Showing papers in "Lighting Research & Technology in 2019"
TL;DR: The daylight glare probability (DGP) delivered the highest performance amongst the tested metrics and was also found to be the most robust, while metrics considering the saturation effect as a main input in their equation perform better and are more robust in daylight-dominated workplaces.
Abstract: This study evaluates the performance and robustness of 22 established and newly proposed glare prediction metrics. Experimental datasets of daylight-dominated workplaces in office-like test rooms w...
82 citations
TL;DR: In this paper, a field study was conducted at two U.S. federal government office sites and two embassies to demonstrate whether circadian-effective lighting (providing circadian stimulus (CS) values of CS) < 0.
Abstract: A field study was conducted at two U.S. federal government office sites and two U.S. embassies to demonstrate whether circadian-effective lighting (providing circadian stimulus (CS) values of CS ≥ ...
74 citations
TL;DR: The volunteers had better visual comfort, felt more alert and happier in the morning and evening under daylight LED than conventional LED, while the diurnal melatonin profile, psychomotor vigilance and working memory performance were not significantly different.
Abstract: LED *Shared senior authors. light sources have a discontinuous light spectrum with a prominent ‘blue’ peak between 450 and 470 nm that influences non-image forming responses in humans. We tested an...
59 citations
TL;DR: The model of human circadian phototransduction is extended to incorporate factors such as exposure duration and participant age to better predict effective circadian stimulus, suggesting an increased sensitivity to short-wavelength radiation.
Abstract: This study investigated how light exposure duration affects melatonin suppression, a well-established marker of circadian phase, and whether adolescents (13-18 years) are more sensitive to short-wavelength (blue) light than adults (32-51 years). Twenty-four participants (12 adolescents, 12 adults) were exposed to three lighting conditions during successive 4-h study nights that were separated by at least one week. In addition to a dim light (<5 lux) control, participants were exposed to two light spectra (warm (2700 K) and cool (5600 K)) delivering a circadian stimulus of 0.25 at eye level. Repeated measures analysis of variance revealed a significant main effect of exposure duration, indicating that a longer duration exposure suppressed melatonin to a greater degree. The analysis further revealed a significant main effect of spectrum and a significant interaction between spectrum and participant age. For the adolescents, but not the adults, melatonin suppression was significantly greater after exposure to the 5600 K intervention (43%) compared to the 2700 K intervention (29%), suggesting an increased sensitivity to short-wavelength radiation. These results will be used to extend the model of human circadian phototransduction to incorporate factors such as exposure duration and participant age to better predict effective circadian stimulus.
51 citations
TL;DR: Melatonin suppression did not significantly differ between the two Night Shift interventions, which indicates that changing the spectral composition of self-luminous displays without changing their brightness settings may be insufficient for preventing impacts on melatonin suppression.
Abstract: The increased use of self-luminous displays, especially in the evening prior to bedtime, has been associated with melatonin suppression, delayed sleep and sleep curtailment. The present study set out to investigate whether the Night Shift application provided by Apple Inc. for use on its portable electronic devices is effective for reducing acute melatonin suppression, a well-established marker of circadian phase. Participants experienced four experimental conditions: a dim light control, a high circadian stimulus true positive intervention and two Night Shift interventions delivering low and high correlated colour temperature light from the devices. Melatonin suppression did not significantly differ between the two Night Shift interventions, which indicates that changing the spectral composition of self-luminous displays without changing their brightness settings may be insufficient for preventing impacts on melatonin suppression.
48 citations
TL;DR: This paper compares a human’s subjective feeling towards a physical lighting environment and three alternative reproduction technologies, namely, virtual reality reproduction, video reproduction and photographic reproduction, and discusses the feasibility of using virtual reality in representing lighting environments.
Abstract: In the study of lighting, as the construction of a physical test room is costly and time-consuming, researchers have been actively looking for alternative media to present physical environments. Vi...
45 citations
TL;DR: In this article, the bias towards the initial anchor was investigated and the results confirmed significant bias: glare settings were biased towards the luminance of the anchor, the setting of the variable stimulus immediately before an adjustment is made.
Abstract: Luminance adjustment is a procedure commonly used to evaluate discomfort glare and the results from adjustment experiments form the basis of some recommendations for limiting its occurrence. There are, however, strong reasons to expect that settings made using adjustment are unintentionally influenced by extraneous variables. This paper discusses bias towards the initial anchor, the setting of the variable stimulus immediately before an adjustment is made. Specifically, the initial luminance is expected to influence the setting that is made by adjustment; for example, a lower initial luminance leads to a lower setting than a high initial luminance. To investigate anchor bias, a Hopkinson-like multiple-criterion adjustment experiment was undertaken, but with three different anchors. The results confirmed significant bias: glare settings were biased towards the luminance of the initial anchor. This demonstrates a need for caution when using adjustment to explore discomfort glare and when interpreting the results of past studies that used discomfort glare models fitted to data obtained with this procedure.
37 citations
TL;DR: Under stable atmospheric conditions, the brightness of the urban sky varies throughout the night following the time course of the anthropogenic emissions of light as mentioned in this paper, and different types of artificial light sources are used.
Abstract: Under stable atmospheric conditions the brightness of the urban sky varies throughout the night following the time course of the anthropogenic emissions of light. Different types of artificial ligh...
37 citations
TL;DR: In this article, a field study was conducted to investigate how changes in the illuminance affect pedestrian reassurance when walking after dark in an urban location, which was conducted in daytime and after dark.
Abstract: A field study was conducted to investigate how changes in the illuminance affect pedestrian reassurance when walking after dark in an urban location. The field study was conducted in daytime and af...
36 citations
TL;DR: Tristimulus colour calibration procedures for high dynamic range photography are developed to measure circadian lighting and demonstrate that measurements from high dynamicrange photographs can correspond to the physical quantity of circadian luminance with reasonable precision and repeatability.
Abstract: The human ocular system functions in a dual manner. While the most well-known function is to facilitate vision, a growing body of research demonstrates its role in resetting the internal body clock...
33 citations
TL;DR: It is found that existing workflows often overlook relevant aspects of daylight in residential spaces, such as diurnal and seasonal availability of daylight and access to direct sunlight, and a concept for a new climate-based, annual evaluation framework that overcomes these shortcomings is introduced.
Abstract: Residential architecture constitutes one of the largest market segments in the construction sector. However, the attention that it is given in the field of daylight performance simulation is surprisingly low. This poses the question of whether existing daylighting metrics are well suited for residential design. Findings from 79 references are summarized, and a critical review of current climate-based daylighting metrics in the context of residential architecture is provided. It is found that existing workflows often overlook relevant aspects of daylight in residential spaces, such as diurnal and seasonal availability of daylight and access to direct sunlight. Hence, a concept for a new climate-based, annual evaluation framework that overcomes these shortcomings, called the residential daylight score, is introduced.
TL;DR: In this article, real spectra were strategically structured to have systematic variation in average fidelity, average gamut, and gamut shape (no shape shape variation was observed in different spectra.
Abstract: Twenty-four real spectra were strategically structured to have systematic variation in average fidelity (IES Rf = 65, 75, 85, 95), average gamut (IES Rg = 80, 90, 100, 110, 120) and gamut shape (no...
TL;DR: In this article, two psychophysical experiments, one on colour preference and the other on colour discrimination, were conducted to investigate the color preference for blue jeans, 27 subjects with different skin tones.
Abstract: In this study, two psychophysical experiments, one on colour preference and the other on colour discrimination, were conducted. To investigate the colour preference for blue jeans, 27 subjects with...
TL;DR: It is shown conclusively that, contrary to common belief, larger gamut area is not associated with better colour discrimination, and a direct way to interpret the Rd score is offered, which is a strong predictor of colour discrimination.
Abstract: We show conclusively that, contrary to common belief, larger gamut area is not associated with better colour discrimination We propose a new measure of colour discrimination, Rd, which quantifies
TL;DR: In this article, the authors discuss how a pedestrian evaluates the intentions of other people using outdoor lighting in public spaces, such as pathways and subsidiary roads, to evaluate the intention of other pedestrians.
Abstract: One of the aims of outdoor lighting in public spaces, such as pathways and subsidiary roads, is to help pedestrians to evaluate the intentions of other people. This paper discusses how a pedestrian...
TL;DR: In this paper, an alternative approach is to use objective data, specifically the number of pedestal pedestals, to investigate the reactions to changes in lighting from people who walk or cycle.
Abstract: Many studies have used surveys to investigate the reactions to changes in lighting from people who walk or cycle. An alternative approach is to use objective data, specifically the number of pedest...
TL;DR: Light- and photosensitizer-based antimicrobial photodynamic therapy (aPDI) is a very promising approach to control microbial infections and based on the proper characterization of light emitted by each LED at each point of the illuminated area, a homogeneous distribution of light can be achieved, which is crucial for precise dosimetry.
Abstract: Light- and photosensitizer-based antimicrobial photodynamic therapy (aPDI) is a very promising approach to control microbial infections. Other applications of aPDI are also being studied, for examp...
TL;DR: It is discussed how to apply this user preference model in the Internet of Things network structure of luminaires in order to obtain an ‘Internet of Luminaires’ for good user acceptance.
Abstract: The objective and subjective factors influencing human-centric lighting design and their effect on the user of the lighting system are analysed with the aim of developing a user preference model. I...
TL;DR: Considering the low market penetration of smart-lighting technology, the authors investigates the drivers and consequences of consumer resistance to these innovative lighting products, and proposes a solution to solve the problem.
Abstract: Considering the low market penetration of smart-lighting technology, this study investigates the drivers and consequences of consumer resistance to these innovative lighting products. The paper bui...
TL;DR: An approach based on effective watts and melanopic/photopic ratios that is both simpler and more closely aligned with CIE standard unit definitions is proposed.
Abstract: Over the past decade, there has been a growing interest in lighting research on the effects of the recently discovered melanopsin receptor (also referred to as the intrinsically photosensitive reti...
TL;DR: In this article, human subjective and pupil responses to small, high-luminance light sources seen against low-lighted backgrounds were examined, and subjective judgements of glare using a seven-point rating sca...
Abstract: This study examined human subjective and pupil responses to small, high-luminance light sources seen against low-luminance backgrounds. Subjective judgements of glare using a seven-point rating sca...
TL;DR: In this paper, the authors presented experimentally obtained luminous flux to input power characteristics of high pressure sodium and LED luminaires used in road lighting, confirming that when applying dimming scen...
Abstract: This paper presents experimentally obtained luminous flux to input power characteristics of high-pressure sodium and LED luminaires used in road lighting, confirming that when applying dimming scen...
TL;DR: The study showed that the noticeability of light changes due to dimming, increases when fading times become shorter, and provides insights to system behaviour that does not compromise user experience while addressing energy efficient use of electric lighting.
Abstract: Sensor-triggered control strategies can limit the energy consumption of lighting by considering the presence of users in the office and dimming lighting down when it is not needed. In multi-user of ...
TL;DR: In this paper, an exploratory study compared two different light sources and found that light can impact psychobiological processes in a healthy or harmful way, challenging designers to better understand the resources they are manipulating.
Abstract: Light can impact psychobiological processes in a healthy or harmful way, challenging designers to better understand the resources they are manipulating. The present exploratory study compared two f...
TL;DR: The Lumiroute® sections offer optimized performance and increased efficiency in comparison with the ordinary sections, particularly with regard to light and energy performance.
Abstract: Taking into account the actual photometric characteristics of a road surface to design and then adjust a lighting installation is seldom done. In a lighting renovation, one of the Commission Intern...
TL;DR: In this article, the influence of saturation level was modelled by existing colour rendition measures and by the measure colour quality combining a colour fidelity index and an overall object colour object saturation measure taken from Part 4 of this work.
Abstract: Subjects rated the colour preference of a colourful object scene illuminated to 2000 lx by 28 different spectra from a four-channel LED light engine at different object saturation levels and different white points (3200 K, 4200 K, 5000 K and 5600 K). Mean colour preference ratings had a maximum at a moderate saturation level. The lowest correlated colour temperature (3200 K) exhibited lower preference ratings than the three higher correlated colour temperatures. The influence of saturation level was modelled by existing colour rendition measures and by the measure colour quality combining a colour fidelity index and an overall object colour object saturation measure taken from Part 4 of this work.
TL;DR: In this paper, it is shown that one of the most important parameters is colour difference, which is a consequence of chemica and it is possible to assess the damage to artworks by measuring different physical and chemical parameters.
Abstract: It is possible to assess the damage to artworks by measuring different physical and chemical parameters. One of the most important parameters is colour difference, which is a consequence of chemica...
TL;DR: In this paper, the authors investigated the atmosphere perception of dynamic coloured lighting over warm and cool hue ranges in a living room environment, using eight fully functional multi-channel audio devices.
Abstract: This paper investigates the atmosphere perception of dynamic coloured lighting over warm and cool hue ranges in a living room. Experiments were carried out with eight fully functional multi-channel...
TL;DR: In this article, a method for calculating scalar illuminance using cubic illuminances values in a light field has been proposed, which enables exact measurement of the illuminant vector direction.
Abstract: A method for calculating scalar illuminance using cubic illuminance values in a light field has been proposed in the literature. This enables exact measurement of the illuminance vector direction a...
TL;DR: Overall, the linear mixing for variable CCT employed in this experiment did not provide obvious utility for surgeons making visual evaluations, and surgeons may develop individual opinions about which spectra are most effective.
Abstract: A surgical luminaire containing two types of phosphor-converted LEDs was employed to illuminate a large midline incision in a 90 kg pig. The PC-LEDs were proportionally blended to create four spect...