White LEDs have caused a bit of controversy as to how accurate is the white temperature that they produce, and their impact on the human body.
White LEDs colour inconsistencies
While more traditional light bulbs produce light in only one color, LEDs can generate different or several colours. This may cause an issue when you are after a specific white tone. Not all white LEDs are the same color. Some white LEDs produce a slightly bluish white light, others produce a much warmer, soft white tone.
LED bulb temperature is measured in Kelvins. Warm white LEDs are usually between 2,500 and 3,000 K. Bright white is 4,500 to 5,000 K. If you are after a neutral white LEDs, try to stay away from high colour temperatures. Ideally stick between 3000K – 4500K, which is similar to a day white light. Above these figures you will get a blue mixture in the light which may not be what you are after.
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Alternatively, you may try to buy a warm white strip and put it up next to the cool white; the color temperatures will mix to a to hopefully produce a neutral white tone. Also, if you have the right controllers, you can dim them separately until the color is just as you want.
“Production tolerances of white LEDs and the definition of ‘correlated colour temperature’ lead to samples of the same product awakening a different colour impression. Unfortunately designers cannot do anything about this. Added to this is the age-related colour shift of LEDs. The designer usually has no information about the colour shift to be expected after 10,000, 20,000 or even 50,000 operating hours. ” – Source article by Klaus Bieckmann.
Some drawbacks of using white LEDs
- Multiple researchers have warned that the blue hues emitted by modern LED bulbs could be a cause to sleeping disorders. There is also a growing evidence that blue-rich spectral content may be detrimental to the human health and urban environment because of the dangerous chemicals they contain. A few councils are already considering the replacement of existing cool white LEDs to warmer LEDs for street lighting.
Lighting affects our feelings, functioning, and health. Daylight, i.e. light with a high spectral blue component, activates alertness and increases performance and concentration. With less amount of blue component in light, the body functioning changes over to a calm phase, which is what happens towards the evening. At night, the body is totally at rest. Biologically effective LED lighting can simulate this natural process if we know how to program it correctly to imitate the natural course of the day.
- Cool-white LEDs with high color temperature can cause more light pollution than other light sources because they emit proportionally more blue light than traditional outdoor light sources.The International Dark-Sky Association discourages using white light sources with correlated color temperature above 3,000 K.
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Nevertheless, white LEDs can actually play an important role in reducing crime rate in cities. Whiter light can contribute to easier recognition of people and objects in dark, as well as enhancement of the quality of images from video surveillance systems that supports investigations by the authorities.