Pub Date : 2023-11-13DOI: 10.1177/14771535231203570
A Mehri, R Golmohammadi, M Aliabadi, M Farhadian, JD Bullough, M Samavati
This study aimed to investigate the impact of automotive headlights of different correlated colour temperatures (CCT) on the visual and non-visual performance of drivers. Forty drivers participated in the study, driving in a simulated night road for 45 min in three sessions. The LED headlights had CCTs of 3176 K, 4358 K and 6923 K, with an illuminance of 5 lx perpendicular to the participants’ eyes. Heart rate variability (HRV), psychomotor vigilance task and Karolinska sleepiness scale were measured before and after driving. At the end of the trials, achromatic far and near visual acuity tests, as well as achromatic far and near contrast sensitivity tests, were conducted. The study revealed that CCT did not affect achromatic far and near visual acuity. However, CCT had an impact on achromatic near and far contrast sensitivity, with higher CCT resulting in improved achromatic contrast sensitivity. As the CCT decreased, participants exhibited increased reaction time, made more errors, and reported higher sleepiness. The most significant physiological changes in HRV, including alterations in low frequency (LF), high frequency (HF) and LF/HF, were observed at lower CCT. The findings of this study suggest that both the visual and non-visual performance of drivers were enhanced when high CCTs were used for automotive LED headlights.
{"title":"Visual and non-visual responses of drivers to simulated LED headlights varying in correlated colour temperature","authors":"A Mehri, R Golmohammadi, M Aliabadi, M Farhadian, JD Bullough, M Samavati","doi":"10.1177/14771535231203570","DOIUrl":"https://doi.org/10.1177/14771535231203570","url":null,"abstract":"This study aimed to investigate the impact of automotive headlights of different correlated colour temperatures (CCT) on the visual and non-visual performance of drivers. Forty drivers participated in the study, driving in a simulated night road for 45 min in three sessions. The LED headlights had CCTs of 3176 K, 4358 K and 6923 K, with an illuminance of 5 lx perpendicular to the participants’ eyes. Heart rate variability (HRV), psychomotor vigilance task and Karolinska sleepiness scale were measured before and after driving. At the end of the trials, achromatic far and near visual acuity tests, as well as achromatic far and near contrast sensitivity tests, were conducted. The study revealed that CCT did not affect achromatic far and near visual acuity. However, CCT had an impact on achromatic near and far contrast sensitivity, with higher CCT resulting in improved achromatic contrast sensitivity. As the CCT decreased, participants exhibited increased reaction time, made more errors, and reported higher sleepiness. The most significant physiological changes in HRV, including alterations in low frequency (LF), high frequency (HF) and LF/HF, were observed at lower CCT. The findings of this study suggest that both the visual and non-visual performance of drivers were enhanced when high CCTs were used for automotive LED headlights.","PeriodicalId":18133,"journal":{"name":"Lighting Research & Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136352122","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-13DOI: 10.1177/14771535231207099
V Kumar, DS Bisht, H Garg
The paper presents the design of a Customised Homocentric Fresnel Collector (CHFC) based on the principle of superposition and the longest wavelength of the visible spectrum. A bottom-to-top approach is proposed that uses an individually designed homocentric prism based on visible light at a wavelength of 740 nm. The homocentric prism of the CHFC follows a uniform height method with varying pitch. An area focus is achieved on the plastic optical fibre (POF) bundle inlet without employing any secondary optical element. The CHFC achieves a uniform distribution of concentrated visible spectrum radiation from the Sun with a significant reduction in the hotspot problem. Comparison of the CHFC versus a mid-wavelength-based Fresnel lens shows that the CHFC delivers 9.24% more visible spectrum radiation on the POF bundle inlet. The simulated optical efficiency of the CHFC is 90.6%. Numerical analysis of a CHFC-based daylighting system shows that 331 lm (efficiency of 39.4%) can be delivered via a 10 m long fibre bundle made up of 32 POF each of 1 mm diameter. Experimental observations demonstrated that the maximum temperature recorded on the POF bundle entrance is 56.8°C during peak direct normal illuminance conditions. Note that the spectral distribution of the radiation emerging from the POF differs from the incident sunlight spectrum because of the transmission characteristics of the optical components used in the CHFC testbed.
{"title":"Design, analysis and validation of Customised Homocentric Fresnel Collector based on longest wavelength of visible spectrum","authors":"V Kumar, DS Bisht, H Garg","doi":"10.1177/14771535231207099","DOIUrl":"https://doi.org/10.1177/14771535231207099","url":null,"abstract":"The paper presents the design of a Customised Homocentric Fresnel Collector (CHFC) based on the principle of superposition and the longest wavelength of the visible spectrum. A bottom-to-top approach is proposed that uses an individually designed homocentric prism based on visible light at a wavelength of 740 nm. The homocentric prism of the CHFC follows a uniform height method with varying pitch. An area focus is achieved on the plastic optical fibre (POF) bundle inlet without employing any secondary optical element. The CHFC achieves a uniform distribution of concentrated visible spectrum radiation from the Sun with a significant reduction in the hotspot problem. Comparison of the CHFC versus a mid-wavelength-based Fresnel lens shows that the CHFC delivers 9.24% more visible spectrum radiation on the POF bundle inlet. The simulated optical efficiency of the CHFC is 90.6%. Numerical analysis of a CHFC-based daylighting system shows that 331 lm (efficiency of 39.4%) can be delivered via a 10 m long fibre bundle made up of 32 POF each of 1 mm diameter. Experimental observations demonstrated that the maximum temperature recorded on the POF bundle entrance is 56.8°C during peak direct normal illuminance conditions. Note that the spectral distribution of the radiation emerging from the POF differs from the incident sunlight spectrum because of the transmission characteristics of the optical components used in the CHFC testbed.","PeriodicalId":18133,"journal":{"name":"Lighting Research & Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136347512","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-10DOI: 10.1177/14771535231207810
L Liu, GA Keoleian, GM Lewis
Lighting makes up 17% of electrical loads and the largest energy end use in commercial buildings. Linear fixtures are among the largest opportunities for energy efficiency improvement, given their long operating hours. With continued, rapid light-emitting diode (LED) development and more LED replacement products on the market, lighting replacement decisions become more complex and warrant re-examination. With a goal to inform building managers and other decision-makers with practical guidance on lighting replacement, this study is a life cycle cost (LCC) analysis that compares the cost–benefit of six replacement options (one fluorescent and five LED) for a 0.61 m by 1.22 m (2 ft by 4 ft) T8 recessed troffer based on data for 168 lighting products from an online vendor. Results show that direct wire (i.e. unballasted) LED retrofits are the least-cost option to replacing fluorescent lamps in terms of normalized LCC. Plug-and-play lamps suffer from a lock-in with ballasts, but their ease of installation can help spur LED adoption. In cases where an existing ballast is still usable, hybrid LED retrofits provide the least upfront cost option by deferring the cost of rewiring. LED luminaires can offer improved aesthetics and reliability; however, they have high upfront cost. Among them, luminaires with replaceable lamps offer lower cost than those without.
{"title":"Life cycle cost analysis of LED retrofit and luminaire replacements for four-foot T8 troffers","authors":"L Liu, GA Keoleian, GM Lewis","doi":"10.1177/14771535231207810","DOIUrl":"https://doi.org/10.1177/14771535231207810","url":null,"abstract":"Lighting makes up 17% of electrical loads and the largest energy end use in commercial buildings. Linear fixtures are among the largest opportunities for energy efficiency improvement, given their long operating hours. With continued, rapid light-emitting diode (LED) development and more LED replacement products on the market, lighting replacement decisions become more complex and warrant re-examination. With a goal to inform building managers and other decision-makers with practical guidance on lighting replacement, this study is a life cycle cost (LCC) analysis that compares the cost–benefit of six replacement options (one fluorescent and five LED) for a 0.61 m by 1.22 m (2 ft by 4 ft) T8 recessed troffer based on data for 168 lighting products from an online vendor. Results show that direct wire (i.e. unballasted) LED retrofits are the least-cost option to replacing fluorescent lamps in terms of normalized LCC. Plug-and-play lamps suffer from a lock-in with ballasts, but their ease of installation can help spur LED adoption. In cases where an existing ballast is still usable, hybrid LED retrofits provide the least upfront cost option by deferring the cost of rewiring. LED luminaires can offer improved aesthetics and reliability; however, they have high upfront cost. Among them, luminaires with replaceable lamps offer lower cost than those without.","PeriodicalId":18133,"journal":{"name":"Lighting Research & Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135185929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-01DOI: 10.1177/14771535231204155
{"title":"Opinion: How to foster a motivating ecosystem for our next generation","authors":"","doi":"10.1177/14771535231204155","DOIUrl":"https://doi.org/10.1177/14771535231204155","url":null,"abstract":"","PeriodicalId":18133,"journal":{"name":"Lighting Research & Technology","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139304525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-11-01DOI: 10.1177/14771535231204154
E. Brembilla, K. Chamilothori
{"title":"Editorial: Special issue for early career researchers in lighting","authors":"E. Brembilla, K. Chamilothori","doi":"10.1177/14771535231204154","DOIUrl":"https://doi.org/10.1177/14771535231204154","url":null,"abstract":"","PeriodicalId":18133,"journal":{"name":"Lighting Research & Technology","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139301134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-21DOI: 10.1177/14771535231200390
VKR Hennig, N Gentile, S Fotios, C Sternudd, M Johansson
This research concerns the influence of electric lighting on user behaviour in public squares and whether differences in people’s use of the square can be observed between daylight and darkness. Previous research on pedestrians suggests that lighting can support human needs for reassurance, accessibility, comfort and pleasure. While these findings are also likely to be applicable to the use of public squares, there is little empirical evidence to verify that. A field study was conducted to explore user behaviour in two differently illuminated public squares. Observations of the movements and stationary activities of people in the squares were recorded at both squares for the same times of day in the weeks before and after the daylight savings clock change, enabling a comparison of activity in daylight and after dark. 5296 observations were recorded and lighting conditions were captured with HDR-photography and aerial photos. Kirseberg square, with asymmetric luminaires and metal halide lamps, revealed a decrease in stationary activity after dark. Lindeborg square, with omnidirectional luminaires and high-pressure sodium lamps, revealed an increase in stationary activity. In conclusion, the patterns of user behaviour in the two public squares after dark seem to be differently influenced by electric lighting, pointing to a need for further understanding of users’ experience of the squares after dark.
{"title":"User behaviour in public squares after dark","authors":"VKR Hennig, N Gentile, S Fotios, C Sternudd, M Johansson","doi":"10.1177/14771535231200390","DOIUrl":"https://doi.org/10.1177/14771535231200390","url":null,"abstract":"This research concerns the influence of electric lighting on user behaviour in public squares and whether differences in people’s use of the square can be observed between daylight and darkness. Previous research on pedestrians suggests that lighting can support human needs for reassurance, accessibility, comfort and pleasure. While these findings are also likely to be applicable to the use of public squares, there is little empirical evidence to verify that. A field study was conducted to explore user behaviour in two differently illuminated public squares. Observations of the movements and stationary activities of people in the squares were recorded at both squares for the same times of day in the weeks before and after the daylight savings clock change, enabling a comparison of activity in daylight and after dark. 5296 observations were recorded and lighting conditions were captured with HDR-photography and aerial photos. Kirseberg square, with asymmetric luminaires and metal halide lamps, revealed a decrease in stationary activity after dark. Lindeborg square, with omnidirectional luminaires and high-pressure sodium lamps, revealed an increase in stationary activity. In conclusion, the patterns of user behaviour in the two public squares after dark seem to be differently influenced by electric lighting, pointing to a need for further understanding of users’ experience of the squares after dark.","PeriodicalId":18133,"journal":{"name":"Lighting Research & Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135512977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-19DOI: 10.1177/14771535231204162
M Englezou, A Michael
Since discovering the intrinsically photosensitive retinal ganglion cells (ipRGCs) and their impact on the circadian rhythm, many disciplines have been researching the physiological and psychological effects of light on humans. However, not much research has been conducted on how the spatial configuration of a room (orientation and gaze direction) changes the light quality and quantity. This research examines the variability of the natural lighting spectrum, focusing on light intensity, the spectrum itself, as well as variations across seasons and hours. The metrics examined are the CIE S 026 melanopic equivalent daylight illuminance (melanopic EDI) and melanopic daylight efficacy ratio (melanopic DER). Field measurements were taken in a room with a south orientation located in Cyprus, using a spectrometer. The main parameters under study were eight gaze directions, four seasons (June, September, December and March) and four different hours each day (09:00, 12:00, 15:00 and 18:00) for 20 positions in the test room. The results show the impact of season, time and gaze direction on the melanopic DER and melanopic EDI. Overall, due to the low sun angle and direct sunlight exposure in the winter, the melanopic EDI was much higher compared to the other three seasons, whereas the melanopic DER had the lowest values. For all seasons and times, most of the cases achieved the minimum recommendation for daytime light exposure of melanopic EDI of more than 250 lx.
自发现内在光敏视网膜神经节细胞(ipRGCs)及其对昼夜节律的影响以来，许多学科都在研究光对人类生理和心理的影响。然而，关于房间的空间结构(方向和凝视方向)如何改变光线质量和数量的研究并不多。这项研究考察了自然光照光谱的可变性，重点是光强度、光谱本身，以及季节和时间的变化。所检查的指标是CIE S 026黑视等效日光照度(黑视EDI)和黑视日光效率比(黑视DER)。现场测量是在塞浦路斯一间朝南的房间里使用光谱仪进行的。研究的主要参数为8个注视方向、4个季节(6月、9月、12月、3月)和每天4个不同时段(09:00、12:00、15:00、18:00)，共20个位置。结果显示季节、时间和凝视方向对黑视DER和黑视EDI的影响。总体而言，由于冬季低太阳角度和阳光直射，黑视性EDI明显高于其他三个季节，而黑视性DER值最低。在所有季节和时间，大多数病例都达到了建议的最低黑视性EDI白天光照超过250 lx。
{"title":"Investigation of the daylight spectrum in an indoor environment using CIE S 026 melanopic metrics","authors":"M Englezou, A Michael","doi":"10.1177/14771535231204162","DOIUrl":"https://doi.org/10.1177/14771535231204162","url":null,"abstract":"Since discovering the intrinsically photosensitive retinal ganglion cells (ipRGCs) and their impact on the circadian rhythm, many disciplines have been researching the physiological and psychological effects of light on humans. However, not much research has been conducted on how the spatial configuration of a room (orientation and gaze direction) changes the light quality and quantity. This research examines the variability of the natural lighting spectrum, focusing on light intensity, the spectrum itself, as well as variations across seasons and hours. The metrics examined are the CIE S 026 melanopic equivalent daylight illuminance (melanopic EDI) and melanopic daylight efficacy ratio (melanopic DER). Field measurements were taken in a room with a south orientation located in Cyprus, using a spectrometer. The main parameters under study were eight gaze directions, four seasons (June, September, December and March) and four different hours each day (09:00, 12:00, 15:00 and 18:00) for 20 positions in the test room. The results show the impact of season, time and gaze direction on the melanopic DER and melanopic EDI. Overall, due to the low sun angle and direct sunlight exposure in the winter, the melanopic EDI was much higher compared to the other three seasons, whereas the melanopic DER had the lowest values. For all seasons and times, most of the cases achieved the minimum recommendation for daytime light exposure of melanopic EDI of more than 250 lx.","PeriodicalId":18133,"journal":{"name":"Lighting Research & Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135730207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
When studying discomfort glare, researchers tend to rely on a single questionnaire item to obtain user evaluations. It is unclear whether the choice of questionnaire item affects the distribution of user responses and leads to inconsistencies between studies. This study aims to investigate if different glare questionnaire items yield similar distributions of user discomfort in daylit environments. We conducted a comparative study of selected questionnaire items from previous glare experiments, testing them in three independent user studies with different lighting conditions and glare stimuli. We compared the resulting outputs across questionnaire items with 540 data points from 149 participants. Results indicated that ordinal questionnaire outputs show strong correlations (0.68 < ρ < 0.85), high internal reliability (α = 0.93) and captured the same latent construct. Binary questionnaire items reflected different glare thresholds but still correlated well with ordinal items. The construct validity of tested questionnaire items was confirmed through responses to an open-ended question. These findings suggest that the tested questionnaire items may be used for category rating-type discomfort glare evaluations and consistently capture the same construct.
{"title":"Comparison of questionnaire items for discomfort glare studies in daylit spaces","authors":"Geraldine Quek, Sneha Jain, Caroline Karmann, Clotilde Pierson, Jan Wienold, Marilyne Andersen","doi":"10.1177/14771535231203564","DOIUrl":"https://doi.org/10.1177/14771535231203564","url":null,"abstract":"When studying discomfort glare, researchers tend to rely on a single questionnaire item to obtain user evaluations. It is unclear whether the choice of questionnaire item affects the distribution of user responses and leads to inconsistencies between studies. This study aims to investigate if different glare questionnaire items yield similar distributions of user discomfort in daylit environments. We conducted a comparative study of selected questionnaire items from previous glare experiments, testing them in three independent user studies with different lighting conditions and glare stimuli. We compared the resulting outputs across questionnaire items with 540 data points from 149 participants. Results indicated that ordinal questionnaire outputs show strong correlations (0.68 < ρ < 0.85), high internal reliability (α = 0.93) and captured the same latent construct. Binary questionnaire items reflected different glare thresholds but still correlated well with ordinal items. The construct validity of tested questionnaire items was confirmed through responses to an open-ended question. These findings suggest that the tested questionnaire items may be used for category rating-type discomfort glare evaluations and consistently capture the same construct.","PeriodicalId":18133,"journal":{"name":"Lighting Research & Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135730530","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-01DOI: 10.1177/14771535221077350
A. Villalba, J. Yamín Garretón, A. Pattini
When solar radiation passes through a window, its spectral composition changes due to the presence of shades and glazing. While many studies have analysed the impact of different types of glass on correlated colour temperature (CCT), there are only a few cases in which the effect of shading and daylighting systems on this parameter was tested. This work analyses the impact of woven shade fabrics on the spectrum and intensity of daylight conditions in indoor spaces. A combined analysis of horizontal illuminance (Eh) and CCT was performed. It focused on the impact that physical properties of woven shade fabrics – colour and openness factor (OF) – had on the CCT and Eh values. In this study, 11 fabrics with different colours (white, grey and black) and varying OF were analysed. For the set of studied woven shade fabrics, it was found that fabric OF and colour had a significant effect on CCT and Eh. Results show that white and grey fabrics provided spaces with lower values of CCT than black fabrics. CCT values were compared with those proposed by standard EN 12464-1:2011.
{"title":"The impact of woven shade fabrics on correlated colour temperature and illuminance with daylighting","authors":"A. Villalba, J. Yamín Garretón, A. Pattini","doi":"10.1177/14771535221077350","DOIUrl":"https://doi.org/10.1177/14771535221077350","url":null,"abstract":"When solar radiation passes through a window, its spectral composition changes due to the presence of shades and glazing. While many studies have analysed the impact of different types of glass on correlated colour temperature (CCT), there are only a few cases in which the effect of shading and daylighting systems on this parameter was tested. This work analyses the impact of woven shade fabrics on the spectrum and intensity of daylight conditions in indoor spaces. A combined analysis of horizontal illuminance (Eh) and CCT was performed. It focused on the impact that physical properties of woven shade fabrics – colour and openness factor (OF) – had on the CCT and Eh values. In this study, 11 fabrics with different colours (white, grey and black) and varying OF were analysed. For the set of studied woven shade fabrics, it was found that fabric OF and colour had a significant effect on CCT and Eh. Results show that white and grey fabrics provided spaces with lower values of CCT than black fabrics. CCT values were compared with those proposed by standard EN 12464-1:2011.","PeriodicalId":18133,"journal":{"name":"Lighting Research & Technology","volume":null,"pages":null},"PeriodicalIF":2.5,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139329702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-20DOI: 10.1177/14771535231198564
J. Mardaljevic
This issue focuses on daylight-related research and a camera-based method to measure illuminance. Any form of illumination for occupied spaces – natural or artificial – needs to be considered in terms of both its quantity and its quality. A useful distinction, often made, is to consider quantity in terms of lux received on the task plane and quality in terms of the spectral power distribution of the light. While incomplete, it provided a useful starting point. Both the quantity and quality of illumination received at the eye are now a consideration for the assessment and/or prediction of the non-visual effects of light, for example, for circadian entrainment. The paper ‘Evaluation of sky spectra and sky models in daylighting simulations’ by Inanici et al. delves deeply into the various ways that the spectral component of illumination from sky light can be predicted. This timely study reveals much about the inner workings of these simulations and provides a much needed inter-model comparison. The prevailing qualitative character of illumination can also be inferred from measures of correlated colour temperature (CCT). While CCT has long been used to categorise sources of artificial light, the paper by Villalba et al. describes how to quantify the changes in CCT when direct solar radiation passes through various commonly used window shading materials. Titled ‘The impact of woven shade fabrics on correlated colour temperature and illuminance with daylighting’, the article presents empirical findings for a variety of shading materials. For a basement room where it is not possible have a window to the outside, the potential may exist to ‘collect’ daylight on the roof of the building and ‘transport’ it to the windowless space. One approach, which today has an established market presence, uses highly reflective light-pipes, typically 500 mm or greater in diameter. A promising rival approach uses instead a much thinner conduit made from a fibre-optic bundle, offering the potential for installation in buildings where space constraints may prohibit the use of the much larger light-pipes. Necessarily, the daylight collected on the roof must be concentrated for transport through the fibre-optic. The paper ‘Analysis, evaluation and integration of modular natural illumination system using a rectangular Fresnel lens for high performance’ by Garg et al. describes recent advances which could form the basis of a practical light-transport system based on fibre-optic bundles. Lastly, the paper ‘A joint validation study on camera-aided illuminance measurement’ by Mahlab et al. provides further evidence to support the use of camera-based methods to measure illuminance. As demonstrated in the article, using digital cameras to capture highdynamic range images of scenes has greatly expanded the potential for quantitative lighting analysis in realistic/complex scenes. This edition also offers a timely opportunity to remind potential contributors that the call for papers f
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