Byron the Bulb

[FrodeauxB at aol.com]

Sort of a family tree for you Byron the Bulb freaks. Think TRP had something 
like this handy when he got to the Byron slot in GRGR? Please, let's not 
wheel out the old authorial intent/influence source horse upon which to beat 
yet more. Happy Labor (Labour for our European cousins) Day, fellow prols.


The Best Light Bulb 

By Eliza Truitt


Lately, I've been thinking about light bulbs. Flipping through a
natural products catalog I find, among the buckwheat-hull-filled
yoga mats and water-filtration systems, some two-page spread on
"full-spectrum" light bulbs. The catalog insists that full-spectrum
lighting has "been proven to improve mood and reduce eye stress and
strain." I paid a little bit of attention when super
energy-efficient compact fluorescents first hit the market in the
mid-'80s but never actually started using them. Is it time to
change my light-bulb habits? 

The lighting section of my local hardware store offers a
bewildering array of bulbs: cool-white fluorescents, warm-white
fluorescents, compact fluorescents, tiny halogen bulbs, halogen
bulbs sized for standard Edison sockets, Miser bulbs, Longlife
bulbs, full-spectrum bulbs--not to mention good old-fashioned Soft
Whites. 

So, how are all these bulbs different? Which one is the most
efficient? Do full-spectrum bulbs really prevent cavities? How much
of the packaging terminology is bogus marketing hype? Here are
answers to these questions, as well as everything else you ever
wanted to know about light bulbs (and some you didn't).

Bulb Basics
There are four things you need to know when you're considering a
bulb: 

How much electricity it uses. This is measured in watts, as in a
25- or 75-watt bulb.

How bright it is. This is measured in lumens. Since some types of
bulbs are more or less efficient than others (more on that later),
the best way to compare them is by lumens, which is usually listed
on the package.

How well it renders color. This is measured by the Color Rendering
Index (CRI). Have you ever bought something in a store and then
thought it looked different outdoors? Blame indoor lighting with a
low CRI. Daylight has a perfect 100 on the CRI; the best bulbs
score between 95 and 100, while the worst bottom out at around 52.
(For a detailed explanation of the CRI, click here.) 

The color of the light. This is sometimes called the color
temperature, and it's measured in degrees Kelvin. The system is
somewhat counterintuitive. Low on the Kelvin scale is "warm" (more
red and yellow), and high on the Kelvin scale is "cool" looking
(more blue). Think of heating a block of iron: It starts out red at
low temperature, turns white, and then blue as it gets hotter. One
end of the spectrum isn't necessarily better than another; it just
depends on what you like. But "warm" colors--those around 2,500
degrees Kelvin--supposedly flatter human skin tones more than
"cool" colors, which hover around 5,000 degrees Kelvin.

The Main Types of Bulbs
Light bulbs--or "lamps," as they're known in the industry--work in
one of two ways. Some heat a thin strip of metal until it
glows--the word incandescent means "glowing or white with
heat"--and this is how traditional light bulbs work. Others
electrically excite a gas, which then causes a phosphorescent
coating to glow (like a fluorescent bulb). 

The three main types of lamps you're likely to come across are the
traditional tungsten incandescent bulbs, halogens, and
fluorescents.

Tungsten incandescent
This is the original light bulb. It works by running electricity
through a thin filament made of tungsten, which glows when it gets
hot. This is an inefficient type of bulb--it takes a lot of juice
to get that filament hot enough to glow--and the bulb gets dimmer
over time, as tungsten evaporates from the hot filament and coats
the inside of the bulb with a dark haze. Eventually the filament
wears out and breaks, which is what you hear rattling around inside
a dead bulb. The light it produces is much yellower than sunlight,
something you've noticed if you've ever tried to take color
photographs by lamplight.

Halogen
If you've got one of those torchiere lamps in your office, you've
used a halogen bulb. Like standard bulbs, halogens are
incandescent, which means they have tungsten filaments. What's
different is that the filament is encased by a small quartz glass
capsule, and inside this capsule are halogen compounds (hence the
name) in gas form. When electric current is applied to the
filament, the tungsten evaporates; but instead of coating the
inside of the bulb, the tungsten is captured by the halogen
compounds and redeposited on the filament.

This chemical reaction, called the "halogen cycle," not only keeps
the tungsten from mucking up the inside of the bulb but also helps
the filament last longer, as the tungsten is constantly
replenished. Halogen lamps produce a whiter light than traditional
tungsten bulbs, because they heat up to a higher temperature. Of
course, this also makes them more of a fire hazard because they can
more easily ignite that set of curtains nearby.

Longer bulb life, whiter light, better light quality over
time--this all sounds wonderful. Naturally there's a catch: The
halogen cycle only happens above a certain temperature, so you have
to crank up the bulb to the top of its range for about 15 minutes
once every couple of months (or whenever you see the glass casing
darkening) to keep it from burning out as fast as an incandescent.
If used consistently at the highest setting, a halogen bulb will
last twice as long as a tungsten bulb. 

Fluorescent
Although fluorescent tube lamps are used in basements and under
kitchen cabinets in some homes, the most versatile of fluorescents
is the compact fluorescent. It too consists of a tube, but one that
is smaller and looped over itself. Compact fluorescents are handy
because they can fit in a regular screw-base Edison lamp socket. 

These bulbs work by running electric current through the tube,
which is filled with argon and mercury gasses. The electrified
gasses produce ultraviolet radiation, which then activates a
phosphorous coating on the inside of the glass that produces light.
Fluorescents last for ages and are energy efficient, but generally
don't render color as well as halogens or standard light bulbs.
Tube fluorescents rate anywhere from 52 to 90 on the CRI, while
compact fluorescents rate around 80. They can be purchased
according to color temperature (cool, which is bluer; and warm,
which is redder).

Labels and Marketing Gimmicks
Manufacturers of full-spectrum light bulbs--which can be
incandescent or fluorescent--make elaborate claims about the health
benefits of this type of light. Unlike standard bulbs,
full-spectrum bulbs emit light in all parts of the visual color
spectrum as well as some in the ultraviolet range. Some studies
have suggested that this is why they're better for your eyes and
can lift your mood, combat seasonal affective disorder, reduce
fatigue, and even reduce cavities and hyperactivity in children.
But a recent review of these studies by Canada's National Research
Council's Institute for Research in Construction (those Canadians
take artificial light very seriously) blasted most of those claims
and concluded that there's no concrete evidence to support them. 

The Canadian study did find that the trace amounts of UV light
emitted by full-spectrum bulbs could be helpful for the production
of vitamin D for people in extreme circumstances (living in
submarines, homebound, etc.). And the color rendering was better,
which meant that full-spectrum lights are preferable "in the case
of tasks requiring fine discrimination of colour," such as
"matching dental ceramics." Otherwise, what mattered most was the
brightness of the light, not the width of the spectrum. In fact,
there are some downsides to using full spectrums: They are less
efficient than standard fluorescent bulbs and may not last as long.

Soft White does not refer to brightness or color quality, but
simply to the way the light is diffused. The inside of the bulb is
coated so that the light is less focused and makes shadows with
less-distinct edges. Misers use less energy than regular bulbs but
also may have slightly lower light output. This should be reflected
in lower lumens ratings. Longlife bulbs do just what you
think--they last longer. Like Misers, they may also have slightly
lower light output. Bulbs that are both Misers and Longlifes can
give off as much as one-third less light than standard bulbs.

So, What's the Best Deal?

This chart shows how the various bulbs affect your light bill over
the course of 10,000 hours (that's one lamp, switched on for eight
hours a day, for just under three and a half years). Fluorescent
bulbs are the most expensive, but they also last the longest and
are the most efficient. Even so, the difference isn't huge.
Replacing your incandescent desk lamp with a compact fluorescent
will save about $9.38 in electricity a year, and over three and a
half years you save a little less than $26 after factoring in the
cost of buying the bulbs. (Click here for details about how we
arrived at these figures.)

Plus, fluorescents emit strange noises and make your skin look
funny. I tried switching over to compact fluorescents in my
apartment, and granted, in some cases the difference wasn't
noticeable. The light above my stove, for example, which has a
golden filter covering it, looked just as it always did. But in the
bathroom, the fluorescent light made my skin a distinctly different
color. My lips looked redder, and so did the acne on my forehead.
The worst change was in the living room, where three off-brand
("Lights of America") compact fluorescents flickered and buzzed.
(Later I discovered that this abominable flicker was because the
overhead lights' dimmer was on. When they weren't dimmed, the
flicker was not visible, but the buzz never went away.) I ended up
switching back all but a few in the kitchen and bathroom--I like
the idea of saving a few watts and seeing the acne clearly.

Technically, tungsten incandescents--plain old light bulbs--are the
next most efficient, followed closely by halogens. But halogen
bulbs last longer. A clear 300-watt incandescent bulb rated to last
750 hours gives out about 6200 lumens. A tubular halogen bulb of
the same wattage lasts 2,000 hours and gives out 5950 lumens. To my
eye the halogen looks much better--the light was whiter and somehow
more crisp. 

If the look (and sound) of fluorescent lights doesn't bother you,
they are the cheap, efficient choice. If you are willing to pay
more for the bulbs and willing to spend a little more on
electricity (and risk starting a fire), halogens are the deluxe
choice. The light they provide is bright, white, and pleasant. And
smack in the middle are good old-fashioned tungsten incandescents:
cheap, easy, and pleasantly familiar.