Useful Daylight Illuminance Research Articles

Enhancing Daylight Comfort with Climate-Responsive Kinetic Shading: A Simulation and Experimental Study of a Horizontal Fin System

This study employs both simulation and experimental methodologies to evaluate the effectiveness of bi-sectional horizontal kinetic shading systems (KSS) with horizontal fins in enhancing daylight comfort across various climates. It emphasizes the importance of optimizing daylight levels while minimizing solar heat gain, particularly in the context of increasing energy demands and shifting climatic patterns. The study introduces a custom-designed bi-sectional KSS, simulated in three distinct climates—Wroclaw, Tehran, and Bangkok—using climate-based daylight modeling methods with the Ladybug and Honeybee tools in Rhino v.7 software. Standard daylight metrics, such as Useful Daylight Illuminance (UDI) and Daylight Glare Probability (DGP), were employed alongside custom metrics tailored to capture the unique dynamics of the bi-sectional KSS. The results were statistically analyzed using box plots and histograms, revealing UDI300–3000 medians of 78.51%, 88.96%, and 86.22% for Wroclaw, Tehran, and Bangkok, respectively. These findings demonstrate the KSS’s effectiveness in providing optimal daylight conditions across diverse climatic regions. Annual simulations based on standardized weather data showed that the KSS improved visual comfort by 61.04%, 148.60%, and 88.55%, respectively, compared to a scenario without any shading, and by 31.96%, 54.69%, and 37.05%, respectively, compared to a scenario with open static horizontal fins. The inclusion of KSS switching schedules, often overlooked in similar research, enhances the reproducibility and clarity of the findings. A physical reduced-scale mock-up of the bi-sectional KSS was then tested under real-weather conditions in Wroclaw (latitude 51° N) during June–July 2024. The mock-up consisted of two Chambers ‘1’ and ‘2’ equipped with the bi-sectional KSS prototype, and the other one without shading. Stepper motors managed the fins’ operation via a Python script on a Raspberry Pi 3 minicomputer. The control Chamber ‘1’ provided a baseline for comparing the KSS’s efficiency. Experimental results supported the simulations, demonstrating the KSS’s robustness in reducing high illuminance levels, with illuminance below 3000 lx maintained for 68% of the time during the experiment (conducted from 1 to 4 PM on three analysis days). While UDI and DA calculations were not feasible due to the limited number of sensors, the Eh1 values enabled the evaluation of the time illuminance to remain below the threshold. However, during the June–July 2024 heat waves, illuminance levels briefly exceeded the comfort threshold, reaching 4674 lx. Quantitative and qualitative analyses advocate for the broader application and further development of KSS as a climate-responsive shading system in various architectural contexts.

Multi-objective optimization of switchable suspended particle device vacuum glazing for comfort and energy efficiency in school typologies under hot climate

This study focuses on the multi-objective optimization of a switchable Suspended Particle Device (SPD) vacuum glazing system to reduce energy use while ensuring thermal and visual comfort in schools located in arid desert environments. A detailed synergy analysis was performed on a representative floor from three school classroom typologies, comparing suspended particle device vacuum glazing in its OFF and ON states against conventional double-glazing with air gaps windows. This analysis employed an advanced simulation framework integrating Rhino-Grasshopper with Open Studio Model, Colibri 2.0, and Design Explorer2 software to evaluate energy consumption, Adaptive Comfort Percentage (ACP), and Useful Daylight Illuminance (UDI). Thermal comfort varied across typologies and orientations, with the atrium with skylight typology frequently meeting or approaching the 80 % Adaptive Comfort Percentage benchmark. However, the southern and eastern classrooms in the enclosed atrium with clerestory typology did not exceed a 39 % adaptive comfort percentage. The comprehensive parametric and multi-objective optimization simulation revealed that suspended particle device vacuum glazing in its 'OFF' state did not fulfill the UDI300lux–1000lux criteria across all typologies, even with maximal Window to Wall Ratio (WWR) and skylight ratio (SR). However, the enclosed atrium with clerestory, integrating SPD vacuum glazing with a 40 % Window to Wall Ratio configuration, emerged as particularly effective in achieving optimal useful daylight illuminance distribution, minimizing energy consumption, and ensuring satisfactory adaptive comfort percentage across various orientations. These findings underscore the potential of multi-objective optimization of suspended particle device vacuum glazing, combined with strategic Window to Wall Ratio adjustments, as a viable alternative to traditional glazing systems in hot desert climates. The adaptability of suspended particle device vacuum glazing highlights its significant potential for achieving thermal comfort, enhancing sustainable architectural design, and improving energy efficiency in educational buildings within extreme climate zones.

A Framework for Adaptive Façade Optimization Design Based on Building Envelope Performance Characteristics

The adaptive façades serve as the interface between the indoor and outdoor energy of the building. Adaptive façade optimization design can improve daylighting performance, the thermal environment, view performance, and solar energy utilization efficiency, thus reducing building energy consumption. However, traditional design frameworks often neglect the influence of building envelope performance characteristics on adaptive façade optimization design. This paper aims to reveal the potential functional relationship between building façade performance characteristics and adaptive façade design. It proposes an adaptive façade optimization design framework based on building envelope performance characteristics. The method was then applied to a typical office building in northern China. This framework utilizes a K-means clustering algorithm to analyze building envelope performance characteristics, establish a link to adaptive façade design, and use the optimization algorithm and machine learning to make multi-objective optimization predictions. Finally, Pearson’s correlation analysis and visual decision tools were employed to explore the optimization potential of adaptive façades concerning indoor daylighting performance, view performance, and solar energy utilization. The results showed that the optimized adaptive façade design enhances useful daylight illuminance (UDI) by 0.52%, quality of view (QV) by 5.36%, and beneficial solar radiation energy (BSR) by 14.93% compared to traditional blinds. In addition, each office unit can generate 309.94 KWh of photovoltaic power per year using photovoltaic shading systems. The framework provides new perspectives and methods for adaptive façade optimization design, which helps to achieve multiple performance objectives for buildings.

Daylighting and energy performance of window with transparent insulation slats combined with building shading in the hot-summer and cold-winter zone

The shading from surrounding buildings significantly affects the energy and daylighting performance of transparent insulation materials (TIM) systems. In previous studies, the performance of TIM systems was primarily discussed in ideal situations without considering the influence of surrounding buildings. However, this is not realistic in actual urban scenarios. This study presents a case study conducted in Changsha to evaluate and compare the energy and daylighting performance of the window with transparent insulation slats (WTIS) and normal double glazing (NDG). The study considers the varying degrees of building shading effects. The results show that windows facing west exhibit the best energy efficiency, while windows facing south have the worst. WTIS achieves a higher Useful Daylight Illuminance (UDI) when building shading effects are not significant, whereas NDG achieves a higher UDI when building shading effects are significant. Despite increasing lighting energy consumption by 69.8 % to 84.3 %, WTIS consistently outperforms NDG in terms of total energy savings. Furthermore, strategically utilizing or deactivating WTIS according to recommended periods during winter can enhance the total solar gain for the building by approximately 22.3 %. This study provides valuable recommendations for the application of WTIS systems and the design of buildings in the hot-summer and cold-winter zone.

A novel decision support system for designing fixed shading systems in the early design stage: A case study in Egypt

Solar shading is a crucial element that can significantly impact lighting conditions and energy consumption, especially in hot regions. However, selecting the best shading design that achieves optimal daylight performance while meeting architects' requirements is very challenging. This is because it involves considering many design parameters and balancing multiple objectives. The paper introduces a decision support system for designing fixed shading systems to enhance interior environments and reduce energy consumption. Parametric simulation, a meta-model based on automatic selection of regression machine learning algorithms (RMLA), and non-dominated sorting genetic algorithm II (NSGA-II) are used to prepare the designs for selection. Three multiple criteria decision-making (MCDM) methods are employed: the analytic hierarchy process (AHP), entropy, and the technique for order preference by similarity to the ideal solution (TOPSIS) in two combinations (AHP-TOPSIS and entropy-TOPSIS) to adapt to different expert availability scenarios. The proposed method is coded and automated with an easy-to-use interactive interface for flexibility and easy application. The method is applied to help design a fixed shading system for hot climate regions in Cairo, Egypt, which involves considering five objectives: useful day light illuminance (UDI), energy use intensity (EUI), solar gains (SG), daylight autonomy (DA), and continuous daylight autonomy (CDA). The proposed method can provide an efficient design that significantly improves daylight performance. Different dataset sizes are used for training the meta model to study their effect on the final selected design. A sensitivity analysis is done to explore the impact of changes in experts’ opinions on the decision-making process.

Daylighting Evaluation of Perforated Screen Façade with Light Shelf in the Tropics

The use of large glass facades in buildings without external shading devices leads to a high daylight level, uneven daylight distribution, and glare. A perforated screen facade (PSF) is one of the shading systems that can provide daylight and view and prevent direct solar radiation into a building. More research is needed about the daylight performance of PSF in integration with daylighting systems in the tropics. A combination of PSF and light shelf (LS), a daylighting system that can redirect daylight to the ceiling and enhance daylight distribution, is proposed to improve daylight levels and reduce glare. The research aims to evaluate the daylight performance of PSF and LS in the tropics. The research method is experimental with simulation utilizing IES-VE Radiance IES. Average Daylight Factor (DFavg), Useful Daylight Illuminance (UDI), and Daylight Glare Probability (DGP) of a room with a side window were compared with a room with PSF and LS. The results showed that implementing PSF and LS improved daylight performance by lowering the DFavg by 55%, increasing the UDI, and reducing the DGP.

Energy load analysis according to environmental control strategy of partially applied electrochromic smart window

ABSTRACT The percentage of energy consumed by buildings is very large in industry. Recently, the cases of applying smart technology to efficiently improve the energy waste of these buildings are increasing, and this study targets Electrochromic (EC) smart windows. Smart window means a window that can freely change Visible Light Transmittance (VLT) and Solar Heat Gain Coefficient (SHGC). Since windows are the largest medium that can cause energy loss in buildings, the application of smart windows enables efficient energy management. However, this technology currently has a high-cost problem, so a partial application to windows is proposed. This study aims to analyze the relationship between partially applied smart windows and energy loads. Smart windows require an environment control strategy because windows are primarily to provide a comfortable indoor environment. An environmental control strategy was established according to the application area of the smart window, and Useful Daylight Illuminance (UDI) was used. In addition, the energy load of the smart window in which the environmental control strategy was established was derived, and the relationship with the partially applied area was analyzed. This study provides information on how much the partial application of smart windows can save energy wastage in buildings.

Research on the Design of Recessed Balconies in University Dormitories in Cold Regions Based on Multi-Objective Optimization

Thermal comfort and daylighting are vital components of dormitory environments. However, enhancing indoor lighting conditions may lead to increased annual energy consumption and decreased thermal comfort. Therefore, it is crucial to identify methods to reduce buildings’ energy costs while maintaining occupants’ thermal comfort and daylighting. Taking the dormitory building of Songyuan No. 2 at Shandong Jianzhu University of Architecture, which is located in a cold region, as an example, a field measurement analysis was conducted on the recessed balconies within the dormitory. The measured data were analyzed and utilized to simulate the annual energy consumption, thermal comfort predicted mean vote (PMV), and useful daylight illuminance (UDI) values of the dormitory units using the Grasshopper platform with the Ladybug and Honeybee plugins. The different depths of the balconies and window-to-wall ratios have a significant impact on the indoor physical environment and energy consumption, leading to the design of independent variables and the construction of a simplified parametric model. The simulation results underwent multi-objective optimization using genetic algorithm theory through the Octopus platform, resulting in a Pareto optimal solution set. Comparisons between the final-generation data and simulations of the original Song II dormitory unit indicate potential energy savings of up to 2.5%, with a 25% improvement in indoor thermal comfort satisfaction. Although there was no significant improvement in the UDI value, all the solution sets meet the minimum requirement of 300 lux specified by relevant regulations, according to the simulated average illuminance levels on the indoor work plane. Finally, the 60 optimal solution sets were further screened, filtering out sets deviating excessively from certain objectives, to identify 6 optimal solutions that are more balanced and exhibit a higher overall optimization rate. These findings offer detailed data references to assist in the design of dormitory buildings in cold regions.

Thermal comfort, daylight, and energy performance of envelope-integrated algae-based bioshading and static shading systems through multi-objective optimization

Energy-efficient envelopes integrated with different shading devices, as noticeable passive design strategies, have been of great interest for research studies. However, there is a lack of attention on optimizing envelope-integrated novel algae-based bioshading systems (ABBS) in comparison with other shading devices to enhance buildings’ sustainability-oriented performances. Integrating microalgae culture system with building façade as a state-of-the-art bioshading system is among recent developments in high-performance architecture. Although, challenges/limitations concerning different performances of this technology have not been extensively addressed. The present study conducts a multi-objective optimization framework to investigate the Thermal Comfort Percentage (TCP), Useful Daylight Illuminance (UDI), and Energy Usage Intensity (EUI) in a school building to evaluate the relationship between the performance objectives and design variables (shading characteristics, window-to-wall ratio (WWR)) through comparing different static shading systems and ABBS in the hot (BSh) and cold semi-arid (BSk) climates. The Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method was also applied to determine the best design options within Pareto frontiers. Results demonstrated that horizontal louver by 128.52 % TCP, 15.10 % UDI improvement in south-oriented façade in BSk, and overhang with fin (OF) by 18.99 % EUI reduction in southern facade in BSh climates contribute the most to enhance the objective metrics. Also, ABBS was not a stand-first system to enhance all the objective metrics compared to the other shading systems in none of the examined climates. Sensitivity analysis indicated that WWR has the most significant positive impact on EUI compared to the other studied metrics in almost all design options.

Daylight Availability of Living Rooms in Dense Residential Areas under Current Planning Regulations: A Cross-Region Case Study in China

After the pandemic, as it becomes more feasible to study and work from home, the quality of residential daylighting has attracted increasing attention. With the rapid growth of high-density residential areas, China is confronted with the incoordination between site planning and interior daylight availability across a wide region. Therefore, this paper investigates the applicability of planning regulations for daylight availability in dense residential areas under different climates across China, with the aim of providing data to optimize design strategies. ClimateStudio and ALFA were used to calculate the daylight factor (DF), daylight illuminance, spatial daylight autonomy (sDA), useful daylight illuminance (UDI), and melanopic equivalent daylight illuminance (m-EDI) of living rooms in four practical mixed housing estates in different Chinese daylight climate zones. The results showed that most of the studied units failed to meet current standards of DF and sDA300,50% for residence. However, more than half of these units still had high potential for UDI and met the recommendation of m-EDI by daylight only. The results verified the importance of integrative consideration of the local daylight climate and interior unit design for residential area layout planning. Finally, this paper suggests two topics for further exploration to bridge the gap between area planning and interior daylight availability in dense residential areas.

An integrated climate-based daylight performance evaluation framework for indoor arenas' roof system

Daylight environment plays a crucial role in indoor arenas' comfort and energy performance, characterized by their large spans and large spaces. Design parameters of roof systems in these arenas are essential for enhancing the daylight within competition halls. However, due to the complexity of spatial archetypes in these halls and the unique characteristics of freeform surfaces, more research is needed on the interplay between roof system design parameters and daylight performance. Rapid evaluation of daylight performance in competition halls during the design phase remains a challenge. This study proposes a climate-based evaluation framework for assessing daylight performance in indoor arenas and integrates an efficient practical and research workflow using Rhino + Grasshopper in conjunction with Python.Further, based on this framework and workflow, controlled variable simulation experiments were conducted to explore the relationships between external design conditions, such as climate (represented by three typical climatic zones) and seating capacity, and roof system design parameters, including roof form, redundant height, orientation, skylight form, distribution, and skylight-to-floor ratio (SFR), with time-series, climate-based daylight performance indicators. To integrate the critical factors affecting indoor lighting environments in arenas - illuminance potential, glare evaluation, and uniformity assessment - this study selected Continuous Daylight Autonomy (cDA), Useful Daylight Illuminance (UDI), and Glare Autonomy (GA) as performance indicators, supplemented by two time-series climate indicators specifically for evaluating illuminance uniformity in indoor arenas: “Uniformity Autonomy (UA) “and “Uniformity Variance Autonomy (UVA) ". Statistical analysis of five performance indicators across 860 experimental models in seven groups shows that different design conditions and parameters affect the optimal range of SFR. The significance of the impact of various design parameters varies across different performance indicators. There is a strong correlation between cDA, UDI, and GA, while UA and UVA effectively supplement the evaluation of the first three indicators.

Parametric design and multi-objective optimization of daylight performance in gallery skylight systems: A case study on the high museum expansion

In the realm of museum design, the meticulous planning of natural lighting plays a vital role in enhancing energy efficiency, improving the indoor atmosphere, and preserving and showcasing artifacts. A significant challenge is to ensure visitors' visual comfort while minimizing excessive natural light to prevent damage to exhibits. This study takes Renzo Piano's High Museum Expansion as a case study and employs the medium sensitivity exhibit standards from IESNA as the evaluation criteria. During the preliminary design phase, computer modeling was utilized, daylighting simulations were carried out using the Ladybug tool, and the Octopus genetic algorithm plugin was applied to investigate, optimize, and evaluate the performance of the point skylight system in museum interiors. The findings indicate that optimized point skylight systems not only block direct sunlight, reducing indoor glare, but also ensure that the Annual Cumulative Illuminance (ACI) on interior surfaces stays below 480,000 lx, while the annual effective Useful Daylight Illuminance (UDI) is increased to 75 %. In terms of design parameters, a skylight height of 0.6 to 0.7 m, combined with a shading panel to horizontal angle of 65 to 70 degrees, is found to be effective in enhancing indoor lighting conditions.

Development of novel variable building skin with solar concentrating technology for obtaining energy benefits and optimizing indoor daylighting

Variable building skin, as an interface for human-environment interaction and communication, can adjust the state of the building skin according to the user's needs to optimize the indoor environment. However, many current variable building skin prototypes predominantly draw inspiration from the natural environment (bionics) or material properties, with limited consideration given to integrating solar energy resources, resulting in variable building skins lacking energy production performance. Simultaneously, this development mode also results in most current variable skins controlling the indoor light environment through reflection or shading, failing to maximize solar resource use, and even reducing indoor daylighting comfort. Therefore, it is necessary to explore the additional benefits of variable skins and develop novel energy production skins, which are driven by the goals of decarbonization and comfortable indoor daylighting environments. This study develops a novel variable building skin utilizing solar concentrating technology, with the aim of generating additional energy benefits and optimizing indoor daylighting. Additionally, we perform comprehensive simulations and comparative experiments on the newly developed energy production variable building skin to assess their performance and viability regarding energy production (additional benefits) and optimization of indoor daylighting (fundamental role). The simulation results show that the developed energy production building skin can optimize indoor daylighting and generate energy benefits. Compared to common skin and no skin, the energy production skin can generate a maximum of 5.73 kWh and a minimum of 0.84 kWh in a single day. Additionally, compared to no skin, it can increase the useful daylight illuminance (UDI) by a maximum of 9.36% and reduce the daylight glare probability (DGP) at the second viewpoint by a maximum of 16.71%. The energy production variable building skin maximizes using the sun's resources while balancing aesthetics and application. It can provide design inspirations and methods for transitioning variable building skins toward energy production skins.

Multi-objective optimization of daylight illuminance indicators and energy usage intensity for office space in Tehran by genetic algorithm

One of the important categories in office spaces is the control of daylight and energy consumption. By controlling natural light, it is possible to provide uniform light in the entire space, sufficient daylight, and visual comfort for office workers. In many cases, this important issue can be resolved by choosing the right shading. In this study, the aim is to investigate the significance of some important parameters such as DoS (Depth of Shading), FO (Facade Offset), FSoS (Flip Start of Shading), LoS (Location of Shading), WWR (Window to Wall Ratio), CoS (Count of Shading), AoS (Angle of Shading), and HoW (Height of Window) in the optimal design of shading for an office environment in Tehran. For this purpose, eight variables have been designed and the aim is to improve the indicators of Energy Usage Intensity (EUI), Spatial Daylight Autonomy(sDA), Daylight Glare Probability (DGP), and Tc (Thermal comfort) in the office space. For optimization in the grasshopper environment, Wallacei’s algorithm was used. Then, the algorithm provides a set of optimal points. Then a point was selected as optimal by the WSM (Weighted Sum Method) method. According to the input variables that are DoS, FO, FSoS, LoS, WWR, CoS, AoS, and HoW its optimal point values are 0.4, 0, Up, Horizontal, 80, 5, 30, 0.5, respectively. The results show that the values of sDA, DGP, EUI, and Tc were improved by 43.6%, 52.77%, 13.9, and 3.696%, respectively, before and after shading optimization. Also, the annual glare and the hottest and coldest day of the year were checked where there were around 500(cd/m2) and 200(cd/m2) reduction of glare value in winter and summer seasons, respectively. Finally, the value of Useful Daylight Illuminance (UDI)before and after the installation of the optimal shading was 25.8 and 68.4, respectively.

Environmental performance driven optimization of urban modular housing layout in Singapore

ABSTRACT With the growing size of cities and the need to renew residential areas, architects are calling for more efficient use of already settled areas. This paper presents a performance-driven architectural design (PDAD) workflow for shape generation and genetic optimization based on environmental data, using public housing in the Singapore region as a case study. It integrates three-dimensional cellular automata, parametric performance simulation, genetic optimization algorithms, and hierarchical clustering algorithms. The results show that the average value of Useful Daylight Illuminance (UDI) is 85.19%, the average value of Energy Use Intensity (EUI) is 159.41 kWh/m2, and the average value of Predicted Mean Vote (PMV) is 0.64 for the optimal set of solutions produced after genetic optimization. The optimal solution set was further classified into 4 categories by a hierarchical clustering algorithm and was visualized for further evaluation and selection by the architect. The study helps architects to integrate data analysis results with human decision-making as a design research method in the early stages of design and leads to further discussion on bottom-up design approaches in the urban renewal process.

Daylight Comfort Performance of a Vertical Fin Shading System: Annual Simulation and Experimental Testing of a Prototype

This study aims to develop and evaluate a vertically rotated fin shading system for an energy-efficient, user-friendly office space. The system was designed to protect a 4 × 8 m office room with a south-facing facade from excessive solar radiation and glare. The shading system was modelled and simulated using Rhino/Ladybug 1.6.0 software with Radiance engine, based on real-weather data (*.epw file) for Wrocław, Poland at 51° lat. The simulation calculated the useful daylight illuminance (UDI) for 300–3000 lux and the daylight glare probability (DGP) for ten static and four kinetic variants of the system. The optimal angle of the fin rotation for the static variant was found to be α = 40°. The kinetic variants were activated when the work plane illuminance exceeded 3000 lux, as detected by an internal sensor “A”. The simulation results show that the kinetic system improved the daylight uniformity in the office room, achieving UDI300–3000 values above 80% for more than 40% of the room area. A prototype of the system in a 1:20 scale was built and tested on a testbed at Wrocław University of Science and Technology, using TESTO THL 160 data loggers. The measurements were conducted for a week in early November 2023, and three clear days were selected for analysis. The measurement results indicate that the low solar altitude on clear days causes high illuminance peaks (15–18 Klux) and significant contrast in the room, leading to unsatisfactory DGP values consistent with the simulation outcomes. Therefore, the study concludes that the proposed system may need an additional shading device to prevent glare during periods of low solar altitudes.

Multi-objective optimization of a residential zone by proposing appropriate comfort factors using none dominated sorting genetic algorithm

To identify optimal solutions within a plethora of alternatives with respect to architectural design, multi-objective optimization has been widely acknowledged as a dependable approach. Nevertheless, such optimizations have frequently been conducted as single-objective analyses or have failed to consider both the quantity and uniformity of illumination concurrently with energy consumption as primary objectives. This study posits a proposal consisting of two metrics, one pertaining to the quantity of light and the other to its uniformity. These metrics are derived from the useful daylight illuminance (UDI) and are deemed appropriate for employment in an optimization process. In conjunction with energy consumption, these metrics serve as objectives in a multi-objective optimization that is carried out with a NSGA-II algorithm specifically developed and calibrated for this particular problem. The result of the simulation yields a solution set in three dimensions. The interdependence between the variants and their relationship with each variable were thoroughly examined to facilitate the selection of the optimal solution from the pareto front.

Optimal Design of Tilted Building Envelope Considering Air Conditioning Energy Demand, Daylight Utilization and Glare Protection—Case Study

An important energy-saving method to optimize building envelope design is the integration of local climate characteristics. This study attempts to find sloped facade configurations to balance air conditioning energy demand and daylight utilization for four directions in an area with a hot climate. Tilt angle dependence of the air conditioning energy demand, useful daylight illuminance (UDI) and daylight glare index (DGI) are selected to investigate the acceptance thresholds of the tilt angle. The final facade’s configuration is achieved by employing the graphical optimization method. An acceptable solution that balances better daylight performance and less energy consumption by air conditioning is developed. Due to the considered city being located in a low-latitude area with great daylight availability as well as a fully dimmable light control strategy, unbearable glare reduction can be achieved by benefiting from the sloped facades, without necessarily sacrificing much usable daylight. Meanwhile, there is no obvious increase in the demand for lighting energy consumption, and a good outward view is preserved. The sloped rather than vertical facade provides natural solar shading to the east-, south- and west-oriented windows while allowing low-angle winter solar heat to warm the building space. Tilt angles between 35°and 40° are preferred for the east facade, and smaller tilt angles of between 30°and 35° are recommended for the south facade. Larger tilt angles of between 40°and 45° are preferred for the west facade. However, the north-facing facade’s outward tilt would cause an undesirable increase in air conditioning energy demand. The annual air conditioning energy demand of the east-, south- and west-facing space is found to separately decrease by 7.1%, 7.3% and 9.9%, respectively, benefiting from the sloped facades.

Multi-objective optimization for visual, thermal, and cooling energy performance of building envelope design in the composite climate of Jaipur (India)

Climate-responsive passive envelope features such as windows, louvers, and shading have significant impact on a building's energy and economic performance. This paper presents a multi-objective optimization (MOO) approach to enhance energy, visual and thermal performances of a building by considering a wide range of numerous design possibilities. A residential apartment building located in a semi-arid composite climate (Köppen climate classification: Bsh) of Jaipur, India is considered for the analysis. The multi-objective optimization approach involves three steps: firstly, developing a base simulation model using Rhinoceros software, and then performing multi-objective optimization by Octopus plugin, and finally applying multi-criteria decision-making to select the optimal values of thermal conductivity, window-to-wall ratio of south and west façades, solar heat gain coefficient, visual light transmittance, window sill height, louvers depth, distance between slits, slits angle, external shade depth, and shade (slits) count. The optimized results reported a six-fold Useful Daylight Illuminance (UDI) improvement, 72% cooling energy demand reduction, and 34% thermal comfort enhancement from the worst-case scenario. The presented approach can aid designers in selecting optimal envelope features during building design, refurbishment, and renovation or for green field development.

Optimizing daylighting in lecture halls within hot-arid climates through modification of glazing systems with light-shelves: A parametric design approach

This study focused on enhancing the balance between sufficient daylighting and heat mitigation in lecture halls, set within the challenging hot-arid climate of Saudi Arabia, through the optimization of window designs and the incorporation of light-shelves. To achieve this, a combination of in-detail Parametric Sensitivity Analyses (PSA) was performed in the first stage to find the best configuration of windows, while a multi-objective optimization (MOO) strategy was applied in the second stage considering multiple objectives in each stage. Before running both analyses, the simulation model was validated by field measurement. The optimization results show that the optimal window configurations obtained through PSA and MOO offer significant potential for improving daylighting performance, energy efficiency and comfort. In terms of the overall best solutions from PSA and MOO, the PSA demonstrated substantial improvements, with Useful Daylight Illuminance (UDI) rising by 46.31% to 55.36%, glare decreasing by 52.17% to 82.61% and Energy Use Intensity (EUI) improving by 0.89% to 2.63%. Additionally, MOO solutions yielded even more significant enhancements, increasing UDI by 43.58% to 58.37%, reducing glare by 95% to 100% and enhancing EUI by 1.81% to 3.88%. This has resulted in a more evenly distributed and efficient daylighting throughout the space.