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What Does CFL Mean?
CFL stands for compact fluorescent lamp. These bulbs come in a wide range of different designs e.g. candle, spiral and spotlight, depending on the way that the glass tubes are folded. The tubes loop out of the base unit two to four times. Spiral-coiled designs distribute the light more efficiently. Sometimes the tubes have a glass globe over them to make them look like standard bulbs. Typically these bulbs are over 4 times more efficient than a standard 100W incandescent bulb i.e. 20W.
What Does LED Mean?
LED stands for light emitting diode. Usually these lamps consist of arrays of LEDs. Currently these are mainly available for the GU10 or MR16 fittings. You need to be careful to select the correct voltage as they come in both low voltage (12v) and mains voltage (230v or 110v). These are normally used in spotlight fittings. They are more efficient than incandescent or halogen bulbs and more efficient than a CFL bulb. For comparison they are typically over 10 times more efficient than a 20W halogen bulb i.e. 1-2W.
What Does Lumens Mean?
Lumen (lm) is the unit of luminous flux, a measure of the total power of light emitted. This is a standardised method of measuring the brightness of a light. To put this into perspective, a 100W light bulb gives around 1700 lumens and a 40W bulb is about 500 lumens. The higher the lumens per watt the better the bulbs efficiency.
What Does Candela Mean?
Candela (cd) is sometimes used in a bulbs specification in the form 'mcd' or mill Candela. This is a measure of luminous intensity.
What Does Dichroic Mean?
This is a special chemical coating on a bulbs reflector to let heat escape. This means that objects under the light and the bulb to heat up less. This has the effect of increasing the bulbs life.
What Does Colour Temperature Mean?
Usually measured in degrees Kelvin (K) this is a measure of the colour of light produced by a bulb. Standard incandescent bulbs are around 2800K . Energy cfl saving bulbs typically range between 3000K and 4000K . The higher the colour temperature the bluer the light.
4000K corresponds to a very slightly blue white.
What Is The Reflecting Angle?
This is a measure of the direction and how light spreads out from the bulb.
This can vary between 120 degrees (wide), to 45 degrees (medium), to 7 degrees (very narrow). The narrower the angle the less the light spreads out from the bulb so for general lighting you need the widest angle you can get.
Do CFLs Use More Energy Than A Standard Bulb To Turn On And Off?
No they don't but they do take a few seconds to reach full brightness. Very frequent switching can reduce the life but in practice you won't notice this when they are used normally. It is always best to turn off lights if you are not using them.
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