Industry Knowlage

Flickering, spectrum and our health

The type of lighting used in the places where we live, work, entertain, do shopping or just walk matters much more than we expect. Having „some light“ is not an option for the developed countries any more. The lighting to which we are exposed in our everyday life can have quite significant effects on our sleep, work performance, stamina, eye-vision and etc.

One of the artificial lighting characteristics having negative influence is the flickering light sources.

Even though most of the people could hardly see normally working fluorescent lights flicker, our sensory system somehow detects their flickering. From the very beginning when the fluorescent lighting was introduced in workplaces, the complaints about headaches, eye strain and general eye discomfort are inevitable.

These complaints could be related to the light flickering of fluorescent lights. The reason for this flickering is the AC electric systems that we use. The rated frequency is about 50Hz, which means that the voltage actually crosses the zero line 100 times per minute – which results in flickering leading to creation of discomfort. Part of the proof that discomfort comes from this kind of flickering is the significant drop of 50% of the complains in case high frequency electronic ballasts (20,000 Hz or higher) are used in fluorescent lights instead of magnetic. With the wearing of the fluorescent light sources, additional flickering additionally decreases the frequency. The older a fluorescent tube, the bigger are the black “spots” at its end, the more it flickers. Relation between working in building with fluorescent light can be found with the following symptoms: Eye Strain, Eye Discomfort, Headaches, Migraines

There are research results that say there tend to be fewer complaints of headaches among workers on higher floors compared to those closer to ground level; that is, workers exposed to more natural light experienced fewer health effects.  This doesn’t come as a surprise.

Have you seen big retail supermarkets, which have changed all their lighting with LED, but had left the halogen lighting in the sections with fresh fruits and vegetables? Well, being honest, most likely you haven’t notice that, but I bet you will do notice it after reading this article. You can see in the picture below the difference in the spectrum of the lighting sources. Obviously, the best spectrum after the natural light is the one of the halogen lamps, which make colors, and respectively fruits look better.

If it is known that vegetable, as well as human, feel better is a light with full spectrum, why do we work in offices with “thorny” florescent lights? Yes, efficiency is major part of the answer. The other one, however, is not enough awareness about the possible negative impact on human body and behavior of the florescent lights. That is the simple reason for writing this article. We live in such a stage of social development, in which you could hardly convince me that the look of a pile and pineapples is more important than the environment in our own workplaces. LED lights, especially the high quality ones, provide fairly good spectrum and show significant advantages in terms of savings. We believe the quality of light alone is big enough reason to choose LED lighting, however, the actual monetary saving is not to be underestimated as well. As you can see in some of our articles about efficiency, the pay-back period ranges between 1 and 3 years.

Do you feel annoyed by the spectrum of the fluorescent lights?

Those peaks seem like spikes, not only in the picture of the spectrum, but they also act like that for the eyes. Did you know, that your eyes percept the different colors with different “sensors” called cones. Moreover, your cones are specialized in different types of wavelengths. How “happy” do you think, the cones are with that spikes in the spectrum. The eyes unhappiness is called eye strain or discomfort or even both.

LED lighting spectrum is also not perfect, but it does a fairly good job of smoothly covering all the whole spectrum. Obviously it is much richer than the one of fluorescent light. However, there are two peculiarities. LED can be divided as cool and warm according to their color temperatures. They have completely different influence of the human body and behavior. It is related to the fact that artificial light exists for just a tiny fraction of the existence of the mankind. The human body is used to the daylight, which actually changes it spectrum through the day. In the mornings we are exposed to quite “cool” spectrum of the daylight, which is getting more and more to the warmer part of the spectrum until its picturesque sunset.

The body decodes the light changes as follows: cool white light means morning – a.k.a. time for farming, hunting or working; warm white light means evening – time for contribution to the population growth and rest. It is pretty much the same with the warm and cool white LED. The fist boost productivity and energize workers, but they suffer from insomnia and become overactive, the second one calms down the workers, which is great for their mental health, but deteriorates their productivity.

What light do we choose then?

At that point we can offer to your customers choose of a few color temperatures and respectively spectrum of the LED luminaires, but we strongly recommend – 4000K. It provides fairly good light, which stimulates productivity and in the same time is not significantly overwhelmed by light in the cold part of the spectrum.

However, there is a new technology available – tunable white. It consists of LEDs from the cool and warm parts of the spectrum mounted on one module. It has the advantage to enable the control of the light emitted not only in terms of intensity, but also in terms of light color temperature. At that point the control can be performed manually by push button or via connection with the building management system. InnoLED would soon launch control options for the color temperature with automatic and wi-fi modes.

Best regards,
Innoled Team

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