We investigated whether light conditions have an impact on self-reported mental states, perception, and perceived health symptoms in an exploratory study. Twenty-eight participants, divided into groups of two, experienced the same room in two diffused-light conditions (daylight [DL] or static artificial Light [AL]), which were experienced in a repeated measure design layout, controlled for order. Both light conditions offered a stimulus of at least 250 melanopic equivalent daylight illuminance (mEDI) lx, without a view. Participants were observed during two tasks—an individual reading session and a collaborative construction game session. The results show an effect of light condition on mood and pleasure, mood was higher and pleasure was better in the daylight condition. We did not find an effect of light condition on arousal and on sleepiness during the whole duration of the sessions, although results indicate lower sleepiness in DL during the construction game session. Results indicate that the recommended mEDI levels can be maintained in a day-lit-only space during working hours (9:00 to 17:00 h) around the equinox in Stockholm, 59° N. The current results show that the effects on self-reported mood and pleasure do significantly differ between light conditions, although participants were not aware whether the source was artificial or natural. Thus we presume these effects could be even more relevant in a room with a view. We also suggest that the experience we gathered through this exploration could be of inspiration for lighting design that integrates daylight and artificial lighting dynamics.

We investigated whether differences in light levels and spectral properties have effects on motion. Twenty-two participants, divided into groups of two, experienced the same room in two diffused light conditions (daylight [DL] or static artificial light [AL]), which were experienced in a repeated measures design layout, controlled for order. Both light conditions offered a stimulus of at least 250 melanopic equivalent daylight illuminance (mEDI) lux, without a view. Participants were observed during an individual reading session and a collaborative construction game session. We measured the connectivity of the built structures, activity by actigraphy, and we automatically extracted motion area and quantity of motion from video analysis. We found a correlation between mEDI values in the two light conditions (DL or AL) and activity and a correlation between light condition and motion area. Diffuse daylight conditions were correlated with lower activity and less extended motion than a diffuse static condition at levels recommended for office lighting and to ensure alerting responses. Indeed, static AL was found to be related to increased spatial exploration, which might indicate restlessness, and high mEDI to a more composed motion. Actigraphy measurements correlate with quantity of motion values; therefore, the two methods provided comparable results. Results also showed a high correlation between all photometric values in the daylight condition. These findings offer arguments for favoring DL conditions in the design of places where it is desirable to avoid fidgetiness, like educational institutions, and to support composed motion, like medical institutions.

Although there is a documented preference for daylighting over artificial electric lighting indoors, there are comparatively few investigations of behaviour and perception in indoor day-lit spaces at high latitudes during winter. We report a pilot study designed to examine the effects of static artificial lighting conditions (ALC) and dynamic daylighting conditions (DLC) on the behaviour and perception of two groups of participants. Each group (n = 9 for ALC and n = 8 for DLC) experienced one of the two conditions for three consecutive days, from sunrise to sunset. The main results of this study show the following: indoor light exposure in February in Stockholm can be maintained over 1000 lx only with daylight for most of the working day, a value similar to outdoor workers’ exposure in Scandinavia; these values can be over the recommended Melanopic Equivalent Daylight Illuminance threshold; and this exposure reduces sleepiness and increases amount of activity compared to a static artificial lighting condition. Mood and feeling of time passing are also affected, but we do not exactly know by which variable, either personal or group dynamics, view or variation of the lighting exposure. The small sample size does not support inferential statistics; however, these significant effects might be large enough to be of importance in practice. From a sustainability point of view, daylighting can benefit energy saving strategies and well-being, even in the Scandinavian winter.

Researchers and designers use the words "artificial" or "electric" to describe lighting products, design, or research related practices, and there appear to be differing opinions about which is the more appropriate term. Generally, there are challenges with a common use of language and vocabulary in interdisciplinary research and this might be also valid for design and research in lighting design across different disciplines. The authors were educated in opposing practices of using "electric" lighting vs "artificial" lighting; this started a discussion and the conceptualization of this article. The paper explores, summarizes and discusses through literature review and a survey the concepts described and conveyed by both terms in different disciplines. Interestingly we could find differences among and between disciplines and professional backgrounds. This might indicate that the education and nomenclature in the field influences the use of terms. We found a tendency to refer to light sources either in terms of the energy used to generate the light, e.g. electric light or gaslight, but also in terms of the effect that it evokes, e.g. candle light is defined natural. Generally, a common lighting glossary could be developed through continuous discussion and studies. As today's complex questions are discussed in interdisciplinary teams, a common language might promote effective communication and stimulate sustainable solutions.

This study was conducted to optimise daylight admission as ambient lighting in an open-plan examination room of a dental hospital in Bandung, Indonesia. Parametric design was conducted for new light shelves, to be placed on the east and west façades of the building. Optimisation was performed using genetic algorithm, taking into account the external and internal widths, external tilt angles, and specularity of the light shelves, for two scenarios: keeping and removing the existing overhangs on both façades. The optimisation objectives were to maximise the spatial daylight autonomy at the perimeter area (sDA300/50%(p)) and minimise the annual sunlight exposure (ASE1000,250) on the occupied floor area of the examination room. Different optimised values were obtained for the east and west façades. In the first scenario, the resulting objective function yields an increase of 4.9% compared to existing condition, whereas the increase is 16.7% in the second scenario. Both metrics in the second scenario have satisfied the criterion. Uncertainty in the first scenario is found smaller than that in the second scenario, due to the removal of overhangs that bring more daylight in the latter.

This report reports the published evidence in scientific papers with a focus on Nordic research, but also includes relevant technical reports and books. The results are mainly presented for the non-visual effects of daylight.

The report indicates that more attention should be paid to the health-promoting effects that natural daylight provides in the living environment. Building design is the most important determining factor for natural daylight exposure in times when the general trend is for reduced time spent outdoors. It is especially important to consider good lighting at schools and in health care facilities.

Light is crucial for the regulation of circadian rhythms, sleeping and waking cycles, the regulation of mood, and the activation of stress responses. 

including access to daylight, windows, and views, becomes crucial. Good access to natural daylight in the environment facilitates the regulation of circadian rhythms and improves sleep, and daylight entering through windows promotes orientation in the room, reduces falls, and prevents depressive symptoms.

There is a linear relation between time spent outdoors and good health, and the more natural daylight that is obtained, the fewer the health complaints that are reported. In an environment devoid of daylight, sensitivity to other evening light sources such as computer screens and tablets increases, and this affects sleep and circadian rhythms negatively.

 In this paper we present a string-based, interactive, largescale installation for a new museum dedicated to performing arts, Scenkonstmuseet, which will be inaugurated in 2017 in Stockholm, Sweden. The installation will occupy an entire room that measures 10x5 meters. We aim to create a digital musical instrument (DMI) that facilitates intuitive musical interaction, thereby enabling visitors to quickly start creating music either alone or together. The interface should be able to serve as a pedagogical tool; visitors should be able to learn about concepts related to music and music making by interacting with the DMI. Since the lifespan of the installation will be approximately five years, one main concern is to create an experience that will encourage visitors to return to the museum for continued instrument exploration. In other words, the DMI should be designed to facilitate long-term engagement. Finally, an important aspect in the design of the installation is that the DMI should be accessible and provide a rich experience for all museum visitors, regardless of age or abilities.

We investigated the effect of the exposure to daylight and artificial light indoor during Scandinavian winter. Twenty-one subjects experienced two radically different lighting solutions for three days in a row, eight hours each day: one group (n=12) was exposed only to daylight, one (n=9) only to artificial electric lighting (>500lx average on work plane, 3000K). We observed an effect between light conditions on mood, which was elevated in the daylight room. Mean levels of alertness and perceived energy ratings were higher in the daylight condition. An effect of the lighting condition was found for activity levels as measured by the actigraphs, especially in the morning. Due to the experimental design it is at present difficult to tease out if observed effects were due to the lighting exposure or to other environmental factors, e.g. architectural layout, timing or intensity of the exposure, therefore future further studies would be needed to examine different combinations of factors.

BACKGROUND: In many western countries individuals will need to continue their professional careers beyond the current retirement age. This requires adaptation of the working conditions to compensate for age related visual changes. OBJECTIVE: The aim of this paper is to compile and structure knowledge concerning age related changes in visual and non-visual functions among older-age workers and to describe in what way these changes relate to light and work performance. METHOD: An overview of the literature was performed in PubMed and EMBASE concerning visual changes among elderly people, light, visual ergonomics and consequences at work. RESULTS: Visual conditions and lighting design have an impact on work performance in those over age 65 even if there are few studies available. Natural age related changes in the eyes or ocular diseases can result in reduced visual function and performance. Moreover, evidence of the importance of light and dark rhythms for circadian regulation is mounting; there are indications that the older-age population might need specific attention related to this issue. Finally, visual deteriorations might also, secondarily, induce strained postures and musculoskeletal symptoms, pain and injury. CONCLUSION: Age-related changes in the eyes and also ocular diseases among older-age people have an impact on well-being and work performance, and therefore call for reconsideration of their working conditions. Knowledge about how visual functions, light and ocular diseases is needed for work design and preventive actions.

Employees in an eye hospital spend many hours in semidarkness or darkness performing visually demanding activities that can cause fatigue and eye strain. As preparation for the planning of a new eye hospital, this project was initiated in order to produce knowledge of how to improve lighting in examination rooms. Current light conditions at S:t Erik Eye Hospital were assessed including questionnaires to employees/patients, and measurements of luminance, space analyses and energy consumption. Visits to other prominent eye hospitals and a literature review were performed. The questionnaires revealed that eyestrain problems were common in eye care professionals, especially in women. Working in dark rooms increased the subjective feeling of fatigue. Many, but not all, lacked daylight. The general lighting system was often insufficient with poor light distribution, shadows, and a colour temperature that in general was too low. Improvements included possibilities to regulate inflow of daylight, installation of remote controls, and timing and level of adaptation to different light levels. These improvements have been tested in a real scale installation that used the latest technology in terms of artificial lighting, a lighting control systems and a novel solution to control daylight. Five different light scenarios were preinstalled and evaluated by professionals and patients. A majority reported an improvement compared with traditional solutions. Current and actual energy consumption was monitored. Simulations of future consumption points to a possible energy reduction by 50 %, using new lighting technology, daylight and optimal room design. With improved logistics, new buildings and new work organization, energy savings can be even higher, around 70 %.