What are LED Light bulbs?LED stands for Light Emitting Diode. LED's use the same type of technology as silicone chips found in every electrical device from computers to cameras. There are no elements to burn out, no poisonous materials used like mercury and they are ultra efficient.
Why do we need LED Lightbulbs?Everyone is very aware of climate change and the predicted implications it will have for future generations. The question is are we all doing our bit to prevent it? By switching to LED technologies we can greatly reduce our carbon footprint as well as electricity bills.
Should I consider LED bulbs?
LED lights use significantly less energy than traditional incandescent light bulbs and are also more efficient than current compact fluorescent lamp technology. They also last over 10 times longer than incandescent bulbs (>15,000 - 20,000 hours instead of 1000 - 8,000 hours). Pound for pound LED are much cheaper and last longer which reduces maintenance time for both households and commercial premises.
LED light technology is one of the fastest growing manufacturing industries worldwide. This brings the cost and quality benefits of large scale mass production to the consumer market.
What do LED Bulbs cost?
LED bulbs do cost more money upfront but you recover this investment within the first year of switching. To replace a typical 50W spotlight with a 5W LED spotlight you are saving 90% in energy and electricity. On a commercial scale for say a 20,000 ft warehouse, LED can save thousands of pounds each month on lighting alone. Payback time typically for a commercial warehouse can be as quick as 12 to 18 months.
Light Emitting Diodes
With the development of high efficiency and high power LEDs it has become possible to use them for general lighting purposes. The first commercial LEDs were commonly used as indicator or warning lamps on instrument panels such as trains, telephone systems, computers etc then later cars started to use LED in indicator lights and dash board lighting. As electronic technology became more advanced, the light output was increased gaining more light out of each semi conductor. Osram and Philips advanced this technology followed by GE and Sylvania. In addition, efficiency and the reliability were maintained to a higher standard.
Like a normal diode, an LED consists of a chip of semiconducting material doped with impurities to create a p-n junction. As in other diodes, current flows easily from the p-side, or anode, to the n-side, or cathode, but not in the reverse direction. Charge-carriers, electrons and holes, flow into the junction from electrodes with different voltages. When an electron meets a hole, it falls into a lower energy level, and releases energy in the form of a photon.
The wavelength of the light emitted, and therefore its colour, depends on the band gap energy of the materials forming the p-n junction. In silicon or germanium diodes, the electrons and holes recombine by a nonradiative transition which produces no optical emission, because these are indirect band gap materials. The materials used for the LED have a direct band gap with energies corresponding to near-infrared, visible or near-ultraviolet light.
Initially LEDs were designed to replace and fit into existing fittings such as GU10 downlights but as the technology developed, bespoke GU10 as a complete unit became available as did many other fittings and luminaires. Today, its possible to buy almost any type of LED fitting replace all other types of traditional lighting.
What is Colour Temperature or Kelvin?
Light colour is measured commonly in Kelvins. Kelvin ranges from 1000K - 10,000K. The lower the number the warmer the light is. Traditional light bulbs such as incandescent and halogen were all made to 2700K producing a nice warm ambient light colour. The very old tungsten lamps were 2200K and this colour represented the colour of an old gas light lantern that used to light up the streets.
There has been a lot of confusion with colour and this has entered the public domain and few distributors actually know what colour warm white (soft light), white and daylight colour is. To ensure consistency there is an international standard for measuring the 'whiteness' of light output and this is called the colour temperature. Colour temperature is measured in Kelvin (K) after William Thompson who was the first baron of Kelvin
2700K is a warm yellowish light and represents the traditional incandescent and halogen light generally used in home applications and hotels and restaurants to get that nice warm ambient feeling. 4000K is a crisp white light colour and this is used by retailers, office lighting and warehouse applications. 6000K and 6500K is more of a natural daylight colour and is used for photographers, design studios and hospitals.
What is CRI?
CRI stands for Colour Index Rendition. This is measured from 1 - 10. The higher the number the better CRI. Industry standards used to use a CRI of 5 for example for hotel, commercial premises and most other applications but as technology moved on and a better understanding of how LED light is used the CRI went up dramatically.
To give you and example of this. Years ago retailers used to place clothes near a window in a store. This was because the shopper could not see true colours with lighting using a CRI of 5. Navy blue colors looked like black etc. Shoppers had to carry the garment to the window to see the actual colour of the garment they were buying. Retailers have since changed this and now use a CRI of 8 and this allows us to see true colors with the naked eye without having to move to a window in daylight to see what the real colour of a garment is. This is also true of car showrooms. They too use a CRI of 8 to show car colours exactly as they will be when the vehicle is outside. Nowadays its changed once more and in an effort to make light work better for the consumer and in seeing true colour Philips and Osram have increased the CRI to 9 making it possible for the naked eye to see true colour at this range.
Thank you for reading this blog. It was created after having expert advice from the technical Director at Ecogold Lighting Group. A leading manufacturer and distributor of branded lamps and fittings.