Lighting accounts for almost a fifth of the electricity use in the typical home with non-electric heating. In homes with large numbers of high-wattage bulbs, the figure might be as high as 30%.
There are two obvious ways to reduce the carbon footprint of your lights: turning them off when they're not required, and switching to more energy-efficient bulbs. When you replace an old-fashioned bulb with an equivalently bright compact-fluorescent version, you slash the electrtcity use by up to 80%. Over the five to ten years that such bulbs typically last, each one can reduce your energy bills by more than $100 and save a few hundred kilograms of CO2 emissions.
The cash savings of low-energy bulbs
- An 18W low-energy bulb can last for up to 10,000 hours of use and produces the same amount of light as an old-fashioned 100W bulb. In that time, the overall running cost will be around $25 in electricity (10,000 hours x 0.018kW x $0.14 per kWh), plus perhaps $3 for the bulb itself. Total cost = $28.
- A 100W incandescent bulb lasts around 1000 hours. So to produce 10,000 hours of light you'd get through ten bulbs, at around 50p each, and spend a massive $140 on electricity. Total cost = $145.
That's a saving of $117, and a return of 3900% on your $3 investment. The sav?ings per bulb won't be quite so large when the ones being replaced are rated 40W or 60W, of course, or when the low-energy bulb has a shorter life expect?ancy. Cheaper models often last 6000 hours, rather than 10,000.
The reason compact fluorescent bulbs require so much less energy than their predecessors is that they successfully convert nearly all the power they consume into light, rather than generating heat. By contrast, with an old-style 100W bulb, you're effectively switching on a 20W light source and an 80W electric heater.
Despite their obvious benefits, many people still haven't switched to low-energy bulbs. Over time, everyone will effectively be forced to do so because regular incandescent bulbs are being phased out; 100W globes ceased to be available in many UK stores at the start of 2009, and 60W globes will follow in 2010. This has led to cries of outrage from some quarters, due to a number of largely spurious claims about low-energy bulbs. Let's take a quick look at some of these supposed disadvantages.
Low energy bulbs - myths and truths
- "They produce bad light" It's true that the colour rendering of low-energy bulbs is slightly different to that produced by incandescent bulbs, but that doesn't mean the light is less good. When US science magazine Popular Mechanics asked people to assess the quality of the light from ten bulbs, without telling them which was which, all nine low-energy bulbs tested scored better - for faces and reading as well as general ambience - than the traditional incandescent bulb used as a benchmark.
- "They're not available for most fittings" In fact, you can get lower-energy replacements for almost all fittings, including halogen spots.
- "They don't work with dimmer switches" Megaman and other brands produce low-energy dimmable bulbs. They cost more than other bulbs (around $12 each) but will still lead to huge overall cash savings.
- "They delay and flicker on start-up" This was once a problem, but decent modern bulbs fire up instantly, without flickering, and reach full brightness within a few seconds (except perhaps in very cold conditions).
- "They're dangerous due to their mercury content" According to most estimates, there's less mercury inside each low-energy bulb than would be emitted directly into the atmosphere by a coal-fired power station producing the extra electricity required by a traditional bulb. So in fact low-energy bulbs can theoretically reduce atmospheric mercury levels. But it's true that you should dispose of them properly. Check your local council's website for advice on where to drop them off.
- "Old-fashioned bulbs let you turn the heating down" It's true that the heat generated from old-fashioned bulbs isn't always wasted. In the winter, some of that heat may be useful, allowing you to turn the central heating down. However, this only applies during those periods when you have your heating switched on. Moreover, each unit of heat created by an electric bulb will cause more than double the CO2 emissions of a unit of heat generated by a gas boiler. Furthermore, light bulbs are very often placed high up in a room - on the ceiling, for example - which is a very inefficient spot from which to heat a room, due to the simple fact that hot air rises.
Source: http://www.homeimprovementcaddy.com/2012/10/how-to-reduce-electricity-use-for.html
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