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Abstract

The effects of indoor environmental conditions on human health, satisfaction, and performance have been the focus of research for decades. This paper reviews and summarizes the impact of lighting environment on task performance, specifically for the built environment audience. Existing studies included a variety of performance tests on cognitive performance and perception, visual acuity and reaction, memory, reasoning, and labor productivity. Illuminance, luminance ratio and correlated color temperature were found to affect performance in different ways, reflecting the impact of experimental techniques, conditions, performance evaluation methods used and data analysis methods. These were reviewed and categorized, with discussion on limitations related to sample size, modeling approach, carryover effects and other factors affecting individual differences in performance, with recommendations for future improvement. Although no universal conclusions can be made, in general, task performance seems to improve with higher illuminances, contrast ratios in the range of 7-11:1 (while always making sure that glare will not occur in the space) and higher correlated color temperature, while spectral tuning in the red or blue wavelengths has also shown positive effects. To obtain more generic evidence, future studies should be more consistent in terms of experimental procedures and overall light conditions, and also consider the effects of vertical illuminance, daylight provision/control, and outside views on task performance. Finally, studying performance with multi-factorial designs in a human-centered optimized manner (such as deploying variable lighting scenarios optimized for various tasks) can lead to deeper understanding of lighting effects on task performance, and ultimately to improved lighting design and operation in buildings overall.

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... The indoor lighting environment affects occupants' sensitivity and efficiency. A light environment for each activity improves work motivation, productivity, and accuracy [4][5][6], increasing learning efficiency, memory, and concentration [7][8][9]. On the other hand, an unsuitable lighting environment can negatively affect occupants, such as causing drowsiness or impeding learning [3,10]. In general, illuminance, which indicates the amount of light, and CCT (Correlated Color Temperature), which is an evaluation factor of light color, were considered when we arrange indoor lighting environments [11]. ...
... Table 2 shows the control standards for each use objective of the currently set lighting. By referring to previous research cases, three modes of lighting environment suitable for "general office work," "low-intensity work," and "high-intensity work" were set [7,17,18]. In addition, an arrangement was made to add control standards for other uses in the future. ...
... 5,6 Properly designed lighting can enhance users' emotions, productivity and overall satisfaction. 1,2,7,8 It addresses both basic needs, like visibility, and higher-level aspects, such as aesthetics and emotion. 3 Numerous studies have explored how different lighting designs affect users, consistently highlighting illuminance and colour as the key components influencing emotions and user experience. ...
... After a two-week field test, we administered a questionnaire to evaluate our lighting control algorithm to the participants. The evaluation used a 7-point Likert scale and eight pairs of adjectives from the short version of the User Experience Questionnaire (UEQ-S) 57 : (1) obstructive to (7) supportive, (1) complicated to (7) simple, (1) inefficient to (7) efficient, (1) confusing to (7) clear, (1) boring to (7) exciting, (1) not interesting to (7) interesting, (1) conventional to (7) inventive and (1) usual to (7) leading edge. The UEQ-S provides meaningful measures of a system's pragmatic and hedonic qualities as experienced by participants, with its simplicity contributing to its widespread adoption in various studies. ...
Article
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This study proposes context-aware lighting presets for the office lounge based on user behaviour. We explored five kinds of optimised light scenarios: empty, relaxation, discussion , chatting and party, while matching them with patterns of user behaviours. Firstly, we designed lighting solutions for each context through expert interviews. Using these, we developed an algorithm that detects the number of users, their movement and their sound volume using a camera and microphone and suggests appropriate lighting settings based on this data. Then, we implemented the algorithm in two types of office lounges. Finally, user assessments and interview results confirmed that the adaptive lighting preset enriched users' experience. We also discussed the challenges for better implementation.
... Pearson's correlation analysis confirms that increased acceptance of light for welding activities enhances workplace comfort and a brighter atmosphere improves workers' comfort. Worker performance moderately correlates with acceptable lighting for work activities (r = 0.619; p < 0.05), supporting the positive impact of increased lighting, as observed by Konstantzos et al. [25], who identified horizontal and vertical illuminance as factors affecting performance. Table 3 displays physical measurement results with a moderate correlation (between 0.3 to 0.7) to worker's performance. ...
... Additionally, Dianat et al. [26] found that 41.5% of workplaces didn't meet noise standards, 46.9% didn't meet illuminance standards, and 54.6% didn't meet WBGT standards, aligning with workers' perceptions and low satisfaction. moderately correlates with acceptable lighting for work activities (r = 0.619; p < 0.05), supporting the positive impact of increased lighting, as observed by Konstantzos et al. [25], who identified horizontal and vertical illuminance as factors affecting performance. Dianat et al. [26] found that 41.5% of workplaces didn't meet noise standards, 46.9% didn't meet illuminance standards, and 54.6% didn't meet WBGT standards, aligning with workers' perceptions and low satisfaction. ...
... While daylight enhances perceived workspace quality, glare from direct sunlight can negatively impact visual comfort and task performance. Users engaged in screen-based tasks may find window seats less appealing and opt for seats in more uniformly lit environments [83]. 2. The variations of temperature and humidity level around the interior space are subtle, yet having some impacts on the space preferences. ...
... Lighting supports diverse activities in residential spaces, particularly in multi-functional areas like the living room [8]. The living room typically serves as a flexible environment for relaxation, socializing, reading, and screen-based activities, each benefiting from specific lighting qualities. ...
Article
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Lighting is a key factor in shaping comfort, ambiance, and functionality within residential spaces, influencing not only visibility but also a room’s overall experience and usability. In living rooms, where activities range from socializing and relaxation to reading and television viewing, lighting design must balance visual clarity, warmth, and adaptability to meet diverse needs. This study investigates the effects of specific lighting placements—overhead, wall-mounted, and floor/table lamp setups—across warm (2700 K), neutral (4000 K), and cool (6500 K) color temperatures on visual and physical comfort in a simulated residential living room environment. Using a mixed-methods approach, quantitative metrics, such as brightness consistency and luminance contrast, were combined with qualitative assessments of perceived comfort and activity suitability. Findings reveal that warm-toned floor and table lamps (2700 K) provide the highest levels of perceived warmth and relaxation, with average ratings of 4.9 and 4.8, making them particularly suitable for social and leisure activities. Overhead lighting in cool tones (6500 K) enhanced visual clarity, achieving an average clarity rating of 4.5, making it more suited to tasks requiring focused attention, such as reading. Wall-mounted lighting in neutral tones (4000 K) offered a balanced solution, with comfort and activity suitability ratings of 4.5, supporting a range of activities without compromising ambiance or clarity. These results underscore the importance of selecting lighting configurations that align with the intended use of residential spaces. Warm lighting, especially at lower levels, creates a cozy, inviting atmosphere most effectively, while cooler overhead lighting offers enhanced brightness and clarity for more visually demanding tasks. By highlighting the impact of lighting placement and color temperature on residential comfort, this study provides practical insights for interior designers and homeowners, contributing to developing adaptable, user-centered lighting solutions that optimize functionality and ambiance in home environments.
... A wide literature on the acute effects of light on work performances is reported in the review by Konstantzos et al. [16]. This paragraph extends the analysis to other studies and considers the influence of lighting conditions on peoples' mood and general comfort in addition to those on work performances. ...
... However, issues such as illuminance requirements according to the building layout and orientation (Le-Thanh et al., 2022), task performance (Konstantzos et al., 2020), risk of glare (Bian et al., 2020), distribution of light on the work surface and in the surrounding areas (Alrubaih et al., 2013), as well as light consistency during the day and throughout different seasons should be taken into account. In addition, façade glazings can contribute to significant heat loss/gain in buildings (Hee et al., 2015). ...
Article
In buildings with double skin façades (DSF), the amount of light entering the internal spaces depends on the properties of the outer surface, the build-up of the layers of the façade, as well as their architectural features and shading devices (if any). However, studies focusing on the incidence of daylighting in buildings with DSF are still few and far between. In this context, this study aims at reviewing the previous academic research on the effects of DSF on daylighting in buildings, analysing the impacts of architectural design and detailing parameters (e.g. shading device, cavity depth, structure, skin fabric materials, and build-up, and the building and façade orientations) on the natural lighting of buildings with DSF. This study uses a scoping methodology to filter through the state-of-the-art in the literature on DSF. In this study, the literature search has been conducted using Scopus, Web of Science, and ScienceDirect leading into 148 major publications. The final number was narrowed down to 33 due to several reasons. Overall, results indicate that, compared to conventional façades, DSF decreases daylight levels, prevents glare, and enhances a more uniform distribution of light in internal spaces of buildings. Concluding remarks identify the gaps in the knowledge and pinpoint potential areas for future research.
... As individuals age, attaining quality sleep and maintaining an appropriate level of cognitive stimulation becomes increasingly crucial to enhancing overall health and well-being. Cognitive performance, which encompasses an individual's capacity to interact with (process, retain, and recall) information, make decisions, and perform tasks [1,2], is influenced by several factors. Notably, emerging research highlights the significant role of sleep quality and human circadian rhythm as vital biological determinants impacting cognitive performance, memory, and processing speed [3][4][5]. ...
Article
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The impacts of lighting conditions on human circadian rhythms, sleep quality, and cognitive performance have been extensively investigated in the past two decades; however, these studies have yielded inconclusive and variable outcomes. For older adults who are at a higher risk of developing serious physiological and mental illnesses, such as Alzheimer’s or dementia, light therapy has emerged as a low-risk intervention to improve sleep quality and cognitive function. Nevertheless, the optimal methodology for evaluating the efficacy of light therapy in older adults remains unclear. This review has been conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and critically analyzes methodologies in previous studies on lighting's impact on sleep and cognitive performance in healthy older adults, focusing on how these approaches affect the findings. The review is structured into six domains: study setting and type, participant characteristics, lighting conditions, study design, sleep quality evaluation methods, and cognitive performance evaluation methods. Diverse study designs, methods, and population characteristics have influenced the outcomes. Bright light, applied from early morning to early evening, has been shown to enhance sleep and cognitive functions, notably working memory and concentration. It also benefits from dawn simulation throughout the day, which regulates circadian rhythms and improves sleep quality, although the ideal timing is yet to be determined. Intense short-wavelength lights and strong placebo conditions can counteract these positive effects, and using bright light in the evening may impair sleep and indirectly worsen cognitive performance in older adults. Further real-world experimental studies on this demographic, meticulous study designs, a combination of objective and subjective evaluation methods, and comprehensive reporting of lighting interventions are crucial for identifying the optimal lighting design approach for this population.
... Complex tasks (7-8 digits vs. 4-6 digits BDST) exhibited afternoon declines under bright light, while less complex tasks showed improvements. Notably, conclusive insights regarding the time of day and bright light's cognitive performance benefits remain elusive [14]. ...
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This study contributes to the ongoing exploration of methods to enhance the environmental design, cognitive function, and overall wellbeing, primarily focusing on understanding the modulation of human cognitive performance by artificial lighting conditions. In this investigation, participants (N=35) engaged with two distinct architectural contexts, each featuring five different lighting conditions within a virtual environment during specific daytime scenarios. Responding to a series of cognitive memory tests, we measured participant test scores and the corresponding reaction time. The study's findings, particularly in Backward Digit Span Tasks (BDST) and Visual Memory Tasks (VMT), indicate that diverse lighting conditions significantly impacted cognitive performance at different times of the day. Notably, the BDST scores were mainly affected by lighting conditions in the afternoon session, whereas the VMT scores were primarily influenced in the morning sessions. This research offers support for architects and engineers as they develop lighting designs that are sensitive to the cognitive performance of occupants. It highlights the advantages of utilizing VR simulations in the AEC industry to assess the impact of lighting designs on users. Further research can lead to the development of lighting systems that can promote better cognitive function and overall wellbeing.
... Robotic cameras require ideal lighting conditions for accurate functioning [31], much like human eyesight, which depends on a well-balanced lighting environment to operate well [32]. ...
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Mobile service robots employ vision systems to discern objects in their workspaces for navigation or object detection. The lighting conditions of the surroundings affect a robot’s ability to discern and navigate in its work environment. Robot inclusivity principles can be used to determine the suitability of a site’s lighting condition for robot performance. This paper proposes a novel framework for autonomously auditing the Robot Inclusivity Index of indoor environments based on the lighting condition (RII-lux). The framework considers the factors of light intensity and the presence of glare to define the RII-Lux of a particular location in an environment. The auditing framework is implemented on a robot to autonomously generate a heatmap visually representing the variation in RII-Lux of an environment. The applicability of the proposed framework for generating true-to-life RII-Lux heatmaps has been validated through experimental results.
... The red colour cross symbol indicates the points of data measurement. In the modern workplace, lighting has evolved beyond its traditional role of simple illuminance, now recognized as a pivotal element significantly influencing employee well-being and productivity [14]. ...
... It is also reasonable to expect that subjectively preferred lighting conditions would not have direct glare from luminaires, veiling reflections, or reflected luminaire images. However, luminance contrast, to a certain extent, can still be preferred (e.g., 1:10 contrast for a distinct visual cue [59,60]). The optimal balance between visually interesting luminance distributions and the prevention of glare is still under investigation [58,[61][62][63]. ...
Article
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Electric lighting plays a critical role in buildings, not only impacting the well-being, satisfaction, and performance of building occupants but also accounting for a significant portion of energy consumption. The commonly used efficiency metrics for lighting, such as luminous efficacy or lighting power density, fall short of quantifying the effective light in architectural spaces. To address the shortcomings of existing efficiency measures, lighting application efficacy that characterizes the efficient delivery of light from the source to the target should be utilized. Lighting application efficacy can account for efficiencies in temporal, electrical, sensory, and spatial dimensions. This study outlines a method to quantify the spatial efficiency of electric lighting in buildings. As proof of concept, simulated spatial efficiency data are analyzed for two targets (horizontal work plane level and occupant field of view) based on the primary characteristics of the built environment and lighting systems. The findings indicate that design variables (e.g., room size, luminaire distribution type, reflectance of the surfaces, and field of view) can significantly affect the spatial efficiency of lighting in the specified settings. Therefore, spatial efficiency values can exhibit considerable variation among distinct lighting systems and architectural spaces and should be customized to suit the unique requirements of each design setting. Future research will investigate and establish the complementary components of the lighting application efficacy framework.
... Given its crucial role in human live, indoor lighting design has become essential to educational building design [20]. In fact, light has long been recognised as fundamental in creating a conducive learning environment [21] and is known to play a critical role in educational centres [22]. It is well known that the aesthetics and psychological aspects of learning environments are heavily influenced by lighting, but its significance extends beyond basic visibility [23]. ...
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Humans are spending more time indoors than ever due to urbanisation and industrialisation, leading to higher electricity consumption in lighting systems. Recent research has demonstrated the significance of maintaining a balance between daylight and electric light to create an ideal learning environment that can significantly impact students’ academic performance. The objective of this study is to analyse the changes in students’ emotional response depending on the type of lighting in the classroom—whether it is daylight, electric light, or a combination of both. A field study was conducted with 521 university students to assess their affective response to the lighting environment inside their classroom. The results show that students prefer a Clear-efficient lighting environment for writing–reading tasks and a Soft-calm atmosphere for using electronic devices. For the paying attention tasks, a combination of daylighting and electric lighting is determined to be the best solution, while for the tasks of discussing–teamwork, students prefer daylighting. Daylighting is found to be the only lighting option that students like. Despite this, students still consider electric lighting and the combination of daylight and electric light adequate for a classroom. The findings of this study may help educators and designers create learning spaces that promote a positive and stimulating student environment by understanding the relationship between the lighting environment and students’ affective responses.
... Glare causes distraction and reduces individuals' performance. [20] As mentioned, exposure to inappropriate light can cause disturbances in the visual system and mental performance of people. In past studies, the effect of various lighting factors such as lighting intensity and color temperature on human error and work speed has been investigated, and in most studies, lighting sources with different lighting intensities have been considered for the test environment. ...
Article
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Aim The use of appropriate lighting systems can have a significant impact on improving cognitive performance parameters and reducing workplace accidents. The aim of this study was to examine the relationship between different levels of luminance and color temperature of LED lamps on human error and the work speed of individuals in laboratory conditions. Materials and Methods This empirical study was conducted on 12 men and women volunteers. Two LED lamps with two color temperatures of 3000°K and 6000°K were set at angles of 15°, 30°, and 45° and with the same light intensity of 300 lux. Accuracy and work speed parameters were recorded at different time intervals using a target accuracy test. Statistical analysis was performed using SPSS version 26. Results The mean ± standard deviation age of the participants in this study was 20.9 ± 1.2 years, and 50% (6 individuals) were male. The results showed that human error among people in three different angles of luminance for color temperatures of 6000°K and 3000°K was significant ( P < 0.01), and in terms of the work speed, this difference was not significant ( P > 0.05). The comparison of error counts and work speed between two color temperatures of 3000°K and 6000°K at all three angles of luminance independently showed a significant difference only in error counts ( P < 0.001). Conclusion The results demonstrated that the angle of luminance and color temperature have an impact on human error, with individuals exhibiting fewer errors at higher color temperatures. The findings of this research can be utilized in industries that involve high cognitive performance-sensitive occupations.
... Natural light also impacts human health positively through different biological pathways, including circadian rhythm regulation [34] and increased serotonin production [35]. In built environments, window size, orientation, and location affect the amount of natural light exposure, which has been shown to affect well-being in the workplace [36,37]. Increased exposure to natural light due to the presence of windows can decrease stress and anxiety [38,39], promote workers' relaxation [40], and even reduce the number of sick days taken by office employees [41]. ...
... Due to its simplicity in terms of measurement, illuminance is a broadly used method to capture light sufficiency in lighting standards. Also, it is widely explored as a potential variable that influences human performance [32]. The Illuminating Engineering Society (IES) recommends horizontal and vertical illuminance targets to ensure sufficient illumination for occupants. ...
Article
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Parametric design influences on building envelope design are exponentially increasing in the current era due to the dominance of computational design on architectural outcomes. The composition of the building envelope’s patterns, shape, size, and distribution of the perforations can affect the efficiency of daylighting within the space; daylight quality, visual comfort, and daylight performance. Through the manipulation of the daylighting patterns, a balance between illuminance and glare control is created. This research study aims to analyze and evaluate the effect of different parametric patterns integration on daylighting in “Architecture Studio-based” tutoring through the distribution of perforation on façade openings, percentage of perforation, and perforation size in a hot-dry climate. The analysis is conducted through building performance simulation software (Climate Studio). The research concludes that the “Triangles Parametric Pattern” among all the tested patterns, achieves the highest performance in compliance with the recommended thresholds of daylight quality, visual comfort, and daylight performance metrics within the studio space compared to other parametric patterns and the base case model. The implications of such an experiment inform designers to categorize daylight performance while selecting patterns in window design as part of façade design.
Article
Studies have shown that the correlated colour temperature (CCT) of light significantly influences individuals engaged in study and work activities. However, the impact of CCT on stress and task performance, particularly when considering subjective preferences and experiences, has been explored only to a limited extent. This study aims to investigate the relationship between CCT, thermal sensation vote, stress levels and task performance. Forty-two healthy participants (21 female and 21 male, aged 20 to 53 years) participated in the experimental study. Participants completed a paper-based task and subjective questionnaires across three sessions, each conducted under different CCTs (2700 K, 4000 K and 6500 K). During these sessions, electroencephalogram (EEG) and heart rate variability were monitored to objectively assess stress levels. The study primarily focused on the activity of EEG alpha and theta waves in response to varying CCT degrees. Notably, significant activity was observed in the frontal lobes at 2700 K, particularly related to the frontal theta wave. Statistical significance was also identified in different brain regions in both alpha and theta waves among participants who demonstrated successful task performance. Additionally, participants reported optimal thermal comfort at 2700 K, which was associated with enhanced task performance and reduced stress levels.
Article
Brightness, the perceived amount of light within a luminous environment, significantly impacts the functional and aesthetic quality of the built environment. Previous studies have often used conditions that do not fully replicate real-world settings, highlighting the need for further research in this area to inform better lighting practices. This study investigates the overall brightness perception of larger combined stimuli consisting of a central shape and its surround for potential implications for architectural lighting design. An experiment with 42 participants was conducted to investigate the effects of luminance, visual angle, contrast (positive and negative), and edge blur (diffuse and sharp) on the perception of brightness using a two-interval forced choice method. The results suggested that surround luminance had a significant effect on brightness perception. Overall, higher surround luminance was perceived to be brighter. As the visual angle increased, the effect of surround luminance diminished in cases with higher surround luminance. Although the interaction effect of surround luminance and visual angle on brightness perception was significant, the simple main effect of visual angle was not statistically significant in the tested negative contrast conditions. The effect of edge blur depended on the visual angle. The study highlights the importance of careful consideration of luminance and visual angle in optimizing perceived brightness.
Thesis
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Understanding how energy is used in non-residential buildings such as the UK higher education institution is critical not only because of the cost and its environmental impact but also because of legislative compliance and strict national carbon targets to decarbonise the built environment. Previous research has investigated that unoccupied lighting in non-residential buildings in the UK contributes a 9% increase to non-domestic buildings' annual electrical baseload. The implementation of energy efficiency initiatives such as LED lighting and occupancy sensors has potential energy savings; however, turning the lights off entirely saves 100 percent. The aim of this report is to identify potential energy savings from unoccupied lighting in a higher educational building. This study utilised a survey and time-series energy data analysis to investigate the potential savings. Different artificial lighting scenarios were modelled, and the switch-off rate of 62.8% observed from the survey was used to estimate the potential savings from unoccupied lighting. This was done by identifying the different lighting systems, which were broken into several groups based on the operating hours observed during the survey, and the analysis was made possible using Excel. The result shows that turning off the light during unoccupied hours could save 23% at maximum and 9% at minimum. Also, based on our field observation, the third scenario most accurately depicts the current condition of the lighting in the building. That will imply that the university has a 13% saving potential, which is equivalent to at least £23,882.74 and 16 tCO2 per year for a single building. The evidence from the other component of the research, which is the analysis of the half-hourly metre reading, shows that about 30 kW/h of energy is lost from unoccupied hours on a weekly basis. The result of this analysis provides a strong recommendation to switch off lights at lunch time.
Chapter
Colour plays a vital role in modern architectural design, particularly in healthcare and wellness environments. This section provides an insight into how colour can significantly improve the patient experience in healthcare facilities by influencing their mood, perception and overall wellbeing. Research has shown that specific colours can evoke specific emotions and antipathies, such as yellow’s ability to make people feel hopeful, so environmental colours in healthcare-related buildings are crucial in reducing patient stress, enhancing well-being and creating a comfortable environment. In addition, colour plays an important role in the usability of medical equipment and environmental aesthetics.
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Book
This report is a comprehensive review of the scientific knowledge acquired over the last ten years on the effects of solid state lighting (SSL) on human health. The report considers issues that concern both large fractions of the population as well as small sensitive groups of people. The report is primarily intended to support policymakers, offering guidance on lighting and health, as they consider product regulatory requirements, procurement specifications, programmes to raise public awareness, and other initiatives. However, the report will also be useful to the entire lighting community, including scientists engaged in fundamental and applied lighting research, illumination engineers, manufacturers, and lighting practitioners. This report is available at https://www.iea-4e.org/ssl/news/new-comprehensive-report-on-health-effects-of-solid-state-lighting/
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Mental health is a significant public concern. Given that individuals spend extended periods indoors, understanding the psychophysiological health effects of indoor materials on well-being is crucial. This study compared the effects of wooden and resin plaster rooms on psychophysiological well-being. Well-being was assessed using heart rate variability measurements and an affective well-being questionnaire. Subjective perceptions were also evaluated using a semantic differential questionnaire. The results indicated higher heart rate variability in the wooden room compared to the reference room. Participants breathed about one breath per minute more slowly in the wooden room, with a negative correlation between heart rate variability and respiratory rate. Positive affect was elevated, and negative affect was reduced in the wooden room, which was also perceived more favorably in sensory evaluations. The findings suggest that wooden interiors are preferred over artificial materials, enhancing both physiological and psychological well-being.
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Overtime, interest has risen in museum research, with researchers finding answer to issues such as visitors experience, visitors’ interest, visitors need, motivations and desire to revisit. Lighting in museum is one of many crucial factors in museum finishing, that could motivate, promote or discourage more visit by tourists. The intensity of the spatial lighting could be excessive, or not sufficient. The understanding of lighting being sourced primarily from daylighting, and supported with artificial lighting, especially to serve as energy sources for the rainy seasons and the night hours in many parts of the world is a vital design criterion especially in Nigeria. Museum design over time has held on to the philosophy of putting out completely the natural light in museum design, or relegating it to common spaces in the museum such as circulation areas. Research has shown that the essence of natural lighting to the human psychology is very important, for effective productivity within spaces, which includes the museum, which double function today as a learning space too. This research is a step further in emphasizing this importance, and addressing the problem of balance between natural and artificial lighting within the museum exhibition space, to protect artifacts on display and promote maximum productivity amongst tourist and space users of a museum, thereby enhancing cultural tourism. For the purpose of this research, qualitative method of data collection is employed, using case study as the primary source for data collection, aside interview, and literatures for secondary data. Findings show that natural lighting in a museum can be controlled and adequately regulated using strategies such as building orientation with openings in the north and south axis of the site, strategic openings which promote in-direct contact with artifacts on display, treated glazing such as the anti-solar glass, and use of filters on glasses to keep the harmful UV ray out of the indoor space, and use of recesses and shading devices. The, research will enhance museum experience, through lighting within the museum space, and recommends proper control strategies for natural lighting, to enhance visitor’s performance, protect the artifacts on display, and enhance cultural tourism.
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This dissertation examines how immersive technologies can be effectively integrated with BIM technologies to improve processes within the construction project lifecycle. A literature review was conducted to identify research gaps in current immersive BIM literature. An industry workshop was held to identify the existing barriers and future applications of immersive BIM within the construction industry. A software package was developed to overcome interoperability issues associated with immersive BIM applications. Three immersive BIM prototypes were developed and evaluated. The first prototype combines BIM with AR technologies to superimpose BIM models on construction sites for defect management inspections. The second and third prototypes focus on using VR in the architectural phase of the construction project lifecycle to visualise building design features.
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Eye strain merupakan kondisi di mana mata mengalami ketegangan akibat terlalu sering digunakan dalam waktu yang lama, terutama pada aktivitas yang melibatkan penggunaan komputer. NIOSH menyebutkan bahwa sekitar 75 – 90% pengguna komputer yang menghabiskan waktu selama tiga jam atau lebih mengeluhkan gangguan penglihatan. Sebuah studi oleh Kowalska et al (2011) terhadap pekerja kantoran yang menggunakan komputer secara intens menyebutkan bahwa prevalensi eye strain pada pekerja wanita sebesar 50,7% dan pada pria sebesar 32,6%. Penelitian ini bertujuan untuk mengetahui hubungan antara tingkat pencahayaan, reflektansi, dan kekontrasan area kerja terhadap keluhan eye strain pada karyawan office di PT. X. Penelitian dilakukan dari April – Juni 2023 dengan total sampel sebanyak 134 orang secara simple random sampling. Desain penelitian yang digunakan yaitu cross-sectional serta pengambilan data dilakukan dengan menyebarkan kuesioner, yang diadopsi dari Haeny (2009) dan Ramadhani (2012), dan pengukuran langsung menggunakan lux meter. Hasil uji analisis univariat menunjukkan bahwa terdapat 113 orang karyawan (84,3%) mengalami keluhan eye strain dengan gejala paling sering dirasakan yaitu terasa tegang di leher dan bahu (43,3%) dan gejala paling jarang dirasakan yaitu terasa nyeri di kelopak mata (8,2%). Dari hasil uji analisis bivariat menunjukkan bahwa terdapat hubungan antara tingkat pencahayaan (p-value = 0,000), reflektansi (p-value = 0,001), kekontrasan (p-value = 0,027), durasi kerja (p-value = 0,000), dan usia (p-value = 0,022), namun tidak terdapat hubungan antara gangguan penglihatan (p-value = 0,749) dan riwayat gangguan kesehatan mata (p-value = 0,918) terhadap keluhan eye strain.
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Indoor environmental quality (IEQ) significantly impacts human health, well-being, and productivity. However, a comprehensive and in-depth review of the combined effects of IAQ and other multi-domain factors on human productivity is lacking. There has not been any prior review that encapsulates the impact of multi-domain factors on productivity and physiological responses of occupants. To address this gap, this review paper investigates and highlights the impact of IAQ and multi-domain factors (thermal, visual, and acoustic) on human productivity and occupant well-being in the built environment. The review explores various research methods, including evaluation of human productivity and creativity, data collection, and physiological signal analysis. We also examined the interactions between IAQ and multi-domain factors, as well as strategies for optimizing productivity through integrated building design and smart systems. The key findings from this review reveal that IAQ significantly impacts human productivity and occupant well-being, with interactions between IAQ and other IEQ factors further impacting these effects. Despite advances in the field, there are several limitations and gaps in the current research methods and study designs, including small sample sizes, limited and insufficient experimental design and control, reliance on laboratory or simulated environments, lack of follow-up and long-term data, and lack of robust performance metrics. The review proposes future research directions, including specific applications, and follow-up work to address these limitations and further advance the understanding of IAQ and multi-domain factors in the built environment. The implications of this review for policy and practice include the need for holistic and integrated approaches to IAQ and IEQ management, with a focus on creating healthy and productive indoor environments. This review emphasizes the importance of considering the complex interplay between IAQ and multi-domain factors, as well as the potentials of adopting smart control systems and sustainable design strategies to optimize productivity and occupant well-being in the built environment. By addressing these critical issues, we can enhance the overall quality of life for building occupants and contribute to a more sustainable future.
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Presentation
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This report to the Alberta Environmental Research Trust describes what is perhaps the largest controlled experiment of its type (648 participants tested for 3 hours in a between-subjects factorial design using 9 room climate conditions and 3 X 3 X 2 lighting factors). A summary of the some of its results pertaining to thermal comfort together with some related experiments by Nelson was published in the ASHRAE Journal in 1987. This full report points out some major results pertaining to the lighting conditions as well as thermal comfort. It is their combined effects which particularly have much to offer in terms of the scope of its measurements and implications for future research.
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Light is necessary for vision; it enables us to sense and perceive our surroundings and in many direct and indirect ways, via eye and skin, affects our physiological and psychological health. The use of light in built environments has comfort, behavioural, economic and environmental consequences. Daylight has many particular benefits including excellent visual performance, permitting good eyesight, effective entrainment of the circadian system as well as a number of acute non-image forming effects and the important role of vitamin D production. Some human responses to daylight seem to be well defined whilst others require more research to be adequately understood. This paper presents an overview of current knowledge on how the characteristics of daylight play a role in fulfilling these and other functions often better than electric lighting as conventionally delivered.
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First study of how daylighting in elementary school classrooms is associated with improved test scores. Includes analysis from over 9000 student records in three school districts.
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To date, it is largely unknown which light settings define the optimum to steer alertness and cognitive control during regular daytime working hours. In the current article, we used a multimeasure approach combined with a relatively large sample size (N = 60) and a large range of intensity levels (20-2000 lux at eye level) to investigate the dose-dependent relationship between light and correlates of alertness and executive control during regular working hours in the morning and afternoon. Each participant was exposed to a single-intensity light level for 1 h after a 30-min baseline phase (100 lux at the eye) in the morning and afternoon (on separate days) during their daily routine. Results revealed no clear dose-dependent relationships between 1-h daytime light exposure and correlates of alertness or executive control. Subjective correlates showed only very modest linear relationships with the log-transformed illuminance, and we found no significant effects of light intensity on the behavioral and physiological indicators. Overall, these results suggest that daytime exposure to more intense light, at least for 1 h of exposure, may not systematically benefit alertness or executive functioning. However, future research is required to investigate effects of longer exposure durations and potential moderations by prior light exposure, personal characteristics, and spectrum.
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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 ≥ 0.3) could be installed in office buildings, and to determine whether this lighting intervention would reduce sleepiness and increase alertness, vitality and energy in office workers while at work. Desktop and/or overhead luminaires provided circadian-effective lighting at participants’ eyes during a two-day intervention. A pendant-mounted Daysimeter device was used to measure participant-specific CS values during the baseline and the intervention days. Participants also completed questionnaires inquiring about sleep habits, stress and subjective feelings of vitality and energy. The Daysimeter data showed that participants were exposed to significantly higher amounts of circadian-effective light while at work during the two intervention days compared to the baseline day. Self-reported sleepiness scores were significantly reduced during the intervention days compared to the baseline day. As hypothesised, participants also reported feeling significantly more vital, energetic and alert on the intervention days compared to the baseline day. The present results from four independent office environments demonstrate that lighting systems delivering a CS ≥ 0.3 can reduce sleepiness and increase vitality and alertness in office workers.
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Offices are transforming into multi-user, open space environments to stimulate interaction between people and optimize the usage of space. Due to design practices, lighting systems in these multi-user environments are implemented as a regular grid of luminaires that often does not match the furniture layout. Consequently, purely personal control over general lighting is not achievable in most cases. As a result, a single luminaire affects several neighbouring desks, creating shared lighting controls and conditions. Therefore, providing satisfying lighting conditions to everyone becomes a challenge. This paper proposes a first method for modelling lighting preference profiles of users based on their control behaviour and preference information. Based on objective measurements and subjective data obtained in two field studies, users can be profiled based on their control behaviour, regarding characteristics as activeness, dominance, lighting tolerance, and dimming level preference. The results show significant differences between lighting preference profiles of users. This paper also proposes a first method for discovering and triggering submissive users to express their preferences in order to derive their profiles as accurate as possible. This will help to secure users' comfort by offering satisfying lighting conditions to their preference. By knowing the lighting preference profiles of users, the probability of conflict between users can be predicted and minimized.
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This paper extends the applicability of emerging frameworks for evaluating the non-visual effects of light through the development of a novel area-based daylighting metric addressing goals of human circadian stimulus and entrainment in buildings. Procedures using annual, climate-based daylight modeling of eye-level light exposures are developed to analyze and map indoor environments in regard to spatial and seasonal changes in the availability of a circadian-effective daylight stimulus. Because the biological effects of light exposure are not instantaneous, a novel approach is developed to assess the duration of an effective stimulus on a daily basis, as well as the frequency an effective stimulus is present over the course of a year. Results can be used to identify and visually examine building zones where long-term occupancy may lead to disruption of the circadian system in the absence of supplemental electrical lighting capable of effective circadian stimulus. The metric and visualization techniques are implemented in a parametric, simulation-based workflow utilizing publicly available software tools. The workflow can be used to assess and differentiate the performance of various daylighting strategies during the design phases of a project, or to examine existing spaces. The applicability of the workflow is demonstrated using two example models: a portable school classroom, and a generic open-plan commercial office floor plate.
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The effects of pre-set environmental conditions of temperature and lighting on the preferred personal settings, comfort experience and task performance of office workers were investigated in an individually controlled workstation. Twenty subjects performed standardized tasks at a prototype workstation with individually controlled radiant heating and lighting in a climate room. In a repeated measures design, their adjustments to pre-set values were evaluated: low and high radiant heating power, low and high direct illuminance, low and high indirect illuminance. Results showed that preferred personal settings are dependent on the initial, pre-set values of radiant heating power and illuminance. Higher pre-set values result in higher adjusted operative temperatures and higher illuminances on desk, although the differences for heating were too small to show a convincing effect. After adjustment, visual comfort was higher, but it was not dependent of the pre-set values. For thermal comfort no differences were found. Individual task performance was not negatively affected. Providing personal environmental control and the way these concepts and interfaces are designed, play a significant role in user behavior and preferences. The design and control of individually controlled workstations as well as the interaction with the general level of the office environment should be carefully considered in order to obtain maximum comfort and energy efficiency.
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The effect of indoor environment may have an influence on the performance, productivity health and well-being of office workers. Environmental factors such as indoor temperature and illumination have been investigated at three levels. A neurobehavioral test (NBT) has been proposed for the evaluation of office workersc performance. A field lab to emulate an office has been created. In controlled condition of environmental factors, the neurobehavioral test was conducted. The response time and the number of errors in each test have been recorded. A randomized block factorial design was used to analyze the responses of office worker’s performance. The results revealed that the independent and interaction effect of temperature and illumination have significant effect on the office workers’ performance. The effect of indoor room temperature has more influences than the effect of illumination. The effect of indoor temperature has 38.56% of contribution on the performance. The optimum levels of indoor temperature at 21°C and illumination at 1000 lux have improved the work performance and health of office workers. The indoor room temperature and illumination are more influence on the performance of the office workers. It may be concluded that the impact of indoor room temperature (38.56%) is more on the office worker’s performance than the effect of illumination (19.91%). Further, it may be concluded that the optimum level of indoor room temperature (21°C) and illumination (1000lux) have improved the work performance, health and productivity of office workers.
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Alertness-enhancing effects of bright light are particularly strong at night or after sleep deprivation. Alerting effects during daytime also exist, yet these appear to be more modest. In this study, we investigate whether a higher illuminance level particularly benefits individuals who suffer from mental fatigue – not from sleep pressure, but from mental exertion. A 2x2 within-subjects design (N = 28; 106 sessions) was applied to investigate effects of 1000 vs. 200 lx at the eye on self-report measures, task performance and physiological arousal after a mental antecedent condition (fatigue vs. control). Results showed that participants felt less sleepy, more vital and happier when exposed to bright light. Effects on subjective sleepiness and self-control capacity were stronger under mental fatigue. Vigilance benefited from bright light exposure – although this effect emerged with a delay irrespective of the antecedent condition. Other tasks showed more mixed and sometimes even adverse effects of bright light.
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Light is a potent stimulus for regulating circadian, hormonal, and behavioral systems. In addition, light therapy is effective for certain affective disorders, sleep problems, and circadian rhythm disruption. These biological and behavioral effects of light are influenced by a distinct photoreceptor in the eye, melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs), in addition to conventional rods and cones. We summarize the neurophysiology of this newly described sensory pathway and consider implications for the measurement, production, and application of light. A new light-measurement strategy taking account of the complex photoreceptive inputs to these non-visual responses is proposed for use by researchers, and simple suggestions for artificial/architectural lighting are provided for regulatory authorities, lighting manufacturers, designers, and engineers.
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The importance of lighting for performance in human adults is well established. However, evidence on the extent to which lighting affects the school performance of young children is sparse. This paper evaluates the effect of lighting conditions (with vertical illuminances between 350 lux and 1000 lux and correlated colour temperatures between 3000 and 12 000 K) on the concentration of elementary school children in three experiments. In the first two experiments, a flexible and dynamic lighting system is used in quasi-experimental field studies using data from 89 pupils from two schools (Study 1) and 37 pupils from two classrooms (Study 2). The third experiment evaluated two lighting settings within a school-simulating, windowless laboratory setting (n = 55). The results indicate a positive influence of the lighting system on pupils’ concentration. The findings underline the importance of lighting for learning. Several suggestions are made for further research.
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There is less discomfort glare from a window with an interesting view than from either a neutral screen or a window with a poor view having the same daylight glare index. A view with patches of high luminance is more glaring than a more uniform view with the same mean luminance. In two experiments carried out during May and June 2005, subjects assessed glare from windows in a 20-storey building in Sheffield, UK. The rooms used were identical except that at different levels and orientations the prospects varied from close views of other buildings to extensive urban and natural scenes. In the first experiment, with 72 university students as subjects, the reported discomfort glare from a diffusing screen covering the window was compared with that from a view onto a nearby obstructing wall and from a view with trees and distant landscape. The weather was changeable so each scene was observed over a range of different luminances. In the second experiment, with 96 subjects, the glare from an urban view that included nearby elements, the middle distance and the far distance was compared with a restricted urban view, with an extensive natural view and with a restricted natural view. Independent groups of subjects rated the interest of all the views. It was found that subjects' reported discomfort from glare varied significantly between all three cases in the first experiment and all four cases of the second experiment: glare discomfort decreased as interest increased. The luminance range within a view also affected the experience of glare. The results are consistent with those of an earlier study of glare from small screens.
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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 LED lighting solution mimicking a daylight spectrum on visual comfort, circadian physiology, daytime alertness, mood, cognitive performance and sleep. Fifteen young males twice spent 49 hours in the laboratory under a conventional-LED and under a daylight-LED condition in a balanced cross over design flanked by a baseline and a post-light exposure night. Despite different light spectra, the photopic lux and the correlated colour temperature of the lighting were the same for both LEDs. The colour rendering index and the melanopic strength were 25.3% and 21%, respectively, higher for the daylight LED than the conventional LED. 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. Delta EEG activity (0.75–4.5 Hz) was significantly higher after daylight-LED than conventional-LED exposure during the post-light exposure night. We have evidence that a daylight-LED solution has beneficial effects on visual comfort, daytime alertness, mood and sleep intensity in healthy volunteers.
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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 LED lighting solution mimicking a daylight spectrum on visual comfort, circadian physiology, daytime alertness, mood, cognitive performance and sleep. Fifteen young males twice spent 49 hours in the laboratory under a conventional-LED and under a daylight-LED condition in a balanced cross over design flanked by a baseline and a post-light exposure night. Despite different light spectra, the photopic lux and the correlated colour temperature of the lighting were the same for both LEDs. The colour rendering index and the melanopic strength were 25.3% and 21%, respectively, higher for the daylight LED than the conventional LED. 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. Delta EEG activity (0.75–4.5 Hz) was significantly higher after daylight-LED than conventional-LED exposure during the post-light exposure night. We have evidence that a daylight-LED solution has beneficial effects on visual comfort, daytime alertness, mood and sleep intensity in healthy volunteers.
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Existing research on visual comfort conducted with children has focused on the impacts of lighting on their academic performance and not specifically on preferences. The aim of this study is to present a multimethod approach to identify children’s preferences for luminous environments and window views in preschool classrooms. The study was conducted in six classrooms in Florianópolis (Brazil) in 2016, with approximately 84 children. More than 240 preference votes for luminous environment and 83 preference votes for window views were obtained, and 253 drawings of preferred elements of the views were produced. The reasons for the preferences of the children were investigated by reviewing the content of the surveys and drawings. The association of age, gender and physical environment with the preferences was investigated. The results indicated that young children can differentiate lighting needs according to the activity performed. Visual contact with the view seen through the classroom window was important to the children, with a higher preference for natural views. Of the relationships tested, “age” was the personal variable that was neither associated with the preference for the use of curtains, nor artificial lighting. Although a tendency between gender and the type of preferred window view was identified, such relationship was not statistically significant. Based on the methodological approach used for data collection methodological recommendations are presented for future research. This work underlines the need to involve young children in studies of visual comfort, as they can provide valuable information from their own experiences of built spaces.
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Periodic, well timed exposure to light is important for our health and wellbeing. Light, in particular in the blue part of the spectrum, is thought to affect alertness both indirectly, by modifying circadian rhythms, and directly, giving rise to acute effects. We performed a systematic review of empirical studies on direct, acute effects of light on alertness to evaluate the reliability of these effects and to assess to what extent they depend on other factors, such as time of day, exposure duration and sleep pressure. In total, we identified 74 studies in which either light intensity, spectral distribution, or both were manipulated, and the effects on behavioral measures of alertness were evaluated, either subjectively or measured in performance tasks. The results show that increasing the intensity or the color temperature of polychromatic white light in general has been found to increase subjective ratings of alertness, though a substantial proportion of these studies failed to find significant effects. There is little evidence in the literature that these subjective alerting effects of light also translate into improvements on performance measures of alertness. For monochromatic or narrowband light exposure, some studies have shown improvement in reaction time tasks with exposure to blue light, but generally this was not accompanied by changes in subjective alertness. Thus, the alerting effects of light are far less clear than often suggested. We suggest that in future studies more attention should be paid to other factors that may influence the effects of light, such as chronotype, circadian phase, homeostatic state and prior light history.
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Objective: We tested whether the effects of a dynamic lighting system are superior to conventional lighting on emotions, agitation behaviour, quality of life, melatonin secretion and circadian restactivity cycles in severely demented patients. As a comparison, an age matched control patient group was exposed to conventional lighting. For none of the output measures were significant differences between the two lighting conditions found during the 8 study weeks in fall/winter. Methods: Thus, we divided the patient cohort (n = 89) into two groups, solely based on the median of their daily individual light exposure. Patients with higher average daily light exposure (>417 lx) showed significantly longer emotional expressions of pleasure and alertness per daily observations than patients with lower daily light exposure. Moreover, they had a higher quality of life, spent less time in bed, went to bed later and initiated their sleep episodes later, even though the two groups did not differ with respect to age, severity of cognitive impairment and mobility. In general, men were more agitated, had shorter sleep with more wake episodes, had a lower circadian amplitude of relative rest-wake activity and interdaily circadian stability than women. In particular, lower daily light exposures significantly predicted lower circadian amplitudes of rest-activity cycles in men but not in women. This may indicate sex specific susceptibility to daily light exposures for rest-activity regulation in older demented patients. Results: Our results provide evidence that a higher daily light exposure has beneficial effects on emotions and thus improved quality of life in a severely demented patient group.
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We compared the effects of bedroom-intensity light from a standard fluorescent and a blue- (i.e., short-wavelength) depleted LED source on melatonin suppression, alertness, and sleep. Sixteen healthy participants (8 females) completed a 4-day inpatient study. Participants were exposed to blue-depleted circadian-sensitive (C-LED) light and a standard fluorescent light (FL, 4100 K) of equal illuminance (50 lx) for 8 h prior to a fixed bedtime on two separate days in a within-subject, randomized, cross-over design. Each light exposure day was preceded by a dim light (< 3 lx) control at the same time 24 h earlier. Compared to the FL condition, control-adjusted melatonin suppression was significantly reduced. Although subjective sleepiness was not different between the two light conditions, auditory reaction times were significantly slower under C-LED conditions compared to FL 30 min prior to bedtime. EEG-based correlates of alertness corroborated the reduced alertness under C-LED conditions as shown by significantly increased EEG spectral power in the delta-theta (0.5–8.0 Hz) bands under C-LED as compared to FL exposure. There was no significant difference in total sleep time (TST), sleep efficiency (SE%), and slow-wave activity (SWA) between the two conditions. Unlike melatonin suppression and alertness, a significant order effect was observed on all three sleep variables, however. Individuals who received C-LED first and then FL had increased TST, SE% and SWA averaged across both nights compared to individuals who received FL first and then C-LED. These data show that the spectral characteristics of light can be fine-tuned to attenuate non-visual responses to light in humans.
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This paper introduces a novel approach for the assessment of daylight performance in buildings, venturing beyond existing methods that evaluate 2-dimensional illumination and comfort within a fixed field-of-view in order to predict human responses to light concerning non-visual health potential, visual interest, and gaze behavior in a visually immersive scene. Using a 3D rendered indoor environment to exemplify this coordinated approach, the authors assess an architectural space across a range of view directions to predict non-visual health potential, perceptual visual interest, and gaze behavior at the eye level of an occupant across an immersive field-of-view. This method allows the authors to explore and demonstrate the impact of space, time, and sky condition on three novel daylight performance models developed to predict the effects of ocular light exposure using a human-centric approach. Results for each model will be presented in parallel and then compared to discuss the need for a multi-criteria assessment of daylight-driven human responses in architecture. A parallel and comparative approach can allow the designer to adapt the architectural space based on the program use and occupants needs.
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We previously developed a Camera-Like Light Sensor (CLLS) to record images using a novel High Dynamic Range (HDR) imaging vision sensor. The device was equipped with customized filters for adapting the camera’s spectral sensitivity to both photopic and circadian sensitivities. Here, we aim at investigating photometric and circadian metrics to assess and simulate the potential of light on non-visual functions. The CLLS was used to monitor luminance and circadian weighted radiance (Lec) over time in two test rooms, equipped with different daylight re-directing devices: venetian blinds (VB) and optical louver systems (OLS). Additionally, a computer simulation was performed for the two test rooms using the software RADIANCE: false colour images were used to demonstrate distribution of luminance and absolute values of Lec. Circadian weighted irradiance (Eec) was also computed at different positions corresponding to the gaze directions of a seated office worker. From our results, the VB provided overall higher illuminance compared to the OLS, but when a virtually seated observer was facing desk, the OLS provided larger circadian weighted irradiance in the afternoon. Our results illustrate the use of simulations for circadian metrics, which will be applicable in the future to predict the potential impact of light on non-visual functions for daylighting optimization in buildings.
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In a recent office study, clerical workers had an average gain in productivity of 5 percent and 9 percent, respectively, when lighting was increased from 50 to 100 and from 50 to 150 footcandles. The higher lighting levels were evaluated as being more desirable by both younger and older workers. Older workers gave lower ratings to the acceptability of the two lower lighting levels than did the younger group. The findings strongly document the cost-effectiveness of properly lighting the working environment.
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The paper presents a field study on human interactions with motorized roller shades and dimmable electric lights in private offices of a high performance building. The experimental study was designed to (i) extend the current knowledge of human-building interactions to different and more advanced systems, including intermediate shading positions and light dimming levels, and (ii) reveal behavioral characteristics enabled through side-by-side comparisons of environmental controls ranging from fully automated to fully manual and interfaces with low or high level of accessibility (wall switch, remote controller and web interface). The research methodology includes monitoring of physical variables, actuation and operation states of building systems, as well as online surveys of occupant comfort and perception of environmental variables, their personal characteristics and attributes (non-physical variables). The analyzed datasets provide new insights on the dynamics of interdependent human interactions with shading and electric lighting systems. Higher daylight utilization was observed in offices with easy-to-access controls, which implies less frequent use of electric lights and less energy consumption accordingly. Analysis of occupant satisfaction, in terms of comfort with the amount of light and visual conditions, based on datasets from offices with variable accessibility to shading and lighting control, reveals a strong preference for customized indoor climate, along with a relationship between occupant perception of control and acceptability of a wider range of visual conditions.
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The technique of iterative weighted linear regression can be used to obtain maximum likelihood estimates of the parameters with observations distributed according to some exponential family and systematic effects that can be made linear by a suitable transformation. A generalization of the analysis of variance is given for these models using log- likelihoods. These generalized linear models are illustrated by examples relating to four distributions; the Normal, Binomial (probit analysis, etc.), Poisson (contingency tables) and gamma (variance components). The implications of the approach in designing statistics courses are discussed.
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Lighting conditions in workplaces contribute to a variety of factors related to work satisfaction, productivity and well-being. We tested whether different photometric variables also influence visual perception and the comfort of the lighting, as well as subjective non-visual variables such as mood, alertness and well-being. Twenty-five young subjects spent two afternoons either under electric light or daylighting conditions (without view from the window). Subjects overall preferred the daylighting for visual acceptance and glare. Changes of photometric variables modulated changes in visual light perception, alertness and mood in the course of the afternoon. Finally, we found several associations of visual and non-visual functions, indicating a potential relationship of visual comfort with other circadian and wake-dependent functions in humans, which consequently could impact office lighting scenarios in the future.
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Light is a powerful zeitgeber that synchronizes our endogenous circadian pacemaker with the environment and has been previously described as an agent in improving cognitive performance. With that in mind, this study was designed to explore the influence of exposure to blue-enriched white light in the morning on the performance of adolescent students.58 High school students were recruited from four classes in two schools. In each school, one classroom was equipped with blue-enriched white lighting while the classroom next door served as a control setting. The effects of classroom lighting on cognitive performance were assessed using standardized psychological tests. Results show beneficial effects of blue-enriched white light on students׳ performance. In comparison to standard lighting conditions, students showed faster cognitive processing speed and better concentration. The blue-enriched white lighting seems to influence very basic information processing primarily, as no effects on short-term encoding and retrieval of memories were found.
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Daylight has been associated with multiple health advantages. Some of these claims are associations, hypotheses or beliefs. This review presents an overview of a scientific literature search on the proven effects of daylight exposure on human health. Studies were identified with a search strategy across two main databases. Additionally, a search was performed based on specific health effects. The results are diverse and either physiological or psychological. A rather limited statistically significant and well-documented scientific proof for the association between daylight and its potential health consequences was found. However, the search based on specific health terms made it possible to create a first subdivision of associations with daylight, leading to the first practical implementations for building design.
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A window is important for daylight access as well as for the outside view it provides. In this paper the D&V (Daylight and View) analysis method is described, which is used to assess objectively both the daylight and view quality of windows. The basis of the method is a 180o equidistant projection of the windows and view through the windows. After the projection is made, the access of daylight can be measured and visualized. Existing daylight and sunpath diagrams are converted to new diagrams which are used as overlay on the projection. Furthermore, a method is developed for the assessment of view quality. A view quality score is calculated by answering a series of questions. The applicability of the method was tested by comparing the view quality scores of 23 pictures to view quality ratings of participants in a questionnaire study. Overall the results show a similar rank order from high to low view quality. With the new projection method the daylight access and view quality of different window configurations can be studied simultaneously.
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This is the second report of a series describing experiments designed to explore and define relationships between illumination level and the performance of tasks having selected realistic components of typical office tasks. The first report described an experiment involving proofreading of paragraphs for misspelled words.1 In that experiment, performance improved with increased illumination at different rates for a group of young and a group of older subjects and for different print qualities. The experiment described in this report involved reading for information.
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This paper reports daily and seasonal patterns of lighting use in offices where occupants were able to vary the level of illuminance falling on their working areas. The results show that occupants set a wide range of illuminances, many of which are significantly below CIBSE Code recommendations leading to significant energy savings throughout the year. Although users report use of controls for a variety of reasons, the results of the long-term monitoring of switching behaviour reveals that very few in fact use them for anything other than to switch on upon arrival at work, with further use of systems during the day being rare. Evidence suggests that the way in which systems are configured exerts influence over the level of electric light occupants work under. There is some evidence of an effect of daylight availability on levels set but little evidence to suggest pervasive and consistent user preferences for levels of electric light.
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Light-emitting diodes (LED) are becoming an increasingly common lighting option for industrial applications, offering superior power efficiency and longevity relative to conventional fluorescent technologies. This study examined the visual perceptual, affective and cognitive implications of equipping temporary military shelters with either fluorescent or one of three advanced LED lighting systems with varied color temperature and luminance. Twenty-four volunteers were each tested over the course of five consecutive days, including a practice session and four test sessions, one for each of the lighting conditions. Volunteers showed highest visual acuity as measured on symbol identification and color recognition tasks with LED relative to fluorescent lighting and this effect was greatest at highest color temperatures. In terms of psychological and cognitive performance, volunteers showed increased fatigue ratings with fluorescent relative to LED, and this effect was associated with slower response times on tasks measuring spatial and verbal memory.Relevance to industryRecent increases in the number of LED technologies being incorporated into industrial lighting applications carry implications for worker performance. We provide evidence that these advanced lighting technologies can promote increased alertness and visual cognitive efficiency among workers when compared to more traditional alternatives.
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Subjects judged the orientation of a 2 min. gap Landolt C located at a distance of 2.4 m. The stimuli were presented in central vision on a CRT, at low to medium contrast. The effects of varying the spectrum and luminance of surround lighting were assessed on both pupil size (measured using infrared pupillometry during task performance) and task accuracy. The task display was protected from the surround lighting, so that its luminance and contrast could be varied independently of the changes in the surround lighting. Indirect surround illumination was provided by either two illuminants of very different scotopic spectral content but with the same photopic luminance (Experiments 1 and 3), or by using the same illuminant at two different luminance levels (Experiment 2). In Experiment 3, the effect of changing surround spectrum was compared to the effect of varying task background luminance between 12 cd/m² and 73 cd/m². In all experiments, scotopically enhanced surround lighting produced pupil areas which were reduced by almost 50% in comparison with surround lighting with relatively less scotopic luminance. Concomitantly there was improvement in Landolt C task performance with the scotopically enhanced surround lighting at all contrast and luminance levels. In these experiments, smaller pupil sizes were associated with significantly better visual-task performance in spite of lower task retinal illuminance when compared to the condition with larger pupils. These results suggest that changes in surround spectrum can compensate for the effect on task performance of a reduction in task luminance and supports the hypothesis that lighting energy savings could accrue in the workplace by shifting lamp spectra to obtain greater scotopic efficacy.
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The use of windows is the most common way of providing natural lighting to interior spaces of buildings. Natural lighting in buildings can displace the requirement for artificial lighting, and thus, has high potential to save energy. Discomfort glare from windows, however, is one of the fundamental barriers to the effective use of natural lighting in buildings. This study examined the potential effects of different window views on the subjective assessment of discomfort glare. Forty-eight subjects (24 men and 24 women) participated in the experiments. The experiment results indicated that the type of view and the distance of the view object are two critical factors of the subjective evaluation of discomfort glare. The results further showed that variations in the luminance distribution of a window (i.e., the ratio of the highest to the lowest luminance of the window) are not a statistically significant factor of subjective discomfort glare, but that there is a significant relationship between the mean luminance of a window and its subjective discomfort glare. This suggests that the mean luminance of a window, the type of window view, and the distance of the view objects should also be considered in the evaluation of the subjective discomfort glare from a window. This paper also discussed the energy-saving potential of daylighting strategies that consider discomfort glare from windows.