Temporal variables and personal factors in glare sensation

Previous laboratory experiments have provided evidence of an effect of time of day on glare sensation. During the tests, temporal variables and personal factors were also measured to analyse their influence on levels of visual discomfort as the day progresses. The results revealed statistically significant and practically relevant tendencies towards greater tolerance to source luminance from artificial lighting at all times of day for earlier chronotypes and for participants not having ingested caffeine. No conclusive evidence was found for the effect of fatigue, sky condition and prior light exposure on glare sensation throughout the day. These findings suggest that temporal variables and personal factors should be measured in conjunction with visual discomfort levels to explore the causes of the wide individual differences commonly associated with the subjective evaluation of glare sensation

Discomfort glare and time of day

There are strong reasons to suspect that glare sensation varies with time of the day. This study was designed to test whether such a relationship exists. Thirty subjects were exposed to an artificial lighting source at four times of the day. The source luminance was progressively increased and subjects were required to give Glare Sensation Votes (GSVs) corresponding to the level of visual discomfort experienced. Glare indices were calculated for every reported GSV, and results were statistically analysed. The findings indicated a tendency towards greater tolerance to luminance increases in artificial lighting as the day progresses. This trend was found not to be statistically related to the possible confounding variable of learning, providing evidence of an effect of time of the day on glare sensation

Improving lighting quality by practical measurements of the luminance distribution

\u3cp\u3eLight is one of the important aspects for a comfortable office environment. Too often high quality lighting is not achieved. Lighting quality can be defined by different aspects that are relevant such as the quantity, distribution, glare, spectral power distribution, daylight, directionality, and dynamics of light. The luminance distribution seems to be a suitable measure to achieve high quality lighting. The luminance distribution can be measured, with a practical accuracy, by commercially available cameras and fisheye lenses. All these aspects spectral power distribution can be measured using a camera-based luminance distribution measurement device. So, a luminance distribution measurement device is an excellent tool to measure or indicate lighting quality. It can be used to achieve a better understanding of lighting quality and potentially it can be implemented in automated building control systems.\u3c/p\u3