Average Horizontal Illuminance Research Articles

An approach to ensure joint illumination & communication performance of a forward error corrected indoor visible light communication (VLC) system in presence of ambient light interference

Abstract In recent time of looming radio frequency (RF) spectrum crisis, visible light communication using lighting infrastructure emerged as a potential alternative at an indoor environment. This paper addresses the setback associated with ambient light interference in an indoor Visible Light Communication (VLC) system to ensure joint communication and illumination performance inside an office room. A novel VLC architecture with suitable white light emitting diode (WLED) luminaire arrangement is presented to minimize the dispersion of signal to interference plus noise ratio (SINR) across the room. Luminaires are categorized in two groups viz. data transmitting illuminants and illuminants for lighting purpose. The first group is dedicated to transmit data as well as serves the purpose of illumination. The other set creates only ambient illumination to achieve quality lighting attributes. The proposed forward error corrected receiver configuration discards the ambient light noise originated by the illuminants that serve the ambient illumination. Tail biting convolutional encoder and viterbi decoder are used at the encoding section of the transmitter and decoding section of the receiver respectively to improve bit error rate. Results obtained through MATLAB simulation shows better average bit error rate (BER) in the order of 10−8 measured at uniformly distributed 25 grid points over the working plane. At the same time achieved average horizontal illuminance with good uniformity comply with ISO recommendation.

On the average horizontal illuminance in rooms with one or two point light sources

ABSTRACT To ensure high-quality lighting in indoor spaces, many objective parameters have been suggested in building codes and standards all over the world. Despite the emergence of luminance-based metrics, the average horizontal illuminance (E av) remains popular in practice. For the case of relatively small rooms with one or two point light sources, it is often intended to determine the point with horizontal illuminance equal to E av. It is also intended to have the computation for various room scenarios, so that the outcome can be predicted using a simple model. This study, therefore, aims to propose a method to identify the location of point of E av on horizontal plane in cuboid rooms with various sizes, with one or two point light sources, and to further verify the theoretical concept. To achieve the objective, scenarios and assumptions are described using mathematical tools, followed with verification using grid computations and Monte Carlo simulation of 10,000 random scenarios. Logarithmic models to predict E av value and its representative location are proposed. The room length-to-width ratio is found more influential, compared to the source luminous intensity characteristics, in affecting the location of point of E av.

Daylighting performance and discomfort glare assessment of granular aerogel glazing system: A full-scale comparative experiment

Energy saving, natural lighting, and visual comfort are essential factors to be considered in window design. Granular aerogel glazing system (AGS) has great energy-saving potential, whereas the studies on daylighting performance, especially the visual comfort of AGS are very limited. In this study, a full-scale experiment was conducted to evaluate the daylighting performance and discomfort glare of AGS compared to that of the double-glazed system (DGS) in overcast and sunny days. The horizontal illuminance in the front, middle, and back positions, the vertical illuminance, and the illuminance uniformity were comprehensively analyzed. The high dynamic range (HDR) photograph technique was used and validated. The daylight glare probability (DGP) and daylight glare index (DGI) identified by the task area method, threshold method, and factor method were extracted from HDR images by Evalglare. The results showed that the average horizontal illuminance in the AGS test room is lower than that in the DGS test room. However, due to the scattering effect of AGS, the horizontal illuminance of the AGS test room may be higher than that of the DGS test room in positions where no direct sunlight directly hitting at noon in sunny days. The maximum increasing rate of the hourly horizontal illuminance in the middle and back positions of the AGS test room in September is 37.8% and 54.5%. It is also found that glare may occur in the AGS test room mainly due to excessive luminance. The discomfort glare in the AGS test room may be intolerable in sunny days.

Survey of lighting systems and aesthetic illumination design for various major parks in Ho Chi Minh City

The study was carried out from August 2019 to August 2020 at five major parks in Ho Chi Minh City. We aimed to survey the lighting system including bulb types, lamp types, illumination type, and average horizontal illuminance. The study was carried out by several methods such as a questionnaire of the characteristics of the lamp, observing, measuring, analyzing, synthesizing data, and evaluating. We divided each park by area, for example, main gate, side gate, main axis, branch road, lawn, activity area for investigation. The result showed that the parks having LED and HQ compact bulbs, which were popular chandeliers. Most parks had direct lighting to provide panoramic illumination, but did not reach the average horizontal illuminance. We propose an aesthetic illumination design for the central area of ​​the park with ideas from the history of the park's formation and development. The research results contribute to the improvement of the lighting system for the parks in Ho Chi Minh City.

Research on Night Light Comfort of Pedestrian Space in Urban Park.

The outdoor light environment significantly affects aspects of public psychological and physiological health. This study conducted experiments to quantify the effects of the light environment on visitor light comfort in urban park pedestrian space. Nine sets of lighting conditions with different average horizontal illuminance (2 lx, 6 lx, 10 lx) and colour temperatures (5600 K, 4300 K, 3000 K) were established virtual reality scenarios. Subjective light comfort was evaluated, and electroencephalogram (EEG) was measured on 18 subjects to comprehensively study the effects of different light environments on human light comfort. The results of the comprehensive evaluation showed that colour temperature had a very significant impact on subjective light comfort, with warm light being generally more favourable than cool light in enhancing human subjective light comfort. The results of the EEG analysis show that the average horizontal illuminance is an important factor in the level of physiological fatigue, and that physiological fatigue can be maintained in a superior state at an appropriate level of illuminance. Based on the results of both subjective and objective factors, a comprehensive analysis was carried out to propose a range of average horizontal illuminance (4.08 lx, 6.99 lx) and a range of colour temperature (3126 K, 4498 K) for the comprehensive light comfort zone in urban park pedestrian space.

Signal to interference plus noise ratio improvement of a multi‐cell indoor visible light communication system through optimal parameter selection complying lighting constraints

AbstractTo achieve improved communication and illumination performances of a multi‐cell indoor visible light communication system, the selection of transmitter configuration and receiver's field of view (FoV) play a critical role. Based on multiple criteria decision modeling, a design‐centric methodology is proposed in this paper to determine the optimal transmitter configuration and receiver's FoV under lighting constraints. These optimal parameter selections are instrumental to obtain a highly uncorrelated channel, thus significantly mitigate both co‐channel interference from the neighboring transmitter and intersymbol interference due to multipath reflection. The implication for the optimum selection is explored using two communication and two lighting (Eavg, UO) performance indicating metrics. For a typical indoor scenario, three different transmitter arrangements with varying half‐power beam‐width are considered as alternatives. Furthermore, the signal to interference plus noise ratio (SINR) is tested over the communication floor (CF) by a simple receiver structure with a single photodiode. Incorporating the optimal transmitter configuration and receiver's FoV, 36.13 dB average SINR and 345 lx average horizontal illuminance is achieved. Analytically obtained SINR is also validated using a commercial ray tracing optical software for different positions over the CF. In comparison with the state of the art non‐optimal and sub‐optimal solutions, the proposed scheme, without real‐time computational complexity exhibits noteworthy improvement in SINR performance at expense of a trivial drop in overall uniformity of horizontal illuminance.

Simulation and analysis of the effects of room surface reflectance combinations on a proposed retrofit illumination system of an office

Purpose An indoor office space should not only provide adequate illuminance on horizontal planes but also cater to the physiological and psychological requirements of the occupants. This paper aims to describe a lighting simulation-based work conducted in Kolkata, India which modeled an indoor office to investigate the effects of variation in room surface reflectance combinations on user perception, mean room surface exitance (MRSE), average horizontal illuminance and overall uniformity of horizontal illuminance. Design/methodology/approach A fluorescent illumination system–based office space was modeled and retrofitted with tubular LED lamps in DIALux. Simulations were conducted for 16 different room surface reflectance combinations and a five-point Likert scale-type survey questionnaire was formulated to conduct a survey with 32 test subjects to assess the subjective preferability of each resultant light scene. Findings Simulation results demonstrate that the relationship between average horizontal illuminance and MRSE as well as between average horizontal illuminance and overall uniformity of horizontal illuminance, was statistically significant (p < 0.001). In the conducted survey, the resultant light scene arising out of the reflectance combination of wall:ceiling:floor = 60%:90%:20% was the most well-received one with 187 convinced agreements (“agree” and “strongly agree” responses). Originality/value This work found strong linear correlation between average horizontal illuminance and MRSE and between average horizontal illuminance and overall uniformity. A five-point Likert scale-type survey questionnaire with seven questions was formulated and validated with 32 test subjects (Cronbach’s alpha > 0.9295), which showed that the wall:ceiling:floor reflectance combination of 60%:90%:20% was the most favored choice.

Design, Development and Practical Realization of a VLC Supportive Indoor Lighting System

In an office space, an LED-based lighting system allows you to perform the function of a data transmitter. This article discusses the cost-effective design and development of a data-enabled LED driver that can transmit data along with its receiving part. In addition, this paper clearly outlines the application of the proposed VLC system in an office environment where ambient light interference is a severe issue of concern. The result shows satisfactory lighting characteristics in general for this area in terms of average horizontal illuminance and illuminance uniformity. At the same time, to evaluate real-time and static communication performance, Arduino interfaced MATLAB Simulink model is developed, which shows good communication performance in terms of BER (10–7) even in presence of ambient light noise with 6 dB signal to interference plus noise ratio. Our designed system is also flexible to work as a standalone lighting system, whenever data communication is not required.

Research Note: Describing average illuminance for P-class roads

Design criteria for lighting in subsidiary roads usually include a minimum average horizontal illuminance, widely assumed to be the arithmetic mean illuminance. Analyses of the illuminance distributions over thirty road sections shows that the distributions are not normal and hence the median is more appropriate than the arithmetic mean as a measure of central tendency: the medians are significantly lower than the arithmetic means but the two are highly correlated. Design recommendations should state whether it is the arithmetic mean or median and not just the ‘average’ that is required.

Daylight integrated indoor VLC architecture: An energy‐efficient solution

AbstractIn an indoor space, visible light communication (VLC) can form a promising enhancement of future illumination infrastructures with communication functionalities. This illumination infrastructure consumes 20% of the total energy consumption in the world. In this perspective, daylight integration with indoor VLC system is a promising area of research to conserve a considerable amount of energy. This paper deals with the design and practical realization of an energy‐efficient indoor VLC system through daylight integration. Dimming control mechanism using continuous current reduction topology is adopted to design the transmitter section of the VLC system. Thrust has been given to accomplish the required communication performance in terms of the bit error rate and illumination performance in terms of average horizontal illuminance and short‐term flicker severity. Both the communication and illumination performances have been evaluated under five different daylight conditions. At maximum ambient daylight condition, 37.29% of total energy has been saved, while the bit error rate lies in the order of 10−10. Simultaneously, satisfactory illumination performance in accordance with international guidelines has been achieved.

Performance assessment of the BTDF data compression based on wavelet transforms in daylighting simulation

The bidirectional transmittance distribution function (BTDF), which is used to characterize the light transmission of a complex fenestration system (CFS), commonly involves bulky volume of data that can be a challenge to data storage and transmission in lighting simulation tools and on compact platforms. This paper introduces a compression scheme that is based on planar wavelet transforms with three levels of decomposition to efficiently compress the BTDF data of CFSs and maintain fidelity in daylighting simulation. The root-mean-square error (RMSE) and transmittance error (TE) of compressed medium-resolution BTDF data using three different wavelet bases were evaluated for five different CFS samples at various compression ratio. Based on the results, the generic error from compression did not exceed 20% with CDF9.7 basis for compression ratio up to 200. In the case of rendering an image of a scene in which a CFS was installed at the upper daylighting section of an unilateral façade, errors began to be noticeable at a compression ratio above 70. The uniformity factor g1 was discovered to be relatively sensitive to compression (below 15% error), while the average horizontal illuminance and daylight glare probability (below 10% error) were immune to compression ratio below 100. Compression was also evaluated for a high-resolution BTDF data of external Venetian blinds in the simulation of work-plane illuminance (WPI). With a HDR imaging technique based sky luminance map, the WPI simulation had unnoticeable errors for compressed BTDF data within a compression ratio of 100.

Dimming strategies for open office lighting: User experience and acceptance

Sensor-triggered control strategies can limit the energy consumption of lighting by considering the presence of users in the office and dimming lighting down when it is not needed. In multi-user offices, the application of occupancy-based dimming at room level limits the energy saving potential. However, zone- or desk-based dimming may affect the comfort of co-workers due to its dynamics. This paper reports the assessment by 17 participants (30–50 years of age) of occupancy-based dimming in a mock-up office, using different dimming speeds. Participants consisted of co-workers experiencing changes triggered by others, and actors triggering these light changes. While the participants performed an office-based task, the luminaire above the actors’ desk was dimmed from approximately 550 lx to 350 lx (average horizontal illuminance), and vice versa. The participants evaluated the dimming conditions regarding their noticeability and acceptability. The study showed that the noticeability of light changes due to dimming, increases when fading times become shorter. Dimming with a fading time of at least two seconds was experienced as acceptable by more than 70% of the participants. The results of this experiment provide insights to system behaviour that does not compromise user experience while addressing energy efficient use of electric lighting.

Comparison of Static and Ambulatory Measurements of Illuminance and Spectral Composition That Can Be Used for Assessing Light Exposure in Real Working Environments

ABSTRACTReliable measurements are of utmost importance when investigating the relationship between light and human reactions. The aim of the present study was to compare two methods for measuring light exposure in real working environments. Ambulatory recordings of illuminance and irradiance were compared with static field measurements of horizontal illuminance at the normal working position, average horizontal illuminance in the room, vertical illuminance at the position of the eye in the normal angle of gaze, and spectral composition of the light radiation at the normal working position and at the position of the eye in the normal angle of gaze. The ambulatory measurements were carried out during a 3-day experimental period and were repeated monthly throughout the year. The static field measurements in the subjects’ offices were conducted five times during the year, in the morning and afternoon during one day. The relationship between the illuminances and irradiances measured with the portable instruments and the static measurements was statistically analyzed. Results from the analyses revealed that more than one third of the static measurements of vertical illuminances recorded were below 200 lx, and only 7% of the measurements exceeded 1000 lx. Measurements of the spectral composition of the light radiation in the rooms suggested that the light, although at a fairly low intensity, included relatively much radiation that can have a non-image forming effect. Furthermore, only a small number of significant correlations between the ambulatory and static measurements were found. Results from the t-tests showed that there were no differences between ambulatory measurements, and static measurements of horizontal illuminance at the normal position, average illuminance in the room and vertical illuminance at the position of the eye during three, five, and seven of the 10 measurements, respectively. There is a need to define appropriate parameters in order to describe the quality of a lit environment with respect to the non-image-forming effects of light radiation.

Assessment of pitch floodlighting and glare condition in the Main Stadium of Gelora Bung Karno, Indonesia

Lighting for pitch area of a football stadium is an important aspect to consider in the design and operation phase. Despite the provided guidelines and regulations, actual conditions of lighting and visual comfort in stadiums are seldom reported. This article discusses the measurement of pitch floodlighting and glare condition in a stadium, taking the Main Stadium of Gelora Bung Karno (GBK) in Jakarta, Indonesia as a case study. The objectives are to determine the existing conditions of actual lighting performance and glare rating on and around the pitch area. A series of measurement following the FIFA guideline and other novel techniques in lighting technology such as applying high dynamic range (HDR) photograph images were conducted. The average horizontal illuminance on the pitch was measured 1300 lx, much lower than the minimum criterion of 3500 lx. Uniformity on the pitch for horizontal, vertical, and 30° tilted illuminance was also much smaller than the required minimum values. Based on luminance maps of the HDR images, no risk of glare is estimated on and around the pitch. The existing floodlights at the tribune’s roof are recommended to be replaced and added. To assess the proposed design concept, a total of 592 units of LED floodlights, each having 500 W, 55000 lm, and 17° beam angle, were introduced in simulation models. The floodlights were proposed to be installed in typical arrays consisting of four horizontal rows. The resulting horizontal illuminance variables and glare ratings at all points have been shown to satisfy the recommended criteria.

Evaluación de iluminancia en canchas públicas localizadas en el área urbana de la ciudad de Cuenca

En la ciudad de Cuenca del Ecuador, en su área urbana existen canchas deportivas públicas, de libre acceso para la ciudadanía y para un nivel de juego de carácter recreativo. Estos escenarios son utilizados en algunos días de la semana en horas de la noche con horario restringido, para lo cual están provistas de un sistema de iluminación, cuya prestación lumínica es motivo de esta investigación. En el presente trabajo se describen inicialmente las responsabilidades jurídicas de la prestación del servicio de alumbrado público en canchas deportivas públicas que en estos casos recae sobre el Municipio de Cuenca, denominado legalmente “Gobierno Autónomo Descentralizado del Cantón Cuenca”, luego de lo cual se describe la arquitectura de estos espacios públicos así como sus sistemas de iluminación, y posteriormente indica la metodología empleada para la obtención de la iluminancia horizontal media sobre las superficies de los escenariosanalizados, posteriormente analiza los niveles de iluminación comparando con valores de iluminancia media recomendados en el “Reglamento Técnico de Iluminación y Alumbrado Público – RETILAP”, para este tipo de escenarios deportivos y finalmente presenta conclusiones y recomendaciones.

Improving community street lighting using CPTED: A case study of three communities in Korea

This study proposes design alternatives for community street lighting by applying “Crime Prevention Through Environmental Design” (CPTED) concepts to enhance natural surveillance and feelings of safety. We conducted simulations to analyze how these designs would improve three communities. To find ways to enhance community safety at night, we considered lighting standards and CPTED guidelines, using Relux Pro for a simulation analysis. We came up with design alternatives considering visibility and the facial recognition for street lighting; based on this, we proposed that more security lights be installed or existing lights be modified or oriented in a different direction. When we applied the proposed changes to the study areas, we found that our simulations would improve the “average horizontal illuminance” and the basic conditions for perceiving people. The study contributes alternatives for community street lighting based on CPTED, compares the alternatives to existing lighting using simulation software, and discusses the effects of these alternatives.

Energy and user acceptability benefits of improved illuminance uniformity in parking lot illumination

This study set out to understand the benefits of improved illuminance uniformity in parking lots in terms of user perception and acceptability, as well as energy use, and to demonstrate that light-emitting diodes (LEDs) can achieve uniform distributions more efficiently than traditional light sources. The results from a field evaluation showed that more uniform illuminance distributions are favourably perceived by people in terms of goodness of illumination, ability to see around and at a distance, and perception of safety – all of this at a much lower average horizontal illuminance. Thus, improving uniformity alone can translate into lower energy use and potential for less glare and light pollution. Optical modelling showed that LEDs have a much greater potential to efficiently produce uniform illuminance distributions than larger light sources such as high pressure sodium or metal halide.

Relationship between Roadway Illuminance Level and Nighttime Rural Intersection Safety

Almost all existing research about intersection lighting indicates that the presence of lighting reduces nighttime crashes. This study aimed to quantify the effect of lighting level and lighting quality on the night-to-day (ND) crash ratios at rural intersections. Illuminance measurements were collected from 99 lighted and unlighted rural intersections in Virginia. The measurements were then combined with the crash data, obtained from the Virginia Department of Transportation, for each of the intersections. A negative binomial regression was used to model the crash and lighting data. Results indicated that lighting level (average horizontal illuminance) significantly affected the ND crash ratios at rural intersections. A 1 lux (lx) increase in the average horizontal illuminance at all rural intersections in Virginia corresponded to a 7% decrease in the ND crash ratio. For the lighted intersections, a 1 lx increase in average horizontal illuminance corresponded to a 9% decrease in the ND crash ratio. The largest decrease in the ND crash ratio was for unlighted intersections, where a 1 lx increase in the average horizontal illuminance corresponded to a 21% decrease. Stop-controlled intersections had smaller ND crash ratios than signalized intersections. Intersections with a posted speed limit of less than or equal to 40 mph had lower ND crash ratios than intersections with a posted speed limit of greater than 40 mph. Each of the results is discussed with respect to the impacts of the lighting measurements on nighttime driving safety and overall visibility.

Space Brightness Evaluation for Day-Lit Offices

To promote energy saving for office lighting, effective utilization of daylight illumination is necessary. It is very important to evaluate the brightness of a room taht is illuminated by both daylight and ceiling lamps. In this case, even if the average horizontal illuminance is kept constant, it is difficult to estimate the brightness perception of the room because of the very high intensity of daylight and the uneven distribution of light flux. In this paper, we investigated the effect of window size and intensity of daylight on the brightness perception of an office room with a window on one side. We examined the brightness perception and expressed it as a function of average horizontal illuminance attributed to the daylight and to the ceiling lamps.

Perceptions of safety at night in different lighting conditions

Lighting has been shown to be an effective tool in the fight against crime, but too often the tool has been a sledgehammer. The four field studies described in this paper set out to answer two questions: 'How much light is needed to provide a perception of safety at night in urban and suburban areas?' and 'How important is light spectrum to that tion?' The first two field studies examined people's perceptions of the quality of the lighting for security on streets in New York City and Albany, New York. The third measured people's perceptions of safety when walking alone in urban and suburban parking lots, by day and night. The fourth measured perceptions of safety in a parking lot lit by high-pressure sodium and metal halide lamps. Taken together, these studies indicate that an average horizontal illuminance on a parking lot surface or street sidewalk of about 30 Ix provides enough light to ensure that perceptions of safety are close to what they are in daylight. The light spectrum is a minor factor relative to illuminance.