F.A.Q

What you need to know about LED?

LED technology has a completely different approach and features of well-known lamps such as fluorescent lamps, halogen lamps and incandescent lamps.

LED lights have many new aspects in this new technology, so not every LED light can be used for any purpose.

If you are buying a LED lamp, you need to know exactly what you want. For example, if you buy LED lights to light up a tunnel, you do not buy high-power CRI light, because no one in the tunnel can read books. Or to get the brightest light possible, do not opt for warm light colors, but for the cold colors. All these functions are related to each other

Each new technology requires a new approach and mind shift in the use of it.

On this website we wish to advice you as specialist in LED lights what you need to consider when you are buying LED lights. What you should know about LED lights and what marketing tricks are used in advertising LED lights. We will present each particular property of LED lighting, and which features are important for a variety of lighting application. We hope you will enjoy learning about the new LED technology.

LED lights are brighter
LED lights are much brighter than other lights available on the market. The comparisons are shown on the graph below. LED lights are two times brighter than CFL (Compact Fluorescent Light) and six times brighter than Incandescent Light Bulbs. Nowadays LED’s can achieve up to 231lm/W. We often neglect the importance of suitable light in our working and living spaces. The Maastricht University study of lighting impact on cardiac patients proved that patients who had appropriate quality of light during the day have slept 8% longer at night.

LED lights consume less power
If we compare LED lights with other lights in the 50.000h of operation, we can see that LED lights consume much less power than other lights. LEDs consume 57% less power than CFLs and 90% less than incandescent light bulbs. The Japanese economic research states that if the current lights were replaced with LED lights, the total power consumption would be reduced for 92.2 TWh/yr. With such action 36% of the nuclear reactors in Japan could be shut down.

LED lights have a longer lifespan
LED’s lifespan is more than 50.000h which is equal to 12 years, if the light is turned on for 12 hours a day. LED’s lifespan is 6 times longer than CFL’s and 40 times longer than the lifespan of incandescent light bulbs. Practically in one LED light lifespan you would replace 5 CFL’s and 42 incandescent light bulbs.

LED lights are environment friendly
LED lights do not contain mercury like CFL’s and are RoHS compliant. Mercury is very toxic to your health and the environment. Because LED lights have very low power consumption we can achieve lower energy consumption and consequently the decrease of CO2 emissions and high-level nuclear waste.

LED lights have even more advantages
• LEDs are not sensitive to low temperatures.
• LEDs are not sensitive to humidity.
• Frequent on/off switching does not decrease the lifespan of the LEDs.
• LEDs turn on instantly; they do not take time to heat up to operational temperature.
• LEDs emit much less heat then other lights. They emit nine times less heat then CFL’s. You can not burn yourself by touching the light source.
• LEDs can be very colourful. RGB LEDs can shine in any colour tone you wish.
• LEDs have high durability because, unlike other lights, they do not contain any parts of glass.

• LED lighting is compatible to house and building lights automation systems like DALI. The automation of lighting with constant light and presence sensors can decrease the power consumption for at least 40%.

What is a LED Diode?

LED stands for Light Emitting Diode. They are used in almost each electronical device. We can find them in digital clocks, they are used as indicators on electronic circuits and they can transmit information on optical fibers or on remote controls. They are used for backlighting of LCD displays on jumbo displays and they are used as basic building blocks. They are more and more popular in lighting in all kinds of lighting systems.

Practically the LED diodes are small lamps which can be very easily installed in electronic circuits. Unlike the other traditional lighting, like incandescent light bulb and CFLs, the LED diodes basic material is not burning out to produce light. This is the reason that the LED diodes life span is much longer than other lighting system and they don’t heat so much than other light system. On the market we can find set of various types of LED diodes. We can chose from high, middle and low power LED diodes. There can be arrays of LED diodes in one chip or single LED diodes. We can get them in different colors, color temperatures and even multi color RGB LED diodes.

In physical terms the LED diode is a basic diode which conducts electrical current only in one direction. When the LED diode is conducting electrical current, which is flow of electric charge in matter, the matter itself is emitting the photons. The photons are relished when electron jumps from one electronic orbit of atom to the other orbit. This electron jump occurs because the electric voltage is connected to the diode. The bigger the electron jump the larger the energy of emitted photon. Different energies and frequencies of photons result in different colors and power of lights.

The LED diode white light was discovered only a few years ago. We can get it from LED diodes which are emitting red, green and blue light together. Or with more efficient technology where the blue LED diode is covered with a phosphor layer which converts the blue light to white light. With the thickness of the phosphor layer we can adjust the color temperature of the light. The thicker the phosphor layer is the warmer the color temperature.

What is a Lumen?

Lumen measures the amount of light you will get from a lighting fixture. The more lumen a light fixture has the brighter it will be and vice versa fewer lumens equals dimmer light. This information is essential if you want to brighten up or cut down brightness for your businesses, parking lots, homes, and buildings.

An energy efficient lighting supplier Jet Lighting Technology Co.,Ltd. advises “As the owner of a business or a commercial space, you should be more concerned about how bright is the light emitted by a bulb(s). After all, you have to ensure that commercial and manufacturing spaces should be brightly lit so that employees are not hampered, bothered, or unimpressed with the lighting situation while trying to perform their professional responsibilities. So when buying lights for your business, you need to consider their lumens value.” There’s a misunderstanding that Wattage is what dictates how bright a lighting fixture will be, however, Wattage only measures the amount of energy the lighting fixture is consuming to operate.

What is a Foot Candle?

“A foot-candle is a measure that describes the amount of light reaching a specified surface area as opposed to the total amount of light coming from a source (luminous flux).” Foot Candles are measured in lumens per square foot as appose to simply Lumens. This measurement will give you accurate information on much light is illuminating your desired target.

What is Color Temperature?

The CCT or Correlated Color Temperature is a specification of the color appearance of the light emitted by a light source, relating its color to the color of light from a reference source when heated to a particular temperature, measured in degrees Kelvin (K). The CCT rating for a light is a general "warmth" or "coolness" measure of its appearance. However, opposite to the temperature scale, lamps with a CCT rating below 3000 K are usually considered "warm" light sources, while those with a CCT above 4000K are usually considered "cool" in appearance.

For example the daylight color temperature changes thru the day. At sunrise and sunset the CCT is around 3000K. On the other hand at noon the CCT is on the highest level around 5000K or higher. The color temperature of light has important effects on human beings. For the places where people are gathering such as coffee shops, restaurants, and hotel lobbies the warmer light color around 3000K is desired. The warmer color of light causes people to relax. For the places where people should be more focused on their work, like in classrooms, offices and conference rooms the light color temperature should be cooler around 4000K. LED lights have the best possibilities to tune the desired CCT.

The color temperature of light is represented by chromaticity diagram on which the wavelengths of the light and its intensity to the human eye meets with the color temperature. If you look on the chromaticity diagram you can see that warmer temperature colors have more red and orange hues and coolest colors have more blue hues.

Very interesting way of representing the intensity of each wavelength is made with spectral power distributions diagrams. From diagrams below we can see the distribution of four different sources of light. If we compare the artificial light sources with daylight we can conclude that the light for LED light source has the best approximation with daylight.

What is Color Rendering Index?

Color Rendering Index (CRI) of a lamp tells us how rich colors look under the lamp. Two lamps may have the same Color Temperature but they can render colors differently. The Color Rendering Index of the lamp is determined with the emitted light spectrum.

CRI is the ability of a light source to reproduce the colors of various objects faithfully in comparison with an ideal or natural light source. A reference source, such as daylight, is defined as having a CRI of 100. The best possible faithfulness to a reference is specified by a CRI of 100, while the very poorest is specified by a CRI below 0.

If we compare different light sources the tri-phosphor warm-white fluorescent tubes can reach CRI 70. The best LED lights can reach a CRI up to 95. The color rendering index has been used to compare fluorescent and HID lamps for over 40 years, but the International Commission on Illumination (CIE) does not recommend its use with white LED lights. In fact, many RGB-based LED products have CRI 20, yet the light appears to render colors well. CIE is already developing new CRI measuring method which will be capable of comparing traditional light sources and LED light sources.

Glare and UGR?

Glare occurs in both natural (daylight) and interior lighting situations. The glare annoyance depends on a number of factors.

Areas of high brightness right next to areas of low brightness cause glare, making people feel uncomfortable. For instance, having a bare light bulb for your desk lamp may provide more than enough light. However, it would cause more light to shine directly into your eyes than reflects off the desktop, making it difficult to read or do other tasks. Having a shade on the lamp keeps the light from glaring into your eyes while brightly illuminating your desktop.

For the measurements of glare the discomfort glare constant is used.

More visually demanding tasks with high luminance levels as drawing and fine visual inspections are less tolerant of glare. Very sensible to glare is working behind a computer. Since computer screens have shiny surfaces and are very susceptible to glare.

We can reduce the impact of glare with some simple methods. The higher you put the lights the lower the glare. To lower the glare keep light sources high, away from the field of view.

If we cut down the luminance of the light source we can decrease its glare. This does not mean reducing the light level in the room. Rather than having one very bright lamp, you should have a number of dimmed luminaries. The higher the illumination of the background, the smaller the glare constant.

Unified Glare Rating or UGR method is an international index presented by CIE (International Commission on Illumination) and is used to evaluate and limit the psychological impact of direct glare from luminaries. Contrary to the glare index where the glare was rated using the luminance values of a single luminaries, this method calculates the glare of the entire lighting installation at a defined position. An exact calculation of the UGR value at a defined position in a room is possible with modern lighting design programs such as Dialux. The lower the UGR value, the lower the glare.

In conclusion: glare is a very annoying side effect of lighting, but we can eliminate it with methods explained above. When we are choosing the lights it is very important that we know where we will put them and how much illumination we need in the room and working places.