To ensure high-quality lighting in indoor spaces, many objective parameters have been suggested in building codes and standards all over the world. Despite the emergence of luminance-based metrics, ...the average horizontal illuminance (E
av
) remains popular in practice. For the case of relatively small rooms with one or two point light sources, it is often intended to determine the point with horizontal illuminance equal to E
av
. It is also intended to have the computation for various room scenarios, so that the outcome can be predicted using a simple model. This study, therefore, aims to propose a method to identify the location of point of E
av
on horizontal plane in cuboid rooms with various sizes, with one or two point light sources, and to further verify the theoretical concept. To achieve the objective, scenarios and assumptions are described using mathematical tools, followed with verification using grid computations and Monte Carlo simulation of 10,000 random scenarios. Logarithmic models to predict E
av
value and its representative location are proposed. The room length-to-width ratio is found more influential, compared to the source luminous intensity characteristics, in affecting the location of point of E
av
.
The purpose of this research is to examine the causal relationship on comprehensive impression evaluation based on the perceived spatial distribution of light. The evaluation grid method was ...conducted to derive a causal hypothesis on the evaluation of various lighting environments in living-dining rooms, followed by a subjective experiment in actual spaces to analyze the causal relationship between perception and impression through structural equation modeling. The results showed that “brightness” and “dimness” caused by the position of light in the space are perceived as spatial distribution, and “spaciousness” or “interest” with those balances leads to a “preferable” impression through “comfort”.
As global energy crisis is growing, energy-saving in architecture becomes more and more important. In addition, residential lighting especially living room lighting is an important part of energy ...consumption. In order to create green building, this paper analyzes energy-saving status based on joint investigations across China, Japan and Korea. It has been also compared the differences about energy-saving awareness and the selections of lighting equipments. The investigation results about residential lighting energy situation are reference to make proposals on lighting energy efficiency and quality improvement.
Lighting is a critical design element in the construction of functional and efficient operating rooms. Before the invention of electric lights, the challenge was to adequately light the surgical ...field and the work area to allow doctors, nurses, and support staff to see what they are doing. Procedures could only be done when there was sufficient daylight. For the last 50 years, during the time of open surgery and electric lights, the challenge was to provide even lightingSurgical lighting without shadows that was consistent and color corrected in order to enhance the ability of surgical staff to see and focus in the surgical site. With the advent of robotic minimally invasive, image-guided laparoscopic procedures and other enhanced visualization and guidance systems, PACS and electronic medical records, the demands and needs for different qualities, types and intensities of light as well as variations of brightness and focus in the different zones around the room have become primary functional and design challenges and concerns.
In the classroom, visual fatigue resulting from unfavorable non-visual impacts will diminish learning efficiency and affect eye health. To maintain the quality of the classroom lighting environment, ...it is crucial to set a combination of lighting parameters that minimizes visual fatigue. However, describing lighting quality traditionally by combining illuminance and color temperature fail in intuitively expressing the complexity of the lighting environment in the human visual field. For this reason, this study introduced the idea of luminance gradients and defined 20 lighting parameters for classroom lighting based on luminance and correlated color temperature (CCT). Using the experimental method of combining a subjective questionnaire survey with a critical flicker-fusion frequency test, four parameters with a significant impact on the comprehensive index of visual fatigue (VF) out of the 20 lighting parameters are extracted, i.e., directional luminance gradients (D31 and D12), the mean value of luminance (Lm), and CCT. Based on the findings of the impact of four lighting parameters on visual fatigue, an optimal range of lighting parameters conducive to reducing visual fatigue was established. Additionally, a mathematical model for predicting visual fatigue (VF) was developed as VF = g (D31, D12, Lm, CCT), providing a quantitative tool for evaluating and improving classroom lighting quality.
•Introduces the concept of luminance gradients and defines 20 lighting parameters for classroom lighting.•Identifies four key lighting parameters that significantly impact visual fatigue in the classroom.•Establishes an optimal range of lighting parameters that can minimize visual fatigue.•Develops a mathematical model for predicting visual fatigue in the classroom.
We examined the impact of an 8-h exposure to short-wavelength-enriched white light during the day on the cognitive performance, alertness, and mood of moderately sleep-restricted university students ...in a simulated classroom setting. A total of 28 participants (mean age: 23.57 ± 2.69; 19 female) were assigned to one of two short-wavelength-enriched white light conditions, each with an equal melanopic daylight efficacy ratio (melDER∼0.9). However, they differed in photopic and melanopic illuminances, falling within the upper and lower limits of prescribed standards for classroom lighting: low illuminance (LI; 309.33 ± 3.04 horizontal photopic and 128.26 ± 7.37 vertical melanopic EDI lux) and high illuminance (HI; 513 ± 12.59 horizontal photopic and 213.70 ± 11.62 vertical melanopic EDI lux). Cognitive performance, procedural memory, declarative memory, subjective alertness, and mood were evaluated using the N-back Task, Finger Tapping Task, Free Recall Task, Modified Karolinska Sleepiness Scale, and Visual Analogue Scales, respectively. No statistically significant differences were observed in any of the memory, alertness, and mood measures between the two lighting conditions (p.adjusted > 0.05). These results indicate that short-wavelength-enriched light exposures at illuminances falling within the upper and lower limits of current classroom lighting standards do not adversely affect cognitive performance, alertness, and mood, as assessed in this study. These findings have meaningful implications for classroom lighting design, providing an opportunity to enhance energy efficiency without compromising working memory, procedural memory, declarative memory, subjective alertness, and mood.
•We investigated the impact of short-wavelength-enriched light at both the high and low ends of the specified photopic illuminance standards for classroom lighting on cognitive, alertness, and mood outcomes.•The study was carried out in a simulated classroom equipped with spectrally tunable LED luminaires.•No notable distinctions were observed in memory measures, alertness, or mood between the two extremes of lighting standards, maintaining the same melDER.•The upper and lower range of standard light levels in classrooms can be used without adverse effects on the cognitive functions tested when short-wavelength-enriched light is used.
Classroom lighting significantly influences students’ performance and productivity, as well as building energy consumption. Numerous studies highlight prevalent suboptimal lighting in education, with ...almost half of students expressing discomfort, emphasizing the need to enhance lighting environments. To address the issues mentioned and accommodate diverse learning activities with varying lighting needs and equipment, this paper introduces an innovative HDRi Surveillance Lighting Control System (HSLDCS). An experimental study investigates the implementation of the HSLDCS in ten classrooms with various learning activities. High Dynamic Range image (HDRi) photography is employed to assess lighting quality using the HDRi spatial luminance distribution, DGP and UGR, while a questionnaire survey is conducted to evaluate student well-being. Despite limitations regarding the adjustment time for window blinds and lamps, the results demonstrate that the adoption of appropriate HSLDCS can yield energy savings ranging from approximately 43%–63%, while still ensuring visual comfort for the majority of students. Over 70% of the students expressed satisfaction, even when classroom brightness was reduced by 30%. Considering the widespread use of laptops or tablets by students during class, reducing brightness levels is as a viable strategy for conserving energy and preventing visual fatigue. The implementation of the HSLDCS is a promising solution for alleviating suboptimal lighting conditions, enhancing energy efficiency, and promoting user well-being. This study also creates new opportunities for further exploration in the field of lighting technology and emphasizes the importance of prioritizing perceived brightness over illuminance.
•An HDRi surveillance lighting and daylighting control system (HSLDCS) is proposed.•The HSLDCS is designed to be adaptable to multiple classroom learning activities.•The HSLDCS effectively reduces energy consumption by approximately 43–63%.•A comfortable environmental illumination can be provided through the HSLDCS.•Perceived brightness is more crucial than illuminance in evaluating visual comfort.
