water Light Filter Design

The use of agricultural greenhouses in hot climates requires transparent enclosures to enable cooling for optimal plant growth. However, the cooling process incurs high water and energy costs due to solar gain and heat trapping. To address this issue, a novel enclosure design featuring a layer of liquid or water solution between two commercial grade glass layers has been proposed. This water solution absorbs thermal radiation and can be circulated through an active heat dissipation system. Carefully selected dyes can also be added to enhance water filter performance, allowing sufficient photosynthetically active radiation (PAR) through to the plants while blocking more of the non-PAR radiation.To evaluate the efficiency of the proposed filter, a shading filter was used as a benchmarking scheme. The tests were conducted using clear water, mineral oil, and water with four commercially available pigments. Results indicated a reduction in the thermal load ranging from 31-62%, while the reduction in the photosynthetically active portion of the solar spectrum ranged from 32-79%. The clear water filter performed the best, blocking 45% of the thermal load while allowing 69% of weighted PAR radiation. This allowed for an additional 14% of PAR radiation compared to an equivalent 45% transparent shading device.This new liquid filter design is effective in reducing cooling costs for agricultural greenhouses in hot climates, while still allowing for optimal plant growth. The clear water filter was found to be the most effective in blocking non-PAR radiation while still allowing sufficient PAR for the plants. However, there is potential for future work to identify additives that could enhance the filter’s overall performance. Engineering and technoeconomic development should be pursued to implement this technology for practical use in the field.

Development of a rapid assessment tool for integrating thermal comfort in early design stage of energy-efficient office buildings

Comprehending and predicting energy performance of existing buildings and new constructions is crucial towards decarbonization. Instead of utilizing simulation software, multiple regression models are utilized to predict building energy consumption while ensuring indoor thermal comfort to speed up this process. However, previous predictive models prioritize reducing energy demand, with limited focus on thermal comfort. This study aims to support decision-making during retrofitting and new construction planning though developing a prediction model. An air-conditioned office building served as a reference building for simulation. 21 design parameters were analyzed, including aspects of weather, building envelope, internal loads, ventilation, and temperature settings. Stepwise regression results unveiled the crucial variables in the final model, with 8, 9, 13, and 6 variables remaining for peak cooling load, annual cooling load, overheating hours (WE), and Environmental Quality Index for thermal comfort (EQITC) in the perimeter zones, and 5, 6, 8, and 5 variables for the core zones, respectively. Furthermore, insights into the important variables regarding cooling load and thermal comfort were respectively provided. Weather- and envelope-related variables, such as cooling degree-days, global solar radiation, solar heat gain coefficient (SHGC), and U-value, have the highest impacts on cooling load. For thermal comfort, variables including temperature setpoint, occupant activity level, and factors related to window sunlight transmission performance, such as SHGC, window area ratio, and overhang projection ratio, proved to be influential. Overall, this study provided accurate models for assessing optimal strategies for energy efficiency and thermal comfort during the early design phases, advancing building performance practices.

Smarter Window Selection for Smarter Energy Consumption: The Case of the United Arab Emirates

The energy consumption levels of buildings in the United Arab Emirates (UAE) are among the highest in the world. One of the main reasons for this energy consumption is the need to cool buildings due to the hot climate of the UAE. As a large part of the heat accumulated inside buildings comes from windows, in this study, the effects of window size and direction in a typical building in the UAE on energy consumption and thermal performance are investigated through numerical modeling. The modeling process includes thermal conductivity, thermal convection, and solar radiation simulation. The energy performance of any building at any location can be obtained based on local weather data and the computational thermal characteristics of the building elements, such as its walls, roofs, windows, and doors. The study covered all different seasons of the year and different orientations for the windows, allowing the daily and yearly energy consumption associated with the windows to be obtained. Furthermore, the energy consumption was obtained for solar radiation and heat gain separately for both single- and double-glazed windows. It was found that north-facing windows consume significantly less annual energy (36% less), when compared with windows facing in the other three directions. Furthermore, the east- and west-facing windows consumed about 41% and 35% more daily cooling energy in August, when compared to north- and south-facing windows, respectively. The use of a window with a height equal to that of the wall can cause a clear greenhouse effect; hence, it is recommended to limit the window’s height to two-thirds of the wall height, which can save about one-third of the associated yearly cooling energy. This study should be considered as a general guideline, as the thermal performance of any specific building will be affected by its own thermal characteristics.

Optimization Control Strategy for Transition Season Blinds Balancing Daylighting, Thermal Discomfort, and Energy Efficiency

Natural lighting in office buildings is often affected by excessive solar heat gain and discomfort glare, and the transitional seasons are no exception. Therefore, addressing the issue of natural lighting in buildings has always been a challenge in developing shading control strategies. This study designed a model-based calculation method for shading blind control indicators. The method combines existing physical models for sky conditions, solar radiation, heat transfer, thermal comfort, glare, and illuminance calculations and incorporates modifications and additions. Additionally, an equivalent energy-saving model for shading was established. A shading blind control strategy balancing indoor light and the thermal environment with energy savings during transitional seasons was proposed. In transitional seasons, this method can eliminate 100% of glare, reduce discomfort illuminance duration by 81.3% and heat discomfort duration by 87.5% and save 81.3% of lighting energy consumption when air conditioning is used. By comparing the simulation results of an office building in Xi’an with the results obtained from this calculation method, the absolute error percentage was found to be 6.83%, verifying the reliability of the calculation method. Finally, the proposed control strategy was compared with common methods such as no blinds, end-angle control, and fixed-angle control to evaluate its performance in terms of daylighting, thermal comfort, and energy savings. The results showed that the control strategy proposed in this study has significant advantages with respect to various performance indicators.

Effect of angle of incidence on the optical-electrical-thermal performance of photovoltaic insulated glass units

Photovoltaic insulated glass units (PV-IGUs) possess significant potential for achieving simultaneous power generation, thermal insulation, and natural lighting in buildings. However, the optical properties of PV-IGUs are influenced by real-time variations of the Angle of Incidence (AOI), thereby intricately impacting its optical-electrical-thermal performance. Therefore, an optical-electrical-thermal coupling model was developed to evaluate the impact of real-time AOI on the optical-electrical-thermal performance of cadmium telluride (CdTe) PV-IGUs. Through outdoor experiments, the model's accuracy was validated with acceptable errors between experimental and simulated data. After validation, the optical-electrical-thermal performance of PV-IGUs were analyzed under different operational conditions and AOIs. Results revealed that when AOI exceeds 45o, there is a reduction in absorptance up to 60.76% in terms of optical performance. Notable variations were observed across AOIs regarding thermal-electrical performance, with a maximum temperature difference of 16.08 °C for the PV cells and a maximum disparity in power generation of 140.51 Wh/m2 under solar radiation of 800W/m2. Additionally, an increase of AOI and decrease of photovoltaic coverage ratio (PVR) for PV-IGUs result in higher variation of the solar heat gain coefficient (SHGC), reaching up to 69.81% when PVR is 0.1. This study established a reliable foundation for accurately evaluating the performance of PV-IGUs.

Perceived Air Quality, Thermal Comfort and Health: A Survey of Social Housing Residents in Kazakhstan

Kazakhstan is in Central Asia and is the ninth-largest country in the world. Some socially vulnerable segments of the Kazakh population residing in subsidised social housing have experienced a range of problems due to the low quality of housing construction and its planning. Poor indoor environmental conditions in social housing contribute to occupants’ comfort, health, and general well-being. This study assessed social housing residents’ health and quality of life, focusing on their perceived indoor air quality and thermal comfort satisfaction. A cross-sectional survey in Kazakhstan was conducted to test the effects of environmental factors on social housing residents’ health and satisfaction. Four hundred thirty-one responses were analysed, and the SF12v2 questionnaire was used to measure the health-related quality of life. Multiple regression analysis showed that air quality negatively predicted the respondents’ physical (PCS) and mental (MCS) health. In addition, age, smoking, and employment status had a significantly negative effect on PCS, while education level had a predictive positive effect. Thermal conditions negatively predicted only MCS, as well as alcohol consumption. Next, the air-conditioning control factor had a negative effect. In contrast, low air circulation, low humidity, high solar gain, temperature imbalance, duration of the residence and alcohol consumption had a significantly positive effect on overall satisfaction with the temperature. The odour sources from tobacco, furniture and external sources were predictors of respondents’ overall air quality satisfaction, along with the duration of the residence, alcohol consumption and smoking status.

A novel method for calculating solar radiation on indoor human body under different weather conditions

Indoor occupants may receive large solar heat that affect their health, productivity, and comfort. Most of previous studies focus on indoor occupants with strong direct solar radiation and weak diffuse radiation. Considering the non-uniform solar radiation distribution in the sky, this study proposes the improved HNU Solar Model, a novel method for calculating solar radiation on indoor human body under different weather conditions. The improved HNU Solar Model proposes a new calculation algorithm for calculating non-uniform radiation distributed on indoor human body under different weather conditions, via adding the human body points, windows points, and clearness index to improve the calculation accuracy; then it converts the human-body-received solar radiation into the increase in the mean radiant temperature (Delta MRT). The calculated Delta MRT values by the improved HNU Solar Model were compared with those calculated by Radiance. The results indicate that, for Delta MRT by total solar radiation on typical days with different weather conditions, the absolute error (AE) and the relative error (RE) of the improved HNU Solar Model are usually less than 1.5 °C and 15%, respectively. For the whole-year hourly Delta MRT values, the corresponding AE and RE are usually less than 1 °C and 15%, respectively. Moreover, according to the proposed model, for large-window buildings in medium-latitude regions, indoor occupants are more exposed to direct solar radiation (63%) than diffuse solar radiation (37%); while diffuse radiation can be the dominant solar heat gain of indoor occupants (up to 55%) in buildings in low-latitude regions.

Porous covalent polymer framework-based molecular platform for polychromatic Vis-to-NIR electrochromic smart window to modulate solar irradiation

Employing advanced electrochromic technology, the low energy-consuming smart windows seamlessly regulate light transmission, optimizing energy efficiency without compromising comfort. This innovation marks a significant stride toward sustainable architecture, offering dynamic control over interior luminosity while reducing reliance on conventional power sources. In that context, a porous perylene diimide (PDI) and triazine-containing covalent polymeric framework, PD-CPF, was synthesized for electrochromic (EC) applications. The PD-CPF-based electrochromic device (ECD) exhibited a multicolored, durable visible-to-NIR electrochromism when used in an ECD. The low-power-consuming (3.05 mW/cm2) electrochromic (EC) smart window remarkably lowered the solar irradiance gain by 68%.

Enhancing the Thermal and Energy Performance of Clay Bricks with Recycled Cultivated Pleurotus florida Waste

The development of energy-efficient and sustainable building materials is imperative to reduce energy consumption in the construction sector. This study addresses both the applied problem of increased solar heat gain and decreased indoor thermal comfort, as well as the scientific problem of reducing the thermal conductivity of clay bricks. It investigates the incorporation of recycled spent mushroom materials, consisting of Pleurotus florida mycelia and rice husk waste, as a novel additive in the production of fired clay bricks (FCBs) to enhance thermal insulation properties. The developed bricks were utilized in an optimized wall design for a residential building in New Cairo, Egypt. The wall design is created using energy modeling software, including Honeybee, Ladybug, Climate Studio, and Galapagos. The results demonstrate that an optimal waste content of 15% and a firing temperature of 900 °C yield the best thermal performance. Compared to traditional FCB walls, the new design incorporating the florida waste additive significantly improves thermal comfort, as indicated by a lower predicted mean vote and predicted percentage of dissatisfaction. Furthermore, the developed walls contribute to a reduction in CO2 emissions of 6% and a decrease in total energy consumption of 38.8%. The incorporation of recycled florida waste offers a sustainable approach to enhancing standard brick fabrication processes. This work highlights the promise of agricultural waste valuation for the development of eco-friendly and energy-efficient building materials. Future research should explore the mechanical strength, acoustics, cost–benefit analysis, and field implementation of the developed walls, thereby addressing both the scientific and applied aspects of the problem.

Fluorine-doped ATO NCs with enhanced LSPR effect for smart windows with adaptive solar modulation

Smart windows with excellent near-infrared (NIR) light shielding capacity and controlled visible light transmittance are expected to reduce building energy consumption and improve indoor comfort. However, the ability of current thermochromic materials to regulate solar gain with the tunable extinction of phase-change materials is still far from optimum. In this work, an fluorine (F)-doped ATO (FATO) nanocrystals (NCs) are designed as a photothermal material to optimize the solar modulation of thermochromic hydrogels. F ion doping can modify the electronic structure of ATO, resulting in a high concentration of oxygen vacancies and free electrons, thereby enhancing the NIR absorption performance and photothermal conversion performance of the ATO NCs. On this premise, the designed smart window based on FATO NCs and thermochromic hydrogels exhibits the remarkable features of excellent NIR shielding, high initial visible transmittance and fast response speed. The window is capable of shielding 99.5% of the solar radiation from 300 to 2500 nm and permitting 75.0% of initial visible light. Moreover, the simulated indoor temperature of the smart window was 17.2 °C lower compared with the black one, demonstrating potentials in practical application of building energy saving.

Optimizing Residential Building Orientation for Sustainable Daylighting in the Tropics: A Case Study in Lagos, Nigeria

Daylighting is an essential aspect of sustainable building design as it reduces reliance on artificial lighting, improves energy efficiency, and promotes a healthier indoor environment. However, in the tropics, where excessive solar heat gain and intense sunlight prevail, designing residential buildings that maximise daylight while minimising heat gain relies heavily on correctly obtaining the building orientation. This study explores the challenges faced in achieving optimal residential building orientation in the tropics and proposes guidelines and tools for operationalising residential building orientation in Lagos State. A mixed-method approach was employed by combining field observations, subjective surveys, and physical measurements. The orientations of the sampled residential buildings were identified using field observation procedures. A total of 1,168 residential buildings were sampled across 20 Local Government Areas of Lagos State. The findings reveal variations in residential building orientations across the North and South zones of Lagos State, with the majority having a northwest/southeast orientation. The implications of these orientations on energy efficiency, thermal comfort, and daylighting are discussed. Recommendations were provided for each orientation, suggesting strategies to address potential issues and optimise daylighting. This study underscores the importance of considering building orientation for sustainable design practices in Lagos, Nigeria. By implementing the suggested building orientation guidelines, architects can achieve and enhance the visual comfort and energy efficiency of residential building occupants in Lagos State.

Simulation-Driven Strategies for Improving Natural Ventilation in Educational Spaces: A Case Study of An Educational Building in Sari

Any architectural space, especially the architecture of an educational complex, should provide comfort for human beings in the face of geographical and climatic characteristics. Climatic factors have always profoundly affected the formation of the physical environment of buildings. Energy demand has always been one of society’s most critical issues. Saving resources is one of the architectural design goals to achieve a suitable environment-friendly architecture. This architectural approach, which comes from the concepts of sustainable development, is one of the basic human needs in the current world due to its compatibility with the environment. The goal is to build constructions that can improve the climate, prevent the waste of energy consumption, and avoid the adverse effects of construction on the environment. In traditional Iranian architecture, there are numerous passive methods; natural ventilation is an essential part of Iranian conventional building design, which is being ignored today. Since humid and moderate climates have high relative humidity on most days of the year, one important goal is to move the stagnant moisture inside to establish a suitable thermal environment for occupants. The research method of the present study is descriptive-analytical, which has been experimented with according to library studies in addition to climate and meteorological data. Then, analysis of the data is provided by an energy simulator. It is concluded that the best orientation of the educational building is south, which can provide proper natural ventilation and solar heat gain. In other words, optimal interior air quality is achieved in this orientation.

Tilted global solar irradiance in Bahrain: an experimental study

Abstract In the present work, tilted global solar irradiance data are presented and analysed, measured for a period of 1 year on the campus of Bahrain Polytechnic, Kingdom of Bahrain, from both a fixed photovoltaic panel and a moving one via a two-axis solar tracker. The fixed panel faces south with an angle of 26° with respect to the horizontal, coinciding with the local geographical latitude. The second panel is moved by two motors, controlled by a global positioning system and suitable software so that the Sun’s rays are perpendicular to the panel surface. A pyranometer is installed on each panel, recording the tilted global solar irradiance, stored by using a data logger. The analysis of the data obtained shows a 33% solar energy gain on an annual basis for the moving panel (2780 versus 2088 kWh/m2 on the fixed panel). More importantly, in June, when the energy demand in Bahrain is elevated due to the increased residential cooling loads, the solar energy received by the moving panel is 54.7% higher compared with that of the fixed panel. On a percentage basis, the increase in solar energy from the moving panel is profound in the early morning and late evening hours. Moreover, the reduction in the solar energy received by the fixed panel from May to June does not appear in the moving panel because of the adjustable orientation of the latter. Throughout the year, the mean daily solar power varies between 0.37 and 0.56 kW/m2 for the fixed panel, and 0.45 and 0.70 kW/m2 for the moving panel. In winter, solar energy fluctuations are elevated due to erratic weather conditions that present a peak standard deviation of 28% of the corresponding mean. The data presented are useful for potential solar investments in Gulf countries.

Refractive Index Modulation for Metal Electrodeposition-Based Active Smart Window Applications.

One of the remarkable choices for active smart window technology is adopting a metal active layer via reversible metal electrodeposition (RME). As the metal layer efficiently blocks the solar energy gain, even a hundred-nanometer-thick scale, RME-based smart window has great attention. Recent developments are mainly focused on the various cases of electrolyte components and composition meeting technological standards. As metal nanostructures formed through the RME process involve plasmonic phenomena, advanced analysis, including plasmonic optics, which is beyond Beer-Lambert's law, should be considered. However, as there is a lack of debates on the plasmonic optics applied to RME smart window technology, as research is mainly conducted through an exhaustive process. In this paper, in order to provide insight into the RME-based smart window development and alleviate the unclear part of plasmonic optics applied to the field, finite-difference time-domain electromagnetic simulations are conducted. In total, two extremely low-quality (Cr) and high-quality (Mg) plasmonic materials based on a nanoparticle array are considered as a metal medium. In addition, optical effects caused by the metal active layer, electrolyte, and nanoparticle embedment are investigated in detail. Overall simulations suggest that the effective refractive index is a decisive factor in the performance of RME-based smart windows.