Q My shopkeeper tells me I can no longer buy the old incandescent light bulbs I want — now it’s all energy- saving devices. Do these really help to save the planet and where can I buy one of these bulbs that I can use to read? They all seem so dim to me.

A. The most common energy-efficient light bulb, the compact fluorescent light or CFL, was one of those products that came on to the market too early, before it was properly developed. A friend made the mistake of fitting a CFL to his outside sensor: by the time the bulb had exerted itself to throw out a yellowish, hazy light, a burglar could have made off with the entire house contents. Greenies who rushed to install early CFLs found themselves switching on lights only to stumble round in the dark waiting for the bulb to warm up.

Such premature marketing gave CFLs a bad name. Things have now improved considerably. Today’s CFLs should come on full blast more or less straightaway: they are far less chunky than they were and have become more powerful.

Your shopkeeper is not quite right about the unavailability of incandescent light bulbs. From September this year the sale of incandescents of 100W or more was banned: next year the wattage ban will be dimmed down to 75W and by 2012 the old bulbs will not be obtainable.

Incandescents are ridiculously energy inefficient, with more than 90 per cent of electricity wasted as heat. CFLs undoubtedly save energy and by fitting them you can do your little bit to help the planet: CFL lobbyists say that if each household in the country replaced one 100W bulb with an energy saver, the savings in CO2 emissions would be equivalent to taking 200,000 cars off the road for a year.

The Energy Saving Trust (energysavingtrust.org.uk), which gives a rundown of the various types of energy-efficient bulbs, says lighting makes up about 20 per cent of the electricity bill in the average home. Installing CFLs is a no-brainer. Their price has dropped substantially, they last far longer than incandescents and they can reduce bills by at least a third.

Whether or not CFLs give the same light as incandescents is a contentious issue. One measure of light intensity is expressed in what is called lux: several CFLs perform badly on the lux scale compared with incandescents.

But again, the technology is improving all the time. So maybe, for now, keep one naughty incandescent for your reading.

Send your eco-dilemmas to greenandconfused@thetimes.co.uk

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