To clarify the effects of melanopsin cells on spatial brightness, we conducted an experiment in which the brightness of the space was evaluated using a magnitude estimation method during AM (9.00 to 10:00) and PM (18.00 to 19.00) periods by modulating the stimulus value of melanopsin cells while keeping the chromaticity values of a light environment constant. The light environment was constructed and installed on the ceiling of a windowless room model of a typical office space, using a 24-colour multispectral light source device with variable spectral distribution characteristics. The results showed that the influence of melanopsin cells under high-illuminance conditions depends on the time slot. The floor illuminance, at which the influence of melanopsin cells begins to emerge, was suggested to exist between 500 lx and 1000 lx. This study can contribute to the development of lighting design methods to balance energy efficiency and comfort by controlling melanopsin stimulation.
Lighting conditions and room atmosphere are crucial aspects to consider for ensuring performance, comfort and well-being in a learning environment, where the transfer of information and interaction occur during different learning activities. To investigate requirements in learning environments, a lecture room was converted into a dynamic testbed featuring adjustable lighting systems, flexible furniture configurations and real-time monitoring of indoor environmental quality parameters via an advanced Internet of Things sensing network. An evaluation of the testbed was conducted in a pilot field study, utilising three lighting scenes. Participants rated subjective alertness and perception of the lit environment in the scenes: Lecture, Workshop and Presentation. Physical measurements of lighting conditions and exposure were continuously recorded with static and ambulatory instruments. The data were statistically analysed, and the results showed satisfaction with the lighting. Furthermore, a reasonable alertness was maintained despite a preference for lighting levels lower than recommended.
Little is known about the impact of lighting in rooms designated for critical conversations in counselling or policing contexts, such as therapy, clinical interviewing and police interviews. Lighting may affect bodily stress, discomfort, nervousness, anxiety, mood and self-disclosure. The aim of this study was to map and report research on how illumination affects people’s perception, mood and interaction in healthcare and policing contexts. A scoping review was conducted in which six databases were searched. Twelve studies were included: ten quantitative, one qualitative and one mixed method. The results were presented in two overarching categories: impact of lighting on communication and behaviour. The first category consisted of four sub-categories. The second main category depicted methods and experimental design. The findings indicate that this specific area remains relatively under-researched. The studies were mostly experimental and consisted of small samples. An improved understanding of lighting in contexts for critical and personal dialogue can support professionals, patients and organisations, not least in psychiatric healthcare and other socially vulnerable settings. In addition, our results may inform future design intervention studies and the configuration of rooms designated for conversational and policing environments where critical conversations are conducted.
Direct flicker is a perception effect causing discomfort generated from lighting systems. While the short-term flicker indicator, P st LM , is most widely used, perceptual modulation ( M P ) is also a perception-based direct flicker metric used in many commercial instruments. However, M P values show substantial variation due to different starting phases of waveforms, caused by Fourier transform spectral leakage. Such variation was mostly removed by revising M P ’s calculation, applying a Hann window function and a correction factor to counteract the spectral broadening from the window when summing the DC-normalized spectral components. This approach is generalized to improve frequency-domain temporal light artefact metrics without loss of perceptual relevance when different windows are applied. To harmonize M P with direct flicker at a broader frequency range and viewing conditions eliciting higher direct flicker sensitivity, its original sensitivity curve (5 Hz to 65 Hz) is replaced by the one from Perz’s experiment, with a slight change of frequency range to 3 Hz to 80 Hz. With these improvements, M P,26 has been developed. A linear mixed-effects model is used to compare the different measurement conditions of M P,26 , providing guidance for recommended measurement conditions, i.e. measurement duration ≥5 s, sampling rate ≥2 kHz and a second-order anti-aliasing filter with cut-off frequency ≥400 Hz are recommended for robust result of M P,26 .
Lighting controls are essential for the operation of all buildings and the well-being of the people who work, live and play in them. The current designs and applications of lighting controls often do not consider why or how a building occupant might wish to make operational changes to the lighting system. This lack of appreciation likely leads to wasted electric energy and, financially more significantly, a loss in occupant productivity. The aim of the extended sequential narrative (ESN) described here is to help manufacturers, specifiers and installers develop a more empathetic understanding of why and how a building occupant interacts with lighting system control points. The six-phased ESN is a starting point in the thought processes of product designers and specifiers of lighting control systems. It is argued that lighting control product designs and applications following the ESN process will reduce lighting energy consumption and support more productive building occupants. The paper concludes with a series of general hypotheses to facilitate the acceptance or refutation of the ESN’s validity and utility.
The Guth position index P is a key geometric parameter used in glare-evaluation models to quantify the positional contribution of a light source to visual discomfort. Its practical relevance spans lighting design, photometric assessment and the calibration of discomfort glare metrics. Despite its longstanding use in lighting practice, the technical literature reveals significant inconsistencies in how the index is defined, parameterized and computed. These discrepancies concern the interpretation of the operational angles, the choice of reference geometry and the compatibility between institutional models. The purpose of this paper is to document and systematize the technical literature concerning the terminology used in defining the P /Guth position index, with emphasis on longstanding inconsistencies among models belonging to the same technical family. The motivation arises from persistent disagreements regarding the definition and geometric placement of the operational angles. The literature reveals a field shaped by partially compatible models, competing angular conventions and institution-specific computational practices rather than theoretical convergence. The contribution of this paper lies in exposing the methodological, notational and descriptive fragmentation affecting the equation and practical use of the Guth position index.
It has been shown that the use of CIE standard r-tables, instead of actual reflection properties of stabilised pavements, frequently leads to non-compliance with EN 13201 standard, particularly in terms of uniformities. Furthermore, the conventional observation geometry of 1 degrees does not represent the preferred observation geometries of different road users in urban areas. In this paper, we present the device COLUROUTE2 that can be used to measure the r-table of a road surface on site for observation angles between 1 degrees and 10 degrees. Our experimental campaigns carried out on 18 different pavements (with bituminous mixtures and cement concretes) confirm that the CIE road photometric indicators S1, Q0 and Qd generally decrease as the observation angle increases. Our results show that the assumption of equivalence of Q0 and Qd measurements between 1 degrees and 2.29 degrees in the CIE 144 technical report is not always valid, but there are strong correlations between the different observation angles.
The International Commission on Illumination recently issued a position statement advocating for proper light at proper time, specifically recommending a melanopic equivalent daylight illuminance of 250 lx at eye level during daytime. However, the statement also cautions that avoiding glare from windows requires 'advanced lighting design guidance', implying a conflict between achieving healthy lighting and managing daylight-induced glare. This study examines this potential conflict. Through theoretical analysis and a user study across six locations, we found that between the recommended illuminance levels for healthy lighting and the vertical illuminance levels at which glare becomes an issue lies a difference of a factor 10 roughly. This provides fa & ccedil;ade designers with considerable flexibility in selecting appropriate shading solutions. Furthermore, vertical illuminance levels between 250 lx and 1000 lx from daylight typically reduce perceived glare from fa & ccedil;ades. A supporting simulation study positioned a sample office in three European climates and employed typical shading devices and controls, confirming these findings for positions up to 2 m from the fa & ccedil;ade. For deeper room positions in multi-user spaces, solutions become more complex and require advanced lighting design, with higher diffuse transmittance shading appearing beneficial. Overall, the results demonstrate that healthy daytime lighting through daylight does not inherently increase glare risk.
Studies investigating the effects of coloured lighting on specific affective dimensions remain limited. Based on Russell's circumplex model and Cacioppo's evaluative space model, this empirical study investigates the psychological effects of six coloured lighting conditions - red, green, blue, yellow, cyan and magenta on affective dimensions of Pleasure, Activation, Negative affect and Positive affect. We analysed whether different coloured lighting leads to significant differences in affective outcomes, and whether Positive affect and Negative affect are independently, mutually or inversely elicited under coloured lighting exposure. A total of 351 valid responses were collected. Results indicated that under the six coloured lighting conditions, all four affective dimensions differed significantly, and Negative affect and Positive affect were independently elicited by coloured lighting. The findings suggest that the distribution captured by the Pleasure-Activation affective model directly reflects the overall effect of coloured lighting on individuals' levels of pleasure or activation, whereas the Negative-Positive affective model may indicate the capacity of different coloured lighting to elicit positive or negative affective response. For instance, among the six lighting conditions, red lighting showed the highest activation level and the lowest pleasure level. Within the Negative-Positive affective model, red lighting also exhibited the highest level of Negative affect and the second-highest level of Positive affect.
Traditional Jun porcelain constitutes a significant cultural heritage, yet how lighting conditions affect its aesthetic perception remains underexplored. This study investigated the influence of correlated colour temperature (CCT) on multi-dimensional perception of Jun porcelain and examined the moderating role of gender. Using a THOUSLITE LED Cube lighting system, standardized Jun porcelain specimens with Lilac Purple glaze were illuminated under eight CCT conditions (2700 K to 6000 K) at constant 150 lx illumination, with spectral characteristics verified using a THOUSLITE FS spectroradiometer. Thirty participants (15 males and 15 females) evaluated five perceptual dimensions (glossiness, translucency, roughness, temperature and relief perception) of the specimens. Results revealed significant linear relationships between CCT and four dimensions, with higher CCTs enhancing perceived glossiness and translucency while reducing perceived roughness and temperature. Relief perception exhibited negligible sensitivity to CCT. Gender significantly modulated these relationships, with females showing greater sensitivity to CCT variations in perceiving glossiness, translucency and temperature, while males demonstrated stronger responses in roughness evaluation. These findings demonstrate predictable, linear CCT effects on Jun porcelain aesthetic qualities with dimension-specific and gender-based perceptual differences. This study advances understanding of lighting-material perception interactions and provides targeted lighting strategies for culturally authentic ceramic exhibition design.
