Simulating Physiological Potentials of Daylight Variables in Lighting Design

A holistic approach to daylight dynamics in our built environment can have beneficial outcomes for both physiological and visual effects on humans. Simulations of how daylight variables affect light levels on the horizontal work plane are compared to their physiological effects, measured as melanopic EDI (Melanopic Equivalent Daylight Illuminance) on a vertical plane. The melanopic EDI levels were calculated in a simulated office space in ALFA software (Adaptive Lighting for Alertness) employing the daylight variables of orientation, time of day, season, sky conditions and spatial orientation. Results were analyzed for how daylight design can contribute to the physiological effects of dynamic light in office buildings. Daylight is shown to be a sufficient light source in the majority of cases to meet the recommended values of EDI and provide the suggested horizontal lx level according to the Danish Standards. A mapping of daylight conditions, focusing on the specific factors presented here, can provide guidelines in the design process and future smart building systems. The complex interrelationship between these parameters is important to acknowledge when working with daylight dynamics as a sustainable element in architecture and lighting design.

The Effects of Depth-Related Environmental Factors on Traits in Acropora cervicornis Raised in Nurseries

Populations of Acropora cervicornis, one of the most important reef-building corals in the Caribbean, have been declining due to human activities and global climate change. This has prompted the development of strategies such as coral farms, aimed at improving the long-term viability of this coral across its geographical range. This study focuses on comprehending how seawater temperature (ST), and light levels (LL) affect the survival and growth of A. cervicornis fragments collected from three reefs in Culebra, Puerto Rico. These individuals were fragmented into three pieces of the similar sizes and placed in farms at 5, 8, and 12 m depth. The fragments, ST and LL were monitored for 11 months. Results show that fragments from shallow farms exhibit significantly higher mortalities when compared to the other two depths. Yet, growth at shallow farms was nearly 24% higher than at the other two depths. Corals grew fastest during winter, when temperature and LL were lowest, regardless of the water depth. Fragment mortality and growth origin were also influenced by reef origin. We conclude that under the current conditions, shallow farms may offer a slight advantage over deep ones provided the higher growth rate at shallow farms and the high fragment survival at all depths.

Adjustable light source for low light level with nearly constant correlated color temperature

Low light level (LLL) calibration becomes more and more important since the rapid growth of remote sensing. The spectral radiance at normal higher light levels can be calibrated with good accuracy, while LLL spectral radiance cannot. If an adjustable light source can be designed at nearly constant correlated color temperature (CCT) covering several orders of magnitude, low light level spectral radiance can be obtained with the help of a photodetector. Whether or not the spectral distribution of an integrating sphere based light source is nearly constant is investigated. By adjusting the diameter of the variable aperture between the integrating sphere and tungsten lamp, the spectral radiance can be varied over 6 orders of magnitude. However, the relative spectrum in the red region increases notably when the spectral radiance is decreased to 1/100000. If the spectral radiance is decreased further, the spectral difference can be more than 300% and CCT decreases more than 250 K. By using baffles and another integrating sphere, low light level radiation source at nearly constant spectral distribution is obtained. The variation of CCT is less than 50 K over 6 orders of magnitude.

Еdapho-climatic characteristics of Рrecarpathian biotopes with the participation of price populations of species of the genus Рolygonatum Мill.

Grouping of research sites according to the set of analyzed edapho-climatic parameters by the method of cluster analysis showed that the dominant factor in the formation of abiotic conditions is the type of habitat. Therefore, characterized the population and ecological characteristics of species of the genus Polygonatum Mill. in the Precarpathians by analyzing the key edapho-climatic factors of the studied habitats, namely the humus content, acidity, moisture content, the sum of active temperatures, light levels and N, P, K.

LESSONS LEARNED FROM REGISTRATION OF OCCUPANCY AND USE OF LIGHTING IN OFFICES, SCHOOLS, UNIVERSITIES AND INDUSTRY BUILDINGS, A CROSS COUNTRY STUDY

The paper presents a registration of occupancy and the use of (day)light in four buildings representing respectively offices, primary schools, universities, and industry buildings; it was done across Europe in 2020. A self-registration method was used, assisted with light technical measurements outdoors and indoors. In general, occupants consider the visual environment at the workplace when they are coming in or out of the room. It happens mainly at the beginning (adjustment of blinds and switching light on) and at the end of the working day (switching light off). In the primary school building, where users move in-out many times during the day, the adjustment happens more frequently. Also use of projector generates very low general light level; covering windows and switching off the electric light happens accordingly, but the pattern is not consistent. In general, the changes in the electrical lighting use follow the occupancy pattern, not the light levels.

PERCEIVED CHROMA AND HUE CHANGES OF COLOURS AT HIGH ILLUMINANCE LEVELS DUE TO HUNT EFFECT

The purpose of this study is to quantify the Hunt Effect in a range from indoor lighting levels to outdoor daylight levels so that a perception model of Hunt Effect for lighting can be developed with outdoor daylight as the reference. Our previous study experimentally quantified the perceived chroma changes due to the Hunt Effect at 100 lx and 1000 lx. To extend this to light levels closer to outdoor daylight, a vision experiment was conducted at ≈1000 lx and ≈6000 lx for red, green, yellow, and blue patches. A reference patch on one side of a double booth at 1000 lx was compared to a set of 20 test patches on the other side of the booth at ≈6000 lx using haploscopic view condition. Results showed that the perceived chroma changes are much smaller and insignificant compared to the results between 100 lx and 1000 lx found in our previous study.

A NOVEL METHOD FOR STUDYING THRESHOLD LEVELS FOR POSITIVE PHOTOTAXIS IN INSECTS

This paper presents a novel method for studying threshold levels for positive phototaxis of insects and smaller mobile organisms. Outdoor lighting affects light sensitive species and there is a need to evaluate the effect of light levels, spectral composition of the light and light distribution to mitigate the ecological impacts of the artificial light. For this purpose, a test box investigating the effect of light on insects in a controlled manner has been constructed. The box is equipped with a luminance source and the light levels can be varied from a maximum value continuously down to zero. The spectral composition of the light can be varied by changing the lamp or using optical filters. For visibility of the insects the box has infrared light emitting diodes in the ceiling and two wide-angle cameras monitor the light response. The functionality of the box is tested with the species greater wax moth.

LIGHT EXPOSURE OF WORKERS IN DIFFERENT OCCUPATIONS

Twenty-four hours light exposure of employees in three different occupations was assessed for a working week during both summer and winter. Occupations being exposed to light at night and those exposed to low daytime light levels were represented by night shift working geriatric nurses and daytime working hotel staff, respectively. Their light exposure was compared to the light exposure of outdoor workers represented by refuse collectors. In winter, luminous exposure of night shift working geriatric nurses and daytime working hotel staff amounts to only 2 % and 12 % of the luminous exposure of outdoor workers, respectively. In summer, the respective values are 6 % and 21 %. This could lead to a desynchronization of circadian physiological processes in the human body.