Henryk Wachta

Elements of inferential statistics in a quantitative assessment of illuminations of architectural structures

The topic presented in this paper covers statistical studies on illumination conducted using specialised software dedicated to such simulations. A pre-designed computer visualisation of illumination, which included zonal illuminations of a selected architectural structure was modified by a selected group of respondents. As a result of responders individual aesthetic preferences sets of average luminance of respective facade zones were obtained. During statistical analysis of the results elements of interval estimation were used to estimate an average value of the luminance levels of illuminated facade zones with a probability equal to a confidence coefficient. The results of statistical studies enabled the determination of the most preferred illumination levels of respective facade zones as well as average luminance levels of these areas. These set, given further studies, the basis for a quantitative specification of selected illumination principles.

The technical possibilities of losses reduction in the LED optical systems

The paper presents the results of analysis of losses in a typical optical systems used for forming luminous intensity distribution of LED sources in the context of the application for road lighting. There was discussed the characteristics of LEDs and issues related to energy efficiency of lighting. There was shown typical optical systems, containing reflecting and refracting elements, discussed their characteristics and indicated advantages and disadvantages. Finally transmission efficiency of the luminous flux and the overall efficiency of the system was calculated.

Radiation studies of the illumination lighting luminaires with LED technology

Semiconductor LED sources currently represent the most rapidly growing group of light sources and thanks to their numerous advantages, they have been applied in many areas of light technology. One of these application areas of LED sources is the area of illumination, and the illumination luminaires based on the said light sources, enable the much broader use, compared to the discharge sources, among others, the creation of the dynamic illumination with the possibility to adjust the colour or light output. The key element ensuring the correct operation of the luminaires, stability of its light parameters and the long life is the correct selection of the heat sink, which task is the effective dissipation of heat from the luminaire. Currently, among the available solutions, the vast majority are the passive heat sinks, where the main heat flow path is the convention between the heat sink and the environment. The article presented the results of the thermal analysis for the sample illumination luminaire of high power. The analysis was performed for several heat sink variants, where the number, geometry and arrangement of the fins was changing. Based on the conducted analysis the most effective solution was presented and the conclusions were formulated.

Evaluation of the zonal luminous flux distribution of LED sources

The paper shows results of the analysis of the spatial distribution of the luminous flux of different constructions of LED sources. There was calculated luminous flux emitted in certain areas of the angle. There was analyzed the viewing angles of the sources, and part of the luminous flux emitted in these angles. Knowledge of the spatial distribution of the luminous flux is important from the point of view of optical system design to precisely form the light distribution. It allows the identification of losses in certain parts of the optical system and minimizing these losses. It was also found the existence of discrepancies between the catalog data and digital models of light sources.

Influence of luminaire aiming on LED sources junction temperature

The correct selection of the radiator and ensuring the optimal cooling of the LEDs is the key element associated with the long life and stability of LEDs parameters. Currently, the most widely used radiation system in luminaries with LEDs is the passive system, where the main flow path of heat is the free convention between the radiator and the environment. In the above radiation system, apart from the geometry and size of the radiator, the junction temperature of the LED of the luminaire can also be affected by the angle of inclination of the luminaire relative to the gravity vector. The article presents the results of simulation studies, related to the designation of the junction temperature of the exemplary luminaire in the LED technology, for a different location of the fixture relative to the gravity vector.