Although lighting optimization has been widely explored in various contexts, its specific application to low-vision populations remains largely unexplored. This study represents a first step towards an effort in tailoring lighting conditions to improve colour discrimination, specifically for visually impaired people. A psychophysical experiment was conducted to investigate the influence of different LED light wavelengths on colour discrimination in simulated low-vision conditions. Participants wore goggles simulating central scotoma, blurry vision and tunnel vision. They were asked to sort colour caps of a modified version of the Farnsworth-Munsell 100 Hue Test. An automatic scoring method using a single picture of the arranged caps was implemented to speed up the experimental sessions. Results highlight clear evidence of significant differences across the groups of observers, with the use of goggles simulating central scotoma showing the greatest difficulties in colour discrimination. These results provide a foundation for future research involving individuals suffering from low vision and support the development of new white light solutions tailored to the visual needs of the visually impaired.
This study investigates the performance of silica aerogel-based glazing systems as a sustainable solution for enhancing daylighting, glare control and energy efficiency in building design. A simulation-based analysis compares two aerogel glazing systems (GS1 and GS2) with traditional clear glazing in terms of daylight metrics and glare reduction. The results indicate that while the reference room achieved 77% Spatial Daylight Autonomy (sDA), GS1 and GS2 reduced it to 57% and 49%, respectively. However, despite this reduction, the sDA value for GS1 exceeds the 55% threshold defined by LEED v4.1, qualifying as acceptable, while GS2 remains slightly below but still relatively close to the standard. Despite this decrease, these systems effectively controlled glare, reducing unbearable glare occurrence from 8% in the reference room to 3% (GS1) and 1% (GS2). Additionally, neither GS1 nor GS2 experienced overexposure (Annual Sunshine Exposure >1000 lx for over 250 h), unlike the reference room (27%). These findings suggest that silica aerogel glazing improves visual comfort and thermal performance while mitigating excessive daylight exposure, making it a viable option for sustainable building design, particularly in regions with high solar radiation.
To clarify the effects of melanopsin cells on spatial brightness, we conducted an experiment in which the brightness of the space was evaluated using a magnitude estimation method during AM (9.00 to 10:00) and PM (18.00 to 19.00) periods by modulating the stimulus value of melanopsin cells while keeping the chromaticity values of a light environment constant. The light environment was constructed and installed on the ceiling of a windowless room model of a typical office space, using a 24-colour multispectral light source device with variable spectral distribution characteristics. The results showed that the influence of melanopsin cells under high-illuminance conditions depends on the time slot. The floor illuminance, at which the influence of melanopsin cells begins to emerge, was suggested to exist between 500 lx and 1000 lx. This study can contribute to the development of lighting design methods to balance energy efficiency and comfort by controlling melanopsin stimulation.
To utilise virtual reality in lighting research, realistic simulations of lighting conditions are essential. Game engines could play a vital role in this, as they enable stereoscopic visualisation, immersive experiences and real-time rendering. This paper evaluates the lighting simulation quality of Unity’s High Definition Render Pipeline (HDRP) Lightmapper for electric lighting conditions using the test cases defined in the technical report CIE 171:2006 ‘Test cases to assess the accuracy of lighting computer programs’. The authors provide adjustments to light colour, IES profiles and global illumination to enhance and in some cases correct the simulation. To assess the simulated illuminance in Unity scenes, a coordinate-driven measurement toolbox ( PhotoProbe ) was developed based on Unity’s Rendering Debugger. Without adjustments to the HDRP, high error rates were observed for most of the test cases. With the adjustments specified in this paper, the mean absolute percentage error was below 3% for all analytical test cases and the simulated illuminances for the six experimental test cases were within the global limit threshold defined in CIE 171:2006. For one test case, the average room illuminance limit was not met.
Six analyses of road traffic crashes (RTCs) were carried out to investigate how these change in daylight and darkness. The analyses used purposeful changes in the researcher who conducted the analysis, the analysis software they used and the source of solar altitude data. These decisions are amongst those that may be considered arbitrary in such an analysis, and the analyses were therefore conducted to assess the robustness of the analysis across these decisions. It was also done to compare the outcomes with two previous studies using the same data set (STATS19), the same data period (2005 to 2015) and the same approach to filtering data (the clock change approach). There tended to be good agreement between the analyses except when the analysis required the use of solar altitude to identify the daylight or dark status of an RTC. It was found that one solar altitude calculator (SunCalc) produced different estimates of solar altitude than did the other three used in this work (Astral, PysunNOAA and NOAA Excel). While the difference is small, it was sufficient to bring changes in the outcomes of the analysis.
