LED Low Energy Lighting

Advantages

Use around 90% less electricity

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Yes they really do! Compared to standard incandescent bulbs.

Last up to 25 times longer than
a standard bulb?

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Or do they? It's not yet clear how realistic this life span is because their brightness slowly fades rather than the bulb burning out. If the quoted life span of the LED lamp is quoted as 25,000 hours, this is the point that the brightness has fallen to around 70% of the original brightness. In addition standard bulbs appear to last longer than the quoted 1000 Hrs. However it is safe to say LED bulbs last a long time - I use 15000 hours life for cost comparison purposes, this corresponds to 3 hours a day use for over 13 years. Time will tell if this is realistic.

Brighter than
a standard bulb of equivalent wattage?

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Or are they? This is very subjective but experiments in a number of different positions at home appear to indicate in a lot of situations you can use a lower wattage equivalent LED bulb than the manufacturers suggest. This could be because the eye is more sensitive to the light emitted and/or because they concentrate the light typically in a narrower beam angle. For example in our hall we have 2 three bulb GU10 fittings which originally contained 50W halogen bulbs these were all replaced with 2.8W LED bulbs and subjectively the lighting is brighter (although a little bit harsh) - these 2.8W builds are supposedly equivalent to 15W halogen GU10s. On two mirror fitting we have successfully replaced single 50W Halogen bulbs with 1.3W LED bulbs - supposedly this is only equivalent to 8W Halogen, the original lights were probably too bright anyway.

Disadvantages

High cost

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Vary between just under £1.50 and £30 - these costs are starting to fall with the highest wattage bulbs costing disproportionately more. Currently the 2.8W bulbs referred to above can be obtained for around £6.50 each

Can be heavy

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Not noticed any problems due to this.

Can be larger than a standard bulb

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May not fit some light fittings, especially fittings which have a cap ring.

Smaller beam angle for reflector types

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This can mean more intense illumination with a smaller spread.

Light colour not the same as
standard bulbs

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Depends on your preferences but they are different with the cheaper ones tending to be bluer (even when fitted with a diffuser which lowers the light output). Recently it has been possible to by lights with a slightly yellower tinge and these look far better although they use slightly more electricity than the cheaper ones, they also have a wider beam angle giving a better spread of illumination.

Confusing variety of types and costs

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Be cautious, the cheaper ones typically have a shorter life and can have a lower output in lumens per watt for a given light colour.

Light output drops with time

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Probably not a problem in the medium term.

Not all bulb types available

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Mainly GU10 and bayonet fittings at present but the range is increasing all the time.

GU10 types don't look as nice as standard bulbs

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Again a subjective view, ones with diffusers on look best.

Can flicker occasionally when
switched off

When fed from very long cable runs (e.g. lights switched from the top and bottom of stairs) the capacitive coupling across the cables can cause the lights to flicker occasionally when switched off. This is quite rare.