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How to Design a Lighting System
Published in Albert Thumann, Harry Franz, Efficient Electrical Systems Design Handbook, 2020
Color Temperature is a measure of the color of a light source relative to a black body at a particular temperature expressed in degrees Kelvin (°K). Incandescents have a low color temperature (~2800°K) and have a red-yellowish tone; daylight has a high color temperature (~6000°K) and appears bluish. Today, the phosphors used in fluorescent lamps can be blended to provide any desired color temperature in a range from 2800°K to 6000°K.
The Electrical System Audit
Published in Albert Thumann, Terry Niehus, William J. Younger, Handbook of Energy Audits, 2020
Albert Thumann, Terry Niehus, William J. Younger
Color Temperature—A measure of the color of a light source relative to a black body at a particular temperature expressed in Kelvins. Incandescents have a low color temperature (~2800K) and have a red-yellowish tone; daylight has a high color temperature (~6000K) and appears bluish. Today, the phosphors used in fluorescent lamps can be blended to provide any desired color temperature in the range from 2800K to 6000K.
Lighting
Published in Dorin O. Neacşu, Automotive Power Systems, 2020
The color temperature is measured in temperature degrees of Kelvin (symbol: K) on a scale from 1,000 K to 10,000 K. For commercial and residential lighting applications, Kelvin temperatures fall somewhere on a scale from 2,000 K to 6,500 K. For a color temperature under 3,000 K, colors are called “warm” and look yellowish. This is simply known as “warm light.” A light source with a color temperature of around 3,000 to 3,500 K appears less yellow and more whiteish. Above 5,000 K, the light produced appears bluish-white (sometimes improperly called xenon). This is simply known as “cool light.” Finally, it is noteworthy that the color temperature of daylight varies, but is often in the 5,000 K to 7,000 K range.
A common type of commercially available LED light source allows for colour discrimination performance at a level comparable to halogen lighting
Published in Ergonomics, 2019
Sara Königs, Susanne Mayr, Axel Buchner
Depending on their spectral power distribution, white light sources can have a bluish or a yellowish to reddish appearance. To further specify this appearance either the colour temperature or the correlated colour temperature (CCT) can be used. Colour temperature (in kelvin, K) is determined by the temperature of a black body radiator whose spectral emission is characterised solely by its temperature (Boyce 2014). With an increasing temperature of the black body radiator the emitted energy increases and shifts towards shorter wavelengths (Fairchild 2013). Colour temperature can be applied to light sources which match (at least approximately) the radiation distribution properties of the black body radiator, such as incandescent lamps (Wyszecki and Stiles 1982). However, the CCT is more commonly used because it can be applied to light sources with a radiation distribution different from that of a blackbody radiator, such as LED-based or fluorescent light sources. The CCT “is defined as the temperature of a blackbody radiator whose perceived color most closely resembles that of the given selective radiator at the same brightness and under specified viewing conditions” (Wyszecki and Stiles 1982, p. 225). In our experiment, the term selective radiator refers to the light sources under study.
White light-emitting Dy3+-doped transparent chloroborosilicate glass: synthesis and optical properties
Published in Journal of Asian Ceramic Societies, 2019
Nilanjana Shasmal, Basudeb Karmakar
Figure 10 shows the positions of the chromaticity coordinates of the light emitted by all the samples when excited at 447 nm. It can be seen that all the emitted light is white since all the coordinates lie within the white range of the chromaticity chart. Compared to the color coordinates of all the other glasses under investigation, those of the light emitted by CBSD3 are closest to pure white light. Table 3 presents the color coordinates of the samples and their color temperature values. From the coordinates shown in the table, it is quite clear that the coordinates of light emitted by all the glasses are very close to each other. Since the coordinates of pure white light are x = 0.333, y = 0.333, all the samples under observation emit light that is remarkably close to pure white light. The color temperature ranges from 3800 to 4700 K, which is in the “cool white” range of white light. For CBSD-3, the color temperature is 4716 K, which is comparable to daylight.
Lighting Effects on Older Adults’ Visual and Nonvisual Performance: A Systematic Review
Published in Journal of Housing For the Elderly, 2019
Xiaojie Lu, Nam-Kyu Park, Sherry Ahrentzen
The study by Figueiro and colleagues (2008b) examined effects of a 24-hour lighting scheme on older adults’ sleep quality. This study selected four bedrooms in a long-term care facility. Before installation, all the lamps were incandescent. Newly installed lamps set the living room with illuminance level ranging from 200 to 475 lux at cornea and with cooler color temperature (6500 K) during daytime. Color temperature is the color appearance (warm or cool) of a light source measured in degrees Kelvin (K) (ANSI/IES RP-28–16, 2016). The newly added lighting system with timers turned on lights approximately from 6:45 to 18:00, and then turned off lights at 18:00 (only low-illuminance-level incandescent lamps allowed). This purpose of the lighting system is to give cooler color temperature and higher illuminance level during daytime and warmer color temperature and lower illuminance level at night. In the study, 10 female participants were recruited. However, only four completed the study, with age ranging from 80 to 98 years. The Pittsburg Sleep Quality Index (PSQI) questionnaire evaluated older adults’ sleep quality subjectively, and actigraphs measured rest/activity rhythms objectively. Dependent variables, subjective and objective sleep quality, were collected twice: once before the installation of a new light system and once after installation. The t-test results showed (a) no statistically significant difference between the PSQI before and after the lighting intervention; (b) although sleep efficiency did not reach statistical significance, descriptive statistics showed sleep efficiency increased after the lighting intervention. Given the very small sample size of four individuals, caution needs to be given to the results. Nonetheless, the study does lend support to researchers and designers exploring and further validating new lighting systems for sleep quality.