The Experts below are selected from a list of 20778 Experts worldwide ranked by ideXlab platform
Danny H.w. Li - One of the best experts on this subject based on the ideXlab platform.
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a simplified procedure for determining indoor daylight Illuminance using daylight coefficient concept
Building and Environment, 2006Co-Authors: Danny H.w. Li, G. H.w. CheungAbstract:The first step in evaluating the visual performance and energy efficiency provided by daylight requires an accurate estimation of the amount of daylight entering a building. The actual daylight Illuminance of a room is mainly influenced by the luminance levels and patterns of the sky in the direction of view of the window at that time. The daylight coefficient concept, which considers the changes in the luminance of the sky elements, offers a more effective way of computing indoor daylight Illuminances. Recently, Kittler et al. have proposed a new range of 15 standard sky luminance distributions including the CIE (International Commission on Illumination) standard clear sky. Lately, these 15 sky luminance models have been adopted as the CIE Standard General Skies. This paper presents a graphical method to calculate interior Illuminance for the CIE standard clear sky using the daylight coefficient approach. The simplified techniques in the form of a nomograph and Waldram diagram were established and described. The performance of the proposed approach was evaluated against the results obtained by an independent calculation approach and a computer simulation program. It was shown that the daylight Illuminances estimated by our graphical tool were in reasonably good agreement with those produced from the other two methods. The findings provide building professionals and students a reliable and simple alternative that incorporates the daylight coefficient concept to estimate the interior daylight Illuminance and assess daylighting performance.
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A simplified procedure for determining indoor daylight Illuminance using daylight coefficient concept
Building and Environment, 2006Co-Authors: Danny H.w. Li, G. H.w. Cheung, Chris C.s. LauAbstract:The first step in evaluating the visual performance and energy efficiency provided by daylight requires an accurate estimation of the amount of daylight entering a building. The actual daylight Illuminance of a room is mainly influenced by the luminance levels and patterns of the sky in the direction of view of the window at that time. The daylight coefficient concept, which considers the changes in the luminance of the sky elements, offers a more effective way of computing indoor daylight Illuminances. Recently, Kittler et al. have proposed a new range of 15 standard sky luminance distributions including the CIE (International Commission on Illumination) standard clear sky. Lately, these 15 sky luminance models have been adopted as the CIE Standard General Skies. This paper presents a graphical method to calculate interior Illuminance for the CIE standard clear sky using the daylight coefficient approach. The simplified techniques in the form of a nomograph and Waldram diagram were established and described. The performance of the proposed approach was evaluated against the results obtained by an independent calculation approach and a computer simulation program. It was shown that the daylight Illuminances estimated by our graphical tool were in reasonably good agreement with those produced from the other two methods. The findings provide building professionals and students a reliable and simple alternative that incorporates the daylight coefficient concept to estimate the interior daylight Illuminance and assess daylighting performance. © 2005 Elsevier Ltd. All rights reserved.
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an analysis of measured and simulated daylight Illuminance and lighting savings in a daylit corridor
Building and Environment, 2005Co-Authors: Danny H.w. Li, Ernest K W TsangAbstract:Lighting control integrated with daylighting is recognised as an important and useful strategy in energy-efficient building designs and operations. Prediction of the internal daylight levels is a key stage in daylighting designs. With the advances in computer technology, the computation of daylight Illuminances can be conducted via lighting simulation program. This paper presents a study of the daylight coefficient (DC) approach using RADIANCE lighting software in simulating the indoor daylight Illuminance of a corridor. The interior daylight Illuminance data measured in the corridor were compared with the simulated results based on the computer software. It was found that the DC approach could give satisfactory results especially for the sun-shaded surface and sun-facing surface receiving a large amount of direct sunlight. Further, the daylight Illuminance detected by the photosensor was also simulated in conjunction with measured daylight Illuminance, dimming ratio and electric lighting power to predict the lighting energy savings. The findings suggested that the measured and predicted data showed a good agreement when large electric lighting savings resulted. The probable reasons causing the discrepancies were discussed.
G. H.w. Cheung - One of the best experts on this subject based on the ideXlab platform.
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a simplified procedure for determining indoor daylight Illuminance using daylight coefficient concept
Building and Environment, 2006Co-Authors: Danny H.w. Li, G. H.w. CheungAbstract:The first step in evaluating the visual performance and energy efficiency provided by daylight requires an accurate estimation of the amount of daylight entering a building. The actual daylight Illuminance of a room is mainly influenced by the luminance levels and patterns of the sky in the direction of view of the window at that time. The daylight coefficient concept, which considers the changes in the luminance of the sky elements, offers a more effective way of computing indoor daylight Illuminances. Recently, Kittler et al. have proposed a new range of 15 standard sky luminance distributions including the CIE (International Commission on Illumination) standard clear sky. Lately, these 15 sky luminance models have been adopted as the CIE Standard General Skies. This paper presents a graphical method to calculate interior Illuminance for the CIE standard clear sky using the daylight coefficient approach. The simplified techniques in the form of a nomograph and Waldram diagram were established and described. The performance of the proposed approach was evaluated against the results obtained by an independent calculation approach and a computer simulation program. It was shown that the daylight Illuminances estimated by our graphical tool were in reasonably good agreement with those produced from the other two methods. The findings provide building professionals and students a reliable and simple alternative that incorporates the daylight coefficient concept to estimate the interior daylight Illuminance and assess daylighting performance.
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A simplified procedure for determining indoor daylight Illuminance using daylight coefficient concept
Building and Environment, 2006Co-Authors: Danny H.w. Li, G. H.w. Cheung, Chris C.s. LauAbstract:The first step in evaluating the visual performance and energy efficiency provided by daylight requires an accurate estimation of the amount of daylight entering a building. The actual daylight Illuminance of a room is mainly influenced by the luminance levels and patterns of the sky in the direction of view of the window at that time. The daylight coefficient concept, which considers the changes in the luminance of the sky elements, offers a more effective way of computing indoor daylight Illuminances. Recently, Kittler et al. have proposed a new range of 15 standard sky luminance distributions including the CIE (International Commission on Illumination) standard clear sky. Lately, these 15 sky luminance models have been adopted as the CIE Standard General Skies. This paper presents a graphical method to calculate interior Illuminance for the CIE standard clear sky using the daylight coefficient approach. The simplified techniques in the form of a nomograph and Waldram diagram were established and described. The performance of the proposed approach was evaluated against the results obtained by an independent calculation approach and a computer simulation program. It was shown that the daylight Illuminances estimated by our graphical tool were in reasonably good agreement with those produced from the other two methods. The findings provide building professionals and students a reliable and simple alternative that incorporates the daylight coefficient concept to estimate the interior daylight Illuminance and assess daylighting performance. © 2005 Elsevier Ltd. All rights reserved.
Thierry Baccino - One of the best experts on this subject based on the ideXlab platform.
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effects of luminance and Illuminance on visual fatigue and arousal during digital reading
Computers in Human Behavior, 2014Co-Authors: Simone Benedetto, Andrea Carbone, Veronique Draizerbib, Marco Pedrotti, Thierry BaccinoAbstract:We studied the effect of luminance and Illuminance on visual fatigue and arousal.We employed an approach based on eye, performance and subjective measures.Higher levels of screen luminance increase visual fatigue.Higher levels of either screen luminance or ambient Illuminance increase arousal.Findings might have practical implications for adaptive brightness solutions. We investigated the conjoint effect of screen luminance and ambient Illuminance on visual fatigue and arousal during prolonged digital reading (one hour) by means of a multidimensional approach based on eye, performance and subjective measures. Two levels of screen luminance (low, high) and two levels of ambient Illuminance (low, high) were tested in a 2×2 between-subjects design in which participants were arbitrarily allocated to four groups, one for each combined level of luminance and Illuminance. Results showed that reading under high levels of screen luminance increases visual fatigue, as reflected by a decrease of eye blinks. Concerning arousal, exposure to higher levels of either luminance or Illuminance increased alertness and performance. Faster saccades, increased reading speed and less microsaccades were found under high screen luminance. Fewer regressive saccades and shorter reaction times were observed under high ambient Illuminance. However, the reason why some of these measures are sensitive to screen luminance while other to ambient Illuminance remains unknown. These findings might have practical implications for the implementation of adaptive brightness solutions and for the online detection of both visual fatigue and arousal levels during digital reading.
Chris C.s. Lau - One of the best experts on this subject based on the ideXlab platform.
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A simplified procedure for determining indoor daylight Illuminance using daylight coefficient concept
Building and Environment, 2006Co-Authors: Danny H.w. Li, G. H.w. Cheung, Chris C.s. LauAbstract:The first step in evaluating the visual performance and energy efficiency provided by daylight requires an accurate estimation of the amount of daylight entering a building. The actual daylight Illuminance of a room is mainly influenced by the luminance levels and patterns of the sky in the direction of view of the window at that time. The daylight coefficient concept, which considers the changes in the luminance of the sky elements, offers a more effective way of computing indoor daylight Illuminances. Recently, Kittler et al. have proposed a new range of 15 standard sky luminance distributions including the CIE (International Commission on Illumination) standard clear sky. Lately, these 15 sky luminance models have been adopted as the CIE Standard General Skies. This paper presents a graphical method to calculate interior Illuminance for the CIE standard clear sky using the daylight coefficient approach. The simplified techniques in the form of a nomograph and Waldram diagram were established and described. The performance of the proposed approach was evaluated against the results obtained by an independent calculation approach and a computer simulation program. It was shown that the daylight Illuminances estimated by our graphical tool were in reasonably good agreement with those produced from the other two methods. The findings provide building professionals and students a reliable and simple alternative that incorporates the daylight coefficient concept to estimate the interior daylight Illuminance and assess daylighting performance. © 2005 Elsevier Ltd. All rights reserved.
Hai Ye - One of the best experts on this subject based on the ideXlab platform.
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visual alliesthesia the gap between comfortable and stimulating Illuminance settings
Building and Environment, 2014Co-Authors: Hai YeAbstract:Abstract Based on the theory of “alliesthesia”, there is a gap between how people evaluate an environmental stimulus and how they actually react to the stimulus that changes the state of the interior milieu. Occupants preferred a low Illuminance for comfort without or with less stimulation, but the comfortable setting might fail to generate productive environments because comfort is a reference to elimination of discomfort, which assumes that absence of stimulus (such as brightness) is good. A lighting experiment is conducted to identify the gap between comfortable and stimulating Illuminance settings. Participants were asked to conduct a visual task and to respond a questionnaire under different Illuminances ranging from below 200 Lux to above 900 Lux. The Illuminance setting (401–500 Lux) on which subjects felt neutral and most comfortable well complied with current lighting standards. However, the Illuminance setting (above 900 Lux) on which subjects scored highly in the visual task and perceived the visual task stimulating was much higher than the most comfortable and neutral setting. As an alternative to pursuing comfort based on neutrality, this article argues designing stimulating environments with restorative elements for productivity and well-being.
