The Effect of Overhead Glare on Visual Discomfort

Ngai, Peter Y.; Boyce, P.R.

doi:10.1080/00994480.2000.10748315

Cited by 42 publications

(35 citation statements)

References 3 publications

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“…Yes or no?" This method is adopted by Boyce et al 2,3 and yields the proportion of subjects indicating that a given lighting condition is comfortable. The drawback of this method is that it can only give a rough indication of whether discomfort increases or decreases with, e.g., the intensity of the light source.…”

Section: Subjective Evaluation Methodsmentioning

confidence: 99%

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A study on overhead glare in office lighting conditions

et al. 2011

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Abstract— High‐intensity light sources illuminating the human eye may create discomfort glare, or at higher intensities even disability glare. In many office lighting conditions, light from overhead luminaires in the ceiling may deliver stray light into human eyes, and as such create discomfort glare, generally referred to as overhead glare. In this paper, overhead glare for a LED luminaire comprising a matrix array of small LED sources using subjective evaluation methodologies and theoretical models, commonly accepted to evaluate glare, were investigated. The perceived overhead glare of the LED luminaire is evaluated at various luminance levels and at different angles (i.e., between 55 and 90°) with respect to the line of sight of the viewer. The results show that a luminaire comprising a matrix of high‐intensity point sources can cause overhead glare and can become glary at lower averaged luminance levels than a luminaire with a uniform light source even at high evaluation angles with respect to the line of sight of the viewer. In addition, the conventional UGR model for predicting discomfort glare needs adaptation for a reliable prediction of perceived overhead glare of complex LED luminaires consisting of a matrix of small‐sized high‐intensity light sources.

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Section: Subjective Evaluation Methodsmentioning

confidence: 99%

“…Based on the findings of Takahashi et al 5 we hypothesize that our point-array LED luminaire causes the same level of overhead glare as what is known for uniform light sources. 2,3 In the remainder of the paper, Sec. 4 describes the experimental design, the results of which are summarized in Sec.…”

Section: Introductionmentioning

confidence: 99%

A study on overhead glare in office lighting conditions

et al. 2011

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“…The normalized luminance distribution over the exit window is shown in Fig.1b. During the experiment, subjects were asked to evaluate the discomfort glare of the various light conditions in 2 ways: on the seven-point rating scale (see Table 1), which is the same rating scale as used by Boyce and Ngai in their research [2,3]; and by indicating whether the lighting condition was comfortable or not.…”

Section: Experimental Designmentioning

confidence: 99%

P.30: Effect of the Correlated Color Temperature of Light on Overhead Glare in Offices

Zhang

Yan

Liu

et al. 2013

Symp Digest of Tech Papers

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We performed a subjective experiment measuring perceived overhead glare from a fluorescent luminaire with either a Correlated Color Temperature (CCT) of 4000K or 6300K. The group of 18 participants was equally divided over males and females, and almost equally over subjects wearing glasses and subjects without glasses. The results show that a light source with a higher CCT induces statistically significantly more overhead glare. In addition, differences in perceived overhead glare cannot be attributed to either gender or visual correction means.

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“…An obvious example would be the discomfort described by of ce workers after prolonged viewing of PC monitors. 18 When lighting is non-optimal, observers report fatigue after a relatively short period. These effects would almost certainly be accompanied by above-average levels of EMG activity which, crucially, would be recordable prior to the onset of any sensations of tiredness.…”

Section: Discussionmentioning

confidence: 99%

The ocular stress monitor: a new device for measuring discomfort glare

Murray¹,

Plainis²,

Carden³

2002

Lighting Research & Technology

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Discomfort glare is always accompanied by a strong contraction or spasm in the muscles surrounding the eye. A portable device for measuring the electrical activity generated by this muscle spasm is described. The device samples the signal from electrodes placed around the eye. It is composed of a narrow-band ampli er/transmitter, a receiver/frequency converter and a tone generator. The signal amplitude is proportional to the vertical illuminance at the eye and can therefore be used as an objective index of the discomfort induced. The results compare favourably with subjective assessment.

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The Effect of Overhead Glare on Visual Discomfort

Cited by 42 publications

References 3 publications

A study on overhead glare in office lighting conditions

A study on overhead glare in office lighting conditions

P.30: Effect of the Correlated Color Temperature of Light on Overhead Glare in Offices

The ocular stress monitor: a new device for measuring discomfort glare

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