They have a limited lifespan and average 1,000 hours. They don’t last very long because the tungsten filament will eventually blow apart when you turn it on. You have probably experienced this happening. They are inefficient. This means that only a small amount of their electricity is converted into light. What happens to the rest? It becomes heat. I have an incandescent light bulb in my spot lamp (directional bedside reading lamp) and I am aware of the incredible heat. I have been given two of these things because the previous owners were both afraid of them and believed they would catch fire. They don’t catch fire. The metal lampshade is rated at 60 watts and has to have a wider fitting so you can only put a 40 watt bulb in. The 40 watt bulb produces 4 watts of light and 36 watts of heat. I would be much happier with these devices if they were meant as electric heaters.
The new low energy light bulbs are compact fluorescent lights (cfl) working on the same principle as a fluorescent tube. The original lights produced twice as much light as an ordinary light bulb. Now some can produce a lot more which leads to such claims on the packet as ‘9 watts equivalent to 40 watts.’ People have used 40 watt bulbs for a hundred years and need to be able to imagine how bright this super efficient 9 watt lamp will actually be. The comparison to 40 watts helps people understand that the bulb is really bright enough to go where a 40 watt conventional bulb would usually go. A 9 watt cfl could be used somewhere like a toilet, where it would still be bright, or in a hallway where you’re not really worried about having enough light for reading. Some of the golf ball low energy bulbs use LEDs. Some of the LED bulbs have the wider fitting that would allow them be used in a spot lamp like my bedside reading lamp. Fitting one would overcome the feeling that I have created a new kind of electric cooker.
What do I think of low energy lights? The very first ones in the 1990s were comparatively big, dim and took a long time to warm up. The modern ones don’t have those problems, are smaller and give a much better light. Some of the ones that were around in the 2000s had a lot of tubes on them which snapped easily when putting them in bayonet sockets. The tubes also leak air over a long period of time. Many of our cfl lights at home have dark patches on the tube where a little bit of air has leaked in. If you buy Cfl light bulbs get the golf ball type. They don’t have these problems.
How much energy do they save? If you left an incandescent 40 watt light bulb on for 24 hours it would use one kilowatt hour of electricity – about 12p. If you had eight of them on all day, not impossible in winter, that would still only be £1 worth of electricity. Domestic buildings don’t benefit as much as industrial buildings where the energy consumed by lights can be enormous. Think of your local supermarket and the power of the electric lights in there. I would buy a good low energy bulb with a golf ball fitting instead of tubes. It would make only a slight difference to my electricity bill but it’s a much better product than an ordinary light bulb. It doesn’t create as much heat, especially useful in situations when that is a problem, and it will last longer.
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