Discomfort Glare Research Articles

The impact of installing a concave curved profile blind to a glass window for visual comfort in office buildings

Daylighting strategies to utilise the use of natural light in office buildings are highly favourable, as sufficient levels of visual comfort can be achieved, resulting to a drastically improved working environment with positive effects on employees’ productivity and well-being. The task of bringing daylight into deep plan office buildings with conventional windows, or skylights, proves to be a challenging one and leads to the conclusion that the integration of innovative daylight systems in architectural design must be given serious consideration. The main objective of this research is to explore advanced daylighting system profiles which enable the optimization of the visual comfort in office building interiors. This paper describes the first stage of the research and focuses on the investigation of a daylighting system integrated in building envelopes, which explores the potentials of concave curved profiles in optimizing illumination levels of a deep plan indoor space, commonly found in office buildings. A ray-tracing analysis was developed to define the profile of the blind’s reflective surface by estimating its lighting behaviour. As results show, when the curvature of the substructure elements decreases, then the scatter diagrams obtained were still diffused with all the incident sunlight directed towards the inside of the room. Daylighting simulations were performed for Larnaca, Cyprus, using Diva for Rhino v5.0 to evaluate the selected profile daylighting performance in three representative space typologies, taking an unshaded window as reference. The results are promising, as the model system in general outperforms the reference case by successfully increasing an even distribution of light levels across the room and is thus, more likely to provide visual comfort. More specifically, the system under evaluation did not create the extremely high illuminance values near the openings while a preliminary analysis of glare effects shows that the discomfort glare probability (DGP) is within imperceptible levels.

Energy and Daylighting Evaluation of Integrated Semitransparent Photovoltaic Windows with Internal Light Shelves in Open‐Office Buildings

In modern architecture, highly glazed commercial buildings account for considerable amount of energy, specifically in cold and hot climates because of heating, cooling, and lighting energy load demand. Abatement of this high building energy is possible by employing semitransparent photovoltaic (STPV) window which has triple point advantages as they control the admitted solar gain and daylight and generates benign electricity. Integration of internal light shelves (ILS) to this STPV window assists in controlling visual comfort. Thus, this study aims to evaluate the impact of a nonuniform layout of double‐glazing (DG) low‐e STPV and DG low‐E argon‐filled clear glass integrated into a fully glazed open‐office facade combined with ILS in cardinal orientations under Riyadh, London, Kuala Lumpur, and Algiers climates. Comprehensive energetic and radiance simulations were conducted to evaluate three groups of STPV configurations. The first group replaced the glazing area with amorphous silicon (a‐Si) modules with different transparencies; the second and third groups changed only 75% and 50% of the glazing area, respectively, with STPVs integrated with the ILS. The results revealed that the integration of a‐Si modules did not meet the visual comfort requirements but obtained the maximum saving in the east‐west axis. It was also found that the optimum design on the south‐facing facade with the nonuniform facade achieved 50% of STPV10 coverage in clear glazing windows combined with ILS; the energy saving ratios comparing the reference models were 76%, 83%, 65%, and 70% in Riyadh, London, Kuala Lumpur, and Algiers, respectively. Thus, the integration of STPVs with ILS is considered a more efficient way and effective solution to reduce the possibility of glare discomfort.

The design specifics of the diffused lighting system of premises based on LEDs

In the article the design specifics of the diffused lighting system of premises based on LEDs is being considered, which is determined by such problems of the designing LEDs lighting systems: formation of multiple shadows using groups of open LEDs in luminaires direct light; the need for vision protection of the users from the direct light of LEDs as the high light efficiency and miniature sizes of modern LEDs lead to the significant luminous flux in one point.In the process of work it was defined that the promising solution to the problems outlined above is using the diffused lighting, which is considered to be one of the most comfortable in terms of avoidance of disability glare and discomfort glare. However, the diffused lighting has such a disadvantage as monotony. As a result, the study suggests ways to avoid the monotony of the light environment which is formed by the diffused lighting: the main one is the enrichment of the shape of the luminaires and lighting systems through the use of complex and structured light diffusing surfaces to form them; the additional one is the enriching the colour of the light due to the nuanced differences in colour temperature of separate luminaires among the variety of those, which are in the general lighting system.The theoretical position outlined above are practically applied in: the series designed shades (PU 112427, PU 130594), which construction is based on regular (hexahedron or cube, octahedron, icosahedron) and semi-regular (cuboctahedron, rhombicuboctahedron) polyhedrons; the series LED luminaires for lighting of shades (PU 128832) and for forming the systems of diffused lighting (PU 121313). Also, it was found, that contemporary design of the luminaires with diffused light have frequent use OLED on a rigid or flexible lining as light sources.

Multi-objective simulation-based optimization of controlled blind specifications to reduce energy consumption, and thermal and visual discomfort: Case studies in Iran

This paper aims to present a multi-objective simulation-based optimization of architectural specifications and control parameters of a smart shading blind. Using the proposed method, implementation of control strategies on the window shading device and simultaneous optimization leads to a significant reduction in building energy consumption, and occupants' thermal and visual discomfort. Simulations are carried out using EnergyPlus, objective functions and decision-making parameters are identified by jEPlus, and multi-objective optimization is done by jEPlus + EA through NSGA-II. Optimization of the controlled blind is implemented in a typical office room located on a middle floor of a building, and the results are evaluated for four window orientations in six different climatic regions of Iran according to Köppen-Geiger climate classification. The decision variables are shading control strategy and its set-points and shading location, dimensions, angle, and material. The annual total building energy consumption, the predicted percentage of dissatisfied (PPD) and the discomfort glare index (DGI) are also considered as three objective functions minimized simultaneously. The weighted sum method is used to select the final answer from Pareto solutions. According to the results, based on the climate and the window orientation, the proposed optimization method leads to 2.8–47.8% decrease in the annual total building energy consumption compared to the initial design simultaneously with 15.5–69.9%, and 8.5–56.3% reduction in DGI and PPD indexes, respectively. The results clearly show how appropriate selection of the shadings specifications and their control strategy parameters can significantly not only prevent energy losses but also provide better occupants’ thermal and visual comfort.

Older drivers' self-reported vision-related night-driving difficulties and night-driving performance.

To investigate associations between older drivers' perceived vision-related night-driving difficulties and night-time driving performance measured on a closed-road circuit. Participants included 26 older drivers (71.8±6.3years) who reported vision-related night-driving difficulties assessed with the vision and night driving questionnaire (VND-Q). High-contrast, photopic visual acuity (VA) and ratings of discomfort glare (de Boer scale) were also assessed. Night-time driving performance was measured on a closed-road circuit that involved recognition, hazard avoidance and lane-keeping tasks in the absence and presence of intermittent glare. Generalized linear mixed models investigated the relationship between VND-Q scores and overall driving performance scores, as well as with discomfort glare ratings and VA. Greater levels of vision-related night-driving difficulties (VND-Q scores) were significantly associated with poorer night-driving performance (p=0.003); the association was even stronger for driving performance in the presence of intermittent glare (p=0.001). Reduced VA was associated with poorer night-driving performance (p=0.022) but the association was weaker than for the VND-Q scores. In contrast, ratings of discomfort glare were not significantly associated with driving performance (p=0.14). The VND-Q was significantly associated with night-time driving performance and provides a useful instrument for assessing vision-related night-driving difficulties which can be incorporated into clinical vision assessments.

A contra-lateral comparison of the visual effects of a photochromic vs. non-photochromic contact lens

PurposeTo compare the effects of a photochromic contact lens vs. a non-photochromic control lens on visual function. MethodsA subject-masked, prospective contralateral eye design was used. Sixty-one subjects were enroled based on age (using a 2:1 allocation ratio for ages 18–39 and 40–65 years, respectively). The study lenses were senofilcon A with photochromic additive (Test) that filtered over the entire lens, compared to a non-photochromic Control with no tint. The Test lens was partially activated during testing with a steady-state transmittance of approximately 62%. Eligible subjects were tested using both study lenses, with Test and Control lens randomized by eye. Five visual function outcomes were tested: photostress recovery (PSR), glare disability (GD), glare discomfort (GDC), chromatic contrast (CC) and vernier acuity (VA). Iris colour and macular pigment density were assessed as control variables. PSR was measured as the time needed to recover sight of a target after an intense xenon flash exposure; GD was evaluated as the energy needed to veil a central target by a surrounding xenon annulus; GDC was measured using bio-imaging of the squint response and by self-report using a 9-item Likert scale; CC was measured as thresholds for a yellow grating target superposed on a 460-nm background; VA was determined by measuring vernier offsets of light lines through apertures. ResultsBased on our stimulus conditions, PSR was 43% faster using the Test vs. the Control. The eye wearing the Test had 38% less squint (GDC) compared to the Control. GD was improved by 36% in the Test vs. Control and CC was enhanced by 48% with the Test. There was no significant difference in VA. ConclusionsThere was a beneficial influence on visual function when comparing the photochromic with the non-photochromic contact lens. This benefit was seen specifically with respect to PRT, GDC, GD and CC thresholds.

Quantitative evaluation of the discomfort glare of a tunnel pergola

The light spot on the ground at the portal of a tunnel, which is caused by the sun shining on a pergola, consists of bright areas and dark areas, and it can cause a discomfort glare for drivers. In this study, in order to evaluate the level of discomfort glare, the bright areas were compared to lamps and the dark areas were compared to the backgrounds. Using Unified Glare Rating (UGR), which is used to evaluate the glare degree in lighting places, we established a quantitative evaluation method of the discomfort glare and derived the formulas that could calculate the UGR of the pergola with equal beam spacing and unequal beam spacing. In accordance with the formulas, the UGR of the two kinds of pergolas was calculated. The results showed that the UGR of the pergola with equal beam spacing was smaller than the UGR of the pergola with unequal beam spacing, demonstrating a less level of the discomfort glare. Furthermore, the relationship between the variations of the parameters of the pergola and the UGR was analyzed, which could provide references for the design of the pergola and the improvement of driving comfort.

Glare from Windows Assessment at Offices with Three Types of Internal Solar Shadings

Successful daylighting requires trade off and optimization between competing elements of façade, space, and lighting system. It also requires reliable tool for assessing the indoor visual comfort, especially discomfort glare from windows. The objective of the study was to investigate the users’ glare perception due to the use of internal solar shading systems by using laboratory experimentation with subjects and measurements. The purpose was to compare these results with a glare rating equation and Luminance Distribution Ratio (LDR) and to assess the reliability of this glare assessment tool to be used for assessing glare from window and in the context of humid tropics climate. The laboratory experimentations were conducted at three identical office rooms at the Department of Architecture of ITS in which each of the room’s windows was covered with different internal solar shading types e.i. Venetian, Horizontal, and Roller Blinds. Results showed good correlation between Luminance Distributions Ratio (LDR) with the users’ responses. Among the three internal shading, the Roller blind type had the highest correlation on both working activities and sitting positions to the glare perception as well as the fittest value complying the standard of luminance distribution. The research concluded that the Luminance Distribution Ratio method can be a reliable tool for assessing glare from window for many office situations in humid tropical climate.

Conformity assessment of glare in buildings considering the uncertainty of the parameter UGRL

The evaluation of discomfort related to glare is a common need in buildings, requiring conformity assessment defined in the standard EN 12464-1:2011, using the parameter UGRL index and a related scale with threshold levels associated with perceptible behaviour transitions. The scale is defined for a dimensionless parameter related to the degree of psychological (discomfort) glare of an electric lighting installation in an indoor space. The aim of this paper is to provide a comprehensive understanding of the role of the UGRL uncertainty in the conformity assessment procedure, being a critical quantity used in the definition of a decision rule under the new edition of the ISO / IEC 17025 standard. The impact of the uncertainty of the UGRL quantity is shown using examples of decision rules in measurements near the transition limits of the scale.

Daylight regulated by automated external Venetian blinds based on HDR sky luminance mapping in winter

Automated shading systems have the potential to exploit daylight in buildings to save energy of artificial lighting and cooling loads and improve occupants’f visual comfort. This paper investigates the daylighting performance of automated Venetian blinds based on sky luminance monitoring and lighting computation in winter. ‘fIn-situ’f experiments were carried out in a daylighting test module when the solar elevation angle was 21.7. at noon. Experimental results showed the automated shading was able to maintain work-plane illuminance within [500, 2000] lux range for 88% of the working time under a clear sky and for 83% of the working time under a partly cloudy sky, while mitigating discomfort glare for occupants.

Effect of central hole location in phakic intraocular lenses on visual function under progressive headlight glare sources

To analyze the effect of the central hole location in the V4c implantable collamer lens (ICL) on the quality of vision, including progressive headlight glare simulation and quality of life. IOBA-Eye Institute, Valladolid, Spain. Case series. The central hole location was determined by slitlamp and dual Scheimpflug imaging for 6months or more postoperatively. The visual acuity, mesopic contrast sensitivity, halogen glare contrast sensitivity, xenon glare contrast sensitivity, photostress recovery time after glare, de Boer scale, and Quality of Life Impact of Refractive Correction (QIRC) questionnaire results were evaluated. Multiple regression models were used to analyze the effect of the central hole location on parameters using the pupil center and visual axis as references based on Cartesian and polar coordinates. The safety index was 1.13 and the efficacy index, 1.12. Under all testing circumstances, central hole decentration did not affect the visual acuity or contrast sensitivity. With the visual axis as a reference, worse QIRC values were associated with greater upward central hole displacement (P=.03) and a lower polar angle value (P=.008); also, halogen glare discomfort was greater with a higher radius (P=.04). Using the pupil center as a reference, greater nasal central hole decentration was associated with longer xenon glare photostress recovery time (P=.002). Implantation of the ICL with a central hole yielded excellent visual outcomes, even under increasing glare sources, regardless of the hole's location. However, hole decentration might affect patient-perceived quality of life, bothersome halogen glare, and longer xenon glare photostress recovery time. Such complaints after the early postoperative period might be managed with discrete ICL centration if the central hole is decentered upward or nasally.

Practical application of HDRI for discomfort glare assessment at indoor workplaces

Unified Glare Rating (UGR) is a measure of discomfort glare at indoor workplaces. Image luminance measuring device (ILMD), as an array photometer, makes it possible to measure the luminance distribution in the form of luminance map. It is the base for UGR calculation by an appropriate computer program. The range of measured luminance depends mainly on a glare source luminance, which often significantly exceeds the abilities of an array photometer sensor. High dynamic range (HDR) method, which is used in photography, can solve this problem partially. A practical approach to this problem was presented in the paper. A new procedure for preparing the set of photos for building HDR images was introduced. This effective method was developed to be used in UGR calculations. The use of the proposed procedure makes it possible to perform UGR measurements reliably, quickly, and efficiently, even by nonexperts in the field of lighting engineering.

Lighting for work: A study of the relationships among discomfort glare, physiological responses and visual performance

Objective measures of visual discomfort have the potential to quantify the individual's sensations under discomfort glare conditions although such measures have yet to be circumscribed. The present study aimed to examine the extent to which visual discomfort sensation can be both operationalised and measured, utilising many light-induced physiological measures. These measurements were coupled with visual performance evaluations, in combination with conventional measures of photometric measurements and subjective evaluations. The variables measured were mean Pupil Diameter, Pupillary Unrest Index, Blink Rate, Blink Amplitude, number of fixational eye movements during reading (Fixation Rate), and average Fixation Duration, as well as Combined Visual Performance. The results of this study indicate that most of these parameters show significant differences between high and low lighting conditions. In particular, participants in high discomfort conditions exhibited a higher Fixation Rate, lower Blink Rate, higher Blink Amplitude and a smaller Pupil Diameter than those in both low and medium discomfort conditions. In other words, the studied physiological measures can be used as an index of high levels of glare or visual discomfort. In addition, regarding subjective evaluations, the results of correlation analysis suggest that visual comfort level ratings may provide a more reliable indicator of visual discomfort sensation.

Evaluation of Energy and Daylight Performance of Old Office Buildings in South Korea with Curtain Walls Remodeled Using Polymer Dispersed Liquid Crystal (PDLC) Films

Globally, energy standards for new buildings are being reinforced to improve energy efficiency, and remodeling policies are being promoted for old buildings. The South Korean Government is promoting green remodeling projects, and focusing on research and product development to improve the performance of old windows and curtain walls. In line with this, the present study proposes two remodeling methods using polymer dispersed liquid crystal (PDLC) films, which can adjust solar radiation for old office buildings. In addition, energy efficiency improvement and daylight performance according to remodeling were analyzed. Attaching PDLC films to the glass of old curtain walls was analyzed; this can reduce heating and cooling energy, reduce the annual discomfort glare occurrence rate, and increase the annual indoor appropriate illuminance ratio. Furthermore, producing a window by laminating a PDLC film between two sheets of glass and putting it over the existing curtain wall was also analyzed; this can reduce annual building energy consumption and the annual discomfort glare occurrence rate, and improve the annual indoor appropriate illuminance ratio. Therefore, PDLC film is expected to be applicable as a next-generation green remodeling material because using it in remodeling can improve energy efficiency of old office buildings and indoor daylight performance.

Control method for adaptive façades based on energy conservation and glare protection strategies

This study focuses on the control method of an adaptive façade based on the combination of energy conservation and glare protection strategies. Two evaluation methods are applied. The first method is to determine the appropriate range of the shading states which allow a minimum amount of solar heat gain and lighting energy requirements in the passive zone. The second method is to determine the appropriate range of the shading states which protect discomfort glare. Finally, the hourly optimal shading state can be determined through the two evaluation methods. In the application, the hourly shading state of a dynamic folding system, which can fully close and open in the two directions, is derived and evaluated. The results of the evaluation showed that the optimal control method suggested in this study can deliver effective energy performance while avoiding discomfort glare.

A Study on the Improvement of the Evaluation Scale of Discomfort Glare in Educational Facilities

The lighting environment is a factor that significantly affects the physical and psychological aspects of occupants of a building. In particular, educational facilities should be designed to provide adequate natural lighting because it has a profound impact on students’ health and learning performance. Although environmental certification systems include evaluation items for improving the indoor light environment, there is a lack of evaluation criteria regarding the corresponding issue of glare. Therefore, this study aims to help visualize areas where indoor glare problems occur, and to improve the evaluation scale of discomfort glare in environmental certification systems. A standard high school classroom in Seoul was analyzed to study glare issues in the educational space. DIVA for Rhino—Grasshopper, a light environment simulation program based on Radiance and DAYSIM program, was used to obtain reliable light analysis simulation results, and the daylight glare probability (DGP) measure was used to calculate discomfort glare. The results of the simulation and analysis suggest this is a method for improving glare evaluation measures that are lacking in indoor environmental certification standards. The visualized frequency of discomfort glare data is useful for planning the layout of the indoor space, opening, and shading design of a building to prevent glare problems.

Designing of light-pipe diffuser through its computed optical properties: A novel solution technique and some consequences

Light diffusing modules with improved optical properties could usefully facilitate the quest to achieve smart daylight harvesting in office buildings without detrimentally affecting visual comfort in building interiors. However, direct sunlight and sky light may cause discomfort glare. And a use of optically dense diffusers to reduce this effect and produce more uniform indoor light fields is not an efficient solution because of a concomitant loss of luminous energy. Hence, the need for more environment and people sensitive solutions is pressing in order to improve combined optical efficiency, efficacy and ergonomy of work-place luminance.That design aspiration is addressed and involves semitransparent apertures with the directional distribution of luminous intensity approaching that required. Methods for targeted shaping of an illuminance pattern are certainly advantageous for visual comfort, while supporting more demanding visual work and more flexible visual orientation. The numerical experiments we have conducted have proved that retrieval of optimum optical properties of a diffusing medium is possible through minimizing the differences between theoretical and required illuminance patterns. The inverse transform has been successfully validated for sensitivity, specificity and convergence. Our solution is augmented by the proposal for a possible realization of the diffusing aperture in the form of a particle-doped transparent medium which mimics, thus can personalize, the illuminance patterns desired.

Discomfort Glare from Several Sources: A Formula for Outdoor Lighting

ABSTRACT Many models have been developed to predict the discomfort glare generated by one light source in the visual field. Some of them were generalized to predict discomfort glare from several sources, but they were not directly built from multi-source data. In their generalization, they do not consider the potential interactions due to the fact that the light sources are switched on together. In the present work, a psycho-visual experiment was conducted for a better understanding of the glare produced by several sources using a matching task at the Borderline between Comfort and Discomfort (BCD). A formula is proposed to compute the photometric and geometric characteristics of an equivalent source which generates the same level of discomfort glare as several sources switched on together. This formula is the first step towards a multi-source model of discomfort glare. The practical implications are discussed.

Daylight-Artificial Light Integrated Scheme Based on Digital Camera and Wireless Networked Sensing-Actuation System

Automated lighting can achieve significant energy savings. A daylight-artificial light integrated system with the camera as the sensor and wireless sensor actuator networked (WSAN) system is presented here. The workplane luminance, the window luminance, and the discomfort glare position of the user are extracted from the image of the workspace captured by the camera. The findings of this paper are the usage of the camera as luminance meter and how this information is used in the control of LED dimming based on consumer comfort. A novel camera-based fuzzy controller for window blind, considering visual, and thermal comfort, is designed, based on the parameters extracted from the image, to optimize the illuminance and uniformity for a test space. The control system integrates luminaire and window blind control. The model-based design approach provides visual and thermal comfort for the consumer without compromising on energy consumption. The real time implementation of the shading and lighting integrated model, with daylight adaptation and the wireless networked sensor-actuation system is shown in this paper. The performance of the wireless networked lighting scheme is analyzed, by evaluating the energy consumption of the nodes in idle, transmit, and receive mode.

The Effect of a Pre-Trial Range Demonstration on Subjective Evaluations Using Category Rating of Discomfort Due to Glare

ABSTRACT Category rating is a procedure commonly used to evaluate visual discomfort due to glare. One recommended step for good practise in a category rating procedure is to use a pre-trial demonstration (PTD) of the range of stimuli to be experienced. However, PTD have rarely, if at all, been used in past research on discomfort glare. In this study, two experiments were conducted to test the influence of the PTD on evaluations of discomfort due to glare. In the first experiment participants evaluated four glare source luminances with, and without, a PTD. The results suggest that using a PTD increased the reported degree of discomfort perceived for the same glare setting, although this may depend on the manner in which the PTD is presented. In the second experiment, participants evaluated four glare source luminances using PTD with three different luminance ranges: the results suggest this had significant effect on discomfort evaluations in that evaluations of discomfort were lower when a higher luminance range was used. Along with other recent studies, these findings suggest a need to derive a more robust procedure for measuring the discomfort due to glare.