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

Diakite-Kortlever, Aicha; Weber, Nils; Knoop, Martine

doi:10.1080/15502724.2021.1989310

Cited by 7 publications

(3 citation statements)

References 47 publications

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“…In this sense, daylight has one of the highest potentials to induce nonvisual effects, and it has been described that in its evaluation, orientation-dependent analysis is necessary because of its different spectral properties and colorimetric characteristics. Distinct regions of the sky can vary largely; skylight from a clear north sky can have a CCT between 5000 and 100,000 K and be influenced by parameters such as orientation, seasonality or sky conditions [43][44][45]. Perhaps indoor lighting projects should have a provision for natural light reaching different areas to take advantage of its properties and provide adequate supplementary electric lighting to save energy and obtain healthy surroundings, not only with static light, but also when considering the possibility of dynamic electric light when visual comfort can be maintained [46].…”

Section: Discussionmentioning

confidence: 99%

Method to Calculate Melanopic Light Reaching the Retina Depending on the Optical Density of an Aging Crystalline Lens

et al. 2023

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Lighting studies that take into account the age of the inhabitants of an area and are related to circadian light are difficult to find. This study aims to simplify a method to approximately compute the circadian light reaching the retina based on photopic illuminance reaching the corneal plane and considering the optical density of an aging crystalline lens. As an example of this proposed method, calculations were performed with both the D65 and A standard illuminants, showing how the spectral power distribution is modified by the optical density of the crystalline lens, mainly at short wavelengths. Due to these selective wavelength absorptions of the aged lens, a significant variation in the level of daylight equivalent melanopic illuminance (EDI) is present in the retina. With levels of 200 lux at the corneal plane, these variations ranged from 204 EDI lux to 178 EDI lux for the D65 standard illuminant, and from 99 EDI lux to 101 EDI lux for the A standard illuminant for observers aged 10 and 90, respectively. In this work, we aimed to simplify the greatest possible level of calculation of melanopic light, while describing simple protocols that are easy to translate into practice. Our results will allow researchers to carry out optimized lighting designs from both the photometric and circadian perspectives considering the optical density of an aging lens.

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Section: Discussionmentioning

confidence: 99%

Method to Calculate Melanopic Light Reaching the Retina Depending on the Optical Density of an Aging Crystalline Lens

et al. 2023

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“…The spectral measurement was adapted to be in line with CIE (1994) [21]. Measurements were specified to an observation with a vertical aperture angle of 10 degree [21], [22]. A multi-LED light meter (Tenmars, TM-209M,…”

Section: Methods 21 Analysis Of Spectrometric Properties Of Circadian...mentioning

confidence: 99%

Visual and melanopic performance of a tropical daylight-mimicking lighting: a case study in Thailand

Santimalai,

Tayjasanant

2023

IJECE

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This paper designed and developed a tropical daylight-mimicking lighting system based on photometric, radiometric and International Commission on Illumination (CIE) standard melanopic performances from natural lighting cycles in Thailand. Spectral power distribution (SPD) during daylight in summer and winter were recorded to create a dynamic artificial lighting system that best matches the natural daylight characteristics. Two set-ups light emitting diode (LED) (LED-A and LED-B) were screened, developed, validated and compared with different chromaticity layouts of the correlated color temperatures (CCTs) allocated on Planckian locus and later converted to x-y co-ordinates in a chromaticity diagram. Based on CCT and Duv deviations between two developed setups, LED-A could mimick circadian points on the chromaticity diagram better than LED-B did. CCT and Duv values of LED-A (dCCT=3.75% and dDuv=17.36%) can match closer to the daylight than those of LED-B (dCCT=5.0 % and dDuv=56.84%). For CIE-standard melanopic performances (melanopic efficacy of luminous radiation (mELR), melanopic equivalent daylight (D65) illuminance (mEDI) and melanopic daylight efficacy ratio (mDER)), LED-A is suitable to use indoor with averages of 1.16 W×lm-1, 236 lx and 0.84, respectively, while LED-B is good to use outdoor with averages of 1.53 W×lm-1, 266 lx and 1.06, respectively. The proposed design can be used as a guideline to establish a daylight-mimicking LED lighting system from actual measurement data.

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“…Several studies have shown there are location-specific differences in the colour and spectrum of daylight [13][14][15]. For further development of spectral models for the lighting field, it is suggested that the variability of the different shades of blue and the colour of sunlight and daylight be represented [4].…”

Section: Introductionmentioning

confidence: 99%

A framework to generate local spectral skies for spectral daylight simulations

Balakrishnan,

Knoop,

Doppler

2023

J. Phys.: Conf. Ser.

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Spectral daylight simulations are becoming increasingly important in predicting non-visual responses to light and more accurate daylight colour and temporal patterns. However, the availability of locally measured spectral sky data is limited and current spectral sky models do not capture the local colour variability of skies. This paper presents a novel framework for generating high-accuracy, location-specific spectral sky data using typically measured atmospheric data at meteorological stations as inputs to physics-based radiative transfer programs like libRadtran. A comparison of measured and simulated data across the year demonstrates that using location-specific atmospheric profiles leads to significantly more accurate predictions of irradiances, spectral global and direct irradiances, and better captures the variability of clear skies regarding colour accuracy and appearance than simulations with default settings.

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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

Cited by 7 publications

References 47 publications

Method to Calculate Melanopic Light Reaching the Retina Depending on the Optical Density of an Aging Crystalline Lens

Method to Calculate Melanopic Light Reaching the Retina Depending on the Optical Density of an Aging Crystalline Lens

Visual and melanopic performance of a tropical daylight-mimicking lighting: a case study in Thailand

A framework to generate local spectral skies for spectral daylight simulations

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