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Clearly viewers of Midlands Today are a romantic bunch. Following our story about npower's energy-efficient light bulb giveaway we asked for your thoughts. And overwhelmingly your emails were about using these greener light bulbs with dimmer switches. Here are just a few you sent us;

Jayne in Wolverhampton points out;

I have dimmer switches in quite a few rooms and the energy saving light bulbs don't work with them. I have had a pack of these light bulbs from npower and I have given them away. Total waste of money.

And Sam Forrester in Uttoxeter said;

We think that the energy saving bulbs are very good but they dont work very well with dimmer switches. Please mention this on the show.

But Laurie Loy from Derby reveals;

We received the energy saving light bulbs from npower and we are using a couple of them around the house. The only problem we have with energy saving light bulbs is that they don't seem to work well with dimmer switches. The light constantly flickers and sends out a really dull light.

So do energy efficient light bulbs work with dimmer switches or not?

Well you can certainly plug them into your existing light sockets and control them with a dimmer switch. But as Laurie points out the light will flicker. Indeed not only are the results poor you will also shorten their life.

The modern energy efficient bulb is a compact fluorescent lamp which works in a completely different way to the traditional incandescent bulb. A traditional bulb gives out light because a current passes through a wire inside it. Vary the current with a dimmer switch and you vary the light given out. (you also get lots of heat but we'll come back to that.)

A florescent bulb is filled with gas rather than a filament and has an electrode at each end. A current of electrons passes through the gas from one electrode to the other exciting mercury atoms in the gas which then give out light. Unfortunately this is ultraviolet light which we can't see. So the inside of the tube is coated with a florescent powder that efficiently turns the ultraviolet light into visible light.

It's a much more efficient process than the traditional bulb. But one big disadvantage is it just won't work that well with a dimmer switch. As you turn down the current it becomes harder and harder for the bulb to kick-start itself into life. If like Laurie your bulb is flickering than it hasn't got enough current to work and that continual sputtering on and off is damaging the inside and reducing it's working life.

The solution is to buy a special energy-efficient light bulb designed to be used with a dimmer switch. They tend to cost more because they have extra electronics to enable the dimming effect. A modern energy-efficient bulb already has electronics inside it to help regulate that current passing through the gas. This is called the ballast. In a dimmable bulb extra electronics allow the ballast to work with less power and deliver less power to the bulb itself.

That's probably more than you every wanted to know about this, but the important lesson is that Laurie needs to get some proper dimmable energy-saving bulbs.

Final point from Cyril Kitchen which touches on that heat energy given out by traditional bulbs I mentioned earlier;

I am completely amazed at the number of people who are taken in by this farce of (so-called) "Energy efficient" light bulbs which can only save energy on a warm summer evening.

That's because Cyril maintains the extra heat the old bulbs give out are important for warming our homes. Take that away and we just turn up the thermostat which uses more power anyway. It's a nice idea and certainly there's a lot of waste heat. As my Ö÷²¥´óÐã colleagues on "Bang Goes the Theory" showed recently two traditional light bulbs put out enough heat energy to cook a chicken in 90 minutes! But sadly it isn't enough to make much of a difference to our heating bills. Lights tend to be high up so any heat is usually wasted. And if it really was a noticeable effect then we'd all be turning out old fashioned light bulbs off on a hot summer's night and turning on all the lights in this cold snap. And I don't know of anyone who does that.

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