Should I leave the lights on?

There is a school of thought that believes that energy-saving light bulbs should not be switched off when leaving a room
Kieran Cooke

I grew up being told always to turn lights out when leaving a room. Then, with the arrival of energy-saving bulbs, I was told to leave lights on if returning to a room fairly soon. But the latest versions seem to warm up much more quickly: should I keep lights on or turn them off?
Stick to those old habits that you grew up with. It’s true that when compact fluorescent light bulbs or CFLs first appeared, they took an age to warm up to their full dull sheen, leaving householders knocking into umbrella stands and injuring toes on chair legs. Back then, not switching off the lights was understandable.
Nowadays, unless you’re using old types of CFLs, there should be no need to leave lights on. As you say, the new ones warm up much more quickly. And it’s often the case that though we might think that we’re leaving a room for only a few seconds, various distractions stretch it out to several minutes, thus wasting energy and needlessly running up electricity bills.
A common misconception is that it’s best to leave CFLs on because they need a lot of electricity to start. There is a power surge for less than a tenth of a second that might eat up two or three seconds of normal electricity use. But then the bulb quickly settles down. A general rule of thumb is that if you’re leaving the room for more than five seconds, switch off.
The working life spans of CFLs and incandescent bulbs are shortened by overuse. Switching lights rapidly on and off is obviously not a good idea. On the other hand, the cost of buying new bulbs has to be balanced against the electricity saved by turning off the lights — not always an easy calculation to make.
The subject of light bulbs, particularly those of the energy saving variety, certainly gets pulses running. Under EU regulations the manufacture and import of incandescents is being gradually phased out, with 100W bulbs going last year, the 75W being switched off this year and all incandescents taken off the shelves in 2012.
There are those who see the forced introduction of the CFL as yet another Brussels-inspired move to limit individual choice. Others see CFLs as part of a wider conspiracy by climate-change alarmists.
The Energy Saving Trust (energysavingtrust.org.uk) says that CFLs last up to eight times longer than incandescents and can save the average household about £40 in electricity bills each year. If widely used, CFLs would mean thousands of tonnes of CO2 would not be entering the atmosphere.
In retort, traditionalists allege that CFLs cause migraine and skin problems; and you can’t use them to read. Many are now stockpiling incandescents. Watch out for a shady figure on the street corner: “Psst. You wanna buy an old light bulb?”
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