Selecting the right blub |
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First off, you need to define the required power rating. For an ambient light adequate to distinguish objects, select an incandescent bulb between 40 and 60 watts or a
halogen between 20 and 35 watts.
For a more intense illumination necessary for reading or writing, select an incandescent bulb between 75 and 100 watts or a halogen between 60 and 80 watts.
But most importantly, check inside the lamp fitting itself to see if the maximum usable power rating without risk has been indicated. Also make sure you know the type of socket that the lamp has: a
screw socket, symbolised by an E for Edison, or a bayonet socket, symbolised by a B, which are both available in several sizes.
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Incandescent bulbs
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The most traditional model, this bulb uses a metallic filament to produce light from the passing current. It offers a warm light, but its intensity diminishes over time
and wastes a lot of energy (its expected life span is for 1,500 hours, with 95% of its energy dissipated as heat and only 5% used for lighting).
Generally very cheap, it is available in many sizes
and power ratings (from 25 to 100 watts). Traditionally pear-shaped, there are also some other more original shapes available: flames, spheres, spirals, and tubes are available if the bulb will be
visible. Clear and bright, it can dazzle the eyes but offers a better performance for the same power rating. Opalised or matt finished, it offers a more gentle light, ideal when the bulb will be
visible.
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Halogen bulb
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Many traditionally incandescent lamps are now halogen lamps. More efficient, more powerful and boasting a longer life and more pleasant illumination, they have a multitude
of applications.
A halogen lamp is quite simply an incandescent lamp that has been filled with a diatomic gas belonging to the halogen family or one of its derivatives. It works just like a
traditional incandescent, except that the halogen cycle works to vastly improve performance.
The halogen lamp bulb is constructed with a material that is more resistant to high temperatures
and offers a wide range of variability in light intensity. Do not, however, that the use of a dimmer will reduce the expected life span of a halogen bulb. In order to the halogen bulb to
"regenerate", it must therefore be periodically run at full power.
Recognise that you must avoid touching a halogen bulb with your fingers, as organic matter like the oils on the
skin surface react with heat and produce carbon graphite, among other things, that fades the bulb and reduces its lighting efficiency. In addition, alkaline minerals on the epidermis have a property
of reacting with quartz at high temperatures and weaken it. This can lead to a breakage of the blub, which can sometimes be quite spectacular, or even dangerous.
Halogen lamps are now used
nearly everywhere, and the number of models is unlimited. For example, there are halogen bulbs with a double envelope which are starting to replace traditional bulbs; these make it possible to take
advantage of halogen lighting without altering the recipient lamps themselves. In addition, external halogen flood lights are fitted with a special glass which plays a role in thermal insulation.
Note that the quartz bulbs in halogen lamps do not absorb ultraviolet (UV) rays and because of this, are generally placed behind a transparent plastic or glass protection in order to absorb these
rays which are harmful to human beings.
Lastly, note that halogen lamps are generally more expensive that classic incandescent bulbs, but will, on the other hand, deliver a wide variety of
applications and an unequalled lighting ambiance.
This upgrade incandescent blub delivers a super-white light (with an average life span of 2,500 hours). Its diffuse illumination brings colours
back to life.
Best used for direct lighting, aimed at the ceiling or the upper parts of a wall. Very powerful, it can be purchased up to a 500 watt power rating. The inconvenience lies in the
fact that this bulb dissipates a lot of heat, so it needs to be kept at a good distance from walls and other objects. It is usually accompanied with a dimmer, but make sure to occasionally run it at
full power, or the lamp will die too quickly.
In recent years, halogen lamps have become increasingly popular in the home:
The lamps run at mains power, that being at a low voltage (230
volts), but employ a traditional socket (screw or bayonet)
Bulbs of very low voltage, that being below 50 volts (most commonly 12 volts) running on AC current, operate with a special power
supply, transformer or power converter, designed for small spot lights or office desks (these lamps often include a dichroic reflector). These very low voltage blubs have a better luminous efficacy
(lm/W) that blubs running on mains power, since the shorter and thicker filament can withstand higher temperatures.
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Fluorescent bulbs
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The fluorescent bulb, more commonly referred to as a CFL, is an adaptation of the industrial fluorescent tube for domestic usage. It is a standard fluorescent tube that
emits the light, but the tube is miniaturised, folded two, three or four times or even coiled, and fitted on a base that houses an electronic ballast.
They have the same advantages as linear
fluorescent tubes, except that the tube part is now often no longer replaceable. Fluorescent lamps have two advantages in comparison to incandescent bulbs:
better performance: an incandescent bulb
has an efficiency of between 14 to 25 lumens per watt, with a fluorescent bulb delivering around 60 to 70 lumens per watt (so a fluorescent bulb at 11W will produce the same illumination as an
incandescent bulb of 40 to 60W)
; and a life span that is six to fifteen times longer than an incandescent bulb (being 6,000 to 15,000 hours versus 1,000 hours).
Therefore, even though
the purchase price is higher than an incandescent bulb, its improved performance numbers make it an immediately attractive product to use for the private individual. On a national scale, the energy
savings are substantial.
Incorrectly known as a "neon" tube, this glass cylinder offers a diffuse light but a somewhat "washed out" overall illumination. The tube's
surfaces are coated with a fluorescent powder which is illuminated by the internal radiation. Its only inconvenience, is that it takes some time to reach its maximum luminosity.
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Fluorescent lamps have an extraordinary light diffusion efficiency, which is why they are so frequently used for professional interior lighting. Nonetheless, their usage is rather limited for interior
lighting even if they're sometimes employed in kitchens and bathrooms.
Fluorescent discharge lamps, incorrectly and derisively known as "neons", are tubes filled with argon and a few
small mgs of mercury. At low pressures, the electrically discharged mercury vapour emits UV radiation which does not pass through the glass tube surface, but which excites the fluorescence of a
powdered mixture covering the interior of the tube at a thickness of 10 to 20 mm. The light produced by fluorescent tubes therefore depends on the mix of powders that are used. Tubes known as
"industrial white" use calcium halophosphate. Tubes used in the home use a different mixture of powders.
The luminous efficiency of fluorescent tubes runs between 50 to 100 lm/W, and
their life spans up to 10,000 hours. They are used for professional interior lighting (offices, schools, shops, workshops, etc.) but not, at least for traditional tubes, on the outside, as
temperature of 10°C will reduce their luminous flux by a half. They are seldom used for home lighting, even though they are sometimes employed in kitchens and bathrooms which they are not primarily
well-suited for.
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Compact fluorescent lamps (CFLs)
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Now frequently used in the home, the advantages of these bulbs are numerous, with their low energy consumption being the most often cited, given as they consume around five times less energy than a
traditional incandescent bulb with excellent ease of application (they are completely interchangeable with incandescent bulbs without any need to change the fitting or installation). This means that
a 23W CFL bulb will be enough to replace the ordinary 120W bulb that would have been necessary beforehand.
What's more, these bulbs dissipate very little heat and considerably lower the risks
of scalding, especially for children. Last but not least, they have a much longer expected life span, lasting 10,000 hours in comparison to the 1,000 hours of their traditional incandescent cousins.
Available as standard bulbs, and more recently in flame shapes for chandeliers, these mini-tubes are available in a variety of sizes and colours depending on the lighting effect sought after.
Do not, though, that every time that they are used for less than an hour at a time, the CFL will burn too quickly and will lose some of its life expectancy. From this point of view, further progress
has been made and there are no CFL bulbs on the market that are capable of being switching on and off as often as deemed necessary. Yet, generally speaking, CFLs should be avoided in high-traffic
zones (corridors, for example) and places where they will not normally be illuminated for an hour or more.
For better visual comfort, it is advised to use tubes with colour rendering indices
(CRI) as high as possible. The CRI varies from 60 to 100 (with 100 representing the appearance of colours under daylight).
Finally, note that a CFL costs much more than a normal incandescent
bulb, but its very long life span means that it still means considerable savings can be made. Low in energy consumption, these bulbs last 15 times longer (up to 10,000 hours) than a standard
bulb, and consume 80% less energy.
They are available in several power ratings and socket shapes, and can replace most bulbs in incandescent or halogen fittings. Ideal for lamps that are difficult
to access or left on for long periods of time.
They produce little heat, thereby reducing the risks of scalding hands or burning furniture.
Lighting represents on average 20% of our electricity bills, and poor quality lighting can be the cause of significant increases in electrical consumption. Efficient lighting is not measured by the installed wattage rating, but in the choice of fittings and the usage made of them.
CFL or low energy bulbs have now been on the market for over a dozen years. Although they certainly sport higher prices, they consume very little electrical energy and last so much longer
than traditional bulbs. In addition, they are well suited for rooms requiring extensive continuous lighting (lounge, kitchen, external lighting, etc.) and have been blessed with recent technical
innovations (electronics, shapes, miniaturisation…) allowing them to respond to many novel uses in the home.
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