Light Shelf Research Articles

Artificial Neural Network to Predict Curvature Light Shelf Design Related Daylighting Optimization on Office Spaces

Energy Optimization in building design field now has been revolutionized due to AI and machine learning applications. Leveraging daylight to reduce artificial lighting consumption holds promise for significant energy savings, yet the nonlinear nature of daylight patterns poses challenges in prediction and optimization. This study proposes a novel approach to automated light shelf design using machine learning algorithms, specifically artificial neural networks (ANNs) such as recurrent neural networks (RNN) by long short term memory (LSTM), to accelerate daylighting simulation and optimization processes. The methodology employed two distinct approaches: Firstly, we employed the theoretical-analytical approach to explore methods for utilizing machine learning in natural lighting and light shelf parameters. Second, the practical and applied method involved creating a predictive model for designing the light shelf using appropriate AI and ML techniques. This model is based on an office geometry model at the El Arish weather file in Egypt, four-dimensional training room models with three internal zones-oriented south. Rhinoceros and Grasshopper, two parametric simulation tools, are used to normalize and optimize light shelf parameters like geometry cross-section, curvature surface, width, height position, depth, tilt angle, and reflectance materials. Then, the Galapagos plug-in and Colibri2 are used for dataset creation and optimization. The results demonstrate that automated light shelf operation has a significant impact on internal daylighting quality. RNNs enable rapid prediction of optimization models, reducing time consumption in the early design phase. ML facilitates decision-making by generating evaluative criteria from user-selected design options. RNNs were classified as good and bad and used LSTM to enhance prediction accuracy for efficient illuminance values metric in zones 1 and 2. Challenges include increasing the simulation procedure's efficiency. The results of model accuracy reached 99%. Hence, future research should prioritize resolving the previously identified concerns. In conclusion, this study underscores the importance of ML-driven approaches in early design phases to optimize building energy consumption and pave the way for sustainable architectural practices.

Analytical Study on Reducing the Heating Effects of Daylight and Improving Natural Lighting Performance at Erzincan Train Station in the Context of Climate Change

Climate change is an environmental issue that is rapidly escalating due to the effects of global warming. The increase in carbon emissions, along with various human activities such as industrial processes, land use changes, and the reckless consumption of natural resources, are among the primary causes of global warming. Various architectural interventions are being implemented in historical buildings to mitigate the impact of global warming and its consequence, climate change. The study aims to protect the historical building from the harmful effects of climate change by reducing the heating effects of direct sunlight during the summer and enhancing the efficiency of natural lighting throughout the day. In this context, the Erzincan Train Station is located in Erzincan in Eastern Anatolia. Erzincan is one of the most affected by the climate change crisis has been selected for the study. The plans of the Erzincan Train Station were digitized using AutoCAD software and subsequently modeled in three dimensions using Revit software. Daylight analysis was conducted on the created model using the Insight plugin in Revit software. The analysis determined that recommendations should be made for the building's south facade. Based on the climate data of Erzincan province and the conducted analyses, the light shelf system was designed and implemented due to its applicability, shading, and lighting advantages among daylighting systems. The effects of the proposed system were examined using spatial daylight autonomy (sDA) and annual sunlight exposure (ASE) daylight metrics according to LEED v4 EQc7 standards. The study found that the light shelf system resulted in a 5% reduction in ASE values building-wide and a 6% reduction in the average values of specific areas while increasing sDA values. In this context, it has been observed that areas experiencing a decrease in direct sunlight exposure (ASE values) also show an increase in sufficient daylight exposure (sDA values), which could contribute to improving the building's energy performance.

Optimising Daylighting Performance Through Side light with Passive Devise Design in Buildings

Passive lighting design plays an important role in providing natural lighting to save electricity consumption in buildings. This study aims to investigate the performance of natural lighting and the potential of alternative designs through sidelights with 3 shading device models and light shelves with different sizes in north, west, east, and south orientations. This research method is quantitative, which describes the measurement results in existing conditions and radiance illuminance software simulations. The results showed that at the beginning of field measurements, it was known that there were rooms with lighting intensity too high, too low, and uneven distribution. The simulation results use Radiance Illuminance software to determine the illuminance value of light distribution into space in the morning, afternoon, and evening. Improvised designs are applied with shading device models on the building envelope, namely horizontal, vertical, and egg-crate models in spaces oriented toward the East and West. This study also applied an interior-exterior light self-model measuring 50 cm, 100 cm, and 150 cm of space with the orientation of window openings towards the North and South. The simulation results in this study, show that without a shading device and using a horizontal model, there will be a decrease of 0.4% at a distance of 2 m from window openings oriented to the East, while to the West will be able to increase the illuminance value by 11.5% at a distance of 10.5 m from the window opening. Buildings without using light self and using interior-exterior light shelves measuring 50 cm can increase the illuminance value by 0.5% at a distance of 10.5 m from window openings in a space oriented towards the North, while the orientation towards the south, which can be increased the illuminance value by 0.4% at a distance of 6 m from the window opening. Based on this research analysis, it concluded that the best-improvised design in rooms oriented toward North and South is a 50 cm interior-exterior light shelf and horizontal shading device models are the best for spaces oriented to the East and West. This study, also concluded that the orientation of the building, the passive device model, and the distance of the measuring point in the building envelope, affect the intensity and distribution of daylight entering the building.

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.

A Review of Factors Affecting the Lighting Performance of Light Shelves and Controlling Solar Heat Gain

In areas with a deep floor plan, the distribution of natural light is not uniform. Consequently, relying solely on daylight may not suffice to meet the space’s lighting requirements, necessitating the use of artificial lighting in darker areas. Therefore, a lighting system is needed that not only controls the glare near the windows but also increases the light at the end of the room and provides uniform daylight. One of the widely used systems is the “light shelf”, which has three main functions: shading, increasing the depth of light penetration, and reducing glare. Review articles about light shelves were published in 2015 and 2017, while more than 80% of the studies have been carried out since 2016, and light shelves with more diverse forms and dynamic elements and many consolidations have been proposed. Therefore, there is a need for a more comprehensive review. The main question of this research is how different parameters (including climate, material, ceiling, and integrated systems) can help to increase the efficiency of light shelves. By using a systematic review, studies in the past three decades were classified in order to determine the effect of these parameters on improving lighting performance and controlling solar heat gain.

Analysis of the Influence of Peripheral Light Shelves on Building Lighting

Due to the design problems in modern architecture, it often appears that although the sunlight of the building is sufficient, the lighting quality of the building interior is not good. Due to the reasons of lighting, shading and interior layout, the phenomenon of glare and uneven distribution of light often occurs in buildings. Therefore, it is recommended to use light shelves to reduce problems such as glare and improve the indoor light environment comfort. The effects of six different widths and five different heights of peripheral light shelves on DF, UDI, GA and Uniformity Ratio of Daylighting are analyzed. The results show that the width and height of light shelves have no improvement effect on DF. The height of the light shelves has an improvement effect on indoor UDI, but the width does not; The width and height of light shelves can improve GA and Uniformity Ratio of Daylighting.

2022 개정 교육과정 중학교 기술․가정과 ‘구조물과 건설’ 핵심개념에서 빛 환경 설계를 활용한 지속가능한 건설기술 체험활동 과제 개발

The purpose of this study is to help middle school students understand the concept and practical use of sustainable construction technology by developing hands-on activities using light environment design for‘Structures and Construction’core concept in the 2022 revised curriculum for middle school technology and home economics. In this study, research was conducted in five stages: analysis, design, development, implementation, and evaluation. The main research results of this study are as follows. First, by analyzing the 2022 revised curriculum, previous research, and curriculum, a class curriculum plan for the 8th session, teaching materials for teachers, learning materials for students, and grading rubrics were developed. Second, the hands-on activity applied a light environment design that minimizes the use of artificial lighting and efficiently utilizes natural light, and designed, produced, and evaluated architectural models including light shelves and skylights. Third, as a result of an expert feasibility review, all items including level, time, goal, interest, and problem situation were valid. Fourth, as a result of applying the hands-on activities in class, students were interested in the topic and there was a positive response in that light environment design can be a practical method for sustainable development.

A Multi-objective Optimization of Window and Light Shelf Design in Office Buildings to Improve Occupants’ Thermal and Visual Comfort

In office buildings, an efficient design of windows and using light shelves as a passive design strategy significantly influence the thermal and visual comfort of occupants while enhancing the productivity and health of users. This study proposes a multi-objective optimization for the optimal design of windows and light shelves in office buildings to improve occupants' comfort. Initially, a parametric model was developed using Grasshopper parametric software. Afterward, the Honeybee energy and daylight plugin was employed for simulating thermal and visual conditions, and finally, multi-objective optimization was conducted with the Octopus plugin. This plugin can determine the best solution as a compromise decision for maximizing occupants' comfort. In this paper, an office building in Tehran has been chosen as a case study. The decision variables are window-to-wall ratio (WWR), shading control strategy, viewpoint, the transmission of glass, light shelf length, and light shelf height. The objective functions of the study are the annual average Predicted Percentage of Dissatisfied (PPD) and the annual average Discomfort Glare Probability (DGP). According to the results, the proposed optimization model leads to an 18.5–70.1% and 9.3–57.1% reduction in DGP and PPD indexes, respectively. The study findings provide practical and useful instruction for architects to select optimal specifications of windows and light shelves to develop occupants' thermal and visual comfort in office buildings.

DETERMINATION OF THE PERFORMANCE OF LIGHT SHELVES FOR MORE EFFECTIVE BENEFIT FROM DAYLIGHT IN BUILDINGS

Studies on the efficient use of daylight in sustainable architectural design and energy conservation are increasing. Indoor lighting methods include daylighting, artificial, and integrated lighting. Basic priorities in lighting are such as “effective use of daylight”, “uniform illumination in space”, “glare control”, “visual connection with the external environment” and “daylight harvesting.” Advanced contemporary systems include light shelves and light tubes. Light shelves consist of horizontal or slightly angled elements that can be applied to the inner and outer surfaces of the window openings, usually at eye level, to block the daylight or to reflect it to the ceiling, integrated with the facade, or added later. In this research, light shelves, which is one of the advanced daylighting methods, are emphasized. Daylight analysis method was carried out with the help of a physical model and computer simulation techniques using DiaLux software. To effectively utilize the daylight factor in the internal volume through light shelf, certain parameters such as the height and angle of the light shelf, date and time, and direction of the room's opening, play a crucial role. In daylight analyzes, these parameters were subjected to experimental testing both in physical models and through computer simulations. As a result of the comparison of the obtained data, alternatives that will provide the opportunity to benefit from daylight in the most effective way have been identified. The results obtained have unique value and widespread impact in terms of sustainable architecture and energy saving. The study's originality lies in its specific measurements of the latitude in which it is located, as it is the first time the study is conducted under Eskisehir's conditions. In addition, the examination of the advantages and disadvantages of the light shelf in specific combinations is another original side of the project.

Performance evaluation of a light shelf with a folding reflector (LSFR) to improve daylighting performance

Recently, light shelves have been in the spotlight as a solution to the increasing lighting energy consumption in buildings, and various studies have confirmed their effectiveness. However, there is a lack of research on light shelves that operate according to the solar azimuth. To address this, this study proposes a light shelf with a folding reflector (LSFR) that operates in alignment according to the solar azimuth and validates its effectiveness through a testbed. The key findings are as follows. (1) The proposed LSFR is divided into three modules and becomes an inclined plane by moving the modules at both ends. Moreover, combined with light shelf angle control, the LSFR enables control over the direction of daylight inflow through light shelf reflection. (2) This study determines the optimal angle for a flat light shelf with angle control, highlighting the need to adjust the angle based on the external environment to enhance daylighting efficiency. (3) Upon implementing the optimal specifications, the LSFR reduces lighting energy consumption by an average of 49.5% and enhances the indoor uniformity ratio by 20.1% compared with Case 2 (flat light shelf with angle control). Particularly, the LSFR achieved a satisfactory 300 lx illumination without using additional lighting under the environmental conditions set in this study, which demonstrates the effectiveness of Case 3.

Multi-objective optimization of energy and daylight performance for school envelopes in desert, semi-arid, and mediterranean climates of Iran

Considering global warming as a critical challenge to human life, performance optimization of the building envelope can play a noticeable role to reduce a building's environmental footprint. Meanwhile, shading systems are considered as sustainable passive solutions to contribute to building energy efficiency, and daylight control in early-stage design. Nonetheless, a paucity of research has examined the various shading strategies in diverse climates, particularly arid desert and steppe regions, in conjunction with educational buildings. The present study aims to evaluate the role of fixed exterior shading systems (FESSs), and window-to-wall ratio (WWR) on building’ thermal and daylight performance in Iran with desert, semi-arid, and Mediterranean climates. Pareto Frontier and weighted-sum method for multi-objective optimization, and sensitivity analysis were used to study the optimum solutions, and the relationship between the design variables and the performance metrics. Three objective metrics including Spatial Daylight Autonomy (sDA), Annual Sunlight Exposure (ASE), and Energy Use Intensity (EUI), were defined as performance metrics. Shadings include vertical louver, horizontal louver, light shelf, overhang, and egg-crate. The results showed that EUI was reduced via FESS-integrated façade by 25.22%, 20.84%, 19.14%, 14.06%, and 13.47%, in Yazd, Bushehr, Kerman, Rasht, and Mashhad as selected studied cities, respectively. Based on ASE, the horizontal louver surpasses the other systems by 100% ASE value reduction in all climate zones except for Rasht. sDA level is reduced in all climate zones considering five studied FESSs excluding horizontal louver in Yazd and Rasht and overhang in Mashhad by 100% sDA level. Building energy performance simulation is validated by ASHRAE140-2020.

Experimental evaluation of the thermal, lighting, and energy performances of a mechanically ventilated double-skin façade with Venetian blinds and a light shelf

Double-skin façades (DSFs) are increasingly being utilized as high-performance building envelope structures. Nevertheless, their shortcomings regarding overheating during the summer are apparent. To improve the energy efficiency and indoor environment, a mechanically ventilated DSF with Venetian blinds (VBs) and a light shelf system (multisectional DSF system) was proposed. A multisectional DSF system and a single-glazed window with VBs were compared. The benefits of the multisectional DSF system over a single-glazed window with VBs in Xiamen were investigated in non-air-conditioned environments in summer and winter and air-conditioned environments in summer. The results indicated that using a multisectional DSF system effectively reduced indoor temperatures by up to 6.9 °C under non-air-conditioned environment in summer, improving Useful Daylight Illuminance (UDI300–1000 lx) by 31 % and achieving an energy saving rate of 49.76 % compared to that using VBs. In an air-conditioned environment in summer, an energy-saving rate of 42.96 % was achieved. In a non-air-conditioned environment in winter, using a multisectional DSF system reduced indoor temperatures by up to 7.4 °C in the middle of the day and 1 °C at night compared with that using VBs, improving the UDI300–1000 lx by 4 % and achieving an energy saving rate of 84.16 %.

Daylighting Glare and Design for Visual Comfort

Daylighting and glare simulation provide architecture students, professionals, and researchers with the knowledge and skillsets to design environments for visual comfort. Conducting simulations is essential for better human health and reducing building energy consumption. This paper evaluates the effectiveness of a mixed-methods approach to designing a glare-free environment in a hot-arid region. It examines daylighting and glare distributions in different scenarios with combinations of architectural daylighting devices, such as shading devices, light shelves, etc., using Rhino 7, DIVA, and ClimateStudio. The study concludes by recommending a practical simulation approach for evaluating glare. In this case study, using a customized shading device/light shelf combined with efficient skylights reduces glare to imperceptible and increases the daylit area by 20%.

The Effect of Light Shelf and Translucent Ceiling on Daylighting Performance in Office Building in Thailand

Daylight control strategies were a challenge for a high-rise building in terms of savingenergy consumption. Light shelf was one of the daylight control systems which was usuallyhorizontal or inclined surfaces, placed on the inner and/or the outer side of windows toreflect sunlight to ceiling and distribute the light deeper into the room. This study aimedto investigate the performance of daylight control strategies in office rooms using alight-self with translucent ceiling. The light shelf, which is typically horizontal or inclined,was placed on the inner or outer side of windows to reflect sunlight and distribute itdeeper into the room. The study investigated the effect of type of daylight techniqueswhich are a combination of different light shelves and translucent ceiling on daylightingperformance. The illuminance level in an office room was calculated using DIALux 4.13 andwas performed for working hours in Bangkok, Thailand. The simulation was performedunder clear sky conditions and using real climatic data from four orientations. Fivetypes of daylight techniques, including the existing room, were investigated in terms ofilluminance level and uniformity of daylight in the office room. The CIBSE (2015) and IESNA(2011) standards indicate that offices room should have uniformity of at least 0.8 andan illuminance level of 500 lux. Thus, the objective of this research was to determine thebest combination of light shelves and translucent ceilings for achieving illuminance anduniformity standards. The results showed that the external light shelf with a translucentceiling and static louver at 90o (option 4) was the best solution for office rooms, providingaverage illuminance level 776 lux (above the standard) and uniformity 0.4 (nearly thestandard). This conclusion suggests that a light-shelf with a translucent ceiling guidesdaylight deep into the room but less uniformity.

Evaluation of External Light Shelf Performance in Relation to the Ceiling Types Used in Indoor Spaces

A light shelf is a type of natural daylight system that brings natural light from the outside into an indoor space through a reflector and a ceiling surface. The introduction of light shelves has led to studies evaluating their efficiency. However, past studies on light shelves did not consider the diversity of ceiling types when evaluating their performance. Therefore, this study derives fundamental data involving external light shelf designs by evaluating light shelf performance based on the ceiling type present using a light environment simulation method. This study analyzed the indoor illuminance distribution with Radiance to evaluate the performance according to light shelves and indoor space types. The results derived from this study are as follows: (1) In the case of a flat ceiling, the performance of an external light shelf can be improved by increasing its angle and width. However, adjusting the external light shelf angle to 30° during the middle of the season and 20° in winter is ineffective because natural light is not reflected by the ceiling surface. (2) The performance of a light shelf can be improved by increasing the slope and curvature of the ceiling types specified in this study. However, setting the light shelf angle to 30° during the middle season and to 30° and 20° in winter, when external natural light entering the indoor space is not reflected by the ceiling surface, is ineffective due to the low levels of daylight performance, regardless of the type of space. (3) To increase uniformity levels in gable ceilings and curved ceilings, it is advantageous to increase the number of reflections and diffusion areas on the ceiling’s surface due to the uniqueness of these ceiling shapes. Furthermore, the optimal external light shelf angle for these ceiling types differs from that of other types. (4) Regarding the appropriate external light shelf size according to a particular ceiling type, installing an angle-controllable external light shelf with a width of 1.2 m can improve daylight performance.

Thermal performance of indoor solar shading devices using a thermal nodal model and a lighting simulation model

Various facade designs, such as light shelves, have been proposed to achieve zero emission buildings. However, general thermal load simulation models are unable to properly evaluate the thermal effects of spaces near windows, such as light shelves and counters, which are installed on the interior side of windows for increased daylight utilization. In this study, we propose a method to evaluate the thermal performance of indoor light shelves. The model proposed herein consists of three components: A thermal nodal model of the window area, a lighting simulation model, and a thermal simulation model. The thermal nodal model places a node at each device (glass, ceiling, light shelf, and floor) in the light shelf space. The heat balance equation for each node is then solved. In doing so, the total transmittance of the entire indoor-installed device space, which considers inter-reflections and the solar radiation absorptance of each device, is calculated using the Radiance software. Additionally, the solar heat gain obtained using the thermal nodal model is substituted internally into NewHASP, and the thermal load calculation is performed. Finally, a simulation is performed using an office model, and the indoor-installed light shelf exhibited a 14 % reduction in annual thermal load.

Implementation of light shelves and WWR to improve daylight performance in university classroom

Daylight plays important role in achieving good Indoor Environment Quality (IEQ) because it contributes to human health and optimal working performance. The Engineering Center (EC) building, which is part of Universitas Indonesia in Depok, Indonesia has great daylight potential with an existing design Window-to-Wall Ratio (WWR) of 100%. However, this potential has yet to be maximized due to use of artificial lighting during the day. Moreover, the uneven distribution of sunlight entering the room creates some issues (i.e., glares, dazzled, heat and low uniformity level). This research tries to improve this condition by intervening in Window to Wall Ratio (WWR) and adding Light Shelves (LS) in class 101 (facing south) and 102 (facing north). 56 variations of WWR and LS were simulated using Rhinoceros (RH) and Grasshopper (GH) software with plug-ins (Ladybug and Honeybee). The simulation results show three design configurations WWR 60% - LS straight; WWR 78% - LS straight; and WWR 60% - LS curve in room number 102 facing north produce illuminance close to the maximum and minimum threshold for good lighting in the classroom (350 - 500 lx). This study will provide reference strategies for improving daylight performance in university classrooms with tropical climates.

The impact of aspect ratio of buildings implementing Horizontal light pipe and shading systems on daylight performance

ABSTRACT Deep-plan buildings limit daylight use in spaces far from the building perimeter, leading to uneven daylight distribution. Integrating a Horizontal Light Pipe (HLP) as an optical daylighting system, reflective light shelves, and blinds as shading systems can reduce excessive daylight levels at the perimeter area of a building and improve daylight uniformity. Earlier investigations of HLP daylight performance concentrated on fixed building geometries, but few studies focused on the building aspect ratio, one of the design variables of building geometry that greatly influences daylight performance. This study aims to investigate the impact of the aspect ratio of buildings implementing HLP and shading systems on daylight performance. The research method was experimental, using IES-VE simulation as a tool. The daylight factor (DF), uniformity daylight factor (UDF), and useful daylight illuminance (UDI) of various aspect ratios and depths of office buildings implementing HLP and shading systems were analyzed. The results show that increasing the building aspect ratio from 1:1 to 2.1:1 sequentially increased the average DF and UDF values by 18.47% and 17.2%, respectively. Improving the building aspect ratio from 1:1 to 2.1:1 along the east-west axis improved the UDI by 3%, whereas the north-south axis decreased it by 10.2%.

Daylight Performance of Integrated Horizontal Light Pipe with Shading Devices (Validation) for High-Rise Building in Tropical Climate

Daylight is known to bring benefits to human in terms of productivity, psychology, and physiology. The emergence of deep plan layout in high-rise hinders the utilisation of the abundance daylight available in tropical climate. This brings challenges to ensure a uniform distribution in the interior room. This study focuses on the software validation of the integration of a horizontal light pipe (LP) and shading devices (SD) to illuminate the deep plan where the former provides daylight in the deepest portion of the room while the latter helps to shade the excessive daylight at the window opening. The shading devices that have been chosen are overhang, light shelf, and blinds. The computer simulation, Integrated Environment Solution: Virtual Environment (IESVE), is being validated with physical model experiment with a scale of 1:10. The experiment was conducted in an open carpark in Universiti Sains Malaysia, Penang, Malaysia from 9am to 3pm for two days. The validation was done using graph comparison, Pearson Correlation, relative root mean square error (RRMSE), and relative mean bias error (RMBE). The results shows that the daylight ratio (DR) from the software has positive relationship with the experiment data. Hence, the software can be used to further simulate various integration of LP and SD.

Case study for deriving appropriate light shelf specifications based on indoor space depth

Case study for deriving appropriate light shelf specifications based on indoor space depth