The effectiveness of light-emitting diode lighting for providing circadian stimulus in office spaces while minimizing energy use

2019 ◽  
Vol 52 (2) ◽  
pp. 167-188 ◽  
Author(s):  
C Jarboe ◽  
J Snyder ◽  
MG Figueiro
Keyword(s):  
Energy Use ◽  
Spectral Power ◽  
Light Emitting Diode ◽  
Visual Performance ◽  
Luminous Intensity ◽  
Light Emitting ◽  
Lighting Conditions ◽  
Office Space ◽  
Discomfort Glare ◽  
Architectural Lighting

Architectural lighting has traditionally addressed visual performance and horizontal illuminance on the work plane, later focussing on energy efficiency, while only recently paying particular regard to human health outcomes. The present study evaluated the effectiveness of several light-emitting diode lighting strategies for delivering circadian stimulus to occupants of a typical office space while minimizing energy use. The study employed photometric simulations in a typical open-office space, delivering a criterion circadian stimulus of 0.3 to calculation points modelled at the simulated occupants’ eye level. Six luminaire types, two luminous intensity distributions, six spectral power distributions and two horizontal illuminances were evaluated, resulting in 144 unique lighting conditions. Additionally, the study calculated the discomfort glare for selected luminaires with the highest total lumen output, smallest aperture and direct-only luminous intensity distributions at the higher of the two horizontal illuminances (500 lx). The most impactful strategy involved supplementing common overhead lighting with a desktop luminaire delivering light directly to the simulated office occupants’ eyes, which provided greater circadian stimulus and used less energy than overhead luminaires that were capable of delivering the criterion circadian stimulus of 0.3.

Discomfort glare caused by white LEDs having different spectral power distributions

2017 ◽  
Vol 50 (6) ◽  
pp. 921-936 ◽  
Author(s):  
WJ Huang ◽  
Y Yang ◽  
M Ronnier Luo
Keyword(s):  
White Light ◽  
Spectral Power ◽  
Light Emitting Diode ◽  
Light Emitting ◽  
White Leds ◽  
Significant Difference ◽  
Discomfort Glare ◽  
Led Lights ◽  
Green Leds

This paper describes an experiment to investigate discomfort glare caused by white light-emitting diode (LED) lights having different spectral power distributions. It included two groups: a ‘Metamerism’ group and a ‘correlated colour temperatures (CCT)’ group. In the former group, it was found that white lights at 7000 K constructed from different blue LEDs and the same red and green LEDs gave about the same glare perception. In the latter group, there was a significant difference in glare perception between white lights having different CCTs. Finally, glare models, including unified glare rating (UGR) and the newly derived QUGRspd, and mUGRspd models, were tested using the data from the experiment. All of them gave quite accurate predictions of the data.

Assessing glare, Part 4: Generic models predicting discomfort glare of light-emitting diodes

2017 ◽  
Vol 50 (5) ◽  
pp. 739-756 ◽  
Author(s):  
Y Yang ◽  
MR Luo ◽  
WJ Huang
Keyword(s):  
Power Distribution ◽  
Spectral Power ◽  
Light Emitting Diode ◽  
Human Vision ◽  
Appearance Model ◽  
Generic Model ◽  
Light Emitting ◽  
Generic Models ◽  
Discomfort Glare ◽  
Colour Appearance

Two generic models to predict the influence of the luminance uniformity and spectral power distribution of light-emitting diode luminaires on discomfort glare were developed. One model was an extension of the empirical Unified Glare Rating, the other was based on a colour appearance model for unrelated colours. A new experiment was carried out to verify the performance of the generic models. There were twelve glare sources, having three types of luminance uniformity and four spectral power distributions. The results showed both generic models outperformed Unified Glare Rating but gave similar performance to each other. The generic model based on the colour appearance model bridges the gap between glare perception and human vision theory.

scholarly journals Influences of Spectral Power Distribution on Circadian Energy, Visual Comfort and Work Performance

2021 ◽  
Vol 13 (9) ◽  
pp. 4852
Author(s):  
Jack Ngarambe ◽  
Inhan Kim ◽  
Geun Young Yun
Keyword(s):  
Light Source ◽  
Power Distribution ◽  
Work Performance ◽  
Spectral Power ◽  
Light Emitting Diode ◽  
Essential Element ◽  
Visual Comfort ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Spectral Power Distribution

Spectral power distribution (SPD) is an essential element that has considerable implications on circadian energy and the perception of lit environments. The present study assessed the potential influences of SPD on energy consumption (i.e., considering circadian energy), visual comfort, work performance and mood. Two lighting conditions based on light-emitting diode (LED) and organic light-emitting diode (OLED) were used as proxies for SPDs of different spectral content: dominant peak wavelength of 455 nm (LED) and 618 nm (OLED). Using measured photometric values, the circadian light (CL), melatonin suppression (MS), and circadian efficacy (CE) of the two lighting sources were estimated via a circadian-phototransduction model and compared. Additionally, twenty-six participants were asked to evaluate the said lit environments subjectively in terms of visual comfort and self-reported work performance. Regarding circadian lighting and the associated energy implications, the LED light source induced higher biological actions with relatively less energy than the OLED light source. For visual comfort, OLED lighting-based conditions were preferred to LED lighting-based conditions, while the opposite was true when considering work performance and mood. The current study adds to the on-going debate regarding human-centric lighting, particularly considering the role of SPD in energy-efficient and circadian lighting practices.

Discomfort Glare Caused by R/G/B/W Four-Color Light Emitting Diode Sources

2019 ◽  
Vol 56 (13) ◽  
pp. 132301
Author(s):  
田会娟 Huijuan Tian ◽  
郝甜甜 Tiantian Hao ◽  
关涛 Tao Guan ◽  
胡阳 Yang Hu ◽  
蔡敏鹏 Minpeng Cai ◽  
...  
Keyword(s):  
Light Emitting Diode ◽  
Light Emitting ◽  
Discomfort Glare

Changes in Lighting Source Can Produce Inaccurate Assessment of Visual Poultry Doneness and Induce Consumers To Eat Undercooked Ground Turkey Patties

2019 ◽  
Vol 82 (3) ◽  
pp. 528-534 ◽  
Author(s):  
CURTIS MAUGHAN ◽  
EDGAR CHAMBERS IV ◽  
SANDRIA GODWIN ◽  
DELORES CHAMBERS
Keyword(s):  
Foodborne Pathogens ◽  
Light Emitting Diode ◽  
The United States ◽  
Extrinsic Factors ◽  
Visual Appearance ◽  
Light Emitting ◽  
End Point ◽  
Lighting Conditions ◽  
Compact Fluorescent Lamp ◽  
End Point Temperature

ABSTRACT Undercooked poultry is a potential source of foodborne pathogens, such as Salmonella and Campylobacter. The best way to avoid eating undercooked poultry is to use a food thermometer during cooking. However, consumers who cook poultry often use visual appearance for determining doneness, which relies on extrinsic factors, including lighting conditions. Because the United States recently mandated changes in lighting to promote energy conservation, this study evaluated the effect of lighting sources on consumer perceptions of doneness and willingness to eat cooked poultry patties. Consumers (n = 104) evaluated validated photographs of turkey patties cooked to different end point temperatures (57 to 79°C) and rated the level of perceived doneness and willingness to eat each sample. Evaluations were conducted under different lighting sources: incandescent (60 W, soft white), halogen (43 W, soft white), compact fluorescent lamp (13 W, soft white), light-emitting diode (LED; 10.5 W, soft white), and daylight LED (14 W). Lighting changed perception of doneness and willingness to eat the patties, with some of the energy-efficient options, such as LED and halogen making samples appear more done than they actually were, increasing the willingness to eat undercooked samples. This poses a risk of consuming meat that could contain bacteria not killed by heat treatment. Recent changes in lighting regulations can affect lighting in homes that affects perceptions of poultry doneness, requiring that educators place extra emphasis on the message that properly using a meat thermometer is the only way to ensure meat is cooked to a safe end point temperature.

Colour-enhanced light emitting diode light with high gamut area for retail lighting

2015 ◽  
Vol 49 (3) ◽  
pp. 329-342 ◽  
Author(s):  
XF Feng ◽  
W Xu ◽  
QY Han ◽  
SD Zhang
Keyword(s):  
Light Source ◽  
Light Emitting Diodes ◽  
Spectral Power ◽  
Light Emitting Diode ◽  
Broad Band ◽  
Area Index ◽  
Light Emitting ◽  
High Preference ◽  
Colour Rendering ◽  
Colour Appearance

Light emitting diodes with high colour quality were investigated to enhance colour appearance and improve observers' preference for the illuminated objects. The spectral power distributions of the light emitting diodes were optimised by changing the ratios of the narrow band red, green and blue light emitting diodes, and the phosphor-converted broad-band light emitting diode to get the desired colour rendering index and high gamut area index. The influence of the light emitting diode light on different coloured fabrics was investigated. The experimental results and the statistical analysis show that by optimising the red, green, blue components the light emitting diode light can affect the colour appearance of the illuminated fabrics positively and make the fabrics appear more vivid and saturated due to the high gamut area index. Observers indicate a high preference for the colours whose saturations are enhanced. The results reveal that the colour-enhanced light emitting diode light source can better highlight products and improve visual impression over the ceramic metal halide lamp and the phosphor-converted light emitting diode light source.

Human Factors Impacts of Light-Emitting Diode Airfield Lighting

2017 ◽  
Vol 2626 (1) ◽  
pp. 51-57 ◽  
Author(s):  
John D. Bullough
Keyword(s):  
Human Factors ◽  
Experimental Evidence ◽  
Energy Use ◽  
Light Emitting Diode ◽  
Light Sources ◽  
Light Emitting ◽  
Incandescent Light ◽  
Color Identification ◽  
Lighting Systems ◽  
Maintenance Requirements

Light-emitting diodes (LEDs) differ from incandescent light sources in several ways that are relevant to energy and maintenance requirements of airfield lighting systems. They have higher luminous efficacy and, when designed properly, have longer useful operating lives; both factors make LEDs attractive candidates for airfield lighting. The photometric, colorimetric, and temporal characteristics of LEDs also differ from those of incandescent light sources, and these can have important implications for the appearance of runway and taxiway lighting systems. The present paper reviews publications summarizing experimental and analytical investigations designed to assess these implications with respect to the following human factors impacts: color identification, brightness and glare, visibility in fog and haze, response to onset of flashing lights, and stroboscopic effects such as the phantom array. Overall, this review of experimental evidence suggests that, in addition to their reduced energy use and maintenance requirements, LED airfield lighting can be advantageous in comparison with incandescent lighting systems used to delineate airport runways and taxiways.

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