Light is a condition that human beings are subjected to in nature. Light is not only a physical parameter but also an important factor, which is affecting the mental and cognitive performance of the person. For this reason, in recent years, many researchers and scientists have been working on and exploring this direction of light. The spectral structure of light in the natural environment shows a continuous change. We can define this natural environment as the spectral transformation of daylight in open air. Thus, people who remain in closed environments during the day are living under unfavourable conditions, such as constant colour temperatures and luminous flux of illumination. The studies aimed at reducing this harmful effect the most. These studies are based on the principle that all intermediate colours are obtained by blending the light in 2 different colours (usually one is very warm white and the other is very cold white) and that the intermediate colours are timed within a certain scenario and illuminated indoors to simulate the outside environment. In this study, the mixture of light sources in different colours was mathematically modelled in computer environment and the CCT in K of the mixture was calculated. It is also optimized to obtain the mixture colour with least mistakes of the mixture functions by comparing with the actual measurement results.
Turkey is rich in terms of renewable energy sources and, therefore, is now encouraging the use of sustainable clean lighting systems in road applications. High pressure sodium lamp is the most widely used type in main roads, but other types of lamps such as mercury vapour lamps or metal halide lamps can be utilized for street lighting. Since it enables energy and money saving, LED light technology has replaced high pressure sodium lamps nowadays. Once solar power system (PV) is integrated with LED lamp for street lighting, the amount of saving and local impact might be enriched. LEDs used as light sources in road lighting luminaires with rising lumen values, decreasing junction temperature, higher colour rendering efficiency, longer lifetime have become more efficient than many light sources with the latest developments. Since the structure of the luminaires in which the LED light sources are used differs from that of the conventional light sources, the optical, thermal and electrical design of the LED luminaires must be considered differently. Thus, this study concentrates upon design considerations and the operating principle of solarpowered LED road lighting luminaire in details. Also, a simple solar panel system was designed and the economical values obtained at the end of 20 years were compared when using the ongrid system and the off-grid system.
This paper presents a detailed comparison between a new type of antibacterial LED panel and fluorescent lamps connected to electronic ballast in a simple examination room, which requires 300 lx in a healthcare facility. Within the study, power consumption (W), luminous flux (lm) and luminous efficacy of both light sources were measured. Luminous flux values were then compared to the amount of power they consumed. Electrical power consumption of these luminaires was also analyzed. To enable an objective comparison between these two types of luminaires ReluxDesktop_2017.1.10.0 simulation program was used. To verify the results obtained by the ReluxDesktop, photometric measurement results of the products were also obtained. The results obtained by the study have shown that the LED panel to be used in the healthcare facility may decrease the maintenance and lighting costs by saving energy while maintaining the illumination levels required by the healthcare facility lighting standards.
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