Lighting Concepts
In this blog we will discuss about various aspects of Modern Day Lighting. Topics covered are:
1. LED vs CFL vs Filament (incadescent)
2. Light output or Lumens
3. Light Colour Temperature 
1. LED vs CFL vs Filament
Now-a-days we are hearing a lot about LED lights and about replacing old lamps with LED lamps. But what is LED and why should we replace old lamps with LED?  

Lets first talk about Filament or Incadescent bulb. This is the old style bulb which was invented by Edison. It works on the principle of heating a very thin tungsten filament. Once the filament heats up, it emits yellow light. Since heating is required, it results in lot of wastage of electricity, as what we really need is light and not heat. Thats why filament bulbs are very hot and they last only few months as the filament breaks due to constant heating. Filament bulbs are very inefficient way of producing light.

To make lighting more efficient, Flourscent Tubes or CFL bulbs were invented. This is the tubelight that we are all so familiar with. It works on the principle of passing current through a mixture of gas and mercury. It causes the gas to emit light. This works much more efficienctly than filament bulb. It consumes 5 times lesser electricity than filament bulbs. It also lasts about 5 times longer (average life of about 3 years). But there is still a lot of wastage of power in Flourscent tubes and bulbs. Also, they are not environmently friendly as they contain mercury which is poisnous.

The latest breakthrough in the field of lighting was provided by LED or "Light Emitting Diode". LED is an electronic component rather than elecctrical. It is very efficient way of generating light. It consumes about half the power of flourscent lamps or about one tenth the power of filament lamps for generating same about of light. It works on very low voltage (12 to 36 volts), whereas we get a supply of 230 volts in our power lines. Thats why LED requires a AC to DC adapter to convert 230 volts AC power to low voltage DC power. There are many benefits to using LED lights:

1. Very power efficient, consumes very low power (ten times more efficient than filament bulbs)
2. No unnecessary heating
3. Very high life. Good quality LEDs have light of more than 10 years
4. Since LEDs are very small, they can be moulded into a variety of sleek and modern form factors. Thats why you can find LED lights with very nice designs, which was not possible with CFLs
5. Environment friendly as they do not contain mercury or any poisnous elements.

Earlier LEDs were expensive, so very few people could afford. But with the advance of technology, LEDs have become very cheap now and easily affordable by common man. However, one must be careful when buying LEDs. It can also tend to have harmful effects. Badly designed LED lights can emit UV or IR radiation which can be harmful to health. We highly recommend going for LEDs lights from good brands which are BIS certified and marked with 'no UV/IR'. 
2. Light Output or Lumens
Lumens is the measure of Light Output. To put a perspective, an old style Flourscent tube of 36 watts produces 2000 to 2400 lumens light. An old style Filament bulb of 60 watts produces about 600 lumens light. Modern day LED lamps typically produce about 100 lumens per watt. So a 10 watts LED bulb should have light output of about 1000 lumens. With that comparison, a 20 watts LED should produces similar light as a 36 watts flourscsent tube thereby giving a power saving of about 80%. It is recommended to look at the Lumen output of a light before purchasing it as it identifies the efficiency of the light. LED lights with less than 70 lumens per watts are not recommended.
When going with false ceiling lights, the number and wattage of lights should be selected such that total light output is about 2500 lumens for every 100 sq ft. For example in an area of 20ft x 10 ft (200 sq ft), total light output required is 5000 to 5500 lumens. So if you are using a 7 watts false ceiling light that has output of 600 lumens, 8 lights would be required. 
3. Light Colour Temperature
Colour temperature identifies the colour of the light. The colour can vary from yellow light, like that of old style filament bulb to white light, like that of the tubelight. Colour temperature of filament bulb is 2700k, which is also the colour of sunlight early in the morning (dawn) and late in evening just before sunset. This is called Warm White. Most of the day, the colour of natural light is 4000k, which is called Natural white or Neutral White. Colour of tubelight is identified as 6500k or Cool White.
So what colour light should you use? This is quite personal. Most of the Indians are very used to tubelights, which are cool white light or 6500k. They feel uncomfortable sitting in yellow light for long durations or for study. But in western countries, yellow light or warm white is most commonly used. Yellow light gives a glow to the sorroundings, so the colours look bright under yellow light. Thats why most interior decorators would recommend use of warm white or 2700k to 3000k especially in Living Rooms. Many people prefer to use cool white light or 6500k for bedrooms or study areas as well as kitchens.

Now-a-days, we have tunable LEDs where colour of the light can be changed from white to natural to warm as per your convenience and usage. Check out Philips Hue Smart Lights on our website. Other tunable options include Philips Ultron Scene Switch Tube.