What are Compact Fluorescent Lamps (CFLs)?
Compact Fluorescent Lamps (CFLs) are a modern type
of light bulb that will fit into a standard light fitting, usually
a bayonet fitting in the UK, but CFLs are also available with Edison
screw fittings. Most CFLs either consist of a number of short glass
sticks, or two or three small tubular loops. Sometimes, these are
enclosed in a glass bowl or made to look like a traditional bulb.
There are also some older CFLs that look light a clear or white glass
jam-jar and are much heavier, but these are less efficient and are
not recommended. CFLs work in much the same way as a fluorescent strip
light: the inside is coated with a phosphor that gives off the light
and there is an electronic ballast to start the lamp operating.
CFLs are often called low energy lamps because they use less energy
than the traditional tungsten filament bulbs that they replace. As
they plug in directly to the normal light fittings they work off the
UK's standard 230V supply and should not be confused with low-voltage
lamps which do not offer significant energy or cost savings.
What wattage CFL should I buy?
Compact Fluorescent Lamps are sold by the wattage,
in much the same way as normal bulbs. However because they use a lot
less energy, a lower wattage bulb will be needed to give out the same
amount of light. The table below gives the approximate equivalents
that can be used:
So how do the CFLs save money?
Although CFLs cost more to buy, they save money because they use
less electricity
Ordinary
Bulbs |
CFLs |
40W |
7 - 10W |
60W |
15 -18W |
100W |
20 - 25W |
150W |
32W |
The cost of a low energy light bulb can be as low
as £2 and they are now available in most retail stores. As the
CFL will typically last for a total of 8,000 hours, the savings over
its lifetime could reach £35!
Compact Fluorescent Lamps are best used in areas with a fairly high
usage. If a light is used for an average of 3 hours per day over the
year (perhaps 1 hour in mid-summer and 5 hours in winter), then it
would pay for itself in less than a year. On the other hand if it
was only used for an hour a day on average, it would take 2½
years to recover the initial cost.
We also advise people to use well known brands of CFLs from a reputable
store. There were some cheaper lamps, often made in the Far East,
that lasted less long. Although it was still possible to make some
savings with these bulbs, they often proved to be a false economy.
Should I leave CFLs on when I leave a room to keep saving money?
No! There used to be a general belief that because
fluorescent strip lights used more power in their warm-up phase, then
it was better to leave them on all the time. This was never true -
an old style strip light (or non-electronic CFL) only uses as much
energy in the warm-up phase as it does whilst operating for a minute
or so, and modern electronic ballast CFLs use even less energy at
the start. Although CFLs do not use much electricity it is still best
to keep them switched off when not wanted - why throw money away on
anything that not needed?
How can I be sure that CFLs do last longer than old-style bulbs?
The Government's Market Transformation Unit has tested1
several leading brands (including retailers' own-brands) of CFLs and
conventional, tungsten bulbs. It found that, generally, around 8 of
10 bulbs of either type exceed the median (average) life stated on
the box. Specifically, at least 90% of bulbs from all brands of CFLs
with a claimed average life of 6,000 hours or less exceeded this average
life. Even where much longer lives were claimed - of 12,000 to 15,000
hours - over 70% of bulbs exceeded the claimed average life. So the
overall conclusion was the CFLs do really last - on average - at least
as long as the life stated on the box.
When the same team tested conventional bulbs they
found a similar result for bulbs that were claimed to last for in
excess of 1,000 hours - these bulbs typically lasted for 1,150 hours.
Cheaper tungsten filament bulbs, that did not claim to be long life,
still met their manufacturers' claims, but rarely lasted for more
than about 900 hours and some brands only lasted for 600 hours on
average.
This testing means that you CAN believe the claims
on the boxes. What is more, it confirms that even the cheapest energy
saving CFLs will typically last for 5,000 hours of use, compared to
only just over 1,000 hours on average for the best conventional bulbs.
The same team tested the energy efficiency ratings
of the bulbs as well. All bulbs were within one grade of the measured
efficiency, and most were correctly reported. Some CFLs that claimed
to be "B" rated were found to be rated "A" (and
a few vice versa), and similarly some "E" rated ordinary
bulbs actually achieved "D" status. But the message was
clear - CFLs use very much less power and are a lot cheaper to run,
over their lifetime, than ordinary tungsten bulbs.
1 Energy Label (Light Sources) Monitoring
Programme, Market Transformation Programme of Defra, June 2003.
Are low energy lights the same as low voltage lamps?
Again, No! Low voltage lights are usually small bright halogen
bulbs, often needing a transformer to work. They are commonly used
in kitchens where they give a bright narrow beam, often requiring
several lights on a single unit. Although each halogen bulb uses
less power than a conventional light bulb, they use a great deal
more than a CFL and if several halogen bulbs are used, they will
use more energy in total than conventional lights.
Look out for the new European Energy Label
on Light Bulb Boxes.
Energy Saving Bulbs, including almost all CFLs, should have the
best possible rating of A.
