What happened on the LED lighting market in the beginning of the 21st century can only be called a light revolution. Who would have thought that a semiconductor diode, born in the 20s of the last century, discovered by chance and working on completely different principles than classical sources of light, will turn the lighting industry over and become a competitor of traditional High Pressure Sodium (HPS) lamps and will force it out of the market. And all this will happen in 10 years!

White ones start and win!

The technology itself, which allowed to receive visible light using LEDs, appeared in the 60s of the last century. The first LEDs were emitting red, then yellow and green. These LEDs are suitable for display and were in demand in the automotive industry.
However, they were not suitable for light sources for general illumination. To get white light, the blue component of the spectrum was required — you needed to create a super-bright blue LED. Only in 1996, Nichia managed to get a super-bright white LED. From this point on, there were no more obstacles to the use of LEDs in lighting.
The first samples of LED luminaires had a light output of about 20 lumens per watt of power, which was close to that of incandescent lamps, at a cost hundreds of times higher.
LEDs with such parameters could not be widely used in the industry, but were used where their other positive qualities, such as durability, miniature and reliability, were important. Therefore, one of the first places of application of LEDs as a light source was the medical and automotive industry.
But manufacturers of LED crystals have constantly improved the technology and now have achieved significant results. Modern LEDs have overtaken in energy efficiency all traditional sources of illumination. For example, the energy efficiency of sodium lamps (HPS) widely used for street lighting is about 100 lumens per watt. At the same time, the efficiency of modern LEDs already reaches 160-180 lumens per watt. And if we add to this the fact that LEDs are more compact, have much greater mechanical strength, are less dependent on environmental conditions and, most importantly, provide illumination of much higher quality than other traditional light sources, the feasibility of upgrading existing lighting systems by installing LED fixtures becomes apparent.

The strengths of the new light source

Another feature that allows for even greater cost savings when using LED lighting is the possibility of dimming. Dimming is the process of reducing the brightness of the light source. In fact, what is the point of covering the territory in full force when there is no one on it? In this case a weak “duty” lighting is enough. LED lighting allows you to take full advantage of this opportunity. If dimming of other light sources is impossible in general or can only be done within certain limits, then LED lighting makes it easy to change the brightness of the light from 10% to 100% without degrading the quality. Due to dimming, energy costs can be reduced by 40%, and this is not only a reduction in cash costs, but also a reduction in CO2 emissions — a problem that is receiving a special attention today.
Different technologies are used to implement dimming functions. They can be either the simplest, based on motion sensors, or complex, based on controllers connected to the network, allowing you to implement any lighting scenarios and get the most optimal use of the lighting system. Such systems are called Smart Street Light.
For a lighting system, the brightness of the light source and its economy are, of course, one of its most important characteristics. But not the only ones. Commercial operation of lighting systems imposes additional, equally important requirements on luminaires.
First of all, it is low operating costs. A lamp used in a commercial lighting system should require minimal maintenance. By this parameter, LED lamps are far ahead of sodium lamps.
The lifetime of a sodium lamp is from six months to 1 year, after which it either fails or deteriorates its characteristics so much that its further operation makes no sense. So, at least once a year, we must bear the cost of a new lamp and the cost of work on its replacement. LED luminaires not only serve for more than 10 years, but also provide the constancy of the light characteristics all this time. And the LED light source itself has much greater mechanical strength than a glass bulb.
The second, not less important indicator is the quality of light.
The HPS lamps, with all the brightness of the light emitted by them, shine in a very narrow range of the orange spectrum, which severely limits the visual perception of objects with the human eye and distorts color reproduction. At the same time, there is an interesting effect when, with an increase in the luminous intensity, it cannot be said that the object becomes better visible.
This is because of the narrow radiation spectrum. Besides, the colors in this light, either differ with difficulty, or are generally indistinguishable. In addition, the light from the HPS lamps has pulsations that are harmful to the human eye and cause increased fatigue.
LED lamps give a radiation spectrum as close as possible to the one provided by the sun. The sensitivity of the human eye in such light is maximum, there is no color distortion, as well as pulsation, which allows a person to feel as comfortable as possible.
Well, the third, but not the last advantage of LED lighting versus traditional, is stability. When it is severe frost outside HPS lamps may not start. They should also cool down after turning off for a few minutes before turning it on again. Unlike them, LED lamps do not have any difficulties with their launch in cold weather, and when restarting.

Even on the sun we find dark spots

There is nothing ideal in this world, and LED lighting technology has its weak points.
The first is the price. Compared to all other industrial light sources, the price of LED lamps is the highest.
The second point is rather not even a weakness, but a feature of exploitation. Since the LED during operation generates a lot of heat, it needs a high-quality heat sink. Therefore, LED lamps should be properly designed with this in mind, because when LEDs overheat, they quickly degrade and can fail.

Leaders change

The time of the sodium lamps, which were the main source of streetlight, has passed. Most consumers have realized all the benefits of LED lighting. On a growing number of objects there is a replacement of the HPS or Arc Mercury Lamp with LED.
This process becomes avalanche-like. When designing new objects, the use of LED lighting has become not only the norm, but also the rule.
The European Union pays close attention to energy savings and the problem of reducing carbon dioxide emissions into the environment.
European Union governments are encouraging consumers to switch to energy-efficient lighting sources. Significant funds are allocated for the implementation of this program and tax incentives are provided for organizations that support this initiative. The most promising is Smart Light: installation of LED lamps + intelligent lighting control system.
In addition to reducing the cost of electricity and, accordingly, CO2 emissions, the government expresses serious concern about the use of light sources containing harmful substances. In this regard, the European Directive RoHS 2015/863/EU was issued, according to which by July 22, 2019, the Arc Mercury Lamps and High-Pressure Sodium lamps will be prohibited for use as unsafe. In LED light sources, such substances are not used, so their use is welcome.

Did the time come?

Judging by all signs – YES. Despite the rapid development of the LED industry, the technological limit is almost already reached. Each next line of energy efficiency of LEDs led to increased price. The theoretical limit is 300 lumens per watt, but commercially viable is an energy efficiency value of 200 lumens per watt. Therefore, new breakthroughs in energy efficiency are no longer to be expected, and the existing LED lamps can only be slightly cheaper due to scale effect in production.
At the same time, after the EU Directive comes into force, from 2021, penalties are expected for consumers who continue to use obsolete lamps – fluorescent and HPS.
The optimal period for replacing the organization’s lighting system with LED is the spring and autumn period, since in addition to more comfortable working conditions for the installation personnel, this makes it possible to be ready and use the system in winter, when the duration of the night time is maximum and, accordingly, the economic effect of using a more efficient lighting system is also at the maximum level.
Considering the above-mentioned, the transition to a new type of lighting is inevitable in any case, and the winners will be those consumers who take care of updating their lighting in advance. There is only one question still open: how to choose the optimal lamps? You will find the answer in our next article.