What are Energy Saving Bulbs?
Conventional filament bulbs (including halogens) give out less than 20% of the energy they use as light, the rest is heat. Thus, they are not efficient for the purpose for which they are designed. Some people argue that this has hidden benefits, because they contribute to the heating of the room they are in. I think this does not stand up to close scrutiny for two reasons: (a) you often need light in summer, when you do not want heat (b) as most light bulbs are near the top of a room, and hotter air is at the top anyway, they mainly keep the top warm, and little heat gets lower down where it is more useful.
More efficient bulbs (energy saving bulbs) have been available for many years. These have been traditionally compact fluorescents, and these are still the most common form of energy saving bulb. Early types were not so popular, because they were big, took a considerable time to reach full brightness and were expensive. They have been improved, so that they are now much smaller, reach full brightness in a matter of seconds or less, and are considerably cheaper.
The next generation of energy saving bulbs will be ‘light emitting diode’ types (LEDs). These are an order of magnitude more efficient again, but at the present stage of development, they are not bright enough for most lighting. Some LED bulbs are starting to become practical alternatives though; notably those designed to replace GU10 or MR16 halogen bulbs. If you are considering this, you should note that the white LED bulbs have a slightly bluish tinge, which is quite attractive, but may look odd if mixed with other types of light. Another advantage of LEDs is they are available in colours, at no extra cost.
What Types of Energy Saving Bulbs are Available?
There is now an energy saving bulb, of one type or another, that will replace any common household bulb, with the exception of capsule halogens - these are the very small halogens, that look like a capsule. If you want to use energy saving bulbs, avoid light fittings that take this kind of bulb.
Some fittings will take energy saving bulbs only, so you have no choice. Recent building regulations in the UK stipulate that a certain proportion of lighting in new builds must be energy saving. Thus, fittings are put in that will only take this type of bulb. It is unfortunate that these bulbs tend to be more expensive than those which replace ordinary bulbs, probably because there is greater demand for the latter.
Benefits and Drawbacks of Energy Saving Bulbs
The benefits can be summarised as follows:
They use about one-fifth the electricity of filament lamps (less in the case of LEDs).
They last at least six times longer than filament lamps (much more in many cases).
They run cooler, so do not damage light fittings as much as filament lamps, so higher light outputs can be used, e.g. a lampholder which takes a maximum of 60W filament lamp, will take an 18W or more low energy bulb, giving the equivalent of 100W or more lighting.
Over the lifetime of the bulb, there will be considerable savings on electricity bills, and thus carbon emissions associated with electricity consumption.
Possible drawbacks are:
Usually they are more expensive to buy in the first place, but this cost is quickly recouped.
Compact fluorescents are not available in clear, only white or coloured.
Most (but not all) are bigger in size than conventional bulbs.
Cannot be used with dimmer switches (except the new type of dimmable compact fluoescents).
Most security light manufacurers (with PIRs) advise against their use, but with modern CFLs I have used them in security lights with no ill effects; they take a little longer to come on, but this is not usually a problem unless a couple of seconds is important.
These figures are based on typical UK costs of 8p per unit of electricity (a kWhr) with a bulb on for 4 hours per day average and a bulb lifetime of 8000 hours, compared with 1000 hours for a conventional bulb. (You can get longer life bulbs of both types, but they cost more). I have taken a 20W low energy bulb and an equivalent 100W conventional bulb. The costs of the bulbs have been taken from the author’s website.
Running costs alone save Â£9.34 per year.
Running and replacement costs over lifetime of the low energy bulb (5.5 years) Â£53.18 - this is equivalent to a saving of about one-quarter of a tonne of CO2 emissions.
And this is just for one bulb. Imagine the savings if all your bulbs were replaced.
Good for your electricity bills and good for the environment.
Barrie Newton B.Sc. Owner of Rhyl Lightworks Co http://www.thelightworks.net or for information on energy saving light bulbs: http://www.thelightworks.net/index.php?main_page=index&cPath=37_73