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How Do Energy Saving Light Bulbs Work?

By: Kathryn Senior PhD - Updated: 29 Sep 2016 | comments*Discuss
 
Low Energy Light Bulbs Light Bulbs

Reducing the amount of energy that you use up and your carbon footprint is becoming increasingly important. One of the easiest ways to improve energy efficiency in the home is to install low energy light bulbs, rather than traditional ones. But what are low energy light bulbs and how do they work? Why do they use less energy?

Energy Saving Light Bulbs

Energy saving light bulbs are actually compact fluorescent lamps – and are fundamentally different to traditional light bulbs that are incandescent lamps. The latter can be purchased with different wattage outputs – the typical light bulb used in the home is either 60 watts or 100 watts, which means that is how much power they use up in an hour. The low energy equivalents use only 9 or 11 watts each hour, so represent a substantial power saving, even though they give the same amount of light out.

The downside to energy saving light bulbs has been that they are much more expensive than incandescent bulbs – but this is offset by their much longer life. It has been estimated that, over the course of its life, an energy saving light bulb can save about £20 in the cost of the electricity used to run it.

How do Energy Saving Light Bulbs Work?

The glass tubes in the bulb that you can see are filled with gas, which is mercury vapour. The bulb also contains electronic ballast, through which electricity flows when the light is switched on. This causes the mercury vapour to give off light in the ultraviolet range, which, in turn, stimulates the phosphorous coating on the inside the glass tubes to produce light in the visible range.

The design of the base of the bulb means that lower energy lighting tubes can be made with all the standard Edison screw or bayonet fittings to fit most of the lamps and lights that people have around their homes.

Environmental Advantages

The lower power usage of low energy light bulbs means that they do not contribute so much to carbon dioxide levels in the atmosphere. Each low energy light bulb used to replace a traditional bulb saves around 2000 times its own weight in carbon dioxide emissions over the course of its life – which is typically around 5-8 years.

It is now possible to buy different forms of lower energy light bulb – including ones that fit into spotlight fittings and down lighters. The light bulbs formerly used in this type of lighting, which tends to have multiple spots in the ceiling, meant that the lighting system was very power hungry. By replacing 10 spotlight bulbs of 60 watts with 10 of 9 watts, lighting the whole room takes 90 watts instead of 600 watts.

Disposing of Low Energy Light Bulbs

Like traditional light bulbs, energy saving bulbs are also made using a very small amount of mercury. This doesn’t cause problems when the light bulb is in use but it must be disposed of very carefully. It is not ideal for discarded light bulbs to end up in landfill. Recycling is available in the UK and the rest of Europe through the WEEE recycling initiative. During recycling, the mercury is removed from each lamp and is then reused.

Disadvantages of Low Energy Light Bulbs

When they were first brought out, energy saving light bulbs did not look like traditional light bulbs – they were long with looped glass and their additional length meant they did not fit well into lamps and light fittings designed for ordinary, shorter incandescent bulbs. Most low energy light bulbs do not have the facility to allow them to be dimmed – if you put them into a dimming light, they tend to flicker very annoyingly and this can shorten the life of the bulb.

More recently, newer shapes of lower energy light bulb have been developed and some are now available that are specifically designed for dimmers.

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[Add a Comment]
is mercury vapour not harmful?!?! GET THESE OFF THE MARKET!!
bulb lover - 27-Sep-16 @ 10:01 AM
I still remember buying those light bulbs that where long, the two tubed bulb that looped. they were really hard to fit on to lamps and I really had a lot of trouble looking for lamps that would fit or could accommodate this kind of light bulbs. Nonetheless, they're really great. If we all use this kinds of light bulbs, we could really make a big impact on the environment.
Emily - 14-May-15 @ 4:14 AM
how do energy saving light balbs save energy
itiotperson - 19-Feb-15 @ 10:52 PM
There is an error you say: "the low energy equivalents use only 9 or 11 watts each hour", false. if we talk of a bulb of 9,11 watts-hour (watts.hour is a meause of energy not power). It the bulb were of 9 watts in one hour it uses:9*3600=32,4 KJoules of energy.
cromosoft.com - 19-Aug-14 @ 3:22 PM
I use these energy saving bulbs in most places except on the stairs have walked up or down before the bulb warmed up and find them in generalvery good
beckbabe - 7-Jul-14 @ 1:45 PM
Are energy saving light bulbs really saving us energy? I have not seen a decrease in my energy consumption since having these bulbs in my house. I think in my case there are two reasons for this:1. Where I used to manage with a 3 incandescent bulb central light in my kitchen & lounge, I now need to put on the wall lights at the same time to get the same amount of light so that I can see things properly, so 5 lights on now.2. The old 'inefficient' incandescent bulbs also provided heat, so on a slightly chilly dull day they served two purposes. Now I have to put the heating on. Of course in summer this would be creating unnecessary heat but as lighting conditions are brighter & longer in summer I don't need the lights on when it is warm.If you think this sounds ridiculous- just check back to find out the most efficient way of airing clothes- an immersion heater or a single light bulb in your airing cupboard.As always we are often told/made to do things not because they are the best things to do but because the government have to be seen to be doing something & for even if it has no effect on energy saving.
questioner - 27-Feb-12 @ 2:07 PM
I use these energy saving bulbs in most places except on the stairs ( have walked up or down before the bulb warmed up!!) and find them in general very good. I do however argue that they last years. I have already had one "blow" after 2 years in my living room - as this light is rarely used because I prefer lamps I am a bit miffed it cost what it did and only lasted 2 years. Also where do I now get rid of it?? Im sorry but am not going to take it to the "tip" as it's miles away and I don't drive. There should be convenient places (maybe libraries, supermarkets or the like) where they can be left for recycling to prevent them going into landfill.
Paulababe - 22-May-11 @ 2:04 PM
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