Basic Study on Performance Evaluation according to Separation Distance of Internal Double Light-Shelf Reflector

A light-shelf, one of natural lighting methods, has advantages in constructability and economic feasibility in comparison with other passive natural lighting system. A movable light-shelf enables a user in a room to adjust the angle according to his or her preference to control the amount of indoor light. In addition, a light-self serves as a shield to the intense light on window sides when the solar light is strong to relieve glare. The purpose of this study was to investigate the effect of angle adjustment of a mixed type light-shelf on indoor natural lighting and determine efficient light-shelf lighting performance values by using an actual size test-bed. This study was conducted in the following procedures: 1) Previous studies were investigated to analyze the definition of a light-shelf and identify experimental factors for a light-shelf; 2) On the basis of previous studies, the light-shelf experimental factors were set up with reference to the illumination values under clear sky at the meridian transit altitude in each season to perform an experiment; and 3) The performance of the light-shelf was evaluated to examine the effectiveness. The performance evaluation was performed for each season according to the solar altitude of the mixed light-shelf. The indoor distribution of illumination was analyzed on the basis of the day light introduction depending on the angle of the mixed type light-shelf to verify the correlation with variables and the efficacy.

Experimental evaluation of radiant heat transmitted by light shelves

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.

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.

Building-integrated photovoltaics (BIPV) show potential as a means of efficient solar energy harvesting. This paper introduces a multi-objective framework for finding the optimized design of parametrically modeled photovoltaics integrated light shelf systems to maximize their benefits to the indoor environment and users. Since the geometric design of traditional shading devices is restricted to rectangular-shaped panels, we aim to attain a clearer perception of the potential advantages of employing panels with novel design alternatives. First, we developed parametric models of internal and external light shelves; each consisted of either a surface with a curved section or a 4-point planar surface. Next, the assessment of daylight and energy operation along with occupants' thermal and visual comfort was carried out using the environmental plugins of Honeybee and Ladybug. Furthermore, to decrease the required lighting energy and upgrade users' visual satisfaction by providing favorable illuminance levels required for a specific task, we divided the classroom into alterable lighting zones. Lastly, the optimization process was performed via the Octopus plugin for Grasshopper, and optimal solutions were identified. Based on the numerical results of the yearly simulations, we gained noticeable energy-saving up to 29% while improving occupants' thermal and visual comfort.

This study aims to reduce the lighting energy consumption in educational buildings while avoiding an increase in cooling load. The Faculty of Engineering building in Universitas Indonesia, Depok, West Java, Indonesia is used as a case study. Daylight optimization can have an impact on lighting energy, which is the largest energy consumer in educational buildings. However, given Indonesia’s tropical climate, daylight leading to heat gain is a concern. Current passive design interventions for controlling daylight and heat gain include light shelves, clerestories, and glazing materials. Daylighting performance is simulated using DIALux software. Results of each intervention are analyzed quantitatively and qualitatively by theories and parameters, namely illuminance level, light uniformity, and overall thermal transfer value (OTTV). Light shelves result in increased uniformity and lower OTTV. Clerestories result in increased average illuminance but higher OTTV. Active intervention with a dimming and grouping system is applied after daylight increases. The combination of passive design interventions and active dimming of electric lights reduces lighting energy with the same OTTV as existing. This study recommends the use of passive and active daylighting strategies considering their effect on the cooling load of buildings.

The field of office daylighting is vital for both energy efficiency practice and occupants’ visual comfort. With the emergence of green building in Malaysia, building designers are exploring avenues for energy efficiency design; one common strategy is daylighting. The majority literature reviews on daylighting are skewed towards temperate or developed countries, where sky luminous condition is different from that of the Tropics. Conventional daylighting system designs redirect daylight from the envelope or atrium openings, such as light shelves. Presumed to be the pioneer daylight trough in the Tropics, this paper presents the simulated and in-situ lighting level measurements prior to occupancy. This case study presents an as-built daylight trough design which is able to daylight the office space as deep as 6 meters sufficiently. It achieves a lighting power density 1.90W/m2 and saves 39.2% of lighting energy over conventional office lighting energy. Discussed further is the practicality of working with such a system, including cost implication, return on investment and contractual challenges in reaching a consensus on the design. The results reinforce that the effectiveness of daylighting design is very dependable on the sun path and obstacles surrounding the office tower. The RADIANCE simulation correlates well to field measurement results. Further investigation into the light trough, its lighting energy savings, users’ interaction, visual comfort, and glare is still ongoing.

Natural light design for an ancient building: A case study

Light is an inevitable reality, and at the same time the only one capable of overcoming it. The difference between architecture as a whole and underground architecture, is similar to the difference between external light, which produces the masterly play of objects brought into the light, and internal light, which gives life to the spaces enclosed by the volume itself. A difference that translates into a light that wants to embrace everything and is therefore indistinguishable from the construction, and a light that is directed at specific points, illuminating the darkness in which the structure is immersed in a differentiated way. Hence, the subterranean world reveals how a completely dark environment can take on life, vibrate and become space even simply due to the effects of a lit candle.

Tracheal intubation is older than the recognized his-tory of general anesthesia itself. In the late 18th cen-tury, The Royal Humane Society of London used tra-cheal intubation for resuscitating the near-drowned.Approximately 100 years later, MacEwan (1) per-formed a digital tracheal intubation in an awake pa-tient before a chloroform and air general endotrachealanesthetic for the resection of a tongue tumor, and in1928, Magill (2) incorporated blind nasal tracheal in-tubation as a part of a general anesthetic. Althoughlaryngoscopes were invented in the 19th century, tra-cheal intubation under direct visualization was greatlyenhanced by the development of a special laryngo-scope blade by Macintosh (3) in 1943.The first reported use of a lighted stylet used tofacilitate intubation came in 1957 when (by now SirRobert) Macintosh (4) described an 18-inch illumi-nated tracheal tube introducer, which was designed tostiffen the tube and better illuminate the cords bysupplementing the light of the laryngoscope. Berman(5) described a similar device in 1959 and said it wasuseful “when the fickle light of the laryngoscope hasgone out at the most inopportune time.” In the sameyear, Yamamura et al. (6) described a light bulb-tippedwire that was inserted into the tracheal tube beforeblind nasal intubation in awake patients. The tubeposition was then determined by the medial transillu-mination of the external throat and neck.In 1977, Foster (7) used a transilluminating fiberop-tic bundle to facilitate tracheal intubation in a youngchild with trismus, and Ducrow (8), in the followingyear, used a flexible surgical light (Flexi-lum™, Con-cept Corporation, Clearwater, FL) to achieve the sameend by first passing a guide (two plastic suction cath-eters connected end-to-end) into the trachea followedby passage of the tracheal tube over the guide. In acorrespondence to the latter article, Rayburn (9) com-mented that the Flexi-lum™ could be positioned in-side the tracheal tube, thereby shortening the intuba-tion sequence and claimed that the technique,nicknamed “lightwand intubation,” had been used forsome years at the Brooke Army Medical Center.

A light-shelf is a highly efficient daylighting system about which a great deal of research has been performed. However, improvements to the daylighting performance of light-shelves have been limited, because light-shelves could introduce external natural light into the interior space through specular reflection, rather than into a specific region of the interior environment. In this study, to improve the performance of a light-shelf, a light-shelf using the principle of diffused reflection was proposed, and its validity was verified through performance verification. The conclusions of this study are as follows: (1) The optimal angles of a flat type light-shelf and a light-shelf using diffused reflection could vary depending on measurements taken in different seasons. (2) With the installation of the light-shelf using diffused reflection in the summer, the uniformity ratio of illuminance could be improved by 29.9%–34.3% with the external type and by 10.4%–13.7% with the internal type compared to the existing flat type light-shelf. (3) For the light-shelf using diffused reflection, the lighting energy could be reduced by 7.98%–13.3% in the case of the external type and by 1.8%–4.4% in the case of the internal type compared to the existing flat type light-shelf.

All-optical light amplitude tuning functionality is demonstrated in a layered tungsten disulfide (WS2) nanosheets coated microfiber (MF) structure. Due to the strong light-matter interactions between WS2 nanosheets and the evanescent field around the MF, a large variation in the transmitted power can be observed under both external and internal pump light excitations over a broadband spectrum (~100 nm). A power variation rate of ~0.3744 dB/mW is obtained under external violet pump light excitation, whereas the power variation rate of similar devices in the state of the art are usually less than 0.3 dB/mW. In terms of the response time, a moderate rise/fall time of ∼20.5/19.6 ms is achieved, which is mainly limited by the employed structure fabrication methods. These results indicate that the optical transmitted power of the WS2 coated MF can be modulated by different pump light with the power in the order of mW, thus the proposed device might have potential applications in all optical controllable devices and sensors, etc.

Amplitude-modulated continuous wave (AMCW) time-of-flight (ToF) sensor is widely used to capture 3D information of objects due to its relatively high measurement precision in short range. However, the measurement accuracy of AMCW ToF measurement method is generally sensitive to the reflectivity of object, internal stray light, modulation instability, and external light. Consequently, distance measurement error inevitably occurs even in indoor measurement condition. To compensate such error, a post processing method based on machine learning is proposed in this paper. This data driven correction method is validated under indoor measurement condition. According to the experimental results, the distance measurement error correction method presented in this paper shows the most high accuracy compared to other related research results.

Various studies are currently carried out to solve a problem of lighting energy savings, as the importance of it increases. Especially, a variety of researches and application of light-shelf are conducted, as their efficiency has been acknowledged. However, in order to enhance the daylighting performance efficiency of a light-shelf, using materials with high reflectivity becomes a problem due to glare. This study undertakes performance evaluation according to light-shelf's reflectivity on the summer solstice and aims to draw proper light-shelf variables based on the analysis results. The results of this study are presented below: 1) The increase of reflectivity and angle of a light - shelf raises average illuminance and illuminance deviation. 2) the increased angle and reflectivity of light-shelf improve the average of illumination, while uniformity factor varies. This suggests that we should be carefule to construct light-shelf. 3) The number of measured illuminances meeting standard illuminance, 400lx, is the same from 70% to 90% of the reflectivity of a light - shelf, which proves that simple enhancement of light-shelf's reflectivity is not favorable to daylighting performance improvement. 4) Proper variables of a light-shelf on the summer solstice are drawn to 10° in angle and 70% in reflectivity.

For about a century now, several telecommunication devices have been developed by engineers and scientists to assist man for easy information communication and reception. A popular one among the telecommunication devices is the base station antennas which uses radiofrequency electromagnetic wave energy to broadcast radio information signals during operation. The main concern of these BS antennas and their cellular phone devices is the possible adverse human and public health effect of the amount of electromagnetic (EM) wave radiations that emanate from them, especially at proximity during usage. The exposure to EM waves emanating from BSs is a continuous process, and it irradiates the entire body parts and tissues exposed to them at different levels based on position and separation distance. In this work, a combination of both analytical calculation and field strength measurement approach is proposed to the amount EM waves radiation from a randomly selected BS antennas operating in a typical urban residential area of Benin City. With calculation method, highest power density values for operator A and B are 2.34 and 1.17W/m 2 . By means of field measurement, highest power density values are 0.0016 W/m 2 , 0.0024 W/m 2 , 0.0021 W/m 2 for operator A and 0.0019 W/m 2 , 0.0021W/m 2 , 0.0004 W/m 2 for operator B. By comparing the above results with the recommended safety limit of 9W/m 2 by ICNIRP for the public, it is clear that the level of electromagnetic radiation from the investigated antennas are safe for human health.