Pub Date : 2022-07-03DOI: 10.1080/15502724.2021.1951289
Peiyu Wu, Yi Lin, Qi Yao
ABSTRACT The lamp spectrum and the surface reflection both contribute to the luminous efficiency of the illuminated object. Hence, it may not be comprehensive to evaluate the luminous efficiency in a lighting environment only through the metrics with respect to lamps. Previous studies have investigated the effect of surface reflection on luminous efficiency, but few quantitative metrics have been proposed so far. In this study, statistical analysis and a validation experiment were conducted to investigate the extent to which the luminous efficacy of radiation (LER) determines the luminous efficiency of a colored surface. The correlation analysis was performed based on an index of the surface spectral reflectance, namely, the spectral reflectance luminous efficacy of radiation (SRLER). The correlation between the SRLER and LER varied with respect to the hues and saturation levels of the colored objects. In particular, highly linear correlations were observed in slightly saturated and highly saturated green, yellow, and purple-blue samples but not in highly saturated reddish samples. This suggests that when the illuminated environment contains a large portion of highly saturated reddish objects, the effectiveness of the LER is dependent on the spectral selectivity of the colored surface. The findings of this study contribute significantly to the comprehensive design of light source spectra and energy saving in actual lighting scenarios.
{"title":"Effectiveness of Light Source Efficiency for Characterization of Colored Surface Luminance","authors":"Peiyu Wu, Yi Lin, Qi Yao","doi":"10.1080/15502724.2021.1951289","DOIUrl":"https://doi.org/10.1080/15502724.2021.1951289","url":null,"abstract":"ABSTRACT The lamp spectrum and the surface reflection both contribute to the luminous efficiency of the illuminated object. Hence, it may not be comprehensive to evaluate the luminous efficiency in a lighting environment only through the metrics with respect to lamps. Previous studies have investigated the effect of surface reflection on luminous efficiency, but few quantitative metrics have been proposed so far. In this study, statistical analysis and a validation experiment were conducted to investigate the extent to which the luminous efficacy of radiation (LER) determines the luminous efficiency of a colored surface. The correlation analysis was performed based on an index of the surface spectral reflectance, namely, the spectral reflectance luminous efficacy of radiation (SRLER). The correlation between the SRLER and LER varied with respect to the hues and saturation levels of the colored objects. In particular, highly linear correlations were observed in slightly saturated and highly saturated green, yellow, and purple-blue samples but not in highly saturated reddish samples. This suggests that when the illuminated environment contains a large portion of highly saturated reddish objects, the effectiveness of the LER is dependent on the spectral selectivity of the colored surface. The findings of this study contribute significantly to the comprehensive design of light source spectra and energy saving in actual lighting scenarios.","PeriodicalId":49911,"journal":{"name":"Leukos","volume":"24 1","pages":"374 - 386"},"PeriodicalIF":3.6,"publicationDate":"2022-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72839245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2022-06-22DOI: 10.1080/15502724.2022.2077754
C. Martinsons, Nicolas Picard, S. Carré
ABSTRACT This paper presents a study of the spectral characteristics of temporal light modulation in several technologies of lighting products. An optical lock-in spectrometer was designed for this purpose and integrated in a spectral radiant flux measurement facility. It was applied to incandescent and fluorescent lamps, as well as lamps based on white phosphor-converted LEDs and tunable RGB LEDs. The results are well correlated with the light emission processes of each technology. For incandescent lamps, the spectral modulation follows a 1/λ relationship in agreement with the blackbody radiation laws. Measurements performed on halophosphate and tri-phosphor tubes agree well with published data. The modulation and phase spectra of fluorescent lamps reveal a variable modulation rate across the visible range, directly related to the fluorescence lifetimes of the different luminophores, which were estimated from our data using a model of single exponential decay.The spectral modulation of white phosphor-converted LED lamps is nearly constant across the visible spectrum, demonstrating that their color parameters can be assessed from the lock-in modulation amplitude spectrum. In the case of tunable RGB LED lamps using PWM, the spectral modulation widely differs from the steady-state spectral distribution and changes with the user settings, confirming the possible occurrence of temporal color artifacts. Optical lock-in spectrometry can be used to improve spectral and color measurements of solid-state lighting, opening new opportunities for laboratory and remote sensing applications. Other foreseeable applications of optical lock-in spectrometry are also presented.
{"title":"Optical Lock-in Spectrometry Reveals Useful Spectral Features of Temporal Light Modulation in Several Light Source Technologies","authors":"C. Martinsons, Nicolas Picard, S. Carré","doi":"10.1080/15502724.2022.2077754","DOIUrl":"https://doi.org/10.1080/15502724.2022.2077754","url":null,"abstract":"ABSTRACT This paper presents a study of the spectral characteristics of temporal light modulation in several technologies of lighting products. An optical lock-in spectrometer was designed for this purpose and integrated in a spectral radiant flux measurement facility. It was applied to incandescent and fluorescent lamps, as well as lamps based on white phosphor-converted LEDs and tunable RGB LEDs. The results are well correlated with the light emission processes of each technology. For incandescent lamps, the spectral modulation follows a 1/λ relationship in agreement with the blackbody radiation laws. Measurements performed on halophosphate and tri-phosphor tubes agree well with published data. The modulation and phase spectra of fluorescent lamps reveal a variable modulation rate across the visible range, directly related to the fluorescence lifetimes of the different luminophores, which were estimated from our data using a model of single exponential decay.The spectral modulation of white phosphor-converted LED lamps is nearly constant across the visible spectrum, demonstrating that their color parameters can be assessed from the lock-in modulation amplitude spectrum. In the case of tunable RGB LED lamps using PWM, the spectral modulation widely differs from the steady-state spectral distribution and changes with the user settings, confirming the possible occurrence of temporal color artifacts. Optical lock-in spectrometry can be used to improve spectral and color measurements of solid-state lighting, opening new opportunities for laboratory and remote sensing applications. Other foreseeable applications of optical lock-in spectrometry are also presented.","PeriodicalId":49911,"journal":{"name":"Leukos","volume":"172 1","pages":"146 - 164"},"PeriodicalIF":3.6,"publicationDate":"2022-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90979227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2022-06-21DOI: 10.1080/15502724.2022.2067866
Aiman Raza, D. Dumortier, S. Jost-Boissard, C. Cauwerts, M. Dubail
ABSTRACT This study aims to compare different hyperspectral imaging devices and identify their suitability for in-situ color and lighting research. Three hyperspectral cameras were compared for radiometric, photometric, and colorimetric accuracy. The visual quality of the images obtained with each device was also evaluated to test their suitability for psychophysical experiments on color perception. The accuracies were evaluated for LED sources with correlated color temperatures ranging from 2351 K to 6922 K. The hyperspectral cameras tested were found to have acceptable radiometric accuracies for chromatic content and different photometric and colorimetric accuracies. It was also identified that a good radiometric/photometric accuracy does not necessarily indicate a good colorimetric accuracy for the same device and color. It depends on the light sources and color patches, thus highlighting the need to identify the reproduction accuracy of every test device methodically. This accuracy study thus describes a formal layout for the characterization of hyperspectral imaging devices using identifiable error metrics.
{"title":"Accuracy of Hyperspectral Imaging Systems for Color and Lighting Research","authors":"Aiman Raza, D. Dumortier, S. Jost-Boissard, C. Cauwerts, M. Dubail","doi":"10.1080/15502724.2022.2067866","DOIUrl":"https://doi.org/10.1080/15502724.2022.2067866","url":null,"abstract":"ABSTRACT This study aims to compare different hyperspectral imaging devices and identify their suitability for in-situ color and lighting research. Three hyperspectral cameras were compared for radiometric, photometric, and colorimetric accuracy. The visual quality of the images obtained with each device was also evaluated to test their suitability for psychophysical experiments on color perception. The accuracies were evaluated for LED sources with correlated color temperatures ranging from 2351 K to 6922 K. The hyperspectral cameras tested were found to have acceptable radiometric accuracies for chromatic content and different photometric and colorimetric accuracies. It was also identified that a good radiometric/photometric accuracy does not necessarily indicate a good colorimetric accuracy for the same device and color. It depends on the light sources and color patches, thus highlighting the need to identify the reproduction accuracy of every test device methodically. This accuracy study thus describes a formal layout for the characterization of hyperspectral imaging devices using identifiable error metrics.","PeriodicalId":49911,"journal":{"name":"Leukos","volume":"4 1","pages":"16 - 34"},"PeriodicalIF":3.6,"publicationDate":"2022-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86346488","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2022-05-06DOI: 10.1080/15502724.2022.2055428
Won Hee Ko, S. Schiavon, S. Altomonte, M. Andersen, A. Batool, William Browning, Galen C. Burrell, K. Chamilothori, Y. Chan, G. Chinazzo, J. Christoffersen, Nancy Clanton, Christopher Connock, T. Dogan, B. Faircloth, L. Fernandes, L. Heschong, K. Houser, Mehlika Inanici, Alstan Jakubiec, Anjali Joseph, C. Karmann, M. Kent, K. Konis, Iason Konstantzos, Kera Lagios, Linda Lam, F. Lam, Eleanor S. Lee, Brendon Levitt, Wenting Li, P. MacNaughton, Ahoo Malekafzali Ardakan, J. Mardaljevic, B. Matusiak, W. Osterhaus, S. Petersen, Matt Piccone, C. Pierson, Brent Protzman, T. Rakha, C. Reinhart, Siobhan Rockcastle, Holly W. Samuelson, Luis Santos, A. Sawyer, S. Selkowitz, E. Sok, Jakob Strømann-Andersen, W. Sullivan, Irmak Turan, G. Unnikrishnan, William Vicent, Dan Weissman, J. Wienold
Window views that provide visual connections to the outdoors have been shown to have multiple positive effects on occupants (Heschong 2021). These effects include improved health, well-being (Beute and de Kort 2014), emotion (Ko et al. 2020), cognitive performance (Boubekri et al. 2020; Jamrozik et al. 2019; Ko et al. 2020), environmental satisfaction (Yildirim et al. 2007), reduced discomfort (Aries et al. 2010) and stress recovery (Ulrich 1984). A good window view may also increase the economic value of buildings (Baranzini and Schaerer 2011; Damigos and Anyfantis 2011; Turan et al. 2021). Even though many benefits from window views have been recognized, there are few design guidelines for assessing window view quality (CEN/TC 169, CEN/TC 169 2018; IWBI 2020; USGBC 2019). Moreover, the proposed approaches are not often supported by comprehensive and conclusive research findings. Although existing research has attempted to evaluate window view quality using a variety of assessment methods (Hellinga and Hordijk 2014; Li and Samuelson 2020; Mardaljevic 2019; Matusiak and Klöckner 2016; Turan et al. 2021), there is little alignment between methodologies and each of these studies only partially addresses the complex relationships between windows, outdoor and indoor conditions, and occupants (Ko et al. 2021; Waczynska et al. 2020). We lack consensus on a unified definition for window view quality that is applicable across occupancies and building types. In addition, while this is a topic of growing interest, there is limited research underway due to its complex nature, insufficient funding, and a lack of coordinated effort to move the field forward. In response to these problems, some of the authors of this editorial participated in a workshop on window view quality on October 28, 2021 at the University of California, Berkeley, which was complementary to a Virtual Symposium on Research and Design Practice Related to Window Views (“Symposium on Research and Design Practice Related to Window Views” 2021). This position statement started to take shape during this workshop. The symposium aimed to enhance interest and understanding among stakeholders regarding the benefits, complexities, and assessment methods for window views. The workshop aimed to engage the building science and design communities in this growing field, reach a consensus on the primary components of window view quality, and identify research gaps in current view assessment methods.
提供与室外视觉联系的窗户景观已被证明对居住者有多种积极影响(Heschong 2021)。这些影响包括改善健康、幸福感(Beute and de Kort 2014)、情绪(Ko et al. 2020)、认知表现(Boubekri et al. 2020;Jamrozik et al. 2019;Ko et al. 2020)，环境满意度(Yildirim et al. 2007)，减少不适(Aries et al. 2010)和压力恢复(Ulrich 1984)。良好的窗户景观也可能增加建筑物的经济价值(Baranzini和Schaerer 2011;Damigos and Anyfantis 2011;Turan et al. 2021)。尽管人们已经认识到窗户景观的许多好处，但很少有评估窗户景观质量的设计指南(CEN/TC 169, CEN/TC 169 2018;IWBI 2020;USGBC 2019)。此外，所提出的方法往往没有得到全面和结论性研究结果的支持。尽管现有的研究已经尝试使用各种评估方法来评估窗景质量(Hellinga and Hordijk 2014;李和萨缪尔森2020;Mardaljevic 2019;Matusiak and Klöckner 2016;Turan et al. 2021)，方法之间几乎没有一致性，这些研究中的每一项都只部分解决了窗户、室外和室内条件以及居住者之间的复杂关系(Ko et al. 2021;Waczynska et al. 2020)。对于适用于不同占用率和建筑类型的窗景质量的统一定义，我们缺乏共识。此外，尽管这是一个越来越受关注的话题，但由于其复杂性、资金不足以及缺乏协调一致的努力，正在进行的研究有限。针对这些问题，本社论的一些作者于2021年10月28日在加州大学伯克利分校参加了一个关于窗户景观质量的研讨会，这是对与窗户景观相关的研究和设计实践虚拟研讨会(“Symposium on Research and Design Practice Related to window Views”2021)的补充。这一立场声明是在这次研讨会上形成的。研讨会的目的是提高利益相关者对窗户景观的好处、复杂性和评估方法的兴趣和理解。研讨会旨在让建筑科学和设计界参与这一不断发展的领域，就窗户景观质量的主要组成部分达成共识，并确定当前景观评估方法的研究差距。
{"title":"Window View Quality: Why It Matters and What We Should Do","authors":"Won Hee Ko, S. Schiavon, S. Altomonte, M. Andersen, A. Batool, William Browning, Galen C. Burrell, K. Chamilothori, Y. Chan, G. Chinazzo, J. Christoffersen, Nancy Clanton, Christopher Connock, T. Dogan, B. Faircloth, L. Fernandes, L. Heschong, K. Houser, Mehlika Inanici, Alstan Jakubiec, Anjali Joseph, C. Karmann, M. Kent, K. Konis, Iason Konstantzos, Kera Lagios, Linda Lam, F. Lam, Eleanor S. Lee, Brendon Levitt, Wenting Li, P. MacNaughton, Ahoo Malekafzali Ardakan, J. Mardaljevic, B. Matusiak, W. Osterhaus, S. Petersen, Matt Piccone, C. Pierson, Brent Protzman, T. Rakha, C. Reinhart, Siobhan Rockcastle, Holly W. Samuelson, Luis Santos, A. Sawyer, S. Selkowitz, E. Sok, Jakob Strømann-Andersen, W. Sullivan, Irmak Turan, G. Unnikrishnan, William Vicent, Dan Weissman, J. Wienold","doi":"10.1080/15502724.2022.2055428","DOIUrl":"https://doi.org/10.1080/15502724.2022.2055428","url":null,"abstract":"Window views that provide visual connections to the outdoors have been shown to have multiple positive effects on occupants (Heschong 2021). These effects include improved health, well-being (Beute and de Kort 2014), emotion (Ko et al. 2020), cognitive performance (Boubekri et al. 2020; Jamrozik et al. 2019; Ko et al. 2020), environmental satisfaction (Yildirim et al. 2007), reduced discomfort (Aries et al. 2010) and stress recovery (Ulrich 1984). A good window view may also increase the economic value of buildings (Baranzini and Schaerer 2011; Damigos and Anyfantis 2011; Turan et al. 2021). Even though many benefits from window views have been recognized, there are few design guidelines for assessing window view quality (CEN/TC 169, CEN/TC 169 2018; IWBI 2020; USGBC 2019). Moreover, the proposed approaches are not often supported by comprehensive and conclusive research findings. Although existing research has attempted to evaluate window view quality using a variety of assessment methods (Hellinga and Hordijk 2014; Li and Samuelson 2020; Mardaljevic 2019; Matusiak and Klöckner 2016; Turan et al. 2021), there is little alignment between methodologies and each of these studies only partially addresses the complex relationships between windows, outdoor and indoor conditions, and occupants (Ko et al. 2021; Waczynska et al. 2020). We lack consensus on a unified definition for window view quality that is applicable across occupancies and building types. In addition, while this is a topic of growing interest, there is limited research underway due to its complex nature, insufficient funding, and a lack of coordinated effort to move the field forward. In response to these problems, some of the authors of this editorial participated in a workshop on window view quality on October 28, 2021 at the University of California, Berkeley, which was complementary to a Virtual Symposium on Research and Design Practice Related to Window Views (“Symposium on Research and Design Practice Related to Window Views” 2021). This position statement started to take shape during this workshop. The symposium aimed to enhance interest and understanding among stakeholders regarding the benefits, complexities, and assessment methods for window views. The workshop aimed to engage the building science and design communities in this growing field, reach a consensus on the primary components of window view quality, and identify research gaps in current view assessment methods.","PeriodicalId":49911,"journal":{"name":"Leukos","volume":"1 1","pages":"259 - 267"},"PeriodicalIF":3.6,"publicationDate":"2022-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90892254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2022-05-05DOI: 10.1080/15502724.2022.2059669
A. Wilkerson, S. Safranek, L. Irvin, Lauri Tredinnick
ABSTRACT The advancement of LED and controls technology, computing capacity, and software provides new opportunities for researchers and designers to work together to further optimize spaces for occupant benefit. Lighting system control data from five neonatal intensive care unit patient rooms was collected over a 25-week monitoring period and analyzed to better understand occupant response to a tunable lighting system with automatic transitions throughout the day. Lighting systems are very rarely refined after installation based on actual use. Objective data detailing how the lighting system is used by the actual occupants highlights the opportunities for optimization after installation and provides insight for improving the next design. As use of the data becomes more commonplace, it can be leveraged for design recommendations. The collection of the data required no additional cost beyond the time for examining the data. The analysis revealed several clear opportunities for improvement, including adjustments to the default control setting at night, re-labeling of the control stations, and adjustments to the nighttime fade rate. The patient room occupants were active users of the different zones, dimming options, and manual overrides made available by the lighting system.
{"title":"Lighting System Control Data to Improve Design and Operation: Tunable Lighting System Data from NICU Patient Rooms","authors":"A. Wilkerson, S. Safranek, L. Irvin, Lauri Tredinnick","doi":"10.1080/15502724.2022.2059669","DOIUrl":"https://doi.org/10.1080/15502724.2022.2059669","url":null,"abstract":"ABSTRACT The advancement of LED and controls technology, computing capacity, and software provides new opportunities for researchers and designers to work together to further optimize spaces for occupant benefit. Lighting system control data from five neonatal intensive care unit patient rooms was collected over a 25-week monitoring period and analyzed to better understand occupant response to a tunable lighting system with automatic transitions throughout the day. Lighting systems are very rarely refined after installation based on actual use. Objective data detailing how the lighting system is used by the actual occupants highlights the opportunities for optimization after installation and provides insight for improving the next design. As use of the data becomes more commonplace, it can be leveraged for design recommendations. The collection of the data required no additional cost beyond the time for examining the data. The analysis revealed several clear opportunities for improvement, including adjustments to the default control setting at night, re-labeling of the control stations, and adjustments to the nighttime fade rate. The patient room occupants were active users of the different zones, dimming options, and manual overrides made available by the lighting system.","PeriodicalId":49911,"journal":{"name":"Leukos","volume":"27 1","pages":"94 - 109"},"PeriodicalIF":3.6,"publicationDate":"2022-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91101587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2022-04-01DOI: 10.1080/15502724.2022.2043163
J. Nie, Zhizhong Chen, F. Jiao, Yifan Chen, J. Zhan, Yiyong Chen, Z. Pan, X. Kang, Yongzhi Wang, Qi Wang, Weimin Dang, W. Dong, Shuzhe Zhou, Xin Yu, Yuzhen Tong, Guoyi Zhang, B. Shen
ABSTRACT The blue light hazard (BLH) and luminous efficacy of a source ( ) are associated with the photobiological safety and energy saving of light-emitting diodes (LEDs), respectively. In this study, we used genetic algorithm (GA) to optimize the BLH, , and color rendering parameters of five-chip hybrid white LEDs. Based on the optimal results, we used five-chip LEDs to obtain the hybrid white light. Their peak wavelengths were 461.5 (blue), 523.9 (green), 588.2 (orange), 643.3 (red), and 694.2 nm (far-red), respectively. In practice, the blue light hazard efficiency of radiation (BLHER) of the hybrid white light was less than 0.10, which was lower than half of the most common light sources. The ranged from 51.6 to 115.6 lm/W at correlated color temperature (CCT) from 2700 to 6500 K. On average, the CIE general color rendering index (Ra), CIE special color rendering index for the ninth deep red test sample (R9), ANSI/IES TM-30 color fidelity index (Rf), and color gamut index (Rg) of hybrid white light were 91.3, 87.8, 83.3, and 96.7, respectively. The melanopic efficacy of luminous radiation ( ) was tunable in the range of 0.60 to 1.35 mW/lm. These results demonstrated that we used far-red LEDs to fabricate white light with low BLH and relatively high efficiency.
{"title":"Utilization of far-red LED to minimize blue light hazard for dynamic semiconductor lighting","authors":"J. Nie, Zhizhong Chen, F. Jiao, Yifan Chen, J. Zhan, Yiyong Chen, Z. Pan, X. Kang, Yongzhi Wang, Qi Wang, Weimin Dang, W. Dong, Shuzhe Zhou, Xin Yu, Yuzhen Tong, Guoyi Zhang, B. Shen","doi":"10.1080/15502724.2022.2043163","DOIUrl":"https://doi.org/10.1080/15502724.2022.2043163","url":null,"abstract":"ABSTRACT The blue light hazard (BLH) and luminous efficacy of a source ( ) are associated with the photobiological safety and energy saving of light-emitting diodes (LEDs), respectively. In this study, we used genetic algorithm (GA) to optimize the BLH, , and color rendering parameters of five-chip hybrid white LEDs. Based on the optimal results, we used five-chip LEDs to obtain the hybrid white light. Their peak wavelengths were 461.5 (blue), 523.9 (green), 588.2 (orange), 643.3 (red), and 694.2 nm (far-red), respectively. In practice, the blue light hazard efficiency of radiation (BLHER) of the hybrid white light was less than 0.10, which was lower than half of the most common light sources. The ranged from 51.6 to 115.6 lm/W at correlated color temperature (CCT) from 2700 to 6500 K. On average, the CIE general color rendering index (Ra), CIE special color rendering index for the ninth deep red test sample (R9), ANSI/IES TM-30 color fidelity index (Rf), and color gamut index (Rg) of hybrid white light were 91.3, 87.8, 83.3, and 96.7, respectively. The melanopic efficacy of luminous radiation ( ) was tunable in the range of 0.60 to 1.35 mW/lm. These results demonstrated that we used far-red LEDs to fabricate white light with low BLH and relatively high efficiency.","PeriodicalId":49911,"journal":{"name":"Leukos","volume":"138 1","pages":"53 - 70"},"PeriodicalIF":3.6,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73280332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2022-03-07DOI: 10.1080/15502724.2022.2029710
Michael P. Royer, M. Murdoch, Kevin A. G. Smet, L. Whitehead, A. David, K. Houser, T. Esposito, Jason Livingston, Y. Ohno
ABSTRACT This article describes a method for calculating and specifying light source chromaticity using the International Commission on Illumination (CIE) 2015 10° color matching functions (CMFs), which, according to analysis of existing psychophysical experiment data, can reduce visual mismatch compared to specifications based on the traditional CIE 1931 2° CMFs in architectural lighting applications. Specifically, this work evaluates, documents, and recommends for adoption by lighting standards organizations a supporting system of measures to be used with the CIE 2015 10° CMFs: a new uniform chromaticity scale (UCS) diagram with coordinates (s, t), a measure of correlated color temperature (CCTst), and a measure of distance from the Planckian locus (Dst). It also presents options for updating nominal classification quadrangles. A complete method of this nature has not yet been standardized, which may be contributing to the slow uptake of the CIE 2015 CMFs. The proposed tools are analogous to u, v, CCT, Duv, and the American National Standards Institute (ANSI) C78.377 chromaticity specifications that are all currently defined in the CIE 1960 UCS diagram using the CIE 1931 2° CMFs. While conceptually equivalent, the differences between the current standard method and the proposed st system are important for reducing unintended visual mismatch in the chromaticity of light. The implications of changing chromaticity specification methods are identified by a comparison over a diverse set of real light source spectral power distributions.
{"title":"Improved Method for Evaluating and Specifying the Chromaticity of Light Sources","authors":"Michael P. Royer, M. Murdoch, Kevin A. G. Smet, L. Whitehead, A. David, K. Houser, T. Esposito, Jason Livingston, Y. Ohno","doi":"10.1080/15502724.2022.2029710","DOIUrl":"https://doi.org/10.1080/15502724.2022.2029710","url":null,"abstract":"ABSTRACT This article describes a method for calculating and specifying light source chromaticity using the International Commission on Illumination (CIE) 2015 10° color matching functions (CMFs), which, according to analysis of existing psychophysical experiment data, can reduce visual mismatch compared to specifications based on the traditional CIE 1931 2° CMFs in architectural lighting applications. Specifically, this work evaluates, documents, and recommends for adoption by lighting standards organizations a supporting system of measures to be used with the CIE 2015 10° CMFs: a new uniform chromaticity scale (UCS) diagram with coordinates (s, t), a measure of correlated color temperature (CCTst), and a measure of distance from the Planckian locus (Dst). It also presents options for updating nominal classification quadrangles. A complete method of this nature has not yet been standardized, which may be contributing to the slow uptake of the CIE 2015 CMFs. The proposed tools are analogous to u, v, CCT, Duv, and the American National Standards Institute (ANSI) C78.377 chromaticity specifications that are all currently defined in the CIE 1960 UCS diagram using the CIE 1931 2° CMFs. While conceptually equivalent, the differences between the current standard method and the proposed st system are important for reducing unintended visual mismatch in the chromaticity of light. The implications of changing chromaticity specification methods are identified by a comparison over a diverse set of real light source spectral power distributions.","PeriodicalId":49911,"journal":{"name":"Leukos","volume":"72 1","pages":"35 - 52"},"PeriodicalIF":3.6,"publicationDate":"2022-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86157004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2022-02-18DOI: 10.1080/15502724.2021.1999257
K. Chamilothori, J. Wienold, C. Moscoso, B. Matusiak, M. Andersen
ABSTRACT While there is a growing use of complex façade designs in contemporary architecture worldwide and across Europe, little is known about the perceptual effects of these façades and the resulting daylight patterns on occupants, or about how such effects might differ between European latitudes. This study examines the perception of façade and daylight patterns across Europe by replicating a virtual reality (VR) experiment in Norway, Switzerland and Greece, using a mixed experimental design to jointly investigate the influence of different factors on the perception of a daylit interior space. These factors included: façade geometry (within-subject factor with four contemporary façade designs of equal aperture ratio), sky type (clear sky with high or low sun angle, or overcast sky), spatial context (socializing or working), and country (Norway, Switzerland, or Greece). Results showed that, among the manipulated factors, only the façade geometry affected the studied attributes (how pleasant, interesting, exciting, calming, complex, spacious, and bright the space was perceived, and the satisfaction with the amount of view in the space). Regional effects were observed only for reported brightness, with higher evaluations from participants in Greece than in Norway, but are difficult to generalize due to limitations stemming from the use of VR and the conduction of experiments in different seasons (summer and early fall) in the two countries. These findings show that façade design is a crucial feature in our spatial experience, inducing equivalent perceptual effects, such as changes in pleasantness or interest, across Europe, and motivate further research on the perception of brightness.
{"title":"Regional Differences in the Perception of Daylit Scenes across Europe Using Virtual Reality. Part II: Effects of Façade and Daylight Pattern Geometry","authors":"K. Chamilothori, J. Wienold, C. Moscoso, B. Matusiak, M. Andersen","doi":"10.1080/15502724.2021.1999257","DOIUrl":"https://doi.org/10.1080/15502724.2021.1999257","url":null,"abstract":"ABSTRACT While there is a growing use of complex façade designs in contemporary architecture worldwide and across Europe, little is known about the perceptual effects of these façades and the resulting daylight patterns on occupants, or about how such effects might differ between European latitudes. This study examines the perception of façade and daylight patterns across Europe by replicating a virtual reality (VR) experiment in Norway, Switzerland and Greece, using a mixed experimental design to jointly investigate the influence of different factors on the perception of a daylit interior space. These factors included: façade geometry (within-subject factor with four contemporary façade designs of equal aperture ratio), sky type (clear sky with high or low sun angle, or overcast sky), spatial context (socializing or working), and country (Norway, Switzerland, or Greece). Results showed that, among the manipulated factors, only the façade geometry affected the studied attributes (how pleasant, interesting, exciting, calming, complex, spacious, and bright the space was perceived, and the satisfaction with the amount of view in the space). Regional effects were observed only for reported brightness, with higher evaluations from participants in Greece than in Norway, but are difficult to generalize due to limitations stemming from the use of VR and the conduction of experiments in different seasons (summer and early fall) in the two countries. These findings show that façade design is a crucial feature in our spatial experience, inducing equivalent perceptual effects, such as changes in pleasantness or interest, across Europe, and motivate further research on the perception of brightness.","PeriodicalId":49911,"journal":{"name":"Leukos","volume":"65 1","pages":"316 - 340"},"PeriodicalIF":3.6,"publicationDate":"2022-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89307086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2022-02-16DOI: 10.1080/15502724.2022.2029086
K. Houser
{"title":"To Measure Is to Know … or Not","authors":"K. Houser","doi":"10.1080/15502724.2022.2029086","DOIUrl":"https://doi.org/10.1080/15502724.2022.2029086","url":null,"abstract":"","PeriodicalId":49911,"journal":{"name":"Leukos","volume":"58 1","pages":"103 - 103"},"PeriodicalIF":3.6,"publicationDate":"2022-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89695614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2022-02-15DOI: 10.1080/15502724.2021.1989310
A. Diakite-Kortlever, Nils Weber, M. Knoop
ABSTRACT Spectrally and spatially resolved information on daylight is critically important when planning for non-image forming (NIF) responses. Nevertheless, the availability of such data is scarce given the high initial costs and complex on-site maintenance of high-end spectral measurement devices. The CIE (Commission Internationale de l’Éclairage) reconstruction procedure allows for the derivation of the daylight spectral power distribution (SPD) from the chromaticity coordinates or the correlated color temperature ( ). However, several studies have suggested that both the daylight locus and the reconstruction procedure are erroneous, and specifically SPDs with a higher cannot be reproduced accurately. This paper studies the reconstruction accuracy of the SPD of daylight, and contextualizes the findings in relation to NIF effects. The analysis comprises a comparative study to determine the accuracy of the CIE procedure compared to two localized reconstruction procedures, and a sensitivity study to examine the impact of accuracy on the assessment of NIF responses, as represented by all five retinal photoreceptors and expressed in the α-opic efficacy of luminous radiation. The results indicated that a localized procedure, adjusting both the daylight locus and the PCA components of daylight, outperformed the CIE reconstruction method. However, improvement in the reconstruction accuracy had no effect on NIF assessment. The RSMPE for α-opic quantities did not exceed 4% for any procedure. In practical terms, this implies that cost-effective sensors and the representation of spectral properties in sky models with a single value – the correlated color temperature – can be used for NIF purposes. These findings bridge theory and practice by opening up new insights into the understanding of simplified methods used to determine NIF effects of daylight. HIGHLIGHTS Using a localized procedure to define spectral power distribution (SPD) based on correlated color temperature ( ) outperforms the CIE method. Accuracy depends on the computation procedure rather than the daylight locus location. Higher accuracy does not affect the α-opic responses used in defining non-image forming (NIF) effects. Findings confirm the applicability of simplified measuring and representation methods for daylight SPDs. can be used to represent daylight SPD in planning software to assess NIF effects.
{"title":"Reconstruction of Daylight Spectral Power Distribution Based on Correlated Color Temperature: A Comparative Study between the CIE Approach and Localized Procedures in Assessing Non-image Forming Effects","authors":"A. Diakite-Kortlever, Nils Weber, M. Knoop","doi":"10.1080/15502724.2021.1989310","DOIUrl":"https://doi.org/10.1080/15502724.2021.1989310","url":null,"abstract":"ABSTRACT Spectrally and spatially resolved information on daylight is critically important when planning for non-image forming (NIF) responses. Nevertheless, the availability of such data is scarce given the high initial costs and complex on-site maintenance of high-end spectral measurement devices. The CIE (Commission Internationale de l’Éclairage) reconstruction procedure allows for the derivation of the daylight spectral power distribution (SPD) from the chromaticity coordinates or the correlated color temperature ( ). However, several studies have suggested that both the daylight locus and the reconstruction procedure are erroneous, and specifically SPDs with a higher cannot be reproduced accurately. This paper studies the reconstruction accuracy of the SPD of daylight, and contextualizes the findings in relation to NIF effects. The analysis comprises a comparative study to determine the accuracy of the CIE procedure compared to two localized reconstruction procedures, and a sensitivity study to examine the impact of accuracy on the assessment of NIF responses, as represented by all five retinal photoreceptors and expressed in the α-opic efficacy of luminous radiation. The results indicated that a localized procedure, adjusting both the daylight locus and the PCA components of daylight, outperformed the CIE reconstruction method. However, improvement in the reconstruction accuracy had no effect on NIF assessment. The RSMPE for α-opic quantities did not exceed 4% for any procedure. In practical terms, this implies that cost-effective sensors and the representation of spectral properties in sky models with a single value – the correlated color temperature – can be used for NIF purposes. These findings bridge theory and practice by opening up new insights into the understanding of simplified methods used to determine NIF effects of daylight. HIGHLIGHTS Using a localized procedure to define spectral power distribution (SPD) based on correlated color temperature ( ) outperforms the CIE method. Accuracy depends on the computation procedure rather than the daylight locus location. Higher accuracy does not affect the α-opic responses used in defining non-image forming (NIF) effects. Findings confirm the applicability of simplified measuring and representation methods for daylight SPDs. can be used to represent daylight SPD in planning software to assess NIF effects.","PeriodicalId":49911,"journal":{"name":"Leukos","volume":"65 1","pages":"118 - 145"},"PeriodicalIF":3.6,"publicationDate":"2022-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88967619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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