Karel Sokanský

Classification of environmental zones in the Czech Republic

Nowadays obtrusive light is discussed quite often and so this term has become well-known not only to professionals in the field of lighting but also to the public, designers and administrators. Quantification of obtrusive light depends on many factors. The biggest factor is the amount of the luminous flux directly emitted into the upper hemisphere. Other factors include the reflection qualities of illuminated surfaces and finally conditions in the atmosphere. Based on knowledge of the amount of luminous flux directly emitted into the upper hemisphere, depending on the surroundings (size of the agglomeration, protected landscape areas – national preserves, observatory, etc.), we can classify obtrusive light into several classes according to the standards EN 12464-2 and EN 12 193. These standards use only four environmental zones. For any outdoor lighting system it is possible to calculate the amount of luminous flux emitted into the upper hemisphere and determine if this potential source of obtrusive light is appropriate for the environmental zone. These calculations can also show if the lighting system is a significant contributor to the amount of obtrusive light. This paper tries to describe problems over larger areas where different environmental zones can exist side by side. Adjacent environmental zones should not differ by more than one level (for example E1 to E2 only). The aim of this paper is to establish methodologies for classifying environmental zones. A specific example of classification relates to a 420 kV outdoor electricity distribution substation, which is located in a selected area of the Czech Republic.

Correlated Colour Temperature Changes of the LED Sources Depending on the Angle of Their Radiation

The aim of the report is a description of an issue connected with subjective perception of colours from the light of the lighting systems stepped by LED. Subjective observation of the colour change on the light of the lighting systems stepped by LED has been mostly related to extensive lighting systems where it was possible to observe identical light source (LED) within various angles. This phenomenon was manifested even more distinctively within lighting systems that made use of optical systems located in luminaries (reflector, diffusers) in a minimal way. Additional optical systems redistribute primary luminous flux coming from light source (LED) and thus there is a blending of luminous flux radiated to a certain angle of the illuminated space from various directions of the luminous flux radiation itself. In case it is not like this and the luminaries are equipped only with LED with a suitable luminous distribution curve, there is no blending of the luminous flux. Thanks to this the observer can also perceive various colours of light within individual luminaries perceived under various angles.

Potential Influence of Light Sources on Human Circadian Rhythms

The article deals with examining light sources used in households from the point of view of their potential influence on circadian rhythms. Nowadays, there are lots of different types of light sources available on the market with different light colours. An inadequate choice of the colour of the light source can result in worsening visual comfort, which can lead to disturbing circadian rhythms. When choosing light sources, it is necessary to take into account the purpose of the room for which the lights are chosen. Especially, it is a question whether LED sources with similar quantitative and qualitative characteristics have stronger influence on circadian rhythms than classical light sources or not. The reason is primary radiation even of white LED in the blue part of visual spectra. The circadian receptors are the most sensitive in the area.

Statistical Evaluation of Dimmable Interior Lighting System Consumption Using Daylight

From the power engineers point of view, at the present time, the necessity to predict the consumption of lighting systems becomes more and more urgent at the time of the project phase. The reason is to compare the projects from different investors and especially to compare the projects with regulated (dimmed) lighting systems (these are regulated at a constant level of illumination) with the projects of unregulated lighting. In that case, the designer has to be able to determine the payback of regulated lighting system in comparison with classic unregulated lighting systems. Nowadays, it is possible to calculate the potential savings. The calculating is determined by the LENI (Lighting Energy Numeric Indicator), according to EN 15193, which is based upon the analytical estimate of potential savings calculated on the base of empirically derived coefficients for standardized rooms, standardized operations, etc. However, this model is not based on real specific situations. Therefore, the team of VSB-TU Ostrava developed a predictive model, which is based on the daylight dynamics in specific lighting conditions. The long-term measurements were carried out to verify whether the model´s results correspond to the real facts. The statistical evaluation of the model´s conclusions and the real measured rates was carried out as well.

Safe lighting of pedestrian crossings

This paper solves the lighting of pedestrian crossings. This type of lighting helps to improve the safety of pedestrians in this conflict area (means a pedestrian crossing). The research was drawn on the basis of measurements of 87 pedestrian crossings in district Ostrava because the regularities can be better understood. Pedestrian crossings were evaluated on the basis of luminance ratio and statistical data of accident rate. This paper also solves the reflectance of clothes which is also important for this research.

Measurement and evaluation of emergency lighting equipped with LED

The issue of emergency lighting is quite complicated and meeting all standard requirements are often very complex. Rapid development in the field of LED light sources has brought new possibilities in the design of emergency lighting. In particular, LED has a higher power output in comparison to conventional light sources used in emergency lighting and also the size of LED is smaller. Another advantage is the possibility of optimal routing of LED diodes by means of suitable optics depending on the areas and the type of emergency lighting. Measurements were performed on a prototype of autonomous emergency lamp, which does not use a conventional battery as a source of energy, but super-capacitor. Especially from the perspective of a long lifespan, its fast charging and reducing of dependence on temperature, the super-capacitor seems like very reliable replacement of batteries previously used.

Luminance ratio at the visual tasks in classroom

Possibilities of action learning methods such as interactive whiteboards, blackboards and whiteboards along with copying to a workbook depends not only on visual comfort, but also on the subjective feeling of the observer. This measurement could be performed objective was chosen as the place of visual task workbook, as the surrounding visual task desk (table) and a background visual task was elected boards according to the type of measurement rooms. Measurements was done by luxmeter and luminance analyzer. Because the evaluating the overall illuminance of the room, so the task area. Further analysis was performed luminance from which it was calculated contrast to which the eye responds and transmits the visual perception.