Glare Evaluation Research Articles

The influence of shading control strategies on the visual comfort and energy demand of office buildings

A lighting control strategy using daylighting is important to reduce energy consumption, and to provide occupants with visual comfort. The objective of this research is to evaluate visual comfort and building energy demand, and suggest lighting and shading control strategies for visual comfort and building energy savings. This research intends to achieve visual comfort and energy savings in an office building, by means of visual environmental control, and focuses on a quantitative criterion (illuminance), and a qualitative criterion (glare index) in daylighting. We used HDR images captured in real scene and simulation (DIVA-for-Rhino) for glare evaluation. The measured data from the mock-up room and the scale model were compared, to validate the simulation tool. Vertical eye illuminance (Ev) is recommended for the glare index, in place of the DGI or DGP. To prevent disturbing glare and to secure maximum daylight, control strategies of lighting and shading are suggested, related to the Ev value. In addition, the EnergyPlus program was used for calculation of the annual energy consumption. Building energy consumption is presented according to three building orientations, and 10 control strategies of lighting and shading. If there is no need to consider glare, a blind slat angle of 0° or dynamic shading is better in winter, regardless of the building orientation. In summer, a blind slat angle of 30° (static angle) or dynamic shading is suitable for an energy efficient and anti-glare control strategy.

Discomfort glare for white LED light sources with different spatial arrangements

Quantitative relations between discomfort glare evaluation and photometric quantities such as illuminance at the observer’s eye, average luminance of the source area, average luminance of the effective area and effective glare luminance for white LED sources having a variety of spatial luminance distributions have been investigated. Effective glare luminance, which is the sum of luminances in the luminaire area divided by the effective area, explains the scaling results of all sources in the same way. In addition, a new equation modified from the Commission Internationale de l'Éclairage Unified Glare Rating formula using the effective glare luminance showed a strong correlation with the scaling results. It is thus suggested that effective glare luminance is a useful index of discomfort glare for light sources having different spatial luminance distributions.

Evaluation of discomfort glare in the 50+ elderly: experimental study.

The aim of the study was to analyze discomfort glare sensation in subjects aged 50 years and more in comparison with younger subjects (i.e. younger than 35 years of age). The experiments were performed on a computer workstation placed in controlled lighting environment where 2 discomfort glare conditions were modeled. Each participant performed for about 1 h specially designed visual tasks, including the tests with Landolt's rings presented on the screen by a computer program. The glare evaluation method consisted of subjective evaluation of discomfort glare on the semantic glare rating scale, tests of mesopic contrast and glare sensitivity, subjective assessment of lighting quality and asthenopic symptoms. The time needed to perform the task and the number of mistakes were also recorded. The subjective evaluation of glare was compared with the Unified Glare Rating (UGR) index calculated by the DIALux simulation program. A higher percentage of the younger group subjects assessed glare after the experimental session as uncomfortable and intolerable than in the 50+ group, who more often assessed glare as acceptable. The assessment of discomfort glare in the younger group corresponded to higher UGR value compared to UGR value calculated by DIALux. In the 50+ group, such correlation was found only for lower discomfort glare (UGR = 19). The results showed that younger participants more frequently suffered from visual fatigue and assessed lighting as less comfortable. However, the mesopic glare sensitivity increased significantly after the experiments only in the 50+ group under both glare conditions. The obtained results showed that discomfort glare sensation changes with age. The younger population seems to be more sensitive and demanding than the older one in relation to discomfort glare limiting, in spite of the lack of significant objective measures of fatigue. The exposure of the elderly to bigger discomfort glare could adversely affect the objective measures of fatigue like mesopic glare sensitivity and visual performance.

Development of new daylight glare analysis methodology using absolute glare factor and relative glare factor

Many glare analysis methods have been developed and utilized for predicting and quantifying discomfort glare issues inside a building. However, the existing methods have not been able to accurately evaluate glare issues when extremely bright glare sources are involved. As luminance values of glare sources get extremely high, the impact of the absolute luminance value begins to dominate the impact of the contrast ratio. This type of glare should be classified as absolute factor glare which is different from relative factor glare in terms of glare analysis. There are many existing luminance thresholds and contrast ratios that address these two factors, but they are not consistent. Due to the inconsistency and inaccuracy issues, the existing glare analysis methods have been barely utilized in design practice. Therefore, it is necessary to develop a more accurate methodology that separates the absolute glare component from the relative glare component. This approach can increase the accuracy of glare evaluation and simplify glare evaluation procedures. This paper makes clear definitions of the absolute and relative glare factors and also suggests three different luminance ranges for absolute glare factor, relative glare factor, and no-glare based on the results of this preliminary study.

The Variation of the Glare Source Luminance According to the Average Luminance of Visual Field

This study was conducted to propose a method of identifying glare sources from windows. Discomfort glare from windows of a classroom was evaluated in the experiments involving subjects, and the features that made the subjects recognize the glare sources in the windows were explored. The results of the evaluation led to the realization that the subjects regarded the patches that were causing discomfort glare as the glare sources on windows. It means that the patches having low luminance were not the causes of discomfort glare and were excluded from glare sources for the discomfort glare evaluation. There was a linear relationship between the average luminance of the visual field and the average luminance of the glare patches. The linear relationship has been expressed by a formula. The proposed formula has made it easier to identify the glare patches from windows. The approach as suggested in this study is distinctive to the others by the fact that the glare source was determined based on the average luminance of the visual field.

EXPERIMENTAL STUDY ON LUMINANCE IN THE DAYTIME OF TRANSLUCENT THERMAL INSULATION WALLS FOR DETACHED HOUSES

The purpose of this study is to identify acceptable luminance range of translucent thermal insulation walls, in order to decide optical transmittance of the walls, especially. Two series of subjective experiments with actual translucent thermal insulation walls were carried out in a full-scale building. The first experiment showed the relationship between the luminance of the walls and discomfort glare evaluation, GSV, while the second experiment showed the relationship between the luminance of the walls and brightness of the walls. It was found that the suitable brightness was give by the luminance ranging from 300 to 3000 [cd/m2], that was influenced by the plan of the room and the size of the walls and the windows.

Influence of Window Views on the Subjective Evaluation of Discomfort Glare

A window is an indispensable element in a building and acts as a view-giving component that keeps occupants in touch with the outside. This study investigated the potential effect of different window views on the subjective assessment of discomfort glare from a simulated window that rendered blank, natural and man-made views from far to close distances. Forty-eight subjects (24 men, 24 women) participated in the experiments. The experimental results confirmed that the subjective evaluation of discomfort glare can vary with the type of window views presented. The results also indicated that there were noticeable variations in the subjective assessments of discomfort glare over the same visual stimuli. A preliminary criterion for classification of subjects’ sensitivity to glare was illustrated and the difference for the ‘‘glare-sensitive’’ and ‘‘glareinsensitive’’ people was statistically significant. This study found that the psychological factor such as window views could be an important factor in the subjective evaluation of discomfort glare. Widely used glare evaluation formulas such as unified glare rating and daylight glare index would not consider psychological factors. Thus, the finding from this study would contribute to a more realistic evaluation of discomfort glare for future design of glare control systems.

Discomfort glare of tungsten halogen and high intensity discharge headlamps

For the evaluation of headlamps in everyday traffic situations, discomfort glare is an important aspect in addition to quality of illumination. The Laboratory of Lighting Technology at the Technische Universitat Darmstadt has been doing research on discomfort glare evaluation for several decades. Now the impact of light source, headlamp optics and spectrum of adaptation field on discomfort glare in real traffic situations was tested for the first time within one test series for tungsten halogen and high intensity discharge (so-called HID or Xenon) headlamps. Moreover, the measured results are compared with calculated values, based on a spectral sensitivity function for discomfort glare.

건축실내 인공조명의 불쾌글레어 평가실험에 적용된 실험변수의 민감도 분석에 관한 연구

본 연구에서는 한국인의 시각적 특성을 반영한 불쾌글레어의 합리적인 예측을 위해 국내에 실제적으로 적용가능 한 불쾌글레어 예측식을 작성하는 것이 최종목표로 하고 있으며, 본 논문에서는 주변의 일반적인 사무실 건물의 조명환경을 대상으로 기본 단위로 구획하여 실물대모형(Mock-up)을 제작하여 실험을 진행하고 글레어에 최대 영향 요인인 광원휘도를 비롯한 배경휘도, 입체각, 광원면적, 루버종류와 불쾌글레어의 관계를 도출하는 것을 목적으로 하였다.BR 본 연구는 다음과 같이 4단계로 나누어 연구를 진행하였다. 첫째, 불쾌글레어 평가등급을 정의하고 분류하기 위하여 선행연구에서 사용된 평가등급을 조사하여 연구목적에 부합되도록 수정하여 실험에 적용할 수 있도록 하였다. 둘째, 기존 불쾌글레어 평가실험식에 대한 검토를 통해 실험변수, 변수범위, 평가대상, 평가내용 등을 선정하였다. 셋째, 연구의 목적에 부합되도록 실험변인을 조절할 수 있는 실물대모형(Mock-up)을 제작하여 불쾌글레어 평가실험을 실시하였다. 최종적으로 불쾌글레어감과 광원휘도, 루버종류, 광원면적, 피험자위치간의 관계분석을 통해 실험 변수의 민감도를 분석하였다.BR 연구 결과 인공광원의 불쾌글레어감에 영향을 주는 주요 변수는 광원휘도, 루버의 유무, 광원면적, 피험자위치(입체각) 순으로 영향을 미치는 것으로 나타났다.

건축실내 인공조명의 불쾌글레어 평가를 위한 기초적 연구

건축 실내의 조명환경의 쾌적성을 평가하는 것은 주로 불쾌감을 유발하는 글레어의 정도를 인식하는 것이라 할 수 있다. 현재 국외에서 연구된 불쾌글레어를 평가하기 위한 실험식을 그대로 적용하기에는 글레어의 감각을 느끼는 정도가 인종에 따라 크게 다르게 나타나기 때문에 무리가 있다. 따라서 본 연구에서는 한국인의 시각적인 특성에 맞는 합리적인 불쾌글레어 평가를 위한 예측식을 작성하는 것을 최종목표로 하였으며 다음과 같이 4단계로 연구를 진행하였다. 첫째, 기존의 불쾌글레어 평가식에 대한 검토를 통해 실험변인들을 선정하였다. 둘째, 본 연구의 목적에 맞는 실험변인과 조건을 제어할 수 있는 실물대모형을 제작하였다. 셋째, 불쾌글레어 평가실험을 실시하였다. 최종적으로, 선행연구에서 서양인을 대상으로 제안된 UGR평가법과의 비교분석을 실시하였다.BR 연구의 결과를 요약하면, 1)불쾌글레어는 광원휘도, 배경휘도, 피험자와 시선의 위치 등에 크게 영향을 받는 것으로 나타났다. 2)실내 불쾌글레어 평가에서 광원과 피험자간의 거리보다 시야내에 글레어 광원이 위치하는 지의 여부가 더 중대한 영향을 미쳤다. 3)대표적인 불쾌글레어 평가시스템인 UGR과 비교ㆍ분석한 결과 다소 차이가 있는 것으로 나타났다. 이것은 한국인의 불쾌글레어감이 서양인과 차이가 있다는 것을 보여준다.

VCP and UGR Glare Evaluation Systems: A Look Back and a Way Forward

We review the discomfort glare evaluation systems of the Illuminating Engineering Society of North America (IESNA), Visual Comfort Probability (VCP), and that of the International Commission on Illumination (CIE), Unified Glare Rating (UGR), as they apply to interior electric lighting. We provide an overview of the history and research behind them and an extensive bibliography.The current IESNA Handbook states that the VCP is very limited in applicability to modern lighting systems, and was validated for lensed fluorescent systems only. The CIE's UGR system has been shown to be a good predictor of human responses for lensed fluorescent systems. Recently, the CIE has proposed extensions to the UGR discomfort glare model, which are applicable to most modern lighting systems, including small, large, and complex systems. We provide a review of these extensions and the research behind them. There are many similarities between VCP and UGR and only minor differences, and so we recommend that research be undertaken to validate the UGR's extensions to small, large, and complex systems.

A new evaluation method for daylight discomfort glare

A proper glare prediction method is needed to promote visual comfort at workplaces. Only a few formulae have been proposed for discomfort glare of daylight origin, and they are inadequate in real daylight situations. No standard monitoring procedure is available for daylight glare evaluation on a comparative basis. This paper introduces an improved glare evaluation method consisting of a standard monitoring protocol and advanced formulae. The results, however, are not shown here. The proposed method appears to yield sensible and consistent glare values when tested against the existing glare evaluation system of Chauvel and it has also been coded into a small program to calculate luminance values and incorporated with Radiance to compute daylight glare indices. The method was developed with the hope that architects and lighting designers would adopt it as an easy and reliable method for evaluating discomfort glare from daylight. The future work, which is an ongoing research, is to create the use of scientific-knowledge computational tools in the later stages of design in an effort to provide optimum choices of daylighting design with respect to light level and glare using the new glare algorithm. Relevance to industry The new method can be applied in the design of daylight responsive lighting control systems, shading devices, daylighting systems and glazing materials. When the efficiency of daylight for the indoor illumination is improved, also the visual comfort and the savings of electric energy for artificial lighting can be increased.

A new daylight glare evaluation method introduction of the monitoring protocol and calculation method

A new daylight glare evaluation method introduction of the monitoring protocol and calculation method

A New Daylight Glare Evaluation Method

Ergonomic design of workplaces requires a proper method for predicting glare to promote visual comfort. Only a few formulae have been proposed for discomfort glare of daylight origin, and they are inadequate in real daylight situations. No standard monitoring procedure is available to establish a basis for daylight glare evaluation on a comparative basis. This paper introduces a new glare evaluation method consisting of a standard monitoring protocol and advanced formulae. The method has been tested against the existing glare evaluation system proposed by Chauvel using Radiance, a lighting simulation program. The two systems are compared here in terms of formulations and their performance when tested on different types of window transmittances over the whole year. Given reliable results, the new DGIN procedure was coded into a small program and incorporated with Radiance to calculate the luminance values and to compute daylight glare indices. Also glare from another daylighting control strategy—the light shelf—was investigated. The new method is sensitive to the vertical illuminance and thereby to the source illuminance, and appears to yield sensible and consistent glare values; the higher is the source luminance, the worse will be the glare sensation. The method was developed with the hope that architects and lighting designers would adopt it as an easy and reliable method for evaluating discomfort glare from daylight. The future work, which is an ongoing research, is to create the use of scientific-knowledge computational tools in the later stages of design in an effort to provide optimum choices of daylighting design with respect to light level and glareusing the new glare algorithm.

A new daylight glare evaluation method: Introduction of the monitoring protocol and calculation method

Ergonomic design of workplaces requires a proper method for predicting glare to promote visual comfort. Only a few formulae have been proposed for discomfort glare of daylight origin, and they are inadequate to predict glare sensation in real daylight situations. No standard monitoring procedure is available to establish a basis for glare evaluation on a comparative basis under real sky conditions. This paper introduces a new glare evaluation method consisting of a standard monitoring protocol and formulae for window luminance, adaptation luminance and exterior luminance, and formulae for the solid angle, the modified solid angle and the configuration factor of the window. The glare evaluation procedure was developed with the hope that architects and lighting designers would adopt it as an easy and reliable method for evaluating discomfort glare sensation from daylighting. The method has yielded in real measurements and computer simulations sensible and consistent glare values. The results of the experiments, however, are not presented here in their entirety because of the large size of that part. The future work, which is an ongoing research, is to create the use of scientific-knowledge computational tools in the later stages of design in an effort to provide optimum choices of daylighting design with respect to light level and glare using the new glare algorithm.

A New Daylight Glare Evaluation Method.

A proper glare prediction method is needed to promote visual comfort at workplaces. Only a few formulae have been proposed for discomfort glare of daylight origin, and they are inadequate in real daylight situations. No standard monitoring procedure is available for daylight glare evaluation on a comparative basis. This paper introduces an improved glare evaluation method consisting of a standard monitoring protocol and advanced formulae. The method has been tested against the existing glare evaluation system of Chauvel on different types of window size using Radiance, a lighting simulation program. Given reliable results, the DGIN procedure was coded into a small program and incorporated with Radiance to compute daylight glare indices. The method was developed with the hope that architects and lighting designers would adopt it as an easy and reliable method for evaluating discomfort glare from daylight. The future work, which is an ongoing research, is to create the use of scientific-knowledge computational tools in the later stages of design in an effort to provide optimum choices of daylighting design with respect to light level and glare using the new glare algorithm.

Applicability of CIE's Glare(GR) Evaluation System for Outdoor Facilities to Indoor Sports Facilities.

We studied whether or not the glare evaluation system for outdoor facilities (CIE112-1994)1) can be applied to indoor sport facilities. Firstly we devised a method for obtaining veiling luminance of environment (Lve), which was hard to measure in indoor facilities, based on the luminance distribution of photographs. We then analyzed the validity of the GR calculating formula +based on the results of glare evaluating experiments in four indoor facilities and data from various luminance measurements taken. In conclusion, we found that the GR calculating formula is applicable to indoor facilities without any modification, and that there was no significant differences in estimated GR values results when evaluating the equivalent veiling luminance of environment using the average luminance (illuminance) of the floor.

光源の位置が背景輝度とグレア感に与える影響に関する試行研究

光源の位置が背景輝度とグレア感に与える影響に関する試行研究

施設用Hf蛍光灯照明器具のグレア評価

施設用Hf蛍光灯照明器具のグレア評価

CIE屋外施設のグレア評価法の屋内スポーツ施設への適応性

CIE屋外施設のグレア評価法の屋内スポーツ施設への適応性