There is no widely accepted discomfort glare metric for stationary or slow-moving observers in outdoor spaces after dark. This review provides background of 16 relevant discomfort glare models that ...exist in outdoor environments at night for observers, residents, and pedestrians, for small sources, and non-uniform sources. It includes relevant model comparison studies for this application. It covers general research methods that study discomfort glare – psychophysical, physiological, and behavioral, and model development methods – empirical and visual system-based. The paper discusses the measurement difficulties of glare-relevant parameters in the field and future needs. Recommendations for future research directions and steps forward are offered.
As daylighting becomes an increasingly important component of design for energy savings and views to the outside, it is necessary to take into disadvantages that windows pose including the ...possibility of glare. It is crucial to understand how current metrics of glare perform this task. Validation studies were performed on five glare indices including Daylight Glare Probability (DGP) and Daylight Glare Index (DGI) that have been developed specifically for daylight glare issues. A parallel human subject study has been performed to collect subjective discomfort glare evaluations of daylit conditions. In addition, high dynamic range imaging was used to capture and analyze the glare scenes that were experienced by those human subjects. More than 450 daylight glare scenes and subjective surveys were collected in a closed office setting. The collected data were processed in Evalglare to obtain glare scores, and the results were compared for statistical analysis of subjective evaluations. The results show that DGP functions best at absence of glare and presence of intolerable glare; but in between it provides disappointingly low predictions. DGI underestimates glare while Visual Comfort Probability and CIE Glare Index overestimate it. This evaluation comparison study supports the findings that the five glare indices have significant inconsistency and inaccuracy issues. The glare indices behaved differently based on the perceived glare categories: imperceptible, perceptible, disturbing, and intolerable. The existing glare score ranges are compared to the newly defined glare score ranges for further improvement.
•450 glare scenes were analyzed to investigate existing discomfort glare metrics.•DGP performs best in evaluating imperceptible and intolerable glare scenes.•DGI underestimates discomfort glare while VCP and CGI overestimate it.•UGR performs best under perceptible and disturbing glare ranges.•Existing glare score ranges should be further verified to improve accuracy.
GLANCE (GLare ANnual Classes Evaluation) is a simplified method to evaluate glare conditions over a grid of points in a space on an annual basis. The method is based on three methodological ...assumptions: (i) the vertical illuminance (Ev) is adopted as the parameter to estimate the daylight glare condition in each point of the space; (ii) daylight glare conditions are expressed in terms of Daylight Glare Comfort Classes (DGCCs); (iii) the annual time-series of Ev and DGP for a single reference point are calculated and correlated to determine the DGCC of each point.
The method allows faster glare analyses to be performed, compared to the time needed for spatio-temporal analyses using DGP. To describe the method and demonstrate its accuracy, a study was carried out using a sample space with three orientations (East, South, and West) and a glazing with various light transmittances in the range 0.05-0.75. A grid of 9 viewpoints, with 5 view directions, was assumed, for a total of 2160 combinations. The performance of the GLANCE method proved to be robust in estimating the DGCCs for the cases analysed, as shown by the Youden index, which was higher than 0.85 for over 90% of the cases considered.
•GLANCE (GLare ANnual Classes Evaluation) allows spatio-temporal glare analyses.•The eye-level vertical illuminance at each viewpoint is used to assess DGP classes.•The performance of using Ev instead of DGP values is calculated and discussed.•The diagnostic performance relative to 2160 cases of a side-lit office is assessed.•GLANCE allows faster glare analyses compared to calculation of DGP annual profiles.
Current discomfort glare prediction metrics usually account for at least one of the two categories of effects that induce discomfort glare – the saturation and contrast effects. Saturation-driven ...metrics (overall illuminance on the eye) are suited for brightly lit scenes in general. On the contrary, contrast-driven metrics (luminance ratio in the field of view) usually perform better in high contrast conditions such as with small-sized bright glare sources. Only a few existing metrics consider both effects, such as the Daylight Glare Probability (DGP). However, even these “hybrid” metrics may underperform in conditions other than those considered when they were developed, such as in dim scenes with high contrast glare. This paper investigates the ability of current glare indicators to predict perceived discomfort glare in user-evaluated scenes depending on two different adaptation levels. Towards this end, we used a composite dataset of six laboratory studies performed previously and separately in various parts of the world. According to Receiver Operator Characteristics (ROC) findings and complementary statistical research, the hybrid metrics DGP and Eccologit perform best in both investigated ranges (dimmer and brighter scenes). For the single-effect metrics, the contrast-driven metrics appear to perform better than saturation-driven metrics in lower adaptation levels (dimmer scenes), while the reverse is seen in higher adaptation levels (brighter scenes). As a result, metrics that only consider one effect should be used with caution. Although hybrid metrics continue to perform well in the investigated scenes, further research is needed to extend their applicability to a larger variety of lighting conditions that may be observed in work environments.
•We classified and compared the predictive performance of glare metrics in bright vs. dim scenes.•We used a composite dataset of six studies done in daylight-dominated office-like settings.•Hybrid metrics generally predict glare well in all investigated scenarios.•In bright-light scenarios, saturation-driven glare metrics outperformed contrast-driven glare metrics.•In low-light scenarios, contrast-driven glare metrics outperformed saturation-driven glare metrics.
The anti‐glare panels along highways can block the dazzling lights of opposing vehicles at night, playing an important role in the highway safety. Inspired by the highway anti‐glare panels, wind ...energy harvesting triboelectric nanogenerator (AG‐TENG) arrays to properly capture energy from highway moving vehicles is developed. A single AG‐TENG installation module can achieve a high power density of 0.2 Wm−2 at a wind speed of 3 m s−1. This wind speed is too low to drive conventional wind energy harvesting equipment. The performance of the AG‐TENG shows no degradation after 80 h of continuous operation (1 440 000 times). Thus, with the rational consideration and features, the system can generate enough power to drive internet of things (IoT) devices and environmental sensors, as well as offer wireless alarming and radio frequency identification vehicle monitoring. This study provides a promising strategy to properly harvest wind energy on highways using existing infrastructures under the condition of even no natural wind, showing broad application prospects in distributed environmental monitoring, intelligent highways, and the IoT.
To properly capture energy from highway moving vehicles, wind energy harvesting triboelectric nanogenerator arrays based on highway anti‐glare panels are developed. A single installation module can achieve a high power density of 0.2 Wm−2 at a wind speed of 3 m s−1. The device shows no performance degradation after 80 h of continuous operation (1 440 000 times).
Because well-being is becoming a major challenge in construction alongside energy efficiency, there is an increasing need to be able to quantify discomfort in buildings. In the case of discomfort ...glare, the kind of glare provoking an irritating or distracting effect, no current indices can properly explain the high variability existing between individuals’ discomfort glare perceptions. This is due to the fact that some of the factors influencing discomfort glare perception are still unknown and the mechanism behind the discomfort glare process is not well understood. Therefore, this article aims to review the factors potentially influencing discomfort glare perception from daylight. Every factor having been studied at least once for its potential influence on discomfort glare perception has been listed, described, and analyzed. Furthermore, this study categorizes the influence of these factors on discomfort glare by introducing an influence indicator based on the number of studies having investigated the factor, the sample size of these studies, and the agreement between them. The suggested categories rate a factor influence as “almost certain,” “more likely,” “somewhat likely,” “inconclusive,” “somewhat unlikely,” “less likely,” or “almost certainly null.” Tables summarize the main information about the studies and the influencing factors. As expected, factors almost certainly influencing discomfort glare perception are the luminance of the glare source, adaptation level, contrast effect, and size and position of the glare source. In contrast, factors that almost certainly do not influence discomfort glare perception are the gender and optical correction of the observer. All other factors from the list of 30, such as the attractiveness of the view through the window or the culture of the observer, require additional studies to determine whether or not they influence discomfort glare perception.
The specular reflectance of a surface is an important factor that determines the gloss and glare observed from a display. This study compares several different methods for measuring specular ...reflectance and demonstrates their accuracy relative to a goniometric BRDF measurement.
In this work, thermal and visual comfort of low heat loss switchable suspended particle device-vacuum (SPD-vacuum) glazing was investigated for less energy-hungry adaptive building’s glazing or ...façade integration at temperate climate. This SPD-vacuum glazing had 38% visible transmittance in the presence of 110 V applied an alternating voltage and 2% visible transmittance in the absence of electrical power. Outdoor test cell characterisation was employed to measure the thermal and daylighting parameters of this glazing. Solar heat gain or solar factor was calculated using non calorimetric methods and varied between 0.38 (Switch OFF/opaque) to 0.51 (Switch ON/transparent). Test cell indoor and ambient parameters (incident solar radiation and ambient temperature) were engaged for thermal comfort analysis by using PMV and PPD methods. Visual comfort was analysed from glare potential, useful daylight index, and colour properties. The comfortable thermal environment was attainable using both states of this glazing for a clear sunny day. Acceptable daylight throughout the day was possible for a clear sunny day for opaque state; however clear state offered allowable/comfortable correlated colour temperature (CCT) of 5786.18 K and colour rendering index (CRI) of 94.83.
•Spectral measurement of combined suspended particle -vacuum glazing provided 38% transmission while 110 V AC was supplied.•Thermal comfort of suspended particle device-vacuum combined glazing was evaluated using PMV and PPD methods.•Visual comfort was calculated using useful daylight, daylight glare and colour properties.
The increasing trend of employing glazed façades to utilize daylight in the buildings has made it necessary to develop measures to avoid excessive sunlight penetration in such daylit spaces. In ...Thailand, only a few studies have focused on daylight glare, and therefore, applicable criteria are required to fulfill the local preference. This study aimed to determine daylight glare thresholds on the basis of the occupants’ responses. A post-occupancy evaluation with a simplified daylight glare probability (DGPs) model was performed in eight open-plan office spaces located in Bangkok, Thailand. The occupants participated in a survey including a subjective questionnaire; the results showed that the DGPs model performed effectively for glare prediction, with a preference for a lower level than that found in the current references. Statistical analysis helped mark the threshold values for each glare sensation level: imperceptible–perceptible = 0.22; perceptible–disturbing = 0.24; and disturbing–intolerable = 0.26. The findings of this study can be considered as initial evidence for improving the understanding of local occupants’ perspectives and illumination standards, which currently encourage daylight utilization without any specific glare control strategies.
The anti-glare facilities in median strips are designed to block opposing headlights in order to avoid disability glare, but a large amount of headlight leakage results in uncomfortable glare, to the ...point that drivers can barely detect dangerous obstacles or road conditions. This paper aims to explore the glare range under high-beam headlights on drivers' visual requirements. Based on an analysis of the mechanism of headlight glare, this paper proposes a subjective headlight glare scale, and classifies glare discomfort into two categories: interference glare, and acceptability glare. Combining the scales, 24 drivers and a standard light-emitting diode automotive headlamp were used to conduct glare effect tests. The size of the laboratory that closes to scotopic vision is 12 m × 6 m. The illuminance thresholds of disability glare-interference glare (DGIG) and interference glare-acceptability glare (IGAG), along with the spatial distribution of each glare level, were collected at the longitudinal distances of 3 m, 5 m, 7 m, 10 m, and 12 m. Meanwhile, the illuminance threshold and the spatial distribution of each glare level up to a longitudinal distance of 120 m were calculated. The results indicate that disability glare is distributed in the central area, while interference glare and acceptability glare are distributed from the center to the margins. At the same longitudinal distance, the vertical illuminance of the driver's eye under the same glare level is almost equal. In the range of a longitudinal distance of 120 m, the spatial distribution of each glare level enlarges with each increase in longitudinal distance. The results can provide scientific evidence for calculating the reasonable heights of anti-glare facilities for expressways with different alignments.
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