Mbc Myriam Aries

Individual control of electric lighting in a daylit space

Participants (N=40) occupied a glare-free, daylit office laboratory for 1 day, and were prompted every 30 min to use dimming control over electric lighting to choose their preferred light level. Illuminances and luminances were recorded before and after each control opportunity; luminance maps were generated using a calibrated, high-dynamic range digital camera. Although there was a wide variation in chosen light levels between individuals, results showed a significant negative correlation between prevailing desktop illuminance and change in dimmer setting. This indicates that, from the perspective of occupants, daylight does displace electric lighting. Surprisingly, we did not find any luminance-based measure that was as good a predictor of participant dimmer choice as illuminance measured on the desktop. On average, manual dimming control in this situation reduced energy use for lighting by 25% compared to a fixed system delivering 500lx of electric lighting on the desktop.

Daylight and health: A review of the evidence and consequences for the built environment:

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.

Light therapy: Methodological issues from an engineering perspective

Light therapy is increasingly administered and studied as a non-pharmacologic treatment for a variety of health-related problems, including treatment of people with dementia. Light therapy comes in a variety of ways, ranging from being exposed to daylight, to being exposed to light emitted by light boxes and ambient bright light. Light therapy is an area in medicine where medical sciences meet the realms of physics, engineering and technology. Therefore, it is paramount that attention is paid in the methodology of studies to the technical aspects in their full breadth. This paper provides an extensive introduction for non-technical researchers on how to describe and adjust their methodology when involved in lighting therapy research. A specific focus in this manuscript is on ambient bright light, as it is an emerging field within the domain of light therapy. The paper deals with how to (i) describe the lighting equipment, (ii) describe the light measurements, (iii) describe the building and interaction with daylight. Moreover, attention is paid to the uncertainty in standards and guidelines regarding light and lighting for older adults.

Simulation of virtual natural lighting solutions with a simplified view

Daylight is limited in time and space. In situations where daylight is insufficiently available, virtual natural lighting solutions (VNLS), which are systems that artificially provide lighting and view comparable to those of real windows and skylights, can be promising. VNLS can turn currently unused floor space into space with daylight qualities. The space-gaining potential of VNLS in buildings can be predicted using computational building performance simulation. This paper describes the approach of modelling VNLS with a simplified view, using the Radiance tool to evaluate the lighting performance in a reference office. The VNLS are modelled as arrays of small light sources resembling the sky, the horizon and the ground. The simulation results show that VNLS with wide beam angles generally offer a better uniformity and a larger percentage of sufficiently lit workplane area compared to those obtained with real windows under overcast sky conditions, while the discomfort glare remains comparable to that received from real windows.

Recommendations for measuring non-image-forming effects of light: A practical method to apply on cognitive impaired and unaffected participants.

BACKGROUND The non-image-forming effects of luminous radiation on people with intellectual disabilities or dementia received attention from researchers. Such studies, however, have generally been conducted using disparate methodologies which precludes generalization and reproducibility. OBJECTIVE The aim of this study was to determine the practical applicability of measurement devices for studies investigating non-image-forming effects of luminous radiation, specifically for people with intellectual disabilities or dementia. METHODS In three experiments, ten cognitive impaired people and thirty-nine unaffected subjects participated by wearing one or more portable devices. Six devices were assessed in total. Measurement data was accompanied with user experiences obtained from questionnaires, interviews and observations in order to assess the devices on practical and comfort issues. RESULTS On average, the devices worn by the cognitive impaired subjects were not experienced as annoying or irritating. No significant differences are found between genders and for one of the portable devices significantly less annoyance was reported by the cognitive impaired participants compared to the unaffected group of participants. INNOVATIVE SOLUTION The three phases of the research process in towards measuring personal luminous exposures are: selection of the most suitable portable device, application of the assessment method, and the application of the device in the (pilot) study. CONCLUSIONS However, the findings of this study suggest that inaccuracies potentially caused by practical and comfort issues associated with the portable devices need to be considered.

Shedding a light on phototherapy studies with people having dementia: a critical review of the methodology from a light perspective

Light therapy is applied to older people with dementia as a treatment to reset the biological clock, to improve the cognitive functioning, and to reduce behavioral symptoms. Although the methodological quality of light therapy studies is essential, many aspects concerning the description of the lighting applied are missing. This study reviewed light therapy studies concerning the effects on people with dementia as a way to check the methodological quality of the description of light from a light engineering perspective. Twelve studies meeting the inclusion criteria were chosen for further analysis. Each study was scored on a list of aspects relevant to a proper description of lighting aspects. The overview demonstrates that the overall quality of the methodologies is poor. The studies describe the lighting insufficiently and not in the correct metrics. The robustness of light therapy studies can be improved by involving a light engineer or specialist.

Analysis of various opening configurations of a second-generation virtual natural lighting solutions prototype

ABSTRACT To address the absence of natural light in working spaces, virtual natural lighting solutions (VNLS) can be promising. VNLS are systems that artificially provide lighting as well as a realistic outside view with properties comparable to those of real windows and skylights. This article discusses the evaluation and analysis of various opening configurations of a second-generation VNLS prototype, which features an array of light emitting diode (LED) tiles coupled with a line of linear LED fixtures with adjustable color temperatures that provide direct light. Simulation using Radiance was performed and validated with the measurement results. Various possibilities of placing the prototypes inside the test room were investigated in Radiance to determine the effect on space availability and visual comfort. Based on the comparison of seven configurations of two prototypes with equal total opening size, it was found that nearly all configurations tested yielded a space availability of 100% with a criterion of 200 lx and where space availability is defined as the percentage of points on a horizontal grid that meet or exceed the target illuminance. Taking 300 lx as the criterion, two openings on each short wall facing each other (configuration 2) and four openings on a long wall (configuration 5) yielded space availabilities of more than 90%. Taking 500 lx as the criterion, configurations 2 and 5 yielded space availabilities between 25% and 50%. The highest uniformity (Emin/Eavg) was achieved under configuration 2 (0.59), whereas the maximum daylight glare probability (DGP) values under all configurations were between 0.25 and 0.30. Our simulation results suggest that the space availability in a private office can be optimized by placing a VNLS prototype on each short wall facing each other or by placing two on a long wall.